TOMOYO Linux Cross Reference
Linux/fs/quota/dquot.c

   // SPDX-License-Identifier: GPL-2.0
   /*
    * Implementation of the diskquota system for the LINUX operating system. QUOTA
    * is implemented using the BSD system call interface as the means of
    * communication with the user level. This file contains the generic routines
    * called by the different filesystems on allocation of an inode or block.
    * These routines take care of the administration needed to have a consistent
    * diskquota tracking system. The ideas of both user and group quotas are based
    * on the Melbourne quota system as used on BSD derived systems. The internal
   * implementation is based on one of the several variants of the LINUX
   * inode-subsystem with added complexity of the diskquota system.
   *
   * Author:      Marco van Wieringen <mvw@planets.elm.net>
   *
   * Fixes:   Dmitry Gorodchanin <pgmdsg@ibi.com>, 11 Feb 96
   *
   *              Revised list management to avoid races
   *              -- Bill Hawes, <whawes@star.net>, 9/98
   *
   *              Fixed races in dquot_transfer(), dqget() and dquot_alloc_...().
   *              As the consequence the locking was moved from dquot_decr_...(),
   *              dquot_incr_...() to calling functions.
   *              invalidate_dquots() now writes modified dquots.
   *              Serialized quota_off() and quota_on() for mount point.
   *              Fixed a few bugs in grow_dquots().
   *              Fixed deadlock in write_dquot() - we no longer account quotas on
   *              quota files
   *              remove_dquot_ref() moved to inode.c - it now traverses through inodes
   *              add_dquot_ref() restarts after blocking
   *              Added check for bogus uid and fixed check for group in quotactl.
   *              Jan Kara, <jack@suse.cz>, sponsored by SuSE CR, 10-11/99
   *
   *              Used struct list_head instead of own list struct
   *              Invalidation of referenced dquots is no longer possible
   *              Improved free_dquots list management
   *              Quota and i_blocks are now updated in one place to avoid races
   *              Warnings are now delayed so we won't block in critical section
   *              Write updated not to require dquot lock
   *              Jan Kara, <jack@suse.cz>, 9/2000
   *
   *              Added dynamic quota structure allocation
   *              Jan Kara <jack@suse.cz> 12/2000
   *
   *              Rewritten quota interface. Implemented new quota format and
   *              formats registering.
   *              Jan Kara, <jack@suse.cz>, 2001,2002
   *
   *              New SMP locking.
   *              Jan Kara, <jack@suse.cz>, 10/2002
   *
   *              Added journalled quota support, fix lock inversion problems
   *              Jan Kara, <jack@suse.cz>, 2003,2004
   *
   * (C) Copyright 1994 - 1997 Marco van Wieringen
   */
  
  #include <linux/errno.h>
  #include <linux/kernel.h>
  #include <linux/fs.h>
  #include <linux/mount.h>
  #include <linux/mm.h>
  #include <linux/time.h>
  #include <linux/types.h>
  #include <linux/string.h>
  #include <linux/fcntl.h>
  #include <linux/stat.h>
  #include <linux/tty.h>
  #include <linux/file.h>
  #include <linux/slab.h>
  #include <linux/sysctl.h>
  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/proc_fs.h>
  #include <linux/security.h>
  #include <linux/sched.h>
  #include <linux/cred.h>
  #include <linux/kmod.h>
  #include <linux/namei.h>
  #include <linux/capability.h>
  #include <linux/quotaops.h>
  #include <linux/blkdev.h>
  #include <linux/sched/mm.h>
  #include "../internal.h" /* ugh */
  
  #include <linux/uaccess.h>
  
  /*
   * There are five quota SMP locks:
   * * dq_list_lock protects all lists with quotas and quota formats.
   * * dquot->dq_dqb_lock protects data from dq_dqb
   * * inode->i_lock protects inode->i_blocks, i_bytes and also guards
   *   consistency of dquot->dq_dqb with inode->i_blocks, i_bytes so that
   *   dquot_transfer() can stabilize amount it transfers
   * * dq_data_lock protects mem_dqinfo structures and modifications of dquot
   *   pointers in the inode
   * * dq_state_lock protects modifications of quota state (on quotaon and
   *   quotaoff) and readers who care about latest values take it as well.
   *
   * The spinlock ordering is hence:
  *   dq_data_lock > dq_list_lock > i_lock > dquot->dq_dqb_lock,
  *   dq_list_lock > dq_state_lock
  *
  * Note that some things (eg. sb pointer, type, id) doesn't change during
  * the life of the dquot structure and so needn't to be protected by a lock
  *
  * Operation accessing dquots via inode pointers are protected by dquot_srcu.
  * Operation of reading pointer needs srcu_read_lock(&dquot_srcu), and
  * synchronize_srcu(&dquot_srcu) is called after clearing pointers from
  * inode and before dropping dquot references to avoid use of dquots after
  * they are freed. dq_data_lock is used to serialize the pointer setting and
  * clearing operations.
  * Special care needs to be taken about S_NOQUOTA inode flag (marking that
  * inode is a quota file). Functions adding pointers from inode to dquots have
  * to check this flag under dq_data_lock and then (if S_NOQUOTA is not set) they
  * have to do all pointer modifications before dropping dq_data_lock. This makes
  * sure they cannot race with quotaon which first sets S_NOQUOTA flag and
  * then drops all pointers to dquots from an inode.
  *
  * Each dquot has its dq_lock mutex.  Dquot is locked when it is being read to
  * memory (or space for it is being allocated) on the first dqget(), when it is
  * being written out, and when it is being released on the last dqput(). The
  * allocation and release operations are serialized by the dq_lock and by
  * checking the use count in dquot_release().
  *
  * Lock ordering (including related VFS locks) is the following:
  *   s_umount > i_mutex > journal_lock > dquot->dq_lock > dqio_sem
  */
 
 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dq_list_lock);
 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dq_state_lock);
 __cacheline_aligned_in_smp DEFINE_SPINLOCK(dq_data_lock);
 EXPORT_SYMBOL(dq_data_lock);
 DEFINE_STATIC_SRCU(dquot_srcu);
 
 static DECLARE_WAIT_QUEUE_HEAD(dquot_ref_wq);
 
 void __quota_error(struct super_block *sb, const char *func,
                    const char *fmt, ...)
 {
         if (printk_ratelimit()) {
                 va_list args;
                 struct va_format vaf;
 
                 va_start(args, fmt);
 
                 vaf.fmt = fmt;
                 vaf.va = &args;
 
                 printk(KERN_ERR "Quota error (device %s): %s: %pV\n",
                        sb->s_id, func, &vaf);
 
                 va_end(args);
         }
 }
 EXPORT_SYMBOL(__quota_error);
 
 #if defined(CONFIG_QUOTA_DEBUG) || defined(CONFIG_PRINT_QUOTA_WARNING)
 static char *quotatypes[] = INITQFNAMES;
 #endif
 static struct quota_format_type *quota_formats; /* List of registered formats */
 static struct quota_module_name module_names[] = INIT_QUOTA_MODULE_NAMES;
 
 /* SLAB cache for dquot structures */
 static struct kmem_cache *dquot_cachep;
 
 int register_quota_format(struct quota_format_type *fmt)
 {
         spin_lock(&dq_list_lock);
         fmt->qf_next = quota_formats;
         quota_formats = fmt;
         spin_unlock(&dq_list_lock);
         return 0;
 }
 EXPORT_SYMBOL(register_quota_format);
 
 void unregister_quota_format(struct quota_format_type *fmt)
 {
         struct quota_format_type **actqf;
 
         spin_lock(&dq_list_lock);
         for (actqf = &quota_formats; *actqf && *actqf != fmt;
              actqf = &(*actqf)->qf_next)
                 ;
         if (*actqf)
                 *actqf = (*actqf)->qf_next;
         spin_unlock(&dq_list_lock);
 }
 EXPORT_SYMBOL(unregister_quota_format);
 
 static struct quota_format_type *find_quota_format(int id)
 {
         struct quota_format_type *actqf;
 
         spin_lock(&dq_list_lock);
         for (actqf = quota_formats; actqf && actqf->qf_fmt_id != id;
              actqf = actqf->qf_next)
                 ;
         if (!actqf || !try_module_get(actqf->qf_owner)) {
                 int qm;
 
                 spin_unlock(&dq_list_lock);
 
                 for (qm = 0; module_names[qm].qm_fmt_id &&
                              module_names[qm].qm_fmt_id != id; qm++)
                         ;
                 if (!module_names[qm].qm_fmt_id ||
                     request_module(module_names[qm].qm_mod_name))
                         return NULL;
 
                 spin_lock(&dq_list_lock);
                 for (actqf = quota_formats; actqf && actqf->qf_fmt_id != id;
                      actqf = actqf->qf_next)
                         ;
                 if (actqf && !try_module_get(actqf->qf_owner))
                         actqf = NULL;
         }
         spin_unlock(&dq_list_lock);
         return actqf;
 }
 
 static void put_quota_format(struct quota_format_type *fmt)
 {
         module_put(fmt->qf_owner);
 }
 
 /*
  * Dquot List Management:
  * The quota code uses five lists for dquot management: the inuse_list,
  * releasing_dquots, free_dquots, dqi_dirty_list, and dquot_hash[] array.
  * A single dquot structure may be on some of those lists, depending on
  * its current state.
  *
  * All dquots are placed to the end of inuse_list when first created, and this
  * list is used for invalidate operation, which must look at every dquot.
  *
  * When the last reference of a dquot is dropped, the dquot is added to
  * releasing_dquots. We'll then queue work item which will call
  * synchronize_srcu() and after that perform the final cleanup of all the
  * dquots on the list. Each cleaned up dquot is moved to free_dquots list.
  * Both releasing_dquots and free_dquots use the dq_free list_head in the dquot
  * struct.
  *
  * Unused and cleaned up dquots are in the free_dquots list and this list is
  * searched whenever we need an available dquot. Dquots are removed from the
  * list as soon as they are used again and dqstats.free_dquots gives the number
  * of dquots on the list. When dquot is invalidated it's completely released
  * from memory.
  *
  * Dirty dquots are added to the dqi_dirty_list of quota_info when mark
  * dirtied, and this list is searched when writing dirty dquots back to
  * quota file. Note that some filesystems do dirty dquot tracking on their
  * own (e.g. in a journal) and thus don't use dqi_dirty_list.
  *
  * Dquots with a specific identity (device, type and id) are placed on
  * one of the dquot_hash[] hash chains. The provides an efficient search
  * mechanism to locate a specific dquot.
  */
 
 static LIST_HEAD(inuse_list);
 static LIST_HEAD(free_dquots);
 static LIST_HEAD(releasing_dquots);
 static unsigned int dq_hash_bits, dq_hash_mask;
 static struct hlist_head *dquot_hash;
 
 struct dqstats dqstats;
 EXPORT_SYMBOL(dqstats);
 
 static qsize_t inode_get_rsv_space(struct inode *inode);
 static qsize_t __inode_get_rsv_space(struct inode *inode);
 static int __dquot_initialize(struct inode *inode, int type);
 
 static void quota_release_workfn(struct work_struct *work);
 static DECLARE_DELAYED_WORK(quota_release_work, quota_release_workfn);
 
 static inline unsigned int
 hashfn(const struct super_block *sb, struct kqid qid)
 {
         unsigned int id = from_kqid(&init_user_ns, qid);
         int type = qid.type;
         unsigned long tmp;
 
         tmp = (((unsigned long)sb>>L1_CACHE_SHIFT) ^ id) * (MAXQUOTAS - type);
         return (tmp + (tmp >> dq_hash_bits)) & dq_hash_mask;
 }
 
 /*
  * Following list functions expect dq_list_lock to be held
  */
 static inline void insert_dquot_hash(struct dquot *dquot)
 {
         struct hlist_head *head;
         head = dquot_hash + hashfn(dquot->dq_sb, dquot->dq_id);
         hlist_add_head(&dquot->dq_hash, head);
 }
 
 static inline void remove_dquot_hash(struct dquot *dquot)
 {
         hlist_del_init(&dquot->dq_hash);
 }
 
 static struct dquot *find_dquot(unsigned int hashent, struct super_block *sb,
                                 struct kqid qid)
 {
         struct dquot *dquot;
 
         hlist_for_each_entry(dquot, dquot_hash+hashent, dq_hash)
                 if (dquot->dq_sb == sb && qid_eq(dquot->dq_id, qid))
                         return dquot;
 
         return NULL;
 }
 
 /* Add a dquot to the tail of the free list */
 static inline void put_dquot_last(struct dquot *dquot)
 {
         list_add_tail(&dquot->dq_free, &free_dquots);
         dqstats_inc(DQST_FREE_DQUOTS);
 }
 
 static inline void put_releasing_dquots(struct dquot *dquot)
 {
         list_add_tail(&dquot->dq_free, &releasing_dquots);
         set_bit(DQ_RELEASING_B, &dquot->dq_flags);
 }
 
 static inline void remove_free_dquot(struct dquot *dquot)
 {
         if (list_empty(&dquot->dq_free))
                 return;
         list_del_init(&dquot->dq_free);
         if (!test_bit(DQ_RELEASING_B, &dquot->dq_flags))
                 dqstats_dec(DQST_FREE_DQUOTS);
         else
                 clear_bit(DQ_RELEASING_B, &dquot->dq_flags);
 }
 
 static inline void put_inuse(struct dquot *dquot)
 {
         /* We add to the back of inuse list so we don't have to restart
          * when traversing this list and we block */
         list_add_tail(&dquot->dq_inuse, &inuse_list);
         dqstats_inc(DQST_ALLOC_DQUOTS);
 }
 
 static inline void remove_inuse(struct dquot *dquot)
 {
         dqstats_dec(DQST_ALLOC_DQUOTS);
         list_del(&dquot->dq_inuse);
 }
 /*
  * End of list functions needing dq_list_lock
  */
 
 static void wait_on_dquot(struct dquot *dquot)
 {
         mutex_lock(&dquot->dq_lock);
         mutex_unlock(&dquot->dq_lock);
 }
 
 static inline int dquot_active(struct dquot *dquot)
 {
         return test_bit(DQ_ACTIVE_B, &dquot->dq_flags);
 }
 
 static inline int dquot_dirty(struct dquot *dquot)
 {
         return test_bit(DQ_MOD_B, &dquot->dq_flags);
 }
 
 static inline int mark_dquot_dirty(struct dquot *dquot)
 {
         return dquot->dq_sb->dq_op->mark_dirty(dquot);
 }
 
 /* Mark dquot dirty in atomic manner, and return it's old dirty flag state */
 int dquot_mark_dquot_dirty(struct dquot *dquot)
 {
         int ret = 1;
 
         if (!dquot_active(dquot))
                 return 0;
 
         if (sb_dqopt(dquot->dq_sb)->flags & DQUOT_NOLIST_DIRTY)
                 return test_and_set_bit(DQ_MOD_B, &dquot->dq_flags);
 
         /* If quota is dirty already, we don't have to acquire dq_list_lock */
         if (dquot_dirty(dquot))
                 return 1;
 
         spin_lock(&dq_list_lock);
         if (!test_and_set_bit(DQ_MOD_B, &dquot->dq_flags)) {
                 list_add(&dquot->dq_dirty, &sb_dqopt(dquot->dq_sb)->
                                 info[dquot->dq_id.type].dqi_dirty_list);
                 ret = 0;
         }
         spin_unlock(&dq_list_lock);
         return ret;
 }
 EXPORT_SYMBOL(dquot_mark_dquot_dirty);
 
 /* Dirtify all the dquots - this can block when journalling */
 static inline int mark_all_dquot_dirty(struct dquot __rcu * const *dquots)
 {
         int ret, err, cnt;
         struct dquot *dquot;
 
         ret = err = 0;
         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                 dquot = srcu_dereference(dquots[cnt], &dquot_srcu);
                 if (dquot)
                         /* Even in case of error we have to continue */
                         ret = mark_dquot_dirty(dquot);
                 if (!err && ret < 0)
                         err = ret;
         }
         return err;
 }
 
 static inline void dqput_all(struct dquot **dquot)
 {
         unsigned int cnt;
 
         for (cnt = 0; cnt < MAXQUOTAS; cnt++)
                 dqput(dquot[cnt]);
 }
 
 static inline int clear_dquot_dirty(struct dquot *dquot)
 {
         if (sb_dqopt(dquot->dq_sb)->flags & DQUOT_NOLIST_DIRTY)
                 return test_and_clear_bit(DQ_MOD_B, &dquot->dq_flags);
 
         spin_lock(&dq_list_lock);
         if (!test_and_clear_bit(DQ_MOD_B, &dquot->dq_flags)) {
                 spin_unlock(&dq_list_lock);
                 return 0;
         }
         list_del_init(&dquot->dq_dirty);
         spin_unlock(&dq_list_lock);
         return 1;
 }
 
 void mark_info_dirty(struct super_block *sb, int type)
 {
         spin_lock(&dq_data_lock);
         sb_dqopt(sb)->info[type].dqi_flags |= DQF_INFO_DIRTY;
         spin_unlock(&dq_data_lock);
 }
 EXPORT_SYMBOL(mark_info_dirty);
 
 /*
  *      Read dquot from disk and alloc space for it
  */
 
 int dquot_acquire(struct dquot *dquot)
 {
         int ret = 0, ret2 = 0;
         unsigned int memalloc;
         struct quota_info *dqopt = sb_dqopt(dquot->dq_sb);
 
         mutex_lock(&dquot->dq_lock);
         memalloc = memalloc_nofs_save();
         if (!test_bit(DQ_READ_B, &dquot->dq_flags)) {
                 ret = dqopt->ops[dquot->dq_id.type]->read_dqblk(dquot);
                 if (ret < 0)
                         goto out_iolock;
         }
         /* Make sure flags update is visible after dquot has been filled */
         smp_mb__before_atomic();
         set_bit(DQ_READ_B, &dquot->dq_flags);
         /* Instantiate dquot if needed */
         if (!dquot_active(dquot) && !dquot->dq_off) {
                 ret = dqopt->ops[dquot->dq_id.type]->commit_dqblk(dquot);
                 /* Write the info if needed */
                 if (info_dirty(&dqopt->info[dquot->dq_id.type])) {
                         ret2 = dqopt->ops[dquot->dq_id.type]->write_file_info(
                                         dquot->dq_sb, dquot->dq_id.type);
                 }
                 if (ret < 0)
                         goto out_iolock;
                 if (ret2 < 0) {
                         ret = ret2;
                         goto out_iolock;
                 }
         }
         /*
          * Make sure flags update is visible after on-disk struct has been
          * allocated. Paired with smp_rmb() in dqget().
          */
         smp_mb__before_atomic();
         set_bit(DQ_ACTIVE_B, &dquot->dq_flags);
 out_iolock:
         memalloc_nofs_restore(memalloc);
         mutex_unlock(&dquot->dq_lock);
         return ret;
 }
 EXPORT_SYMBOL(dquot_acquire);
 
 /*
  *      Write dquot to disk
  */
 int dquot_commit(struct dquot *dquot)
 {
         int ret = 0;
         unsigned int memalloc;
         struct quota_info *dqopt = sb_dqopt(dquot->dq_sb);
 
         mutex_lock(&dquot->dq_lock);
         memalloc = memalloc_nofs_save();
         if (!clear_dquot_dirty(dquot))
                 goto out_lock;
         /* Inactive dquot can be only if there was error during read/init
          * => we have better not writing it */
         if (dquot_active(dquot))
                 ret = dqopt->ops[dquot->dq_id.type]->commit_dqblk(dquot);
         else
                 ret = -EIO;
 out_lock:
         memalloc_nofs_restore(memalloc);
         mutex_unlock(&dquot->dq_lock);
         return ret;
 }
 EXPORT_SYMBOL(dquot_commit);
 
 /*
  *      Release dquot
  */
 int dquot_release(struct dquot *dquot)
 {
         int ret = 0, ret2 = 0;
         unsigned int memalloc;
         struct quota_info *dqopt = sb_dqopt(dquot->dq_sb);
 
         mutex_lock(&dquot->dq_lock);
         memalloc = memalloc_nofs_save();
         /* Check whether we are not racing with some other dqget() */
         if (dquot_is_busy(dquot))
                 goto out_dqlock;
         if (dqopt->ops[dquot->dq_id.type]->release_dqblk) {
                 ret = dqopt->ops[dquot->dq_id.type]->release_dqblk(dquot);
                 /* Write the info */
                 if (info_dirty(&dqopt->info[dquot->dq_id.type])) {
                         ret2 = dqopt->ops[dquot->dq_id.type]->write_file_info(
                                                 dquot->dq_sb, dquot->dq_id.type);
                 }
                 if (ret >= 0)
                         ret = ret2;
         }
         clear_bit(DQ_ACTIVE_B, &dquot->dq_flags);
 out_dqlock:
         memalloc_nofs_restore(memalloc);
         mutex_unlock(&dquot->dq_lock);
         return ret;
 }
 EXPORT_SYMBOL(dquot_release);
 
 void dquot_destroy(struct dquot *dquot)
 {
         kmem_cache_free(dquot_cachep, dquot);
 }
 EXPORT_SYMBOL(dquot_destroy);
 
 static inline void do_destroy_dquot(struct dquot *dquot)
 {
         dquot->dq_sb->dq_op->destroy_dquot(dquot);
 }
 
 /* Invalidate all dquots on the list. Note that this function is called after
  * quota is disabled and pointers from inodes removed so there cannot be new
  * quota users. There can still be some users of quotas due to inodes being
  * just deleted or pruned by prune_icache() (those are not attached to any
  * list) or parallel quotactl call. We have to wait for such users.
  */
 static void invalidate_dquots(struct super_block *sb, int type)
 {
         struct dquot *dquot, *tmp;
 
 restart:
         flush_delayed_work(&quota_release_work);
 
         spin_lock(&dq_list_lock);
         list_for_each_entry_safe(dquot, tmp, &inuse_list, dq_inuse) {
                 if (dquot->dq_sb != sb)
                         continue;
                 if (dquot->dq_id.type != type)
                         continue;
                 /* Wait for dquot users */
                 if (atomic_read(&dquot->dq_count)) {
                         atomic_inc(&dquot->dq_count);
                         spin_unlock(&dq_list_lock);
                         /*
                          * Once dqput() wakes us up, we know it's time to free
                          * the dquot.
                          * IMPORTANT: we rely on the fact that there is always
                          * at most one process waiting for dquot to free.
                          * Otherwise dq_count would be > 1 and we would never
                          * wake up.
                          */
                         wait_event(dquot_ref_wq,
                                    atomic_read(&dquot->dq_count) == 1);
                         dqput(dquot);
                         /* At this moment dquot() need not exist (it could be
                          * reclaimed by prune_dqcache(). Hence we must
                          * restart. */
                         goto restart;
                 }
                 /*
                  * The last user already dropped its reference but dquot didn't
                  * get fully cleaned up yet. Restart the scan which flushes the
                  * work cleaning up released dquots.
                  */
                 if (test_bit(DQ_RELEASING_B, &dquot->dq_flags)) {
                         spin_unlock(&dq_list_lock);
                         goto restart;
                 }
                 /*
                  * Quota now has no users and it has been written on last
                  * dqput()
                  */
                 remove_dquot_hash(dquot);
                 remove_free_dquot(dquot);
                 remove_inuse(dquot);
                 do_destroy_dquot(dquot);
         }
         spin_unlock(&dq_list_lock);
 }
 
 /* Call callback for every active dquot on given filesystem */
 int dquot_scan_active(struct super_block *sb,
                       int (*fn)(struct dquot *dquot, unsigned long priv),
                       unsigned long priv)
 {
         struct dquot *dquot, *old_dquot = NULL;
         int ret = 0;
 
         WARN_ON_ONCE(!rwsem_is_locked(&sb->s_umount));
 
         spin_lock(&dq_list_lock);
         list_for_each_entry(dquot, &inuse_list, dq_inuse) {
                 if (!dquot_active(dquot))
                         continue;
                 if (dquot->dq_sb != sb)
                         continue;
                 /* Now we have active dquot so we can just increase use count */
                 atomic_inc(&dquot->dq_count);
                 spin_unlock(&dq_list_lock);
                 dqput(old_dquot);
                 old_dquot = dquot;
                 /*
                  * ->release_dquot() can be racing with us. Our reference
                  * protects us from new calls to it so just wait for any
                  * outstanding call and recheck the DQ_ACTIVE_B after that.
                  */
                 wait_on_dquot(dquot);
                 if (dquot_active(dquot)) {
                         ret = fn(dquot, priv);
                         if (ret < 0)
                                 goto out;
                 }
                 spin_lock(&dq_list_lock);
                 /* We are safe to continue now because our dquot could not
                  * be moved out of the inuse list while we hold the reference */
         }
         spin_unlock(&dq_list_lock);
 out:
         dqput(old_dquot);
         return ret;
 }
 EXPORT_SYMBOL(dquot_scan_active);
 
 static inline int dquot_write_dquot(struct dquot *dquot)
 {
         int ret = dquot->dq_sb->dq_op->write_dquot(dquot);
         if (ret < 0) {
                 quota_error(dquot->dq_sb, "Can't write quota structure "
                             "(error %d). Quota may get out of sync!", ret);
                 /* Clear dirty bit anyway to avoid infinite loop. */
                 clear_dquot_dirty(dquot);
         }
         return ret;
 }
 
 /* Write all dquot structures to quota files */
 int dquot_writeback_dquots(struct super_block *sb, int type)
 {
         struct list_head dirty;
         struct dquot *dquot;
         struct quota_info *dqopt = sb_dqopt(sb);
         int cnt;
         int err, ret = 0;
 
         WARN_ON_ONCE(!rwsem_is_locked(&sb->s_umount));
 
         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                 if (type != -1 && cnt != type)
                         continue;
                 if (!sb_has_quota_active(sb, cnt))
                         continue;
                 spin_lock(&dq_list_lock);
                 /* Move list away to avoid livelock. */
                 list_replace_init(&dqopt->info[cnt].dqi_dirty_list, &dirty);
                 while (!list_empty(&dirty)) {
                         dquot = list_first_entry(&dirty, struct dquot,
                                                  dq_dirty);
 
                         WARN_ON(!dquot_active(dquot));
                         /* If the dquot is releasing we should not touch it */
                         if (test_bit(DQ_RELEASING_B, &dquot->dq_flags)) {
                                 spin_unlock(&dq_list_lock);
                                 flush_delayed_work(&quota_release_work);
                                 spin_lock(&dq_list_lock);
                                 continue;
                         }
 
                         /* Now we have active dquot from which someone is
                          * holding reference so we can safely just increase
                          * use count */
                         dqgrab(dquot);
                         spin_unlock(&dq_list_lock);
                         err = dquot_write_dquot(dquot);
                         if (err && !ret)
                                 ret = err;
                         dqput(dquot);
                         spin_lock(&dq_list_lock);
                 }
                 spin_unlock(&dq_list_lock);
         }
 
         for (cnt = 0; cnt < MAXQUOTAS; cnt++)
                 if ((cnt == type || type == -1) && sb_has_quota_active(sb, cnt)
                     && info_dirty(&dqopt->info[cnt]))
                         sb->dq_op->write_info(sb, cnt);
         dqstats_inc(DQST_SYNCS);
 
         return ret;
 }
 EXPORT_SYMBOL(dquot_writeback_dquots);
 
 /* Write all dquot structures to disk and make them visible from userspace */
 int dquot_quota_sync(struct super_block *sb, int type)
 {
         struct quota_info *dqopt = sb_dqopt(sb);
         int cnt;
         int ret;
 
         ret = dquot_writeback_dquots(sb, type);
         if (ret)
                 return ret;
         if (dqopt->flags & DQUOT_QUOTA_SYS_FILE)
                 return 0;
 
         /* This is not very clever (and fast) but currently I don't know about
          * any other simple way of getting quota data to disk and we must get
          * them there for userspace to be visible... */
         if (sb->s_op->sync_fs) {
                 ret = sb->s_op->sync_fs(sb, 1);
                 if (ret)
                         return ret;
         }
         ret = sync_blockdev(sb->s_bdev);
         if (ret)
                 return ret;
 
         /*
          * Now when everything is written we can discard the pagecache so
          * that userspace sees the changes.
          */
         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                 if (type != -1 && cnt != type)
                         continue;
                 if (!sb_has_quota_active(sb, cnt))
                         continue;
                 inode_lock(dqopt->files[cnt]);
                 truncate_inode_pages(&dqopt->files[cnt]->i_data, 0);
                 inode_unlock(dqopt->files[cnt]);
         }
 
         return 0;
 }
 EXPORT_SYMBOL(dquot_quota_sync);
 
 static unsigned long
 dqcache_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
 {
         struct dquot *dquot;
         unsigned long freed = 0;
 
         spin_lock(&dq_list_lock);
         while (!list_empty(&free_dquots) && sc->nr_to_scan) {
                 dquot = list_first_entry(&free_dquots, struct dquot, dq_free);
                 remove_dquot_hash(dquot);
                 remove_free_dquot(dquot);
                 remove_inuse(dquot);
                 do_destroy_dquot(dquot);
                 sc->nr_to_scan--;
                 freed++;
         }
         spin_unlock(&dq_list_lock);
         return freed;
 }
 
 static unsigned long
 dqcache_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
 {
         return vfs_pressure_ratio(
         percpu_counter_read_positive(&dqstats.counter[DQST_FREE_DQUOTS]));
 }
 
 /*
  * Safely release dquot and put reference to dquot.
  */
 static void quota_release_workfn(struct work_struct *work)
 {
         struct dquot *dquot;
         struct list_head rls_head;
 
         spin_lock(&dq_list_lock);
         /* Exchange the list head to avoid livelock. */
         list_replace_init(&releasing_dquots, &rls_head);
         spin_unlock(&dq_list_lock);
         synchronize_srcu(&dquot_srcu);
 
 restart:
         spin_lock(&dq_list_lock);
         while (!list_empty(&rls_head)) {
                 dquot = list_first_entry(&rls_head, struct dquot, dq_free);
                 WARN_ON_ONCE(atomic_read(&dquot->dq_count));
                 /*
                  * Note that DQ_RELEASING_B protects us from racing with
                  * invalidate_dquots() calls so we are safe to work with the
                  * dquot even after we drop dq_list_lock.
                  */
                 if (dquot_dirty(dquot)) {
                         spin_unlock(&dq_list_lock);
                         /* Commit dquot before releasing */
                         dquot_write_dquot(dquot);
                         goto restart;
                 }
                 if (dquot_active(dquot)) {
                         spin_unlock(&dq_list_lock);
                         dquot->dq_sb->dq_op->release_dquot(dquot);
                         goto restart;
                 }
                 /* Dquot is inactive and clean, now move it to free list */
                 remove_free_dquot(dquot);
                 put_dquot_last(dquot);
         }
         spin_unlock(&dq_list_lock);
 }
 
 /*
  * Put reference to dquot
  */
 void dqput(struct dquot *dquot)
 {
         if (!dquot)
                 return;
 #ifdef CONFIG_QUOTA_DEBUG
         if (!atomic_read(&dquot->dq_count)) {
                 quota_error(dquot->dq_sb, "trying to free free dquot of %s %d",
                             quotatypes[dquot->dq_id.type],
                             from_kqid(&init_user_ns, dquot->dq_id));
                 BUG();
         }
 #endif
         dqstats_inc(DQST_DROPS);
 
         spin_lock(&dq_list_lock);
         if (atomic_read(&dquot->dq_count) > 1) {
                 /* We have more than one user... nothing to do */
                 atomic_dec(&dquot->dq_count);
                 /* Releasing dquot during quotaoff phase? */
                 if (!sb_has_quota_active(dquot->dq_sb, dquot->dq_id.type) &&
                     atomic_read(&dquot->dq_count) == 1)
                         wake_up(&dquot_ref_wq);
                 spin_unlock(&dq_list_lock);
                 return;
         }
 
         /* Need to release dquot? */
         WARN_ON_ONCE(!list_empty(&dquot->dq_free));
         put_releasing_dquots(dquot);
         atomic_dec(&dquot->dq_count);
         spin_unlock(&dq_list_lock);
         queue_delayed_work(system_unbound_wq, &quota_release_work, 1);
 }
 EXPORT_SYMBOL(dqput);
 
 struct dquot *dquot_alloc(struct super_block *sb, int type)
 {
         return kmem_cache_zalloc(dquot_cachep, GFP_NOFS);
 }
 EXPORT_SYMBOL(dquot_alloc);
 
 static struct dquot *get_empty_dquot(struct super_block *sb, int type)
 {
         struct dquot *dquot;
 
         dquot = sb->dq_op->alloc_dquot(sb, type);
         if(!dquot)
                 return NULL;
 
         mutex_init(&dquot->dq_lock);
         INIT_LIST_HEAD(&dquot->dq_free);
         INIT_LIST_HEAD(&dquot->dq_inuse);
         INIT_HLIST_NODE(&dquot->dq_hash);
         INIT_LIST_HEAD(&dquot->dq_dirty);
         dquot->dq_sb = sb;
         dquot->dq_id = make_kqid_invalid(type);
         atomic_set(&dquot->dq_count, 1);
         spin_lock_init(&dquot->dq_dqb_lock);
 
         return dquot;
 }
 
 /*
  * Get reference to dquot
  *
  * Locking is slightly tricky here. We are guarded from parallel quotaoff()
  * destroying our dquot by:
  *   a) checking for quota flags under dq_list_lock and
  *   b) getting a reference to dquot before we release dq_list_lock
  */
 struct dquot *dqget(struct super_block *sb, struct kqid qid)
 {
         unsigned int hashent = hashfn(sb, qid);
         struct dquot *dquot, *empty = NULL;
 
         if (!qid_has_mapping(sb->s_user_ns, qid))
                 return ERR_PTR(-EINVAL);
 
         if (!sb_has_quota_active(sb, qid.type))
                 return ERR_PTR(-ESRCH);
 we_slept:
         spin_lock(&dq_list_lock);
         spin_lock(&dq_state_lock);
         if (!sb_has_quota_active(sb, qid.type)) {
                 spin_unlock(&dq_state_lock);
                 spin_unlock(&dq_list_lock);
                 dquot = ERR_PTR(-ESRCH);
                 goto out;
         }
         spin_unlock(&dq_state_lock);
 
         dquot = find_dquot(hashent, sb, qid);
         if (!dquot) {
                 if (!empty) {
                         spin_unlock(&dq_list_lock);
                         empty = get_empty_dquot(sb, qid.type);
                         if (!empty)
                                 schedule();     /* Try to wait for a moment... */
                         goto we_slept;
                 }
                 dquot = empty;
                 empty = NULL;
                 dquot->dq_id = qid;
                 /* all dquots go on the inuse_list */
                 put_inuse(dquot);
                 /* hash it first so it can be found */
                 insert_dquot_hash(dquot);
                 spin_unlock(&dq_list_lock);
                 dqstats_inc(DQST_LOOKUPS);
         } else {
                 if (!atomic_read(&dquot->dq_count))
                         remove_free_dquot(dquot);
                 atomic_inc(&dquot->dq_count);
                 spin_unlock(&dq_list_lock);
                 dqstats_inc(DQST_CACHE_HITS);
                 dqstats_inc(DQST_LOOKUPS);
         }
         /* Wait for dq_lock - after this we know that either dquot_release() is
          * already finished or it will be canceled due to dq_count > 0 test */
         wait_on_dquot(dquot);
         /* Read the dquot / allocate space in quota file */
         if (!dquot_active(dquot)) {
                 int err;
 
                 err = sb->dq_op->acquire_dquot(dquot);
                 if (err < 0) {
                         dqput(dquot);
                         dquot = ERR_PTR(err);
                         goto out;
                 }
         }
         /*
          * Make sure following reads see filled structure - paired with
          * smp_mb__before_atomic() in dquot_acquire().
          */
         smp_rmb();
         /* Has somebody invalidated entry under us? */
         WARN_ON_ONCE(hlist_unhashed(&dquot->dq_hash));
 out:
         if (empty)
                 do_destroy_dquot(empty);
 
         return dquot;
 }
 EXPORT_SYMBOL(dqget);
 
 static inline struct dquot __rcu **i_dquot(struct inode *inode)
 {
         return inode->i_sb->s_op->get_dquots(inode);
 }
 
 static int dqinit_needed(struct inode *inode, int type)
 {
         struct dquot __rcu * const *dquots;
         int cnt;
 
         if (IS_NOQUOTA(inode))
                 return 0;
 
         dquots = i_dquot(inode);
         if (type != -1)
                 return !dquots[type];
         for (cnt = 0; cnt < MAXQUOTAS; cnt++)
                 if (!dquots[cnt])
                         return 1;
         return 0;
 }
 
 /* This routine is guarded by s_umount semaphore */
 static int add_dquot_ref(struct super_block *sb, int type)
 {
         struct inode *inode, *old_inode = NULL;
 #ifdef CONFIG_QUOTA_DEBUG
         int reserved = 0;
 #endif
         int err = 0;
 
         spin_lock(&sb->s_inode_list_lock);
         list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
                 spin_lock(&inode->i_lock);
                 if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||
                     !atomic_read(&inode->i_writecount) ||
                     !dqinit_needed(inode, type)) {
                         spin_unlock(&inode->i_lock);
                         continue;
                 }
                 __iget(inode);
                 spin_unlock(&inode->i_lock);
                 spin_unlock(&sb->s_inode_list_lock);
 
 #ifdef CONFIG_QUOTA_DEBUG
                 if (unlikely(inode_get_rsv_space(inode) > 0))
                         reserved = 1;
 #endif
                 iput(old_inode);
                 err = __dquot_initialize(inode, type);
                 if (err) {
                         iput(inode);
                         goto out;
                 }
 
                 /*
                  * We hold a reference to 'inode' so it couldn't have been
                  * removed from s_inodes list while we dropped the
                  * s_inode_list_lock. We cannot iput the inode now as we can be
                  * holding the last reference and we cannot iput it under
                  * s_inode_list_lock. So we keep the reference and iput it
                  * later.
                  */
                 old_inode = inode;
                 cond_resched();
                 spin_lock(&sb->s_inode_list_lock);
         }
         spin_unlock(&sb->s_inode_list_lock);
         iput(old_inode);
 out:
 #ifdef CONFIG_QUOTA_DEBUG
         if (reserved) {
                 quota_error(sb, "Writes happened before quota was turned on "
                         "thus quota information is probably inconsistent. "
                         "Please run quotacheck(8)");
         }
 #endif
         return err;
 }
 
 static void remove_dquot_ref(struct super_block *sb, int type)
 {
         struct inode *inode;
 #ifdef CONFIG_QUOTA_DEBUG
         int reserved = 0;
 #endif
 
         spin_lock(&sb->s_inode_list_lock);
         list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
                 /*
                  *  We have to scan also I_NEW inodes because they can already
                  *  have quota pointer initialized. Luckily, we need to touch
                  *  only quota pointers and these have separate locking
                  *  (dq_data_lock).
                  */
                 spin_lock(&dq_data_lock);
                 if (!IS_NOQUOTA(inode)) {
                         struct dquot __rcu **dquots = i_dquot(inode);
                         struct dquot *dquot = srcu_dereference_check(
                                 dquots[type], &dquot_srcu,
                                 lockdep_is_held(&dq_data_lock));
 
 #ifdef CONFIG_QUOTA_DEBUG
                         if (unlikely(inode_get_rsv_space(inode) > 0))
                                 reserved = 1;
 #endif
                         rcu_assign_pointer(dquots[type], NULL);
                         if (dquot)
                                 dqput(dquot);
                 }
                 spin_unlock(&dq_data_lock);
         }
         spin_unlock(&sb->s_inode_list_lock);
 #ifdef CONFIG_QUOTA_DEBUG
         if (reserved) {
                 printk(KERN_WARNING "VFS (%s): Writes happened after quota"
                         " was disabled thus quota information is probably "
                         "inconsistent. Please run quotacheck(8).\n", sb->s_id);
         }
 #endif
 }
 
 /* Gather all references from inodes and drop them */
 static void drop_dquot_ref(struct super_block *sb, int type)
 {
         if (sb->dq_op)
                 remove_dquot_ref(sb, type);
 }
 
 static inline
 void dquot_free_reserved_space(struct dquot *dquot, qsize_t number)
 {
         if (dquot->dq_dqb.dqb_rsvspace >= number)
                 dquot->dq_dqb.dqb_rsvspace -= number;
         else {
                 WARN_ON_ONCE(1);
                 dquot->dq_dqb.dqb_rsvspace = 0;
         }
         if (dquot->dq_dqb.dqb_curspace + dquot->dq_dqb.dqb_rsvspace <=
             dquot->dq_dqb.dqb_bsoftlimit)
                 dquot->dq_dqb.dqb_btime = (time64_t) 0;
         clear_bit(DQ_BLKS_B, &dquot->dq_flags);
 }
 
 static void dquot_decr_inodes(struct dquot *dquot, qsize_t number)
 {
         if (sb_dqopt(dquot->dq_sb)->flags & DQUOT_NEGATIVE_USAGE ||
             dquot->dq_dqb.dqb_curinodes >= number)
                 dquot->dq_dqb.dqb_curinodes -= number;
         else
                 dquot->dq_dqb.dqb_curinodes = 0;
         if (dquot->dq_dqb.dqb_curinodes <= dquot->dq_dqb.dqb_isoftlimit)
                 dquot->dq_dqb.dqb_itime = (time64_t) 0;
         clear_bit(DQ_INODES_B, &dquot->dq_flags);
 }
 
 static void dquot_decr_space(struct dquot *dquot, qsize_t number)
 {
         if (sb_dqopt(dquot->dq_sb)->flags & DQUOT_NEGATIVE_USAGE ||
             dquot->dq_dqb.dqb_curspace >= number)
                 dquot->dq_dqb.dqb_curspace -= number;
         else
                 dquot->dq_dqb.dqb_curspace = 0;
         if (dquot->dq_dqb.dqb_curspace + dquot->dq_dqb.dqb_rsvspace <=
             dquot->dq_dqb.dqb_bsoftlimit)
                 dquot->dq_dqb.dqb_btime = (time64_t) 0;
         clear_bit(DQ_BLKS_B, &dquot->dq_flags);
 }
 
 struct dquot_warn {
         struct super_block *w_sb;
         struct kqid w_dq_id;
         short w_type;
 };
 
 static int warning_issued(struct dquot *dquot, const int warntype)
 {
         int flag = (warntype == QUOTA_NL_BHARDWARN ||
                 warntype == QUOTA_NL_BSOFTLONGWARN) ? DQ_BLKS_B :
                 ((warntype == QUOTA_NL_IHARDWARN ||
                 warntype == QUOTA_NL_ISOFTLONGWARN) ? DQ_INODES_B : 0);
 
         if (!flag)
                 return 0;
         return test_and_set_bit(flag, &dquot->dq_flags);
 }
 
 #ifdef CONFIG_PRINT_QUOTA_WARNING
 static int flag_print_warnings = 1;
 
 static int need_print_warning(struct dquot_warn *warn)
 {
         if (!flag_print_warnings)
                 return 0;
 
         switch (warn->w_dq_id.type) {
                 case USRQUOTA:
                         return uid_eq(current_fsuid(), warn->w_dq_id.uid);
                 case GRPQUOTA:
                         return in_group_p(warn->w_dq_id.gid);
                 case PRJQUOTA:
                         return 1;
         }
         return 0;
 }
 
 /* Print warning to user which exceeded quota */
 static void print_warning(struct dquot_warn *warn)
 {
         char *msg = NULL;
         struct tty_struct *tty;
         int warntype = warn->w_type;
 
         if (warntype == QUOTA_NL_IHARDBELOW ||
             warntype == QUOTA_NL_ISOFTBELOW ||
             warntype == QUOTA_NL_BHARDBELOW ||
             warntype == QUOTA_NL_BSOFTBELOW || !need_print_warning(warn))
                 return;
 
         tty = get_current_tty();
         if (!tty)
                 return;
         tty_write_message(tty, warn->w_sb->s_id);
         if (warntype == QUOTA_NL_ISOFTWARN || warntype == QUOTA_NL_BSOFTWARN)
                 tty_write_message(tty, ": warning, ");
         else
                 tty_write_message(tty, ": write failed, ");
         tty_write_message(tty, quotatypes[warn->w_dq_id.type]);
         switch (warntype) {
                 case QUOTA_NL_IHARDWARN:
                         msg = " file limit reached.\r\n";
                         break;
                 case QUOTA_NL_ISOFTLONGWARN:
                         msg = " file quota exceeded too long.\r\n";
                         break;
                 case QUOTA_NL_ISOFTWARN:
                         msg = " file quota exceeded.\r\n";
                         break;
                 case QUOTA_NL_BHARDWARN:
                         msg = " block limit reached.\r\n";
                         break;
                 case QUOTA_NL_BSOFTLONGWARN:
                         msg = " block quota exceeded too long.\r\n";
                         break;
                 case QUOTA_NL_BSOFTWARN:
                         msg = " block quota exceeded.\r\n";
                         break;
         }
         tty_write_message(tty, msg);
         tty_kref_put(tty);
 }
 #endif
 
 static void prepare_warning(struct dquot_warn *warn, struct dquot *dquot,
                             int warntype)
 {
         if (warning_issued(dquot, warntype))
                 return;
         warn->w_type = warntype;
         warn->w_sb = dquot->dq_sb;
         warn->w_dq_id = dquot->dq_id;
 }
 
 /*
  * Write warnings to the console and send warning messages over netlink.
  *
  * Note that this function can call into tty and networking code.
  */
 static void flush_warnings(struct dquot_warn *warn)
 {
         int i;
 
         for (i = 0; i < MAXQUOTAS; i++) {
                 if (warn[i].w_type == QUOTA_NL_NOWARN)
                         continue;
 #ifdef CONFIG_PRINT_QUOTA_WARNING
                 print_warning(&warn[i]);
 #endif
                 quota_send_warning(warn[i].w_dq_id,
                                    warn[i].w_sb->s_dev, warn[i].w_type);
         }
 }
 
 static int ignore_hardlimit(struct dquot *dquot)
 {
         struct mem_dqinfo *info = &sb_dqopt(dquot->dq_sb)->info[dquot->dq_id.type];
 
         return capable(CAP_SYS_RESOURCE) &&
                (info->dqi_format->qf_fmt_id != QFMT_VFS_OLD ||
                 !(info->dqi_flags & DQF_ROOT_SQUASH));
 }
 
 static int dquot_add_inodes(struct dquot *dquot, qsize_t inodes,
                             struct dquot_warn *warn)
 {
         qsize_t newinodes;
         int ret = 0;
 
         spin_lock(&dquot->dq_dqb_lock);
         newinodes = dquot->dq_dqb.dqb_curinodes + inodes;
         if (!sb_has_quota_limits_enabled(dquot->dq_sb, dquot->dq_id.type) ||
             test_bit(DQ_FAKE_B, &dquot->dq_flags))
                 goto add;
 
         if (dquot->dq_dqb.dqb_ihardlimit &&
             newinodes > dquot->dq_dqb.dqb_ihardlimit &&
             !ignore_hardlimit(dquot)) {
                 prepare_warning(warn, dquot, QUOTA_NL_IHARDWARN);
                 ret = -EDQUOT;
                 goto out;
         }
 
         if (dquot->dq_dqb.dqb_isoftlimit &&
             newinodes > dquot->dq_dqb.dqb_isoftlimit &&
             dquot->dq_dqb.dqb_itime &&
             ktime_get_real_seconds() >= dquot->dq_dqb.dqb_itime &&
             !ignore_hardlimit(dquot)) {
                 prepare_warning(warn, dquot, QUOTA_NL_ISOFTLONGWARN);
                 ret = -EDQUOT;
                 goto out;
         }
 
         if (dquot->dq_dqb.dqb_isoftlimit &&
             newinodes > dquot->dq_dqb.dqb_isoftlimit &&
             dquot->dq_dqb.dqb_itime == 0) {
                 prepare_warning(warn, dquot, QUOTA_NL_ISOFTWARN);
                 dquot->dq_dqb.dqb_itime = ktime_get_real_seconds() +
                     sb_dqopt(dquot->dq_sb)->info[dquot->dq_id.type].dqi_igrace;
         }
 add:
         dquot->dq_dqb.dqb_curinodes = newinodes;
 
 out:
         spin_unlock(&dquot->dq_dqb_lock);
         return ret;
 }
 
 static int dquot_add_space(struct dquot *dquot, qsize_t space,
                            qsize_t rsv_space, unsigned int flags,
                            struct dquot_warn *warn)
 {
         qsize_t tspace;
         struct super_block *sb = dquot->dq_sb;
         int ret = 0;
 
         spin_lock(&dquot->dq_dqb_lock);
         if (!sb_has_quota_limits_enabled(sb, dquot->dq_id.type) ||
             test_bit(DQ_FAKE_B, &dquot->dq_flags))
                 goto finish;
 
         tspace = dquot->dq_dqb.dqb_curspace + dquot->dq_dqb.dqb_rsvspace
                 + space + rsv_space;
 
         if (dquot->dq_dqb.dqb_bhardlimit &&
             tspace > dquot->dq_dqb.dqb_bhardlimit &&
             !ignore_hardlimit(dquot)) {
                 if (flags & DQUOT_SPACE_WARN)
                         prepare_warning(warn, dquot, QUOTA_NL_BHARDWARN);
                 ret = -EDQUOT;
                 goto finish;
         }
 
         if (dquot->dq_dqb.dqb_bsoftlimit &&
             tspace > dquot->dq_dqb.dqb_bsoftlimit &&
             dquot->dq_dqb.dqb_btime &&
             ktime_get_real_seconds() >= dquot->dq_dqb.dqb_btime &&
             !ignore_hardlimit(dquot)) {
                 if (flags & DQUOT_SPACE_WARN)
                         prepare_warning(warn, dquot, QUOTA_NL_BSOFTLONGWARN);
                 ret = -EDQUOT;
                 goto finish;
         }
 
         if (dquot->dq_dqb.dqb_bsoftlimit &&
             tspace > dquot->dq_dqb.dqb_bsoftlimit &&
             dquot->dq_dqb.dqb_btime == 0) {
                 if (flags & DQUOT_SPACE_WARN) {
                         prepare_warning(warn, dquot, QUOTA_NL_BSOFTWARN);
                         dquot->dq_dqb.dqb_btime = ktime_get_real_seconds() +
                             sb_dqopt(sb)->info[dquot->dq_id.type].dqi_bgrace;
                 } else {
                         /*
                          * We don't allow preallocation to exceed softlimit so exceeding will
                          * be always printed
                          */
                         ret = -EDQUOT;
                         goto finish;
                 }
         }
 finish:
         /*
          * We have to be careful and go through warning generation & grace time
          * setting even if DQUOT_SPACE_NOFAIL is set. That's why we check it
          * only here...
          */
         if (flags & DQUOT_SPACE_NOFAIL)
                 ret = 0;
         if (!ret) {
                 dquot->dq_dqb.dqb_rsvspace += rsv_space;
                 dquot->dq_dqb.dqb_curspace += space;
         }
         spin_unlock(&dquot->dq_dqb_lock);
         return ret;
 }
 
 static int info_idq_free(struct dquot *dquot, qsize_t inodes)
 {
         qsize_t newinodes;
 
         if (test_bit(DQ_FAKE_B, &dquot->dq_flags) ||
             dquot->dq_dqb.dqb_curinodes <= dquot->dq_dqb.dqb_isoftlimit ||
             !sb_has_quota_limits_enabled(dquot->dq_sb, dquot->dq_id.type))
                 return QUOTA_NL_NOWARN;
 
         newinodes = dquot->dq_dqb.dqb_curinodes - inodes;
         if (newinodes <= dquot->dq_dqb.dqb_isoftlimit)
                 return QUOTA_NL_ISOFTBELOW;
         if (dquot->dq_dqb.dqb_curinodes >= dquot->dq_dqb.dqb_ihardlimit &&
             newinodes < dquot->dq_dqb.dqb_ihardlimit)
                 return QUOTA_NL_IHARDBELOW;
         return QUOTA_NL_NOWARN;
 }
 
 static int info_bdq_free(struct dquot *dquot, qsize_t space)
 {
         qsize_t tspace;
 
         tspace = dquot->dq_dqb.dqb_curspace + dquot->dq_dqb.dqb_rsvspace;
 
         if (test_bit(DQ_FAKE_B, &dquot->dq_flags) ||
             tspace <= dquot->dq_dqb.dqb_bsoftlimit)
                 return QUOTA_NL_NOWARN;
 
         if (tspace - space <= dquot->dq_dqb.dqb_bsoftlimit)
                 return QUOTA_NL_BSOFTBELOW;
         if (tspace >= dquot->dq_dqb.dqb_bhardlimit &&
             tspace - space < dquot->dq_dqb.dqb_bhardlimit)
                 return QUOTA_NL_BHARDBELOW;
         return QUOTA_NL_NOWARN;
 }
 
 static int inode_quota_active(const struct inode *inode)
 {
         struct super_block *sb = inode->i_sb;
 
         if (IS_NOQUOTA(inode))
                 return 0;
         return sb_any_quota_loaded(sb) & ~sb_any_quota_suspended(sb);
 }
 
 /*
  * Initialize quota pointers in inode
  *
  * It is better to call this function outside of any transaction as it
  * might need a lot of space in journal for dquot structure allocation.
  */
 static int __dquot_initialize(struct inode *inode, int type)
 {
         int cnt, init_needed = 0;
         struct dquot __rcu **dquots;
         struct dquot *got[MAXQUOTAS] = {};
         struct super_block *sb = inode->i_sb;
         qsize_t rsv;
         int ret = 0;
 
         if (!inode_quota_active(inode))
                 return 0;
 
         dquots = i_dquot(inode);
 
         /* First get references to structures we might need. */
         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                 struct kqid qid;
                 kprojid_t projid;
                 int rc;
                 struct dquot *dquot;
 
                 if (type != -1 && cnt != type)
                         continue;
                 /*
                  * The i_dquot should have been initialized in most cases,
                  * we check it without locking here to avoid unnecessary
                  * dqget()/dqput() calls.
                  */
                 if (dquots[cnt])
                         continue;
 
                 if (!sb_has_quota_active(sb, cnt))
                         continue;
 
                 init_needed = 1;
 
                 switch (cnt) {
                 case USRQUOTA:
                         qid = make_kqid_uid(inode->i_uid);
                         break;
                 case GRPQUOTA:
                         qid = make_kqid_gid(inode->i_gid);
                         break;
                 case PRJQUOTA:
                         rc = inode->i_sb->dq_op->get_projid(inode, &projid);
                         if (rc)
                                 continue;
                         qid = make_kqid_projid(projid);
                         break;
                 }
                 dquot = dqget(sb, qid);
                 if (IS_ERR(dquot)) {
                         /* We raced with somebody turning quotas off... */
                         if (PTR_ERR(dquot) != -ESRCH) {
                                 ret = PTR_ERR(dquot);
                                 goto out_put;
                         }
                         dquot = NULL;
                 }
                 got[cnt] = dquot;
         }
 
         /* All required i_dquot has been initialized */
         if (!init_needed)
                 return 0;
 
         spin_lock(&dq_data_lock);
         if (IS_NOQUOTA(inode))
                 goto out_lock;
         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                 if (type != -1 && cnt != type)
                         continue;
                 /* Avoid races with quotaoff() */
                 if (!sb_has_quota_active(sb, cnt))
                         continue;
                 /* We could race with quotaon or dqget() could have failed */
                 if (!got[cnt])
                         continue;
                 if (!dquots[cnt]) {
                         rcu_assign_pointer(dquots[cnt], got[cnt]);
                         got[cnt] = NULL;
                         /*
                          * Make quota reservation system happy if someone
                          * did a write before quota was turned on
                          */
                         rsv = inode_get_rsv_space(inode);
                         if (unlikely(rsv)) {
                                 struct dquot *dquot = srcu_dereference_check(
                                         dquots[cnt], &dquot_srcu,
                                         lockdep_is_held(&dq_data_lock));
 
                                 spin_lock(&inode->i_lock);
                                 /* Get reservation again under proper lock */
                                 rsv = __inode_get_rsv_space(inode);
                                 spin_lock(&dquot->dq_dqb_lock);
                                 dquot->dq_dqb.dqb_rsvspace += rsv;
                                 spin_unlock(&dquot->dq_dqb_lock);
                                 spin_unlock(&inode->i_lock);
                         }
                 }
         }
 out_lock:
         spin_unlock(&dq_data_lock);
 out_put:
         /* Drop unused references */
         dqput_all(got);
 
         return ret;
 }
 
 int dquot_initialize(struct inode *inode)
 {
         return __dquot_initialize(inode, -1);
 }
 EXPORT_SYMBOL(dquot_initialize);
 
 bool dquot_initialize_needed(struct inode *inode)
 {
         struct dquot __rcu **dquots;
         int i;
 
         if (!inode_quota_active(inode))
                 return false;
 
         dquots = i_dquot(inode);
         for (i = 0; i < MAXQUOTAS; i++)
                 if (!dquots[i] && sb_has_quota_active(inode->i_sb, i))
                         return true;
         return false;
 }
 EXPORT_SYMBOL(dquot_initialize_needed);
 
 /*
  * Release all quotas referenced by inode.
  *
  * This function only be called on inode free or converting
  * a file to quota file, no other users for the i_dquot in
  * both cases, so we needn't call synchronize_srcu() after
  * clearing i_dquot.
  */
 static void __dquot_drop(struct inode *inode)
 {
         int cnt;
         struct dquot __rcu **dquots = i_dquot(inode);
         struct dquot *put[MAXQUOTAS];
 
         spin_lock(&dq_data_lock);
         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                 put[cnt] = srcu_dereference_check(dquots[cnt], &dquot_srcu,
                                         lockdep_is_held(&dq_data_lock));
                 rcu_assign_pointer(dquots[cnt], NULL);
         }
         spin_unlock(&dq_data_lock);
         dqput_all(put);
 }
 
 void dquot_drop(struct inode *inode)
 {
         struct dquot __rcu * const *dquots;
         int cnt;
 
         if (IS_NOQUOTA(inode))
                 return;
 
         /*
          * Test before calling to rule out calls from proc and such
          * where we are not allowed to block. Note that this is
          * actually reliable test even without the lock - the caller
          * must assure that nobody can come after the DQUOT_DROP and
          * add quota pointers back anyway.
          */
         dquots = i_dquot(inode);
         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                 if (dquots[cnt])
                         break;
         }
 
         if (cnt < MAXQUOTAS)
                 __dquot_drop(inode);
 }
 EXPORT_SYMBOL(dquot_drop);
 
 /*
  * inode_reserved_space is managed internally by quota, and protected by
  * i_lock similar to i_blocks+i_bytes.
  */
 static qsize_t *inode_reserved_space(struct inode * inode)
 {
         /* Filesystem must explicitly define it's own method in order to use
          * quota reservation interface */
         BUG_ON(!inode->i_sb->dq_op->get_reserved_space);
         return inode->i_sb->dq_op->get_reserved_space(inode);
 }
 
 static qsize_t __inode_get_rsv_space(struct inode *inode)
 {
         if (!inode->i_sb->dq_op->get_reserved_space)
                 return 0;
         return *inode_reserved_space(inode);
 }
 
 static qsize_t inode_get_rsv_space(struct inode *inode)
 {
         qsize_t ret;
 
         if (!inode->i_sb->dq_op->get_reserved_space)
                 return 0;
         spin_lock(&inode->i_lock);
         ret = __inode_get_rsv_space(inode);
         spin_unlock(&inode->i_lock);
         return ret;
 }
 
 /*
  * This functions updates i_blocks+i_bytes fields and quota information
  * (together with appropriate checks).
  *
  * NOTE: We absolutely rely on the fact that caller dirties the inode
  * (usually helpers in quotaops.h care about this) and holds a handle for
  * the current transaction so that dquot write and inode write go into the
  * same transaction.
  */
 
 /*
  * This operation can block, but only after everything is updated
  */
 int __dquot_alloc_space(struct inode *inode, qsize_t number, int flags)
 {
         int cnt, ret = 0, index;
         struct dquot_warn warn[MAXQUOTAS];
         int reserve = flags & DQUOT_SPACE_RESERVE;
         struct dquot __rcu **dquots;
         struct dquot *dquot;
 
         if (!inode_quota_active(inode)) {
                 if (reserve) {
                         spin_lock(&inode->i_lock);
                         *inode_reserved_space(inode) += number;
                         spin_unlock(&inode->i_lock);
                 } else {
                         inode_add_bytes(inode, number);
                 }
                 goto out;
         }
 
         for (cnt = 0; cnt < MAXQUOTAS; cnt++)
                 warn[cnt].w_type = QUOTA_NL_NOWARN;
 
         dquots = i_dquot(inode);
         index = srcu_read_lock(&dquot_srcu);
         spin_lock(&inode->i_lock);
         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                 dquot = srcu_dereference(dquots[cnt], &dquot_srcu);
                 if (!dquot)
                         continue;
                 if (reserve) {
                         ret = dquot_add_space(dquot, 0, number, flags, &warn[cnt]);
                 } else {
                         ret = dquot_add_space(dquot, number, 0, flags, &warn[cnt]);
                 }
                 if (ret) {
                         /* Back out changes we already did */
                         for (cnt--; cnt >= 0; cnt--) {
                                 dquot = srcu_dereference(dquots[cnt], &dquot_srcu);
                                 if (!dquot)
                                         continue;
                                 spin_lock(&dquot->dq_dqb_lock);
                                 if (reserve)
                                         dquot_free_reserved_space(dquot, number);
                                 else
                                         dquot_decr_space(dquot, number);
                                 spin_unlock(&dquot->dq_dqb_lock);
                         }
                         spin_unlock(&inode->i_lock);
                         goto out_flush_warn;
                 }
         }
         if (reserve)
                 *inode_reserved_space(inode) += number;
         else
                 __inode_add_bytes(inode, number);
         spin_unlock(&inode->i_lock);
 
         if (reserve)
                 goto out_flush_warn;
         ret = mark_all_dquot_dirty(dquots);
 out_flush_warn:
         srcu_read_unlock(&dquot_srcu, index);
         flush_warnings(warn);
 out:
         return ret;
 }
 EXPORT_SYMBOL(__dquot_alloc_space);
 
 /*
  * This operation can block, but only after everything is updated
  */
 int dquot_alloc_inode(struct inode *inode)
 {
         int cnt, ret = 0, index;
         struct dquot_warn warn[MAXQUOTAS];
         struct dquot __rcu * const *dquots;
         struct dquot *dquot;
 
         if (!inode_quota_active(inode))
                 return 0;
         for (cnt = 0; cnt < MAXQUOTAS; cnt++)
                 warn[cnt].w_type = QUOTA_NL_NOWARN;
 
         dquots = i_dquot(inode);
         index = srcu_read_lock(&dquot_srcu);
         spin_lock(&inode->i_lock);
         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                 dquot = srcu_dereference(dquots[cnt], &dquot_srcu);
                 if (!dquot)
                         continue;
                 ret = dquot_add_inodes(dquot, 1, &warn[cnt]);
                 if (ret) {
                         for (cnt--; cnt >= 0; cnt--) {
                                 dquot = srcu_dereference(dquots[cnt], &dquot_srcu);
                                 if (!dquot)
                                         continue;
                                 /* Back out changes we already did */
                                 spin_lock(&dquot->dq_dqb_lock);
                                 dquot_decr_inodes(dquot, 1);
                                 spin_unlock(&dquot->dq_dqb_lock);
                         }
                         goto warn_put_all;
                 }
         }
 
 warn_put_all:
         spin_unlock(&inode->i_lock);
         if (ret == 0)
                 ret = mark_all_dquot_dirty(dquots);
         srcu_read_unlock(&dquot_srcu, index);
         flush_warnings(warn);
         return ret;
 }
 EXPORT_SYMBOL(dquot_alloc_inode);
 
 /*
  * Convert in-memory reserved quotas to real consumed quotas
  */
 void dquot_claim_space_nodirty(struct inode *inode, qsize_t number)
 {
         struct dquot __rcu **dquots;
         struct dquot *dquot;
         int cnt, index;
 
         if (!inode_quota_active(inode)) {
                 spin_lock(&inode->i_lock);
                 *inode_reserved_space(inode) -= number;
                 __inode_add_bytes(inode, number);
                 spin_unlock(&inode->i_lock);
                 return;
         }
 
         dquots = i_dquot(inode);
         index = srcu_read_lock(&dquot_srcu);
         spin_lock(&inode->i_lock);
         /* Claim reserved quotas to allocated quotas */
         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                 dquot = srcu_dereference(dquots[cnt], &dquot_srcu);
                 if (dquot) {
                         spin_lock(&dquot->dq_dqb_lock);
                         if (WARN_ON_ONCE(dquot->dq_dqb.dqb_rsvspace < number))
                                 number = dquot->dq_dqb.dqb_rsvspace;
                         dquot->dq_dqb.dqb_curspace += number;
                         dquot->dq_dqb.dqb_rsvspace -= number;
                         spin_unlock(&dquot->dq_dqb_lock);
                 }
         }
         /* Update inode bytes */
         *inode_reserved_space(inode) -= number;
         __inode_add_bytes(inode, number);
         spin_unlock(&inode->i_lock);
         mark_all_dquot_dirty(dquots);
         srcu_read_unlock(&dquot_srcu, index);
         return;
 }
 EXPORT_SYMBOL(dquot_claim_space_nodirty);
 
 /*
  * Convert allocated space back to in-memory reserved quotas
  */
 void dquot_reclaim_space_nodirty(struct inode *inode, qsize_t number)
 {
         struct dquot __rcu **dquots;
         struct dquot *dquot;
         int cnt, index;
 
         if (!inode_quota_active(inode)) {
                 spin_lock(&inode->i_lock);
                 *inode_reserved_space(inode) += number;
                 __inode_sub_bytes(inode, number);
                 spin_unlock(&inode->i_lock);
                 return;
         }
 
         dquots = i_dquot(inode);
         index = srcu_read_lock(&dquot_srcu);
         spin_lock(&inode->i_lock);
         /* Claim reserved quotas to allocated quotas */
         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                 dquot = srcu_dereference(dquots[cnt], &dquot_srcu);
                 if (dquot) {
                         spin_lock(&dquot->dq_dqb_lock);
                         if (WARN_ON_ONCE(dquot->dq_dqb.dqb_curspace < number))
                                 number = dquot->dq_dqb.dqb_curspace;
                         dquot->dq_dqb.dqb_rsvspace += number;
                         dquot->dq_dqb.dqb_curspace -= number;
                         spin_unlock(&dquot->dq_dqb_lock);
                 }
         }
         /* Update inode bytes */
         *inode_reserved_space(inode) += number;
         __inode_sub_bytes(inode, number);
         spin_unlock(&inode->i_lock);
         mark_all_dquot_dirty(dquots);
         srcu_read_unlock(&dquot_srcu, index);
         return;
 }
 EXPORT_SYMBOL(dquot_reclaim_space_nodirty);
 
 /*
  * This operation can block, but only after everything is updated
  */
 void __dquot_free_space(struct inode *inode, qsize_t number, int flags)
 {
         unsigned int cnt;
         struct dquot_warn warn[MAXQUOTAS];
         struct dquot __rcu **dquots;
         struct dquot *dquot;
         int reserve = flags & DQUOT_SPACE_RESERVE, index;
 
         if (!inode_quota_active(inode)) {
                 if (reserve) {
                         spin_lock(&inode->i_lock);
                         *inode_reserved_space(inode) -= number;
                         spin_unlock(&inode->i_lock);
                 } else {
                         inode_sub_bytes(inode, number);
                 }
                 return;
         }
 
         dquots = i_dquot(inode);
         index = srcu_read_lock(&dquot_srcu);
         spin_lock(&inode->i_lock);
         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                 int wtype;
 
                 warn[cnt].w_type = QUOTA_NL_NOWARN;
                 dquot = srcu_dereference(dquots[cnt], &dquot_srcu);
                 if (!dquot)
                         continue;
                 spin_lock(&dquot->dq_dqb_lock);
                 wtype = info_bdq_free(dquot, number);
                 if (wtype != QUOTA_NL_NOWARN)
                         prepare_warning(&warn[cnt], dquot, wtype);
                 if (reserve)
                         dquot_free_reserved_space(dquot, number);
                 else
                         dquot_decr_space(dquot, number);
                 spin_unlock(&dquot->dq_dqb_lock);
         }
         if (reserve)
                 *inode_reserved_space(inode) -= number;
         else
                 __inode_sub_bytes(inode, number);
         spin_unlock(&inode->i_lock);
 
         if (reserve)
                 goto out_unlock;
         mark_all_dquot_dirty(dquots);
 out_unlock:
         srcu_read_unlock(&dquot_srcu, index);
         flush_warnings(warn);
 }
 EXPORT_SYMBOL(__dquot_free_space);
 
 /*
  * This operation can block, but only after everything is updated
  */
 void dquot_free_inode(struct inode *inode)
 {
         unsigned int cnt;
         struct dquot_warn warn[MAXQUOTAS];
         struct dquot __rcu * const *dquots;
         struct dquot *dquot;
         int index;
 
         if (!inode_quota_active(inode))
                 return;
 
         dquots = i_dquot(inode);
         index = srcu_read_lock(&dquot_srcu);
         spin_lock(&inode->i_lock);
         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                 int wtype;
                 warn[cnt].w_type = QUOTA_NL_NOWARN;
                 dquot = srcu_dereference(dquots[cnt], &dquot_srcu);
                 if (!dquot)
                         continue;
                 spin_lock(&dquot->dq_dqb_lock);
                 wtype = info_idq_free(dquot, 1);
                 if (wtype != QUOTA_NL_NOWARN)
                         prepare_warning(&warn[cnt], dquot, wtype);
                 dquot_decr_inodes(dquot, 1);
                 spin_unlock(&dquot->dq_dqb_lock);
         }
         spin_unlock(&inode->i_lock);
         mark_all_dquot_dirty(dquots);
         srcu_read_unlock(&dquot_srcu, index);
         flush_warnings(warn);
 }
 EXPORT_SYMBOL(dquot_free_inode);
 
 /*
  * Transfer the number of inode and blocks from one diskquota to an other.
  * On success, dquot references in transfer_to are consumed and references
  * to original dquots that need to be released are placed there. On failure,
  * references are kept untouched.
  *
  * This operation can block, but only after everything is updated
  * A transaction must be started when entering this function.
  *
  * We are holding reference on transfer_from & transfer_to, no need to
  * protect them by srcu_read_lock().
  */
 int __dquot_transfer(struct inode *inode, struct dquot **transfer_to)
 {
         qsize_t cur_space;
         qsize_t rsv_space = 0;
         qsize_t inode_usage = 1;
         struct dquot __rcu **dquots;
         struct dquot *transfer_from[MAXQUOTAS] = {};
         int cnt, index, ret = 0, err;
         char is_valid[MAXQUOTAS] = {};
         struct dquot_warn warn_to[MAXQUOTAS];
         struct dquot_warn warn_from_inodes[MAXQUOTAS];
         struct dquot_warn warn_from_space[MAXQUOTAS];
 
         if (IS_NOQUOTA(inode))
                 return 0;
 
         if (inode->i_sb->dq_op->get_inode_usage) {
                 ret = inode->i_sb->dq_op->get_inode_usage(inode, &inode_usage);
                 if (ret)
                         return ret;
         }
 
         /* Initialize the arrays */
         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                 warn_to[cnt].w_type = QUOTA_NL_NOWARN;
                 warn_from_inodes[cnt].w_type = QUOTA_NL_NOWARN;
                 warn_from_space[cnt].w_type = QUOTA_NL_NOWARN;
         }
 
         spin_lock(&dq_data_lock);
         spin_lock(&inode->i_lock);
         if (IS_NOQUOTA(inode)) {        /* File without quota accounting? */
                 spin_unlock(&inode->i_lock);
                 spin_unlock(&dq_data_lock);
                 return 0;
         }
         cur_space = __inode_get_bytes(inode);
         rsv_space = __inode_get_rsv_space(inode);
         dquots = i_dquot(inode);
         /*
          * Build the transfer_from list, check limits, and update usage in
          * the target structures.
          */
         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                 /*
                  * Skip changes for same uid or gid or for turned off quota-type.
                  */
                 if (!transfer_to[cnt])
                         continue;
                 /* Avoid races with quotaoff() */
                 if (!sb_has_quota_active(inode->i_sb, cnt))
                         continue;
                 is_valid[cnt] = 1;
                 transfer_from[cnt] = srcu_dereference_check(dquots[cnt],
                                 &dquot_srcu, lockdep_is_held(&dq_data_lock));
                 ret = dquot_add_inodes(transfer_to[cnt], inode_usage,
                                        &warn_to[cnt]);
                 if (ret)
                         goto over_quota;
                 ret = dquot_add_space(transfer_to[cnt], cur_space, rsv_space,
                                       DQUOT_SPACE_WARN, &warn_to[cnt]);
                 if (ret) {
                         spin_lock(&transfer_to[cnt]->dq_dqb_lock);
                         dquot_decr_inodes(transfer_to[cnt], inode_usage);
                         spin_unlock(&transfer_to[cnt]->dq_dqb_lock);
                         goto over_quota;
                 }
         }
 
         /* Decrease usage for source structures and update quota pointers */
         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                 if (!is_valid[cnt])
                         continue;
                 /* Due to IO error we might not have transfer_from[] structure */
                 if (transfer_from[cnt]) {
                         int wtype;
 
                         spin_lock(&transfer_from[cnt]->dq_dqb_lock);
                         wtype = info_idq_free(transfer_from[cnt], inode_usage);
                         if (wtype != QUOTA_NL_NOWARN)
                                 prepare_warning(&warn_from_inodes[cnt],
                                                 transfer_from[cnt], wtype);
                         wtype = info_bdq_free(transfer_from[cnt],
                                               cur_space + rsv_space);
                         if (wtype != QUOTA_NL_NOWARN)
                                 prepare_warning(&warn_from_space[cnt],
                                                 transfer_from[cnt], wtype);
                         dquot_decr_inodes(transfer_from[cnt], inode_usage);
                         dquot_decr_space(transfer_from[cnt], cur_space);
                         dquot_free_reserved_space(transfer_from[cnt],
                                                   rsv_space);
                         spin_unlock(&transfer_from[cnt]->dq_dqb_lock);
                 }
                 rcu_assign_pointer(dquots[cnt], transfer_to[cnt]);
         }
         spin_unlock(&inode->i_lock);
         spin_unlock(&dq_data_lock);
 
         /*
          * These arrays are local and we hold dquot references so we don't need
          * the srcu protection but still take dquot_srcu to avoid warning in
          * mark_all_dquot_dirty().
          */
         index = srcu_read_lock(&dquot_srcu);
         err = mark_all_dquot_dirty((struct dquot __rcu **)transfer_from);
         if (err < 0)
                 ret = err;
         err = mark_all_dquot_dirty((struct dquot __rcu **)transfer_to);
         if (err < 0)
                 ret = err;
         srcu_read_unlock(&dquot_srcu, index);
 
         flush_warnings(warn_to);
         flush_warnings(warn_from_inodes);
         flush_warnings(warn_from_space);
         /* Pass back references to put */
         for (cnt = 0; cnt < MAXQUOTAS; cnt++)
                 if (is_valid[cnt])
                         transfer_to[cnt] = transfer_from[cnt];
         return ret;
 over_quota:
         /* Back out changes we already did */
         for (cnt--; cnt >= 0; cnt--) {
                 if (!is_valid[cnt])
                         continue;
                 spin_lock(&transfer_to[cnt]->dq_dqb_lock);
                 dquot_decr_inodes(transfer_to[cnt], inode_usage);
                 dquot_decr_space(transfer_to[cnt], cur_space);
                 dquot_free_reserved_space(transfer_to[cnt], rsv_space);
                 spin_unlock(&transfer_to[cnt]->dq_dqb_lock);
         }
         spin_unlock(&inode->i_lock);
         spin_unlock(&dq_data_lock);
         flush_warnings(warn_to);
         return ret;
 }
 EXPORT_SYMBOL(__dquot_transfer);
 
 /* Wrapper for transferring ownership of an inode for uid/gid only
  * Called from FSXXX_setattr()
  */
 int dquot_transfer(struct mnt_idmap *idmap, struct inode *inode,
                    struct iattr *iattr)
 {
         struct dquot *transfer_to[MAXQUOTAS] = {};
         struct dquot *dquot;
         struct super_block *sb = inode->i_sb;
         int ret;
 
         if (!inode_quota_active(inode))
                 return 0;
 
         if (i_uid_needs_update(idmap, iattr, inode)) {
                 kuid_t kuid = from_vfsuid(idmap, i_user_ns(inode),
                                           iattr->ia_vfsuid);
 
                 dquot = dqget(sb, make_kqid_uid(kuid));
                 if (IS_ERR(dquot)) {
                         if (PTR_ERR(dquot) != -ESRCH) {
                                 ret = PTR_ERR(dquot);
                                 goto out_put;
                         }
                         dquot = NULL;
                 }
                 transfer_to[USRQUOTA] = dquot;
         }
         if (i_gid_needs_update(idmap, iattr, inode)) {
                 kgid_t kgid = from_vfsgid(idmap, i_user_ns(inode),
                                           iattr->ia_vfsgid);
 
                 dquot = dqget(sb, make_kqid_gid(kgid));
                 if (IS_ERR(dquot)) {
                         if (PTR_ERR(dquot) != -ESRCH) {
                                 ret = PTR_ERR(dquot);
                                 goto out_put;
                         }
                         dquot = NULL;
                 }
                 transfer_to[GRPQUOTA] = dquot;
         }
         ret = __dquot_transfer(inode, transfer_to);
 out_put:
         dqput_all(transfer_to);
         return ret;
 }
 EXPORT_SYMBOL(dquot_transfer);
 
 /*
  * Write info of quota file to disk
  */
 int dquot_commit_info(struct super_block *sb, int type)
 {
         struct quota_info *dqopt = sb_dqopt(sb);
 
         return dqopt->ops[type]->write_file_info(sb, type);
 }
 EXPORT_SYMBOL(dquot_commit_info);
 
 int dquot_get_next_id(struct super_block *sb, struct kqid *qid)
 {
         struct quota_info *dqopt = sb_dqopt(sb);
 
         if (!sb_has_quota_active(sb, qid->type))
                 return -ESRCH;
         if (!dqopt->ops[qid->type]->get_next_id)
                 return -ENOSYS;
         return dqopt->ops[qid->type]->get_next_id(sb, qid);
 }
 EXPORT_SYMBOL(dquot_get_next_id);
 
 /*
  * Definitions of diskquota operations.
  */
 const struct dquot_operations dquot_operations = {
         .write_dquot    = dquot_commit,
         .acquire_dquot  = dquot_acquire,
         .release_dquot  = dquot_release,
         .mark_dirty     = dquot_mark_dquot_dirty,
         .write_info     = dquot_commit_info,
         .alloc_dquot    = dquot_alloc,
         .destroy_dquot  = dquot_destroy,
         .get_next_id    = dquot_get_next_id,
 };
 EXPORT_SYMBOL(dquot_operations);
 
 /*
  * Generic helper for ->open on filesystems supporting disk quotas.
  */
 int dquot_file_open(struct inode *inode, struct file *file)
 {
         int error;
 
         error = generic_file_open(inode, file);
         if (!error && (file->f_mode & FMODE_WRITE))
                 error = dquot_initialize(inode);
         return error;
 }
 EXPORT_SYMBOL(dquot_file_open);
 
 static void vfs_cleanup_quota_inode(struct super_block *sb, int type)
 {
         struct quota_info *dqopt = sb_dqopt(sb);
         struct inode *inode = dqopt->files[type];
 
         if (!inode)
                 return;
         if (!(dqopt->flags & DQUOT_QUOTA_SYS_FILE)) {
                 inode_lock(inode);
                 inode->i_flags &= ~S_NOQUOTA;
                 inode_unlock(inode);
         }
         dqopt->files[type] = NULL;
         iput(inode);
 }
 
 /*
  * Turn quota off on a device. type == -1 ==> quotaoff for all types (umount)
  */
 int dquot_disable(struct super_block *sb, int type, unsigned int flags)
 {
         int cnt;
         struct quota_info *dqopt = sb_dqopt(sb);
 
         rwsem_assert_held_write(&sb->s_umount);
 
         /* Cannot turn off usage accounting without turning off limits, or
          * suspend quotas and simultaneously turn quotas off. */
         if ((flags & DQUOT_USAGE_ENABLED && !(flags & DQUOT_LIMITS_ENABLED))
             || (flags & DQUOT_SUSPENDED && flags & (DQUOT_LIMITS_ENABLED |
             DQUOT_USAGE_ENABLED)))
                 return -EINVAL;
 
         /*
          * Skip everything if there's nothing to do. We have to do this because
          * sometimes we are called when fill_super() failed and calling
          * sync_fs() in such cases does no good.
          */
         if (!sb_any_quota_loaded(sb))
                 return 0;
 
         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                 if (type != -1 && cnt != type)
                         continue;
                 if (!sb_has_quota_loaded(sb, cnt))
                         continue;
 
                 if (flags & DQUOT_SUSPENDED) {
                         spin_lock(&dq_state_lock);
                         dqopt->flags |=
                                 dquot_state_flag(DQUOT_SUSPENDED, cnt);
                         spin_unlock(&dq_state_lock);
                 } else {
                         spin_lock(&dq_state_lock);
                         dqopt->flags &= ~dquot_state_flag(flags, cnt);
                         /* Turning off suspended quotas? */
                         if (!sb_has_quota_loaded(sb, cnt) &&
                             sb_has_quota_suspended(sb, cnt)) {
                                 dqopt->flags &= ~dquot_state_flag(
                                                         DQUOT_SUSPENDED, cnt);
                                 spin_unlock(&dq_state_lock);
                                 vfs_cleanup_quota_inode(sb, cnt);
                                 continue;
                         }
                         spin_unlock(&dq_state_lock);
                 }
 
                 /* We still have to keep quota loaded? */
                 if (sb_has_quota_loaded(sb, cnt) && !(flags & DQUOT_SUSPENDED))
                         continue;
 
                 /* Note: these are blocking operations */
                 drop_dquot_ref(sb, cnt);
                 invalidate_dquots(sb, cnt);
                 /*
                  * Now all dquots should be invalidated, all writes done so we
                  * should be only users of the info. No locks needed.
                  */
                 if (info_dirty(&dqopt->info[cnt]))
                         sb->dq_op->write_info(sb, cnt);
                 if (dqopt->ops[cnt]->free_file_info)
                         dqopt->ops[cnt]->free_file_info(sb, cnt);
                 put_quota_format(dqopt->info[cnt].dqi_format);
                 dqopt->info[cnt].dqi_flags = 0;
                 dqopt->info[cnt].dqi_igrace = 0;
                 dqopt->info[cnt].dqi_bgrace = 0;
                 dqopt->ops[cnt] = NULL;
         }
 
         /* Skip syncing and setting flags if quota files are hidden */
         if (dqopt->flags & DQUOT_QUOTA_SYS_FILE)
                 goto put_inodes;
 
         /* Sync the superblock so that buffers with quota data are written to
          * disk (and so userspace sees correct data afterwards). */
         if (sb->s_op->sync_fs)
                 sb->s_op->sync_fs(sb, 1);
         sync_blockdev(sb->s_bdev);
         /* Now the quota files are just ordinary files and we can set the
          * inode flags back. Moreover we discard the pagecache so that
          * userspace sees the writes we did bypassing the pagecache. We
          * must also discard the blockdev buffers so that we see the
          * changes done by userspace on the next quotaon() */
         for (cnt = 0; cnt < MAXQUOTAS; cnt++)
                 if (!sb_has_quota_loaded(sb, cnt) && dqopt->files[cnt]) {
                         inode_lock(dqopt->files[cnt]);
                         truncate_inode_pages(&dqopt->files[cnt]->i_data, 0);
                         inode_unlock(dqopt->files[cnt]);
                 }
         if (sb->s_bdev)
                 invalidate_bdev(sb->s_bdev);
 put_inodes:
         /* We are done when suspending quotas */
         if (flags & DQUOT_SUSPENDED)
                 return 0;
 
         for (cnt = 0; cnt < MAXQUOTAS; cnt++)
                 if (!sb_has_quota_loaded(sb, cnt))
                         vfs_cleanup_quota_inode(sb, cnt);
         return 0;
 }
 EXPORT_SYMBOL(dquot_disable);
 
 int dquot_quota_off(struct super_block *sb, int type)
 {
         return dquot_disable(sb, type,
                              DQUOT_USAGE_ENABLED | DQUOT_LIMITS_ENABLED);
 }
 EXPORT_SYMBOL(dquot_quota_off);
 
 /*
  *      Turn quotas on on a device
  */
 
 static int vfs_setup_quota_inode(struct inode *inode, int type)
 {
         struct super_block *sb = inode->i_sb;
         struct quota_info *dqopt = sb_dqopt(sb);
 
         if (is_bad_inode(inode))
                 return -EUCLEAN;
         if (!S_ISREG(inode->i_mode))
                 return -EACCES;
         if (IS_RDONLY(inode))
                 return -EROFS;
         if (sb_has_quota_loaded(sb, type))
                 return -EBUSY;
 
         /*
          * Quota files should never be encrypted.  They should be thought of as
          * filesystem metadata, not user data.  New-style internal quota files
          * cannot be encrypted by users anyway, but old-style external quota
          * files could potentially be incorrectly created in an encrypted
          * directory, hence this explicit check.  Some reasons why encrypted
          * quota files don't work include: (1) some filesystems that support
          * encryption don't handle it in their quota_read and quota_write, and
          * (2) cleaning up encrypted quota files at unmount would need special
          * consideration, as quota files are cleaned up later than user files.
          */
         if (IS_ENCRYPTED(inode))
                 return -EINVAL;
 
         dqopt->files[type] = igrab(inode);
         if (!dqopt->files[type])
                 return -EIO;
         if (!(dqopt->flags & DQUOT_QUOTA_SYS_FILE)) {
                 /* We don't want quota and atime on quota files (deadlocks
                  * possible) Also nobody should write to the file - we use
                  * special IO operations which ignore the immutable bit. */
                 inode_lock(inode);
                 inode->i_flags |= S_NOQUOTA;
                 inode_unlock(inode);
                 /*
                  * When S_NOQUOTA is set, remove dquot references as no more
                  * references can be added
                  */
                 __dquot_drop(inode);
         }
         return 0;
 }
 
 int dquot_load_quota_sb(struct super_block *sb, int type, int format_id,
         unsigned int flags)
 {
         struct quota_format_type *fmt;
         struct quota_info *dqopt = sb_dqopt(sb);
         int error;
 
         lockdep_assert_held_write(&sb->s_umount);
 
         /* Just unsuspend quotas? */
         if (WARN_ON_ONCE(flags & DQUOT_SUSPENDED))
                 return -EINVAL;
 
         fmt = find_quota_format(format_id);
         if (!fmt)
                 return -ESRCH;
         if (!sb->dq_op || !sb->s_qcop ||
             (type == PRJQUOTA && sb->dq_op->get_projid == NULL)) {
                 error = -EINVAL;
                 goto out_fmt;
         }
         /* Filesystems outside of init_user_ns not yet supported */
         if (sb->s_user_ns != &init_user_ns) {
                 error = -EINVAL;
                 goto out_fmt;
         }
         /* Usage always has to be set... */
         if (!(flags & DQUOT_USAGE_ENABLED)) {
                 error = -EINVAL;
                 goto out_fmt;
         }
         if (sb_has_quota_loaded(sb, type)) {
                 error = -EBUSY;
                 goto out_fmt;
         }
 
         if (!(dqopt->flags & DQUOT_QUOTA_SYS_FILE)) {
                 /* As we bypass the pagecache we must now flush all the
                  * dirty data and invalidate caches so that kernel sees
                  * changes from userspace. It is not enough to just flush
                  * the quota file since if blocksize < pagesize, invalidation
                  * of the cache could fail because of other unrelated dirty
                  * data */
                 sync_filesystem(sb);
                 invalidate_bdev(sb->s_bdev);
         }
 
         error = -EINVAL;
         if (!fmt->qf_ops->check_quota_file(sb, type))
                 goto out_fmt;
 
         dqopt->ops[type] = fmt->qf_ops;
         dqopt->info[type].dqi_format = fmt;
         dqopt->info[type].dqi_fmt_id = format_id;
         INIT_LIST_HEAD(&dqopt->info[type].dqi_dirty_list);
         error = dqopt->ops[type]->read_file_info(sb, type);
         if (error < 0)
                 goto out_fmt;
         if (dqopt->flags & DQUOT_QUOTA_SYS_FILE) {
                 spin_lock(&dq_data_lock);
                 dqopt->info[type].dqi_flags |= DQF_SYS_FILE;
                 spin_unlock(&dq_data_lock);
         }
         spin_lock(&dq_state_lock);
         dqopt->flags |= dquot_state_flag(flags, type);
         spin_unlock(&dq_state_lock);
 
         error = add_dquot_ref(sb, type);
         if (error)
                 dquot_disable(sb, type,
                               DQUOT_USAGE_ENABLED | DQUOT_LIMITS_ENABLED);
 
         return error;
 out_fmt:
         put_quota_format(fmt);
 
         return error;
 }
 EXPORT_SYMBOL(dquot_load_quota_sb);
 
 /*
  * More powerful function for turning on quotas on given quota inode allowing
  * setting of individual quota flags
  */
 int dquot_load_quota_inode(struct inode *inode, int type, int format_id,
         unsigned int flags)
 {
         int err;
 
         err = vfs_setup_quota_inode(inode, type);
         if (err < 0)
                 return err;
         err = dquot_load_quota_sb(inode->i_sb, type, format_id, flags);
         if (err < 0)
                 vfs_cleanup_quota_inode(inode->i_sb, type);
         return err;
 }
 EXPORT_SYMBOL(dquot_load_quota_inode);
 
 /* Reenable quotas on remount RW */
 int dquot_resume(struct super_block *sb, int type)
 {
         struct quota_info *dqopt = sb_dqopt(sb);
         int ret = 0, cnt;
         unsigned int flags;
 
         rwsem_assert_held_write(&sb->s_umount);
 
         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                 if (type != -1 && cnt != type)
                         continue;
                 if (!sb_has_quota_suspended(sb, cnt))
                         continue;
 
                 spin_lock(&dq_state_lock);
                 flags = dqopt->flags & dquot_state_flag(DQUOT_USAGE_ENABLED |
                                                         DQUOT_LIMITS_ENABLED,
                                                         cnt);
                 dqopt->flags &= ~dquot_state_flag(DQUOT_STATE_FLAGS, cnt);
                 spin_unlock(&dq_state_lock);
 
                 flags = dquot_generic_flag(flags, cnt);
                 ret = dquot_load_quota_sb(sb, cnt, dqopt->info[cnt].dqi_fmt_id,
                                           flags);
                 if (ret < 0)
                         vfs_cleanup_quota_inode(sb, cnt);
         }
 
         return ret;
 }
 EXPORT_SYMBOL(dquot_resume);
 
 int dquot_quota_on(struct super_block *sb, int type, int format_id,
                    const struct path *path)
 {
         int error = security_quota_on(path->dentry);
         if (error)
                 return error;
         /* Quota file not on the same filesystem? */
         if (path->dentry->d_sb != sb)
                 error = -EXDEV;
         else
                 error = dquot_load_quota_inode(d_inode(path->dentry), type,
                                              format_id, DQUOT_USAGE_ENABLED |
                                              DQUOT_LIMITS_ENABLED);
         return error;
 }
 EXPORT_SYMBOL(dquot_quota_on);
 
 /*
  * This function is used when filesystem needs to initialize quotas
  * during mount time.
  */
 int dquot_quota_on_mount(struct super_block *sb, char *qf_name,
                 int format_id, int type)
 {
         struct dentry *dentry;
         int error;
 
         dentry = lookup_positive_unlocked(qf_name, sb->s_root, strlen(qf_name));
         if (IS_ERR(dentry))
                 return PTR_ERR(dentry);
 
         error = security_quota_on(dentry);
         if (!error)
                 error = dquot_load_quota_inode(d_inode(dentry), type, format_id,
                                 DQUOT_USAGE_ENABLED | DQUOT_LIMITS_ENABLED);
 
         dput(dentry);
         return error;
 }
 EXPORT_SYMBOL(dquot_quota_on_mount);
 
 static int dquot_quota_enable(struct super_block *sb, unsigned int flags)
 {
         int ret;
         int type;
         struct quota_info *dqopt = sb_dqopt(sb);
 
         if (!(dqopt->flags & DQUOT_QUOTA_SYS_FILE))
                 return -ENOSYS;
         /* Accounting cannot be turned on while fs is mounted */
         flags &= ~(FS_QUOTA_UDQ_ACCT | FS_QUOTA_GDQ_ACCT | FS_QUOTA_PDQ_ACCT);
         if (!flags)
                 return -EINVAL;
         for (type = 0; type < MAXQUOTAS; type++) {
                 if (!(flags & qtype_enforce_flag(type)))
                         continue;
                 /* Can't enforce without accounting */
                 if (!sb_has_quota_usage_enabled(sb, type)) {
                         ret = -EINVAL;
                         goto out_err;
                 }
                 if (sb_has_quota_limits_enabled(sb, type)) {
                         ret = -EBUSY;
                         goto out_err;
                 }
                 spin_lock(&dq_state_lock);
                 dqopt->flags |= dquot_state_flag(DQUOT_LIMITS_ENABLED, type);
                 spin_unlock(&dq_state_lock);
         }
         return 0;
 out_err:
         /* Backout enforcement enablement we already did */
         for (type--; type >= 0; type--)  {
                 if (flags & qtype_enforce_flag(type))
                         dquot_disable(sb, type, DQUOT_LIMITS_ENABLED);
         }
         /* Error code translation for better compatibility with XFS */
         if (ret == -EBUSY)
                 ret = -EEXIST;
         return ret;
 }
 
 static int dquot_quota_disable(struct super_block *sb, unsigned int flags)
 {
         int ret;
         int type;
         struct quota_info *dqopt = sb_dqopt(sb);
 
         if (!(dqopt->flags & DQUOT_QUOTA_SYS_FILE))
                 return -ENOSYS;
         /*
          * We don't support turning off accounting via quotactl. In principle
          * quota infrastructure can do this but filesystems don't expect
          * userspace to be able to do it.
          */
         if (flags &
                   (FS_QUOTA_UDQ_ACCT | FS_QUOTA_GDQ_ACCT | FS_QUOTA_PDQ_ACCT))
                 return -EOPNOTSUPP;
 
         /* Filter out limits not enabled */
         for (type = 0; type < MAXQUOTAS; type++)
                 if (!sb_has_quota_limits_enabled(sb, type))
                         flags &= ~qtype_enforce_flag(type);
         /* Nothing left? */
         if (!flags)
                 return -EEXIST;
         for (type = 0; type < MAXQUOTAS; type++) {
                 if (flags & qtype_enforce_flag(type)) {
                         ret = dquot_disable(sb, type, DQUOT_LIMITS_ENABLED);
                         if (ret < 0)
                                 goto out_err;
                 }
         }
         return 0;
 out_err:
         /* Backout enforcement disabling we already did */
         for (type--; type >= 0; type--)  {
                 if (flags & qtype_enforce_flag(type)) {
                         spin_lock(&dq_state_lock);
                         dqopt->flags |=
                                 dquot_state_flag(DQUOT_LIMITS_ENABLED, type);
                         spin_unlock(&dq_state_lock);
                 }
         }
         return ret;
 }
 
 /* Generic routine for getting common part of quota structure */
 static void do_get_dqblk(struct dquot *dquot, struct qc_dqblk *di)
 {
         struct mem_dqblk *dm = &dquot->dq_dqb;
 
         memset(di, 0, sizeof(*di));
         spin_lock(&dquot->dq_dqb_lock);
         di->d_spc_hardlimit = dm->dqb_bhardlimit;
         di->d_spc_softlimit = dm->dqb_bsoftlimit;
         di->d_ino_hardlimit = dm->dqb_ihardlimit;
         di->d_ino_softlimit = dm->dqb_isoftlimit;
         di->d_space = dm->dqb_curspace + dm->dqb_rsvspace;
         di->d_ino_count = dm->dqb_curinodes;
         di->d_spc_timer = dm->dqb_btime;
         di->d_ino_timer = dm->dqb_itime;
         spin_unlock(&dquot->dq_dqb_lock);
 }
 
 int dquot_get_dqblk(struct super_block *sb, struct kqid qid,
                     struct qc_dqblk *di)
 {
         struct dquot *dquot;
 
         dquot = dqget(sb, qid);
         if (IS_ERR(dquot))
                 return PTR_ERR(dquot);
         do_get_dqblk(dquot, di);
         dqput(dquot);
 
         return 0;
 }
 EXPORT_SYMBOL(dquot_get_dqblk);
 
 int dquot_get_next_dqblk(struct super_block *sb, struct kqid *qid,
                          struct qc_dqblk *di)
 {
         struct dquot *dquot;
         int err;
 
         if (!sb->dq_op->get_next_id)
                 return -ENOSYS;
         err = sb->dq_op->get_next_id(sb, qid);
         if (err < 0)
                 return err;
         dquot = dqget(sb, *qid);
         if (IS_ERR(dquot))
                 return PTR_ERR(dquot);
         do_get_dqblk(dquot, di);
         dqput(dquot);
 
         return 0;
 }
 EXPORT_SYMBOL(dquot_get_next_dqblk);
 
 #define VFS_QC_MASK \
         (QC_SPACE | QC_SPC_SOFT | QC_SPC_HARD | \
          QC_INO_COUNT | QC_INO_SOFT | QC_INO_HARD | \
          QC_SPC_TIMER | QC_INO_TIMER)
 
 /* Generic routine for setting common part of quota structure */
 static int do_set_dqblk(struct dquot *dquot, struct qc_dqblk *di)
 {
         struct mem_dqblk *dm = &dquot->dq_dqb;
         int check_blim = 0, check_ilim = 0;
         struct mem_dqinfo *dqi = &sb_dqopt(dquot->dq_sb)->info[dquot->dq_id.type];
         int ret;
 
         if (di->d_fieldmask & ~VFS_QC_MASK)
                 return -EINVAL;
 
         if (((di->d_fieldmask & QC_SPC_SOFT) &&
              di->d_spc_softlimit > dqi->dqi_max_spc_limit) ||
             ((di->d_fieldmask & QC_SPC_HARD) &&
              di->d_spc_hardlimit > dqi->dqi_max_spc_limit) ||
             ((di->d_fieldmask & QC_INO_SOFT) &&
              (di->d_ino_softlimit > dqi->dqi_max_ino_limit)) ||
             ((di->d_fieldmask & QC_INO_HARD) &&
              (di->d_ino_hardlimit > dqi->dqi_max_ino_limit)))
                 return -ERANGE;
 
         spin_lock(&dquot->dq_dqb_lock);
         if (di->d_fieldmask & QC_SPACE) {
                 dm->dqb_curspace = di->d_space - dm->dqb_rsvspace;
                 check_blim = 1;
                 set_bit(DQ_LASTSET_B + QIF_SPACE_B, &dquot->dq_flags);
         }
 
         if (di->d_fieldmask & QC_SPC_SOFT)
                 dm->dqb_bsoftlimit = di->d_spc_softlimit;
         if (di->d_fieldmask & QC_SPC_HARD)
                 dm->dqb_bhardlimit = di->d_spc_hardlimit;
         if (di->d_fieldmask & (QC_SPC_SOFT | QC_SPC_HARD)) {
                 check_blim = 1;
                 set_bit(DQ_LASTSET_B + QIF_BLIMITS_B, &dquot->dq_flags);
         }
 
         if (di->d_fieldmask & QC_INO_COUNT) {
                 dm->dqb_curinodes = di->d_ino_count;
                 check_ilim = 1;
                 set_bit(DQ_LASTSET_B + QIF_INODES_B, &dquot->dq_flags);
         }
 
         if (di->d_fieldmask & QC_INO_SOFT)
                 dm->dqb_isoftlimit = di->d_ino_softlimit;
         if (di->d_fieldmask & QC_INO_HARD)
                 dm->dqb_ihardlimit = di->d_ino_hardlimit;
         if (di->d_fieldmask & (QC_INO_SOFT | QC_INO_HARD)) {
                 check_ilim = 1;
                 set_bit(DQ_LASTSET_B + QIF_ILIMITS_B, &dquot->dq_flags);
         }
 
         if (di->d_fieldmask & QC_SPC_TIMER) {
                 dm->dqb_btime = di->d_spc_timer;
                 check_blim = 1;
                 set_bit(DQ_LASTSET_B + QIF_BTIME_B, &dquot->dq_flags);
         }
 
         if (di->d_fieldmask & QC_INO_TIMER) {
                 dm->dqb_itime = di->d_ino_timer;
                 check_ilim = 1;
                 set_bit(DQ_LASTSET_B + QIF_ITIME_B, &dquot->dq_flags);
         }
 
         if (check_blim) {
                 if (!dm->dqb_bsoftlimit ||
                     dm->dqb_curspace + dm->dqb_rsvspace <= dm->dqb_bsoftlimit) {
                         dm->dqb_btime = 0;
                         clear_bit(DQ_BLKS_B, &dquot->dq_flags);
                 } else if (!(di->d_fieldmask & QC_SPC_TIMER))
                         /* Set grace only if user hasn't provided his own... */
                         dm->dqb_btime = ktime_get_real_seconds() + dqi->dqi_bgrace;
         }
         if (check_ilim) {
                 if (!dm->dqb_isoftlimit ||
                     dm->dqb_curinodes <= dm->dqb_isoftlimit) {
                         dm->dqb_itime = 0;
                         clear_bit(DQ_INODES_B, &dquot->dq_flags);
                 } else if (!(di->d_fieldmask & QC_INO_TIMER))
                         /* Set grace only if user hasn't provided his own... */
                         dm->dqb_itime = ktime_get_real_seconds() + dqi->dqi_igrace;
         }
         if (dm->dqb_bhardlimit || dm->dqb_bsoftlimit || dm->dqb_ihardlimit ||
             dm->dqb_isoftlimit)
                 clear_bit(DQ_FAKE_B, &dquot->dq_flags);
         else
                 set_bit(DQ_FAKE_B, &dquot->dq_flags);
         spin_unlock(&dquot->dq_dqb_lock);
         ret = mark_dquot_dirty(dquot);
         if (ret < 0)
                 return ret;
         return 0;
 }
 
 int dquot_set_dqblk(struct super_block *sb, struct kqid qid,
                   struct qc_dqblk *di)
 {
         struct dquot *dquot;
         int rc;
 
         dquot = dqget(sb, qid);
         if (IS_ERR(dquot)) {
                 rc = PTR_ERR(dquot);
                 goto out;
         }
         rc = do_set_dqblk(dquot, di);
         dqput(dquot);
 out:
         return rc;
 }
 EXPORT_SYMBOL(dquot_set_dqblk);
 
 /* Generic routine for getting common part of quota file information */
 int dquot_get_state(struct super_block *sb, struct qc_state *state)
 {
         struct mem_dqinfo *mi;
         struct qc_type_state *tstate;
         struct quota_info *dqopt = sb_dqopt(sb);
         int type;
 
         memset(state, 0, sizeof(*state));
         for (type = 0; type < MAXQUOTAS; type++) {
                 if (!sb_has_quota_active(sb, type))
                         continue;
                 tstate = state->s_state + type;
                 mi = sb_dqopt(sb)->info + type;
                 tstate->flags = QCI_ACCT_ENABLED;
                 spin_lock(&dq_data_lock);
                 if (mi->dqi_flags & DQF_SYS_FILE)
                         tstate->flags |= QCI_SYSFILE;
                 if (mi->dqi_flags & DQF_ROOT_SQUASH)
                         tstate->flags |= QCI_ROOT_SQUASH;
                 if (sb_has_quota_limits_enabled(sb, type))
                         tstate->flags |= QCI_LIMITS_ENFORCED;
                 tstate->spc_timelimit = mi->dqi_bgrace;
                 tstate->ino_timelimit = mi->dqi_igrace;
                 if (dqopt->files[type]) {
                         tstate->ino = dqopt->files[type]->i_ino;
                         tstate->blocks = dqopt->files[type]->i_blocks;
                 }
                 tstate->nextents = 1;   /* We don't know... */
                 spin_unlock(&dq_data_lock);
         }
         return 0;
 }
 EXPORT_SYMBOL(dquot_get_state);
 
 /* Generic routine for setting common part of quota file information */
 int dquot_set_dqinfo(struct super_block *sb, int type, struct qc_info *ii)
 {
         struct mem_dqinfo *mi;
 
         if ((ii->i_fieldmask & QC_WARNS_MASK) ||
             (ii->i_fieldmask & QC_RT_SPC_TIMER))
                 return -EINVAL;
         if (!sb_has_quota_active(sb, type))
                 return -ESRCH;
         mi = sb_dqopt(sb)->info + type;
         if (ii->i_fieldmask & QC_FLAGS) {
                 if ((ii->i_flags & QCI_ROOT_SQUASH &&
                      mi->dqi_format->qf_fmt_id != QFMT_VFS_OLD))
                         return -EINVAL;
         }
         spin_lock(&dq_data_lock);
         if (ii->i_fieldmask & QC_SPC_TIMER)
                 mi->dqi_bgrace = ii->i_spc_timelimit;
         if (ii->i_fieldmask & QC_INO_TIMER)
                 mi->dqi_igrace = ii->i_ino_timelimit;
         if (ii->i_fieldmask & QC_FLAGS) {
                 if (ii->i_flags & QCI_ROOT_SQUASH)
                         mi->dqi_flags |= DQF_ROOT_SQUASH;
                 else
                         mi->dqi_flags &= ~DQF_ROOT_SQUASH;
         }
         spin_unlock(&dq_data_lock);
         mark_info_dirty(sb, type);
         /* Force write to disk */
         return sb->dq_op->write_info(sb, type);
 }
 EXPORT_SYMBOL(dquot_set_dqinfo);
 
 const struct quotactl_ops dquot_quotactl_sysfile_ops = {
         .quota_enable   = dquot_quota_enable,
         .quota_disable  = dquot_quota_disable,
         .quota_sync     = dquot_quota_sync,
         .get_state      = dquot_get_state,
         .set_info       = dquot_set_dqinfo,
         .get_dqblk      = dquot_get_dqblk,
         .get_nextdqblk  = dquot_get_next_dqblk,
         .set_dqblk      = dquot_set_dqblk
 };
 EXPORT_SYMBOL(dquot_quotactl_sysfile_ops);
 
 static int do_proc_dqstats(const struct ctl_table *table, int write,
                      void *buffer, size_t *lenp, loff_t *ppos)
 {
         unsigned int type = (unsigned long *)table->data - dqstats.stat;
         s64 value = percpu_counter_sum(&dqstats.counter[type]);
 
         /* Filter negative values for non-monotonic counters */
         if (value < 0 && (type == DQST_ALLOC_DQUOTS ||
                           type == DQST_FREE_DQUOTS))
                 value = 0;
 
         /* Update global table */
         dqstats.stat[type] = value;
         return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
 }
 
 static struct ctl_table fs_dqstats_table[] = {
         {
                 .procname       = "lookups",
                 .data           = &dqstats.stat[DQST_LOOKUPS],
                 .maxlen         = sizeof(unsigned long),
                 .mode           = 0444,
                 .proc_handler   = do_proc_dqstats,
         },
         {
                 .procname       = "drops",
                 .data           = &dqstats.stat[DQST_DROPS],
                 .maxlen         = sizeof(unsigned long),
                 .mode           = 0444,
                 .proc_handler   = do_proc_dqstats,
         },
         {
                 .procname       = "reads",
                 .data           = &dqstats.stat[DQST_READS],
                 .maxlen         = sizeof(unsigned long),
                 .mode           = 0444,
                 .proc_handler   = do_proc_dqstats,
         },
         {
                 .procname       = "writes",
                 .data           = &dqstats.stat[DQST_WRITES],
                 .maxlen         = sizeof(unsigned long),
                 .mode           = 0444,
                 .proc_handler   = do_proc_dqstats,
         },
         {
                 .procname       = "cache_hits",
                 .data           = &dqstats.stat[DQST_CACHE_HITS],
                 .maxlen         = sizeof(unsigned long),
                 .mode           = 0444,
                 .proc_handler   = do_proc_dqstats,
         },
         {
                 .procname       = "allocated_dquots",
                 .data           = &dqstats.stat[DQST_ALLOC_DQUOTS],
                 .maxlen         = sizeof(unsigned long),
                 .mode           = 0444,
                 .proc_handler   = do_proc_dqstats,
         },
         {
                 .procname       = "free_dquots",
                 .data           = &dqstats.stat[DQST_FREE_DQUOTS],
                 .maxlen         = sizeof(unsigned long),
                 .mode           = 0444,
                 .proc_handler   = do_proc_dqstats,
         },
         {
                 .procname       = "syncs",
                 .data           = &dqstats.stat[DQST_SYNCS],
                 .maxlen         = sizeof(unsigned long),
                 .mode           = 0444,
                 .proc_handler   = do_proc_dqstats,
         },
 #ifdef CONFIG_PRINT_QUOTA_WARNING
         {
                 .procname       = "warnings",
                 .data           = &flag_print_warnings,
                 .maxlen         = sizeof(int),
                 .mode           = 0644,
                 .proc_handler   = proc_dointvec,
         },
 #endif
 };
 
 static int __init dquot_init(void)
 {
         int i, ret;
         unsigned long nr_hash, order;
         struct shrinker *dqcache_shrinker;
 
         printk(KERN_NOTICE "VFS: Disk quotas %s\n", __DQUOT_VERSION__);
 
         register_sysctl_init("fs/quota", fs_dqstats_table);
 
         dquot_cachep = kmem_cache_create("dquot",
                         sizeof(struct dquot), sizeof(unsigned long) * 4,
                         (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
                                 SLAB_PANIC),
                         NULL);
 
         order = 0;
         dquot_hash = (struct hlist_head *)__get_free_pages(GFP_KERNEL, order);
         if (!dquot_hash)
                 panic("Cannot create dquot hash table");
 
         ret = percpu_counter_init_many(dqstats.counter, 0, GFP_KERNEL,
                                        _DQST_DQSTAT_LAST);
         if (ret)
                 panic("Cannot create dquot stat counters");
 
         /* Find power-of-two hlist_heads which can fit into allocation */
         nr_hash = (1UL << order) * PAGE_SIZE / sizeof(struct hlist_head);
         dq_hash_bits = ilog2(nr_hash);
 
         nr_hash = 1UL << dq_hash_bits;
         dq_hash_mask = nr_hash - 1;
         for (i = 0; i < nr_hash; i++)
                 INIT_HLIST_HEAD(dquot_hash + i);
 
         pr_info("VFS: Dquot-cache hash table entries: %ld (order %ld,"
                 " %ld bytes)\n", nr_hash, order, (PAGE_SIZE << order));
 
         dqcache_shrinker = shrinker_alloc(0, "dquota-cache");
         if (!dqcache_shrinker)
                 panic("Cannot allocate dquot shrinker");
 
         dqcache_shrinker->count_objects = dqcache_shrink_count;
         dqcache_shrinker->scan_objects = dqcache_shrink_scan;
 
         shrinker_register(dqcache_shrinker);
 
         return 0;
 }
 fs_initcall(dquot_init);
 

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