1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Cache operations for Coda.
4 * For Linux 2.1: (C) 1997 Carnegie Mellon University
5 * For Linux 2.3: (C) 2000 Carnegie Mellon University
6 *
7 * Carnegie Mellon encourages users of this code to contribute improvements
8 * to the Coda project http://www.coda.cs.cmu.edu/ <coda@cs.cmu.edu>.
9 */
10
11 #include <linux/types.h>
12 #include <linux/kernel.h>
13 #include <linux/time.h>
14 #include <linux/fs.h>
15 #include <linux/stat.h>
16 #include <linux/errno.h>
17 #include <linux/uaccess.h>
18 #include <linux/string.h>
19 #include <linux/list.h>
20 #include <linux/sched.h>
21 #include <linux/spinlock.h>
22
23 #include <linux/coda.h>
24 #include "coda_psdev.h"
25 #include "coda_linux.h"
26 #include "coda_cache.h"
27
28 static atomic_t permission_epoch = ATOMIC_INIT(0);
29
30 /* replace or extend an acl cache hit */
31 void coda_cache_enter(struct inode *inode, int mask)
32 {
33 struct coda_inode_info *cii = ITOC(inode);
34
35 spin_lock(&cii->c_lock);
36 cii->c_cached_epoch = atomic_read(&permission_epoch);
37 if (!uid_eq(cii->c_uid, current_fsuid())) {
38 cii->c_uid = current_fsuid();
39 cii->c_cached_perm = mask;
40 } else
41 cii->c_cached_perm |= mask;
42 spin_unlock(&cii->c_lock);
43 }
44
45 /* remove cached acl from an inode */
46 void coda_cache_clear_inode(struct inode *inode)
47 {
48 struct coda_inode_info *cii = ITOC(inode);
49 spin_lock(&cii->c_lock);
50 cii->c_cached_epoch = atomic_read(&permission_epoch) - 1;
51 spin_unlock(&cii->c_lock);
52 }
53
54 /* remove all acl caches */
55 void coda_cache_clear_all(struct super_block *sb)
56 {
57 atomic_inc(&permission_epoch);
58 }
59
60
61 /* check if the mask has been matched against the acl already */
62 int coda_cache_check(struct inode *inode, int mask)
63 {
64 struct coda_inode_info *cii = ITOC(inode);
65 int hit;
66
67 spin_lock(&cii->c_lock);
68 hit = (mask & cii->c_cached_perm) == mask &&
69 uid_eq(cii->c_uid, current_fsuid()) &&
70 cii->c_cached_epoch == atomic_read(&permission_epoch);
71 spin_unlock(&cii->c_lock);
72
73 return hit;
74 }
75
76
77 /* Purging dentries and children */
78 /* The following routines drop dentries which are not
79 in use and flag dentries which are in use to be
80 zapped later.
81
82 The flags are detected by:
83 - coda_dentry_revalidate (for lookups) if the flag is C_PURGE
84 - coda_dentry_delete: to remove dentry from the cache when d_count
85 falls to zero
86 - an inode method coda_revalidate (for attributes) if the
87 flag is C_VATTR
88 */
89
90 /* this won't do any harm: just flag all children */
91 static void coda_flag_children(struct dentry *parent, int flag)
92 {
93 struct dentry *de;
94
95 spin_lock(&parent->d_lock);
96 hlist_for_each_entry(de, &parent->d_children, d_sib) {
97 struct inode *inode = d_inode_rcu(de);
98 /* don't know what to do with negative dentries */
99 if (inode)
100 coda_flag_inode(inode, flag);
101 }
102 spin_unlock(&parent->d_lock);
103 }
104
105 void coda_flag_inode_children(struct inode *inode, int flag)
106 {
107 struct dentry *alias_de;
108
109 if ( !inode || !S_ISDIR(inode->i_mode))
110 return;
111
112 alias_de = d_find_alias(inode);
113 if (!alias_de)
114 return;
115 coda_flag_children(alias_de, flag);
116 shrink_dcache_parent(alias_de);
117 dput(alias_de);
118 }
119
120
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