1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (c) 2000-2001 Christoph Hellwig.
4 * Copyright (c) 2016 Krzysztof Blaszkowski
5 */
6
7 /*
8 * Veritas filesystem driver - lookup and other directory related code.
9 */
10 #include <linux/fs.h>
11 #include <linux/time.h>
12 #include <linux/mm.h>
13 #include <linux/highmem.h>
14 #include <linux/kernel.h>
15 #include <linux/pagemap.h>
16
17 #include "vxfs.h"
18 #include "vxfs_dir.h"
19 #include "vxfs_inode.h"
20 #include "vxfs_extern.h"
21
22 /*
23 * Number of VxFS blocks per page.
24 */
25 #define VXFS_BLOCK_PER_PAGE(sbp) ((PAGE_SIZE / (sbp)->s_blocksize))
26
27
28 static struct dentry * vxfs_lookup(struct inode *, struct dentry *, unsigned int);
29 static int vxfs_readdir(struct file *, struct dir_context *);
30
31 const struct inode_operations vxfs_dir_inode_ops = {
32 .lookup = vxfs_lookup,
33 };
34
35 const struct file_operations vxfs_dir_operations = {
36 .llseek = generic_file_llseek,
37 .read = generic_read_dir,
38 .iterate_shared = vxfs_readdir,
39 };
40
41
42 /**
43 * vxfs_find_entry - find a mathing directory entry for a dentry
44 * @ip: directory inode
45 * @dp: dentry for which we want to find a direct
46 * @ppp: gets filled with the page the return value sits in
47 *
48 * Description:
49 * vxfs_find_entry finds a &struct vxfs_direct for the VFS directory
50 * cache entry @dp. @ppp will be filled with the page the return
51 * value resides in.
52 *
53 * Returns:
54 * The wanted direct on success, else a NULL pointer.
55 */
56 static struct vxfs_direct *
57 vxfs_find_entry(struct inode *ip, struct dentry *dp, struct page **ppp)
58 {
59 u_long bsize = ip->i_sb->s_blocksize;
60 const char *name = dp->d_name.name;
61 int namelen = dp->d_name.len;
62 loff_t limit = VXFS_DIRROUND(ip->i_size);
63 struct vxfs_direct *de_exit = NULL;
64 loff_t pos = 0;
65 struct vxfs_sb_info *sbi = VXFS_SBI(ip->i_sb);
66
67 while (pos < limit) {
68 struct page *pp;
69 char *kaddr;
70 int pg_ofs = pos & ~PAGE_MASK;
71
72 pp = vxfs_get_page(ip->i_mapping, pos >> PAGE_SHIFT);
73 if (IS_ERR(pp))
74 return NULL;
75 kaddr = (char *)page_address(pp);
76
77 while (pg_ofs < PAGE_SIZE && pos < limit) {
78 struct vxfs_direct *de;
79
80 if ((pos & (bsize - 1)) < 4) {
81 struct vxfs_dirblk *dbp =
82 (struct vxfs_dirblk *)
83 (kaddr + (pos & ~PAGE_MASK));
84 int overhead = VXFS_DIRBLKOV(sbi, dbp);
85
86 pos += overhead;
87 pg_ofs += overhead;
88 }
89 de = (struct vxfs_direct *)(kaddr + pg_ofs);
90
91 if (!de->d_reclen) {
92 pos += bsize - 1;
93 pos &= ~(bsize - 1);
94 break;
95 }
96
97 pg_ofs += fs16_to_cpu(sbi, de->d_reclen);
98 pos += fs16_to_cpu(sbi, de->d_reclen);
99 if (!de->d_ino)
100 continue;
101
102 if (namelen != fs16_to_cpu(sbi, de->d_namelen))
103 continue;
104 if (!memcmp(name, de->d_name, namelen)) {
105 *ppp = pp;
106 de_exit = de;
107 break;
108 }
109 }
110 if (!de_exit)
111 vxfs_put_page(pp);
112 else
113 break;
114 }
115
116 return de_exit;
117 }
118
119 /**
120 * vxfs_inode_by_name - find inode number for dentry
121 * @dip: directory to search in
122 * @dp: dentry we search for
123 *
124 * Description:
125 * vxfs_inode_by_name finds out the inode number of
126 * the path component described by @dp in @dip.
127 *
128 * Returns:
129 * The wanted inode number on success, else Zero.
130 */
131 static ino_t
132 vxfs_inode_by_name(struct inode *dip, struct dentry *dp)
133 {
134 struct vxfs_direct *de;
135 struct page *pp;
136 ino_t ino = 0;
137
138 de = vxfs_find_entry(dip, dp, &pp);
139 if (de) {
140 ino = fs32_to_cpu(VXFS_SBI(dip->i_sb), de->d_ino);
141 kunmap(pp);
142 put_page(pp);
143 }
144
145 return (ino);
146 }
147
148 /**
149 * vxfs_lookup - lookup pathname component
150 * @dip: dir in which we lookup
151 * @dp: dentry we lookup
152 * @flags: lookup flags
153 *
154 * Description:
155 * vxfs_lookup tries to lookup the pathname component described
156 * by @dp in @dip.
157 *
158 * Returns:
159 * A NULL-pointer on success, else a negative error code encoded
160 * in the return pointer.
161 */
162 static struct dentry *
163 vxfs_lookup(struct inode *dip, struct dentry *dp, unsigned int flags)
164 {
165 struct inode *ip = NULL;
166 ino_t ino;
167
168 if (dp->d_name.len > VXFS_NAMELEN)
169 return ERR_PTR(-ENAMETOOLONG);
170
171 ino = vxfs_inode_by_name(dip, dp);
172 if (ino)
173 ip = vxfs_iget(dip->i_sb, ino);
174 return d_splice_alias(ip, dp);
175 }
176
177 /**
178 * vxfs_readdir - read a directory
179 * @fp: the directory to read
180 * @ctx: dir_context for filldir/readdir
181 *
182 * Description:
183 * vxfs_readdir fills @retp with directory entries from @fp
184 * using the VFS supplied callback @filler.
185 *
186 * Returns:
187 * Zero.
188 */
189 static int
190 vxfs_readdir(struct file *fp, struct dir_context *ctx)
191 {
192 struct inode *ip = file_inode(fp);
193 struct super_block *sbp = ip->i_sb;
194 u_long bsize = sbp->s_blocksize;
195 loff_t pos, limit;
196 struct vxfs_sb_info *sbi = VXFS_SBI(sbp);
197
198 if (ctx->pos == 0) {
199 if (!dir_emit_dot(fp, ctx))
200 goto out;
201 ctx->pos++;
202 }
203 if (ctx->pos == 1) {
204 if (!dir_emit(ctx, "..", 2, VXFS_INO(ip)->vii_dotdot, DT_DIR))
205 goto out;
206 ctx->pos++;
207 }
208
209 limit = VXFS_DIRROUND(ip->i_size);
210 if (ctx->pos > limit)
211 goto out;
212
213 pos = ctx->pos & ~3L;
214
215 while (pos < limit) {
216 struct page *pp;
217 char *kaddr;
218 int pg_ofs = pos & ~PAGE_MASK;
219 int rc = 0;
220
221 pp = vxfs_get_page(ip->i_mapping, pos >> PAGE_SHIFT);
222 if (IS_ERR(pp))
223 return -ENOMEM;
224
225 kaddr = (char *)page_address(pp);
226
227 while (pg_ofs < PAGE_SIZE && pos < limit) {
228 struct vxfs_direct *de;
229
230 if ((pos & (bsize - 1)) < 4) {
231 struct vxfs_dirblk *dbp =
232 (struct vxfs_dirblk *)
233 (kaddr + (pos & ~PAGE_MASK));
234 int overhead = VXFS_DIRBLKOV(sbi, dbp);
235
236 pos += overhead;
237 pg_ofs += overhead;
238 }
239 de = (struct vxfs_direct *)(kaddr + pg_ofs);
240
241 if (!de->d_reclen) {
242 pos += bsize - 1;
243 pos &= ~(bsize - 1);
244 break;
245 }
246
247 pg_ofs += fs16_to_cpu(sbi, de->d_reclen);
248 pos += fs16_to_cpu(sbi, de->d_reclen);
249 if (!de->d_ino)
250 continue;
251
252 rc = dir_emit(ctx, de->d_name,
253 fs16_to_cpu(sbi, de->d_namelen),
254 fs32_to_cpu(sbi, de->d_ino),
255 DT_UNKNOWN);
256 if (!rc) {
257 /* the dir entry was not read, fix pos. */
258 pos -= fs16_to_cpu(sbi, de->d_reclen);
259 break;
260 }
261 }
262 vxfs_put_page(pp);
263 if (!rc)
264 break;
265 }
266
267 ctx->pos = pos | 2;
268
269 out:
270 return 0;
271 }
272
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