xref: /openbmc/linux/fs/freevxfs/vxfs_lookup.c (revision 1da177e4) 
1 /*
2  * Copyright (c) 2000-2001 Christoph Hellwig.
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions, and the following disclaimer,
10  *    without modification.
11  * 2. The name of the author may not be used to endorse or promote products
12  *    derived from this software without specific prior written permission.
13  *
14  * Alternatively, this software may be distributed under the terms of the
15  * GNU General Public License ("GPL").
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
21  * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  */
29 
30 /*
31  * Veritas filesystem driver - lookup and other directory related code.
32  */
33 #include <linux/fs.h>
34 #include <linux/time.h>
35 #include <linux/mm.h>
36 #include <linux/highmem.h>
37 #include <linux/kernel.h>
38 #include <linux/pagemap.h>
39 #include <linux/smp_lock.h>
40 
41 #include "vxfs.h"
42 #include "vxfs_dir.h"
43 #include "vxfs_inode.h"
44 #include "vxfs_extern.h"
45 
46 /*
47  * Number of VxFS blocks per page.
48  */
49 #define VXFS_BLOCK_PER_PAGE(sbp)  ((PAGE_CACHE_SIZE / (sbp)->s_blocksize))
50 
51 
52 static struct dentry *	vxfs_lookup(struct inode *, struct dentry *, struct nameidata *);
53 static int		vxfs_readdir(struct file *, void *, filldir_t);
54 
55 struct inode_operations vxfs_dir_inode_ops = {
56 	.lookup =		vxfs_lookup,
57 };
58 
59 struct file_operations vxfs_dir_operations = {
60 	.readdir =		vxfs_readdir,
61 };
62 
63 
64 static __inline__ u_long
65 dir_pages(struct inode *inode)
66 {
67 	return (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
68 }
69 
70 static __inline__ u_long
71 dir_blocks(struct inode *ip)
72 {
73 	u_long			bsize = ip->i_sb->s_blocksize;
74 	return (ip->i_size + bsize - 1) & ~(bsize - 1);
75 }
76 
77 /*
78  * NOTE! unlike strncmp, vxfs_match returns 1 for success, 0 for failure.
79  *
80  * len <= VXFS_NAMELEN and de != NULL are guaranteed by caller.
81  */
82 static __inline__ int
83 vxfs_match(int len, const char * const name, struct vxfs_direct *de)
84 {
85 	if (len != de->d_namelen)
86 		return 0;
87 	if (!de->d_ino)
88 		return 0;
89 	return !memcmp(name, de->d_name, len);
90 }
91 
92 static __inline__ struct vxfs_direct *
93 vxfs_next_entry(struct vxfs_direct *de)
94 {
95 	return ((struct vxfs_direct *)((char*)de + de->d_reclen));
96 }
97 
98 /**
99  * vxfs_find_entry - find a mathing directory entry for a dentry
100  * @ip:		directory inode
101  * @dp:		dentry for which we want to find a direct
102  * @ppp:	gets filled with the page the return value sits in
103  *
104  * Description:
105  *   vxfs_find_entry finds a &struct vxfs_direct for the VFS directory
106  *   cache entry @dp.  @ppp will be filled with the page the return
107  *   value resides in.
108  *
109  * Returns:
110  *   The wanted direct on success, else a NULL pointer.
111  */
112 static struct vxfs_direct *
113 vxfs_find_entry(struct inode *ip, struct dentry *dp, struct page **ppp)
114 {
115 	u_long				npages, page, nblocks, pblocks, block;
116 	u_long				bsize = ip->i_sb->s_blocksize;
117 	const char			*name = dp->d_name.name;
118 	int				namelen = dp->d_name.len;
119 
120 	npages = dir_pages(ip);
121 	nblocks = dir_blocks(ip);
122 	pblocks = VXFS_BLOCK_PER_PAGE(ip->i_sb);
123 
124 	for (page = 0; page < npages; page++) {
125 		caddr_t			kaddr;
126 		struct page		*pp;
127 
128 		pp = vxfs_get_page(ip->i_mapping, page);
129 		if (IS_ERR(pp))
130 			continue;
131 		kaddr = (caddr_t)page_address(pp);
132 
133 		for (block = 0; block <= nblocks && block <= pblocks; block++) {
134 			caddr_t			baddr, limit;
135 			struct vxfs_dirblk	*dbp;
136 			struct vxfs_direct	*de;
137 
138 			baddr = kaddr + (block * bsize);
139 			limit = baddr + bsize - VXFS_DIRLEN(1);
140 
141 			dbp = (struct vxfs_dirblk *)baddr;
142 			de = (struct vxfs_direct *)(baddr + VXFS_DIRBLKOV(dbp));
143 
144 			for (; (caddr_t)de <= limit; de = vxfs_next_entry(de)) {
145 				if (!de->d_reclen)
146 					break;
147 				if (!de->d_ino)
148 					continue;
149 				if (vxfs_match(namelen, name, de)) {
150 					*ppp = pp;
151 					return (de);
152 				}
153 			}
154 		}
155 		vxfs_put_page(pp);
156 	}
157 
158 	return NULL;
159 }
160 
161 /**
162  * vxfs_inode_by_name - find inode number for dentry
163  * @dip:	directory to search in
164  * @dp:		dentry we seach for
165  *
166  * Description:
167  *   vxfs_inode_by_name finds out the inode number of
168  *   the path component described by @dp in @dip.
169  *
170  * Returns:
171  *   The wanted inode number on success, else Zero.
172  */
173 static ino_t
174 vxfs_inode_by_name(struct inode *dip, struct dentry *dp)
175 {
176 	struct vxfs_direct		*de;
177 	struct page			*pp;
178 	ino_t				ino = 0;
179 
180 	de = vxfs_find_entry(dip, dp, &pp);
181 	if (de) {
182 		ino = de->d_ino;
183 		kunmap(pp);
184 		page_cache_release(pp);
185 	}
186 
187 	return (ino);
188 }
189 
190 /**
191  * vxfs_lookup - lookup pathname component
192  * @dip:	dir in which we lookup
193  * @dp:		dentry we lookup
194  * @nd:		lookup nameidata
195  *
196  * Description:
197  *   vxfs_lookup tries to lookup the pathname component described
198  *   by @dp in @dip.
199  *
200  * Returns:
201  *   A NULL-pointer on success, else an negative error code encoded
202  *   in the return pointer.
203  */
204 static struct dentry *
205 vxfs_lookup(struct inode *dip, struct dentry *dp, struct nameidata *nd)
206 {
207 	struct inode		*ip = NULL;
208 	ino_t			ino;
209 
210 	if (dp->d_name.len > VXFS_NAMELEN)
211 		return ERR_PTR(-ENAMETOOLONG);
212 
213 	lock_kernel();
214 	ino = vxfs_inode_by_name(dip, dp);
215 	if (ino) {
216 		ip = iget(dip->i_sb, ino);
217 		if (!ip) {
218 			unlock_kernel();
219 			return ERR_PTR(-EACCES);
220 		}
221 	}
222 	unlock_kernel();
223 	d_add(dp, ip);
224 	return NULL;
225 }
226 
227 /**
228  * vxfs_readdir - read a directory
229  * @fp:		the directory to read
230  * @retp:	return buffer
231  * @filler:	filldir callback
232  *
233  * Description:
234  *   vxfs_readdir fills @retp with directory entries from @fp
235  *   using the VFS supplied callback @filler.
236  *
237  * Returns:
238  *   Zero.
239  */
240 static int
241 vxfs_readdir(struct file *fp, void *retp, filldir_t filler)
242 {
243 	struct inode		*ip = fp->f_dentry->d_inode;
244 	struct super_block	*sbp = ip->i_sb;
245 	u_long			bsize = sbp->s_blocksize;
246 	u_long			page, npages, block, pblocks, nblocks, offset;
247 	loff_t			pos;
248 
249 	switch ((long)fp->f_pos) {
250 	case 0:
251 		if (filler(retp, ".", 1, fp->f_pos, ip->i_ino, DT_DIR) < 0)
252 			goto out;
253 		fp->f_pos++;
254 		/* fallthrough */
255 	case 1:
256 		if (filler(retp, "..", 2, fp->f_pos, VXFS_INO(ip)->vii_dotdot, DT_DIR) < 0)
257 			goto out;
258 		fp->f_pos++;
259 		/* fallthrough */
260 	}
261 
262 	pos = fp->f_pos - 2;
263 
264 	if (pos > VXFS_DIRROUND(ip->i_size)) {
265 		unlock_kernel();
266 		return 0;
267 	}
268 
269 	npages = dir_pages(ip);
270 	nblocks = dir_blocks(ip);
271 	pblocks = VXFS_BLOCK_PER_PAGE(sbp);
272 
273 	page = pos >> PAGE_CACHE_SHIFT;
274 	offset = pos & ~PAGE_CACHE_MASK;
275 	block = (u_long)(pos >> sbp->s_blocksize_bits) % pblocks;
276 
277 	for (; page < npages; page++, block = 0) {
278 		caddr_t			kaddr;
279 		struct page		*pp;
280 
281 		pp = vxfs_get_page(ip->i_mapping, page);
282 		if (IS_ERR(pp))
283 			continue;
284 		kaddr = (caddr_t)page_address(pp);
285 
286 		for (; block <= nblocks && block <= pblocks; block++) {
287 			caddr_t			baddr, limit;
288 			struct vxfs_dirblk	*dbp;
289 			struct vxfs_direct	*de;
290 
291 			baddr = kaddr + (block * bsize);
292 			limit = baddr + bsize - VXFS_DIRLEN(1);
293 
294 			dbp = (struct vxfs_dirblk *)baddr;
295 			de = (struct vxfs_direct *)
296 				(offset ?
297 				 (kaddr + offset) :
298 				 (baddr + VXFS_DIRBLKOV(dbp)));
299 
300 			for (; (caddr_t)de <= limit; de = vxfs_next_entry(de)) {
301 				int	over;
302 
303 				if (!de->d_reclen)
304 					break;
305 				if (!de->d_ino)
306 					continue;
307 
308 				offset = (caddr_t)de - kaddr;
309 				over = filler(retp, de->d_name, de->d_namelen,
310 					((page << PAGE_CACHE_SHIFT) | offset) + 2,
311 					de->d_ino, DT_UNKNOWN);
312 				if (over) {
313 					vxfs_put_page(pp);
314 					goto done;
315 				}
316 			}
317 			offset = 0;
318 		}
319 		vxfs_put_page(pp);
320 		offset = 0;
321 	}
322 
323 done:
324 	fp->f_pos = ((page << PAGE_CACHE_SHIFT) | offset) + 2;
325 out:
326 	unlock_kernel();
327 	return 0;
328 }
329