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
52static struct dentry *	vxfs_lookup(struct inode *, struct dentry *, struct nameidata *);
53static int		vxfs_readdir(struct file *, void *, filldir_t);
54
55const struct inode_operations vxfs_dir_inode_ops = {
56	.lookup =		vxfs_lookup,
57};
58
59const struct file_operations vxfs_dir_operations = {
60	.readdir =		vxfs_readdir,
61};
62
63
64static inline u_long
65dir_pages(struct inode *inode)
66{
67	return (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
68}
69
70static inline u_long
71dir_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 */
82static inline int
83vxfs_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
92static inline struct vxfs_direct *
93vxfs_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 */
112static struct vxfs_direct *
113vxfs_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 */
173static ino_t
174vxfs_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 */
204static struct dentry *
205vxfs_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 */
240static int
241vxfs_readdir(struct file *fp, void *retp, filldir_t filler)
242{
243	struct inode		*ip = fp->f_path.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	lock_kernel();
250
251	switch ((long)fp->f_pos) {
252	case 0:
253		if (filler(retp, ".", 1, fp->f_pos, ip->i_ino, DT_DIR) < 0)
254			goto out;
255		fp->f_pos++;
256		/* fallthrough */
257	case 1:
258		if (filler(retp, "..", 2, fp->f_pos, VXFS_INO(ip)->vii_dotdot, DT_DIR) < 0)
259			goto out;
260		fp->f_pos++;
261		/* fallthrough */
262	}
263
264	pos = fp->f_pos - 2;
265
266	if (pos > VXFS_DIRROUND(ip->i_size)) {
267		unlock_kernel();
268		return 0;
269	}
270
271	npages = dir_pages(ip);
272	nblocks = dir_blocks(ip);
273	pblocks = VXFS_BLOCK_PER_PAGE(sbp);
274
275	page = pos >> PAGE_CACHE_SHIFT;
276	offset = pos & ~PAGE_CACHE_MASK;
277	block = (u_long)(pos >> sbp->s_blocksize_bits) % pblocks;
278
279	for (; page < npages; page++, block = 0) {
280		caddr_t			kaddr;
281		struct page		*pp;
282
283		pp = vxfs_get_page(ip->i_mapping, page);
284		if (IS_ERR(pp))
285			continue;
286		kaddr = (caddr_t)page_address(pp);
287
288		for (; block <= nblocks && block <= pblocks; block++) {
289			caddr_t			baddr, limit;
290			struct vxfs_dirblk	*dbp;
291			struct vxfs_direct	*de;
292
293			baddr = kaddr + (block * bsize);
294			limit = baddr + bsize - VXFS_DIRLEN(1);
295
296			dbp = (struct vxfs_dirblk *)baddr;
297			de = (struct vxfs_direct *)
298				(offset ?
299				 (kaddr + offset) :
300				 (baddr + VXFS_DIRBLKOV(dbp)));
301
302			for (; (caddr_t)de <= limit; de = vxfs_next_entry(de)) {
303				int	over;
304
305				if (!de->d_reclen)
306					break;
307				if (!de->d_ino)
308					continue;
309
310				offset = (caddr_t)de - kaddr;
311				over = filler(retp, de->d_name, de->d_namelen,
312					((page << PAGE_CACHE_SHIFT) | offset) + 2,
313					de->d_ino, DT_UNKNOWN);
314				if (over) {
315					vxfs_put_page(pp);
316					goto done;
317				}
318			}
319			offset = 0;
320		}
321		vxfs_put_page(pp);
322		offset = 0;
323	}
324
325done:
326	fp->f_pos = ((page << PAGE_CACHE_SHIFT) | offset) + 2;
327out:
328	unlock_kernel();
329	return 0;
330}
331