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
40#include "vxfs.h"
41#include "vxfs_dir.h"
42#include "vxfs_inode.h"
43#include "vxfs_extern.h"
44
45/*
46 * Number of VxFS blocks per page.
47 */
48#define VXFS_BLOCK_PER_PAGE(sbp)  ((PAGE_CACHE_SIZE / (sbp)->s_blocksize))
49
50
51static struct dentry *	vxfs_lookup(struct inode *, struct dentry *, unsigned int);
52static int		vxfs_readdir(struct file *, struct dir_context *);
53
54const struct inode_operations vxfs_dir_inode_ops = {
55	.lookup =		vxfs_lookup,
56};
57
58const struct file_operations vxfs_dir_operations = {
59	.llseek =		generic_file_llseek,
60	.read =			generic_read_dir,
61	.iterate =		vxfs_readdir,
62};
63
64static inline u_long
65dir_blocks(struct inode *ip)
66{
67	u_long			bsize = ip->i_sb->s_blocksize;
68	return (ip->i_size + bsize - 1) & ~(bsize - 1);
69}
70
71/*
72 * NOTE! unlike strncmp, vxfs_match returns 1 for success, 0 for failure.
73 *
74 * len <= VXFS_NAMELEN and de != NULL are guaranteed by caller.
75 */
76static inline int
77vxfs_match(int len, const char * const name, struct vxfs_direct *de)
78{
79	if (len != de->d_namelen)
80		return 0;
81	if (!de->d_ino)
82		return 0;
83	return !memcmp(name, de->d_name, len);
84}
85
86static inline struct vxfs_direct *
87vxfs_next_entry(struct vxfs_direct *de)
88{
89	return ((struct vxfs_direct *)((char*)de + de->d_reclen));
90}
91
92/**
93 * vxfs_find_entry - find a mathing directory entry for a dentry
94 * @ip:		directory inode
95 * @dp:		dentry for which we want to find a direct
96 * @ppp:	gets filled with the page the return value sits in
97 *
98 * Description:
99 *   vxfs_find_entry finds a &struct vxfs_direct for the VFS directory
100 *   cache entry @dp.  @ppp will be filled with the page the return
101 *   value resides in.
102 *
103 * Returns:
104 *   The wanted direct on success, else a NULL pointer.
105 */
106static struct vxfs_direct *
107vxfs_find_entry(struct inode *ip, struct dentry *dp, struct page **ppp)
108{
109	u_long				npages, page, nblocks, pblocks, block;
110	u_long				bsize = ip->i_sb->s_blocksize;
111	const char			*name = dp->d_name.name;
112	int				namelen = dp->d_name.len;
113
114	npages = dir_pages(ip);
115	nblocks = dir_blocks(ip);
116	pblocks = VXFS_BLOCK_PER_PAGE(ip->i_sb);
117
118	for (page = 0; page < npages; page++) {
119		caddr_t			kaddr;
120		struct page		*pp;
121
122		pp = vxfs_get_page(ip->i_mapping, page);
123		if (IS_ERR(pp))
124			continue;
125		kaddr = (caddr_t)page_address(pp);
126
127		for (block = 0; block <= nblocks && block <= pblocks; block++) {
128			caddr_t			baddr, limit;
129			struct vxfs_dirblk	*dbp;
130			struct vxfs_direct	*de;
131
132			baddr = kaddr + (block * bsize);
133			limit = baddr + bsize - VXFS_DIRLEN(1);
134
135			dbp = (struct vxfs_dirblk *)baddr;
136			de = (struct vxfs_direct *)(baddr + VXFS_DIRBLKOV(dbp));
137
138			for (; (caddr_t)de <= limit; de = vxfs_next_entry(de)) {
139				if (!de->d_reclen)
140					break;
141				if (!de->d_ino)
142					continue;
143				if (vxfs_match(namelen, name, de)) {
144					*ppp = pp;
145					return (de);
146				}
147			}
148		}
149		vxfs_put_page(pp);
150	}
151
152	return NULL;
153}
154
155/**
156 * vxfs_inode_by_name - find inode number for dentry
157 * @dip:	directory to search in
158 * @dp:		dentry we search for
159 *
160 * Description:
161 *   vxfs_inode_by_name finds out the inode number of
162 *   the path component described by @dp in @dip.
163 *
164 * Returns:
165 *   The wanted inode number on success, else Zero.
166 */
167static ino_t
168vxfs_inode_by_name(struct inode *dip, struct dentry *dp)
169{
170	struct vxfs_direct		*de;
171	struct page			*pp;
172	ino_t				ino = 0;
173
174	de = vxfs_find_entry(dip, dp, &pp);
175	if (de) {
176		ino = de->d_ino;
177		kunmap(pp);
178		page_cache_release(pp);
179	}
180
181	return (ino);
182}
183
184/**
185 * vxfs_lookup - lookup pathname component
186 * @dip:	dir in which we lookup
187 * @dp:		dentry we lookup
188 * @flags:	lookup flags
189 *
190 * Description:
191 *   vxfs_lookup tries to lookup the pathname component described
192 *   by @dp in @dip.
193 *
194 * Returns:
195 *   A NULL-pointer on success, else a negative error code encoded
196 *   in the return pointer.
197 */
198static struct dentry *
199vxfs_lookup(struct inode *dip, struct dentry *dp, unsigned int flags)
200{
201	struct inode		*ip = NULL;
202	ino_t			ino;
203
204	if (dp->d_name.len > VXFS_NAMELEN)
205		return ERR_PTR(-ENAMETOOLONG);
206
207	ino = vxfs_inode_by_name(dip, dp);
208	if (ino) {
209		ip = vxfs_iget(dip->i_sb, ino);
210		if (IS_ERR(ip))
211			return ERR_CAST(ip);
212	}
213	d_add(dp, ip);
214	return NULL;
215}
216
217/**
218 * vxfs_readdir - read a directory
219 * @fp:		the directory to read
220 * @retp:	return buffer
221 * @filler:	filldir callback
222 *
223 * Description:
224 *   vxfs_readdir fills @retp with directory entries from @fp
225 *   using the VFS supplied callback @filler.
226 *
227 * Returns:
228 *   Zero.
229 */
230static int
231vxfs_readdir(struct file *fp, struct dir_context *ctx)
232{
233	struct inode		*ip = file_inode(fp);
234	struct super_block	*sbp = ip->i_sb;
235	u_long			bsize = sbp->s_blocksize;
236	u_long			page, npages, block, pblocks, nblocks, offset;
237	loff_t			pos;
238
239	if (ctx->pos == 0) {
240		if (!dir_emit_dot(fp, ctx))
241			return 0;
242		ctx->pos = 1;
243	}
244	if (ctx->pos == 1) {
245		if (!dir_emit(ctx, "..", 2, VXFS_INO(ip)->vii_dotdot, DT_DIR))
246			return 0;
247		ctx->pos = 2;
248	}
249	pos = ctx->pos - 2;
250
251	if (pos > VXFS_DIRROUND(ip->i_size))
252		return 0;
253
254	npages = dir_pages(ip);
255	nblocks = dir_blocks(ip);
256	pblocks = VXFS_BLOCK_PER_PAGE(sbp);
257
258	page = pos >> PAGE_CACHE_SHIFT;
259	offset = pos & ~PAGE_CACHE_MASK;
260	block = (u_long)(pos >> sbp->s_blocksize_bits) % pblocks;
261
262	for (; page < npages; page++, block = 0) {
263		char			*kaddr;
264		struct page		*pp;
265
266		pp = vxfs_get_page(ip->i_mapping, page);
267		if (IS_ERR(pp))
268			continue;
269		kaddr = (char *)page_address(pp);
270
271		for (; block <= nblocks && block <= pblocks; block++) {
272			char			*baddr, *limit;
273			struct vxfs_dirblk	*dbp;
274			struct vxfs_direct	*de;
275
276			baddr = kaddr + (block * bsize);
277			limit = baddr + bsize - VXFS_DIRLEN(1);
278
279			dbp = (struct vxfs_dirblk *)baddr;
280			de = (struct vxfs_direct *)
281				(offset ?
282				 (kaddr + offset) :
283				 (baddr + VXFS_DIRBLKOV(dbp)));
284
285			for (; (char *)de <= limit; de = vxfs_next_entry(de)) {
286				if (!de->d_reclen)
287					break;
288				if (!de->d_ino)
289					continue;
290
291				offset = (char *)de - kaddr;
292				ctx->pos = ((page << PAGE_CACHE_SHIFT) | offset) + 2;
293				if (!dir_emit(ctx, de->d_name, de->d_namelen,
294					de->d_ino, DT_UNKNOWN)) {
295					vxfs_put_page(pp);
296					return 0;
297				}
298			}
299			offset = 0;
300		}
301		vxfs_put_page(pp);
302		offset = 0;
303	}
304	ctx->pos = ((page << PAGE_CACHE_SHIFT) | offset) + 2;
305	return 0;
306}
307