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
64
65static inline u_long
66dir_pages(struct inode *inode)
67{
68	return (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
69}
70
71static inline u_long
72dir_blocks(struct inode *ip)
73{
74	u_long			bsize = ip->i_sb->s_blocksize;
75	return (ip->i_size + bsize - 1) & ~(bsize - 1);
76}
77
78/*
79 * NOTE! unlike strncmp, vxfs_match returns 1 for success, 0 for failure.
80 *
81 * len <= VXFS_NAMELEN and de != NULL are guaranteed by caller.
82 */
83static inline int
84vxfs_match(int len, const char * const name, struct vxfs_direct *de)
85{
86	if (len != de->d_namelen)
87		return 0;
88	if (!de->d_ino)
89		return 0;
90	return !memcmp(name, de->d_name, len);
91}
92
93static inline struct vxfs_direct *
94vxfs_next_entry(struct vxfs_direct *de)
95{
96	return ((struct vxfs_direct *)((char*)de + de->d_reclen));
97}
98
99/**
100 * vxfs_find_entry - find a mathing directory entry for a dentry
101 * @ip:		directory inode
102 * @dp:		dentry for which we want to find a direct
103 * @ppp:	gets filled with the page the return value sits in
104 *
105 * Description:
106 *   vxfs_find_entry finds a &struct vxfs_direct for the VFS directory
107 *   cache entry @dp.  @ppp will be filled with the page the return
108 *   value resides in.
109 *
110 * Returns:
111 *   The wanted direct on success, else a NULL pointer.
112 */
113static struct vxfs_direct *
114vxfs_find_entry(struct inode *ip, struct dentry *dp, struct page **ppp)
115{
116	u_long				npages, page, nblocks, pblocks, block;
117	u_long				bsize = ip->i_sb->s_blocksize;
118	const char			*name = dp->d_name.name;
119	int				namelen = dp->d_name.len;
120
121	npages = dir_pages(ip);
122	nblocks = dir_blocks(ip);
123	pblocks = VXFS_BLOCK_PER_PAGE(ip->i_sb);
124
125	for (page = 0; page < npages; page++) {
126		caddr_t			kaddr;
127		struct page		*pp;
128
129		pp = vxfs_get_page(ip->i_mapping, page);
130		if (IS_ERR(pp))
131			continue;
132		kaddr = (caddr_t)page_address(pp);
133
134		for (block = 0; block <= nblocks && block <= pblocks; block++) {
135			caddr_t			baddr, limit;
136			struct vxfs_dirblk	*dbp;
137			struct vxfs_direct	*de;
138
139			baddr = kaddr + (block * bsize);
140			limit = baddr + bsize - VXFS_DIRLEN(1);
141
142			dbp = (struct vxfs_dirblk *)baddr;
143			de = (struct vxfs_direct *)(baddr + VXFS_DIRBLKOV(dbp));
144
145			for (; (caddr_t)de <= limit; de = vxfs_next_entry(de)) {
146				if (!de->d_reclen)
147					break;
148				if (!de->d_ino)
149					continue;
150				if (vxfs_match(namelen, name, de)) {
151					*ppp = pp;
152					return (de);
153				}
154			}
155		}
156		vxfs_put_page(pp);
157	}
158
159	return NULL;
160}
161
162/**
163 * vxfs_inode_by_name - find inode number for dentry
164 * @dip:	directory to search in
165 * @dp:		dentry we search for
166 *
167 * Description:
168 *   vxfs_inode_by_name finds out the inode number of
169 *   the path component described by @dp in @dip.
170 *
171 * Returns:
172 *   The wanted inode number on success, else Zero.
173 */
174static ino_t
175vxfs_inode_by_name(struct inode *dip, struct dentry *dp)
176{
177	struct vxfs_direct		*de;
178	struct page			*pp;
179	ino_t				ino = 0;
180
181	de = vxfs_find_entry(dip, dp, &pp);
182	if (de) {
183		ino = de->d_ino;
184		kunmap(pp);
185		page_cache_release(pp);
186	}
187
188	return (ino);
189}
190
191/**
192 * vxfs_lookup - lookup pathname component
193 * @dip:	dir in which we lookup
194 * @dp:		dentry we lookup
195 * @flags:	lookup flags
196 *
197 * Description:
198 *   vxfs_lookup tries to lookup the pathname component described
199 *   by @dp in @dip.
200 *
201 * Returns:
202 *   A NULL-pointer on success, else an negative error code encoded
203 *   in the return pointer.
204 */
205static struct dentry *
206vxfs_lookup(struct inode *dip, struct dentry *dp, unsigned int flags)
207{
208	struct inode		*ip = NULL;
209	ino_t			ino;
210
211	if (dp->d_name.len > VXFS_NAMELEN)
212		return ERR_PTR(-ENAMETOOLONG);
213
214	ino = vxfs_inode_by_name(dip, dp);
215	if (ino) {
216		ip = vxfs_iget(dip->i_sb, ino);
217		if (IS_ERR(ip))
218			return ERR_CAST(ip);
219	}
220	d_add(dp, ip);
221	return NULL;
222}
223
224/**
225 * vxfs_readdir - read a directory
226 * @fp:		the directory to read
227 * @retp:	return buffer
228 * @filler:	filldir callback
229 *
230 * Description:
231 *   vxfs_readdir fills @retp with directory entries from @fp
232 *   using the VFS supplied callback @filler.
233 *
234 * Returns:
235 *   Zero.
236 */
237static int
238vxfs_readdir(struct file *fp, struct dir_context *ctx)
239{
240	struct inode		*ip = file_inode(fp);
241	struct super_block	*sbp = ip->i_sb;
242	u_long			bsize = sbp->s_blocksize;
243	u_long			page, npages, block, pblocks, nblocks, offset;
244	loff_t			pos;
245
246	if (ctx->pos == 0) {
247		if (!dir_emit_dot(fp, ctx))
248			return 0;
249		ctx->pos = 1;
250	}
251	if (ctx->pos == 1) {
252		if (!dir_emit(ctx, "..", 2, VXFS_INO(ip)->vii_dotdot, DT_DIR))
253			return 0;
254		ctx->pos = 2;
255	}
256	pos = ctx->pos - 2;
257
258	if (pos > VXFS_DIRROUND(ip->i_size))
259		return 0;
260
261	npages = dir_pages(ip);
262	nblocks = dir_blocks(ip);
263	pblocks = VXFS_BLOCK_PER_PAGE(sbp);
264
265	page = pos >> PAGE_CACHE_SHIFT;
266	offset = pos & ~PAGE_CACHE_MASK;
267	block = (u_long)(pos >> sbp->s_blocksize_bits) % pblocks;
268
269	for (; page < npages; page++, block = 0) {
270		char			*kaddr;
271		struct page		*pp;
272
273		pp = vxfs_get_page(ip->i_mapping, page);
274		if (IS_ERR(pp))
275			continue;
276		kaddr = (char *)page_address(pp);
277
278		for (; block <= nblocks && block <= pblocks; block++) {
279			char			*baddr, *limit;
280			struct vxfs_dirblk	*dbp;
281			struct vxfs_direct	*de;
282
283			baddr = kaddr + (block * bsize);
284			limit = baddr + bsize - VXFS_DIRLEN(1);
285
286			dbp = (struct vxfs_dirblk *)baddr;
287			de = (struct vxfs_direct *)
288				(offset ?
289				 (kaddr + offset) :
290				 (baddr + VXFS_DIRBLKOV(dbp)));
291
292			for (; (char *)de <= limit; de = vxfs_next_entry(de)) {
293				if (!de->d_reclen)
294					break;
295				if (!de->d_ino)
296					continue;
297
298				offset = (char *)de - kaddr;
299				ctx->pos = ((page << PAGE_CACHE_SHIFT) | offset) + 2;
300				if (!dir_emit(ctx, de->d_name, de->d_namelen,
301					de->d_ino, DT_UNKNOWN)) {
302					vxfs_put_page(pp);
303					return 0;
304				}
305			}
306			offset = 0;
307		}
308		vxfs_put_page(pp);
309		offset = 0;
310	}
311	ctx->pos = ((page << PAGE_CACHE_SHIFT) | offset) + 2;
312	return 0;
313}
314