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#ident "$Id: vxfs_lookup.c,v 1.1.1.1 2008/10/15 03:27:06 james26_jang Exp $"
31
32/*
33 * Veritas filesystem driver - lookup and other directory related code.
34 */
35#include <linux/fs.h>
36#include <linux/sched.h>
37#include <linux/mm.h>
38#include <linux/highmem.h>
39#include <linux/kernel.h>
40#include <linux/pagemap.h>
41
42#include "vxfs.h"
43#include "vxfs_dir.h"
44#include "vxfs_inode.h"
45#include "vxfs_extern.h"
46
47/*
48 * Number of VxFS blocks per page.
49 */
50#define VXFS_BLOCK_PER_PAGE(sbp)  ((PAGE_CACHE_SIZE / (sbp)->s_blocksize))
51
52
53static struct dentry *	vxfs_lookup(struct inode *, struct dentry *);
54static int		vxfs_readdir(struct file *, void *, filldir_t);
55
56struct inode_operations vxfs_dir_inode_ops = {
57	.lookup =		vxfs_lookup,
58};
59
60struct file_operations vxfs_dir_operations = {
61	.readdir =		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 seach 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 *
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)
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	ino = vxfs_inode_by_name(dip, dp);
214	if (ino == 0)
215		return NULL;
216
217	ip = iget(dip->i_sb, ino);
218	if (!ip)
219		return ERR_PTR(-EACCES);
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, void *retp, filldir_t filler)
239{
240	struct inode		*ip = fp->f_dentry->d_inode;
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	switch ((long)fp->f_pos) {
247	case 0:
248		if (filler(retp, ".", 1, fp->f_pos, ip->i_ino, DT_DIR) < 0)
249			goto out;
250		fp->f_pos++;
251		/* fallthrough */
252	case 1:
253		if (filler(retp, "..", 2, fp->f_pos, VXFS_INO(ip)->vii_dotdot, DT_DIR) < 0)
254			goto out;
255		fp->f_pos++;
256		/* fallthrough */
257	}
258
259	pos = fp->f_pos - 2;
260
261	if (pos > VXFS_DIRROUND(ip->i_size))
262		return 0;
263
264	npages = dir_pages(ip);
265	nblocks = dir_blocks(ip);
266	pblocks = VXFS_BLOCK_PER_PAGE(sbp);
267
268	page = pos >> PAGE_CACHE_SHIFT;
269	offset = pos & ~PAGE_CACHE_MASK;
270	block = (u_long)(pos >> sbp->s_blocksize_bits) % pblocks;
271
272	for (; page < npages; page++, block = 0) {
273		caddr_t			kaddr;
274		struct page		*pp;
275
276		pp = vxfs_get_page(ip->i_mapping, page);
277		if (IS_ERR(pp))
278			continue;
279		kaddr = (caddr_t)page_address(pp);
280
281		for (; block <= nblocks && block <= pblocks; block++) {
282			caddr_t			baddr, limit;
283			struct vxfs_dirblk	*dbp;
284			struct vxfs_direct	*de;
285
286			baddr = kaddr + (block * bsize);
287			limit = baddr + bsize - VXFS_DIRLEN(1);
288
289			dbp = (struct vxfs_dirblk *)baddr;
290			de = (struct vxfs_direct *)
291				(offset ?
292				 (kaddr + offset) :
293				 (baddr + VXFS_DIRBLKOV(dbp)));
294
295			for (; (caddr_t)de <= limit; de = vxfs_next_entry(de)) {
296				int	over;
297
298				if (!de->d_reclen)
299					break;
300				if (!de->d_ino)
301					continue;
302
303				offset = (caddr_t)de - kaddr;
304				over = filler(retp, de->d_name, de->d_namelen,
305					((page << PAGE_CACHE_SHIFT) | offset) + 2,
306					de->d_ino, DT_UNKNOWN);
307				if (over) {
308					vxfs_put_page(pp);
309					goto done;
310				}
311			}
312			offset = 0;
313		}
314		vxfs_put_page(pp);
315		offset = 0;
316	}
317
318done:
319	fp->f_pos = ((page << PAGE_CACHE_SHIFT) | offset) + 2;
320out:
321	return 0;
322}
323