nfs41: implement DESTROY_CLIENTID operation
[linux-btrfs-devel.git] / fs / cramfs / inode.c
blob739fb59bcdc25123f3bdc620246045ddabdac34d
1 /*
2 * Compressed rom filesystem for Linux.
4 * Copyright (C) 1999 Linus Torvalds.
6 * This file is released under the GPL.
7 */
9 /*
10 * These are the VFS interfaces to the compressed rom filesystem.
11 * The actual compression is based on zlib, see the other files.
14 #include <linux/module.h>
15 #include <linux/fs.h>
16 #include <linux/pagemap.h>
17 #include <linux/init.h>
18 #include <linux/string.h>
19 #include <linux/blkdev.h>
20 #include <linux/cramfs_fs.h>
21 #include <linux/slab.h>
22 #include <linux/cramfs_fs_sb.h>
23 #include <linux/buffer_head.h>
24 #include <linux/vfs.h>
25 #include <linux/mutex.h>
27 #include <asm/uaccess.h>
29 static const struct super_operations cramfs_ops;
30 static const struct inode_operations cramfs_dir_inode_operations;
31 static const struct file_operations cramfs_directory_operations;
32 static const struct address_space_operations cramfs_aops;
34 static DEFINE_MUTEX(read_mutex);
37 /* These macros may change in future, to provide better st_ino semantics. */
38 #define OFFSET(x) ((x)->i_ino)
40 static unsigned long cramino(const struct cramfs_inode *cino, unsigned int offset)
42 if (!cino->offset)
43 return offset + 1;
44 if (!cino->size)
45 return offset + 1;
48 * The file mode test fixes buggy mkcramfs implementations where
49 * cramfs_inode->offset is set to a non zero value for entries
50 * which did not contain data, like devices node and fifos.
52 switch (cino->mode & S_IFMT) {
53 case S_IFREG:
54 case S_IFDIR:
55 case S_IFLNK:
56 return cino->offset << 2;
57 default:
58 break;
60 return offset + 1;
63 static struct inode *get_cramfs_inode(struct super_block *sb,
64 const struct cramfs_inode *cramfs_inode, unsigned int offset)
66 struct inode *inode;
67 static struct timespec zerotime;
69 inode = iget_locked(sb, cramino(cramfs_inode, offset));
70 if (!inode)
71 return ERR_PTR(-ENOMEM);
72 if (!(inode->i_state & I_NEW))
73 return inode;
75 switch (cramfs_inode->mode & S_IFMT) {
76 case S_IFREG:
77 inode->i_fop = &generic_ro_fops;
78 inode->i_data.a_ops = &cramfs_aops;
79 break;
80 case S_IFDIR:
81 inode->i_op = &cramfs_dir_inode_operations;
82 inode->i_fop = &cramfs_directory_operations;
83 break;
84 case S_IFLNK:
85 inode->i_op = &page_symlink_inode_operations;
86 inode->i_data.a_ops = &cramfs_aops;
87 break;
88 default:
89 init_special_inode(inode, cramfs_inode->mode,
90 old_decode_dev(cramfs_inode->size));
93 inode->i_mode = cramfs_inode->mode;
94 inode->i_uid = cramfs_inode->uid;
95 inode->i_gid = cramfs_inode->gid;
97 /* if the lower 2 bits are zero, the inode contains data */
98 if (!(inode->i_ino & 3)) {
99 inode->i_size = cramfs_inode->size;
100 inode->i_blocks = (cramfs_inode->size - 1) / 512 + 1;
103 /* Struct copy intentional */
104 inode->i_mtime = inode->i_atime = inode->i_ctime = zerotime;
105 /* inode->i_nlink is left 1 - arguably wrong for directories,
106 but it's the best we can do without reading the directory
107 contents. 1 yields the right result in GNU find, even
108 without -noleaf option. */
110 unlock_new_inode(inode);
112 return inode;
116 * We have our own block cache: don't fill up the buffer cache
117 * with the rom-image, because the way the filesystem is set
118 * up the accesses should be fairly regular and cached in the
119 * page cache and dentry tree anyway..
121 * This also acts as a way to guarantee contiguous areas of up to
122 * BLKS_PER_BUF*PAGE_CACHE_SIZE, so that the caller doesn't need to
123 * worry about end-of-buffer issues even when decompressing a full
124 * page cache.
126 #define READ_BUFFERS (2)
127 /* NEXT_BUFFER(): Loop over [0..(READ_BUFFERS-1)]. */
128 #define NEXT_BUFFER(_ix) ((_ix) ^ 1)
131 * BLKS_PER_BUF_SHIFT should be at least 2 to allow for "compressed"
132 * data that takes up more space than the original and with unlucky
133 * alignment.
135 #define BLKS_PER_BUF_SHIFT (2)
136 #define BLKS_PER_BUF (1 << BLKS_PER_BUF_SHIFT)
137 #define BUFFER_SIZE (BLKS_PER_BUF*PAGE_CACHE_SIZE)
139 static unsigned char read_buffers[READ_BUFFERS][BUFFER_SIZE];
140 static unsigned buffer_blocknr[READ_BUFFERS];
141 static struct super_block * buffer_dev[READ_BUFFERS];
142 static int next_buffer;
145 * Returns a pointer to a buffer containing at least LEN bytes of
146 * filesystem starting at byte offset OFFSET into the filesystem.
148 static void *cramfs_read(struct super_block *sb, unsigned int offset, unsigned int len)
150 struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
151 struct page *pages[BLKS_PER_BUF];
152 unsigned i, blocknr, buffer;
153 unsigned long devsize;
154 char *data;
156 if (!len)
157 return NULL;
158 blocknr = offset >> PAGE_CACHE_SHIFT;
159 offset &= PAGE_CACHE_SIZE - 1;
161 /* Check if an existing buffer already has the data.. */
162 for (i = 0; i < READ_BUFFERS; i++) {
163 unsigned int blk_offset;
165 if (buffer_dev[i] != sb)
166 continue;
167 if (blocknr < buffer_blocknr[i])
168 continue;
169 blk_offset = (blocknr - buffer_blocknr[i]) << PAGE_CACHE_SHIFT;
170 blk_offset += offset;
171 if (blk_offset + len > BUFFER_SIZE)
172 continue;
173 return read_buffers[i] + blk_offset;
176 devsize = mapping->host->i_size >> PAGE_CACHE_SHIFT;
178 /* Ok, read in BLKS_PER_BUF pages completely first. */
179 for (i = 0; i < BLKS_PER_BUF; i++) {
180 struct page *page = NULL;
182 if (blocknr + i < devsize) {
183 page = read_mapping_page_async(mapping, blocknr + i,
184 NULL);
185 /* synchronous error? */
186 if (IS_ERR(page))
187 page = NULL;
189 pages[i] = page;
192 for (i = 0; i < BLKS_PER_BUF; i++) {
193 struct page *page = pages[i];
194 if (page) {
195 wait_on_page_locked(page);
196 if (!PageUptodate(page)) {
197 /* asynchronous error */
198 page_cache_release(page);
199 pages[i] = NULL;
204 buffer = next_buffer;
205 next_buffer = NEXT_BUFFER(buffer);
206 buffer_blocknr[buffer] = blocknr;
207 buffer_dev[buffer] = sb;
209 data = read_buffers[buffer];
210 for (i = 0; i < BLKS_PER_BUF; i++) {
211 struct page *page = pages[i];
212 if (page) {
213 memcpy(data, kmap(page), PAGE_CACHE_SIZE);
214 kunmap(page);
215 page_cache_release(page);
216 } else
217 memset(data, 0, PAGE_CACHE_SIZE);
218 data += PAGE_CACHE_SIZE;
220 return read_buffers[buffer] + offset;
223 static void cramfs_put_super(struct super_block *sb)
225 kfree(sb->s_fs_info);
226 sb->s_fs_info = NULL;
229 static int cramfs_remount(struct super_block *sb, int *flags, char *data)
231 *flags |= MS_RDONLY;
232 return 0;
235 static int cramfs_fill_super(struct super_block *sb, void *data, int silent)
237 int i;
238 struct cramfs_super super;
239 unsigned long root_offset;
240 struct cramfs_sb_info *sbi;
241 struct inode *root;
243 sb->s_flags |= MS_RDONLY;
245 sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL);
246 if (!sbi)
247 return -ENOMEM;
248 sb->s_fs_info = sbi;
250 /* Invalidate the read buffers on mount: think disk change.. */
251 mutex_lock(&read_mutex);
252 for (i = 0; i < READ_BUFFERS; i++)
253 buffer_blocknr[i] = -1;
255 /* Read the first block and get the superblock from it */
256 memcpy(&super, cramfs_read(sb, 0, sizeof(super)), sizeof(super));
257 mutex_unlock(&read_mutex);
259 /* Do sanity checks on the superblock */
260 if (super.magic != CRAMFS_MAGIC) {
261 /* check for wrong endianess */
262 if (super.magic == CRAMFS_MAGIC_WEND) {
263 if (!silent)
264 printk(KERN_ERR "cramfs: wrong endianess\n");
265 goto out;
268 /* check at 512 byte offset */
269 mutex_lock(&read_mutex);
270 memcpy(&super, cramfs_read(sb, 512, sizeof(super)), sizeof(super));
271 mutex_unlock(&read_mutex);
272 if (super.magic != CRAMFS_MAGIC) {
273 if (super.magic == CRAMFS_MAGIC_WEND && !silent)
274 printk(KERN_ERR "cramfs: wrong endianess\n");
275 else if (!silent)
276 printk(KERN_ERR "cramfs: wrong magic\n");
277 goto out;
281 /* get feature flags first */
282 if (super.flags & ~CRAMFS_SUPPORTED_FLAGS) {
283 printk(KERN_ERR "cramfs: unsupported filesystem features\n");
284 goto out;
287 /* Check that the root inode is in a sane state */
288 if (!S_ISDIR(super.root.mode)) {
289 printk(KERN_ERR "cramfs: root is not a directory\n");
290 goto out;
292 /* correct strange, hard-coded permissions of mkcramfs */
293 super.root.mode |= (S_IRUSR | S_IXUSR | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH);
295 root_offset = super.root.offset << 2;
296 if (super.flags & CRAMFS_FLAG_FSID_VERSION_2) {
297 sbi->size=super.size;
298 sbi->blocks=super.fsid.blocks;
299 sbi->files=super.fsid.files;
300 } else {
301 sbi->size=1<<28;
302 sbi->blocks=0;
303 sbi->files=0;
305 sbi->magic=super.magic;
306 sbi->flags=super.flags;
307 if (root_offset == 0)
308 printk(KERN_INFO "cramfs: empty filesystem");
309 else if (!(super.flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET) &&
310 ((root_offset != sizeof(struct cramfs_super)) &&
311 (root_offset != 512 + sizeof(struct cramfs_super))))
313 printk(KERN_ERR "cramfs: bad root offset %lu\n", root_offset);
314 goto out;
317 /* Set it all up.. */
318 sb->s_op = &cramfs_ops;
319 root = get_cramfs_inode(sb, &super.root, 0);
320 if (IS_ERR(root))
321 goto out;
322 sb->s_root = d_alloc_root(root);
323 if (!sb->s_root) {
324 iput(root);
325 goto out;
327 return 0;
328 out:
329 kfree(sbi);
330 sb->s_fs_info = NULL;
331 return -EINVAL;
334 static int cramfs_statfs(struct dentry *dentry, struct kstatfs *buf)
336 struct super_block *sb = dentry->d_sb;
337 u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
339 buf->f_type = CRAMFS_MAGIC;
340 buf->f_bsize = PAGE_CACHE_SIZE;
341 buf->f_blocks = CRAMFS_SB(sb)->blocks;
342 buf->f_bfree = 0;
343 buf->f_bavail = 0;
344 buf->f_files = CRAMFS_SB(sb)->files;
345 buf->f_ffree = 0;
346 buf->f_fsid.val[0] = (u32)id;
347 buf->f_fsid.val[1] = (u32)(id >> 32);
348 buf->f_namelen = CRAMFS_MAXPATHLEN;
349 return 0;
353 * Read a cramfs directory entry.
355 static int cramfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
357 struct inode *inode = filp->f_path.dentry->d_inode;
358 struct super_block *sb = inode->i_sb;
359 char *buf;
360 unsigned int offset;
361 int copied;
363 /* Offset within the thing. */
364 offset = filp->f_pos;
365 if (offset >= inode->i_size)
366 return 0;
367 /* Directory entries are always 4-byte aligned */
368 if (offset & 3)
369 return -EINVAL;
371 buf = kmalloc(CRAMFS_MAXPATHLEN, GFP_KERNEL);
372 if (!buf)
373 return -ENOMEM;
375 copied = 0;
376 while (offset < inode->i_size) {
377 struct cramfs_inode *de;
378 unsigned long nextoffset;
379 char *name;
380 ino_t ino;
381 mode_t mode;
382 int namelen, error;
384 mutex_lock(&read_mutex);
385 de = cramfs_read(sb, OFFSET(inode) + offset, sizeof(*de)+CRAMFS_MAXPATHLEN);
386 name = (char *)(de+1);
389 * Namelengths on disk are shifted by two
390 * and the name padded out to 4-byte boundaries
391 * with zeroes.
393 namelen = de->namelen << 2;
394 memcpy(buf, name, namelen);
395 ino = cramino(de, OFFSET(inode) + offset);
396 mode = de->mode;
397 mutex_unlock(&read_mutex);
398 nextoffset = offset + sizeof(*de) + namelen;
399 for (;;) {
400 if (!namelen) {
401 kfree(buf);
402 return -EIO;
404 if (buf[namelen-1])
405 break;
406 namelen--;
408 error = filldir(dirent, buf, namelen, offset, ino, mode >> 12);
409 if (error)
410 break;
412 offset = nextoffset;
413 filp->f_pos = offset;
414 copied++;
416 kfree(buf);
417 return 0;
421 * Lookup and fill in the inode data..
423 static struct dentry * cramfs_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
425 unsigned int offset = 0;
426 struct inode *inode = NULL;
427 int sorted;
429 mutex_lock(&read_mutex);
430 sorted = CRAMFS_SB(dir->i_sb)->flags & CRAMFS_FLAG_SORTED_DIRS;
431 while (offset < dir->i_size) {
432 struct cramfs_inode *de;
433 char *name;
434 int namelen, retval;
435 int dir_off = OFFSET(dir) + offset;
437 de = cramfs_read(dir->i_sb, dir_off, sizeof(*de)+CRAMFS_MAXPATHLEN);
438 name = (char *)(de+1);
440 /* Try to take advantage of sorted directories */
441 if (sorted && (dentry->d_name.name[0] < name[0]))
442 break;
444 namelen = de->namelen << 2;
445 offset += sizeof(*de) + namelen;
447 /* Quick check that the name is roughly the right length */
448 if (((dentry->d_name.len + 3) & ~3) != namelen)
449 continue;
451 for (;;) {
452 if (!namelen) {
453 inode = ERR_PTR(-EIO);
454 goto out;
456 if (name[namelen-1])
457 break;
458 namelen--;
460 if (namelen != dentry->d_name.len)
461 continue;
462 retval = memcmp(dentry->d_name.name, name, namelen);
463 if (retval > 0)
464 continue;
465 if (!retval) {
466 inode = get_cramfs_inode(dir->i_sb, de, dir_off);
467 break;
469 /* else (retval < 0) */
470 if (sorted)
471 break;
473 out:
474 mutex_unlock(&read_mutex);
475 if (IS_ERR(inode))
476 return ERR_CAST(inode);
477 d_add(dentry, inode);
478 return NULL;
481 static int cramfs_readpage(struct file *file, struct page * page)
483 struct inode *inode = page->mapping->host;
484 u32 maxblock;
485 int bytes_filled;
486 void *pgdata;
488 maxblock = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
489 bytes_filled = 0;
490 pgdata = kmap(page);
492 if (page->index < maxblock) {
493 struct super_block *sb = inode->i_sb;
494 u32 blkptr_offset = OFFSET(inode) + page->index*4;
495 u32 start_offset, compr_len;
497 start_offset = OFFSET(inode) + maxblock*4;
498 mutex_lock(&read_mutex);
499 if (page->index)
500 start_offset = *(u32 *) cramfs_read(sb, blkptr_offset-4,
502 compr_len = (*(u32 *) cramfs_read(sb, blkptr_offset, 4) -
503 start_offset);
504 mutex_unlock(&read_mutex);
506 if (compr_len == 0)
507 ; /* hole */
508 else if (unlikely(compr_len > (PAGE_CACHE_SIZE << 1))) {
509 pr_err("cramfs: bad compressed blocksize %u\n",
510 compr_len);
511 goto err;
512 } else {
513 mutex_lock(&read_mutex);
514 bytes_filled = cramfs_uncompress_block(pgdata,
515 PAGE_CACHE_SIZE,
516 cramfs_read(sb, start_offset, compr_len),
517 compr_len);
518 mutex_unlock(&read_mutex);
519 if (unlikely(bytes_filled < 0))
520 goto err;
524 memset(pgdata + bytes_filled, 0, PAGE_CACHE_SIZE - bytes_filled);
525 flush_dcache_page(page);
526 kunmap(page);
527 SetPageUptodate(page);
528 unlock_page(page);
529 return 0;
531 err:
532 kunmap(page);
533 ClearPageUptodate(page);
534 SetPageError(page);
535 unlock_page(page);
536 return 0;
539 static const struct address_space_operations cramfs_aops = {
540 .readpage = cramfs_readpage
544 * Our operations:
548 * A directory can only readdir
550 static const struct file_operations cramfs_directory_operations = {
551 .llseek = generic_file_llseek,
552 .read = generic_read_dir,
553 .readdir = cramfs_readdir,
556 static const struct inode_operations cramfs_dir_inode_operations = {
557 .lookup = cramfs_lookup,
560 static const struct super_operations cramfs_ops = {
561 .put_super = cramfs_put_super,
562 .remount_fs = cramfs_remount,
563 .statfs = cramfs_statfs,
566 static struct dentry *cramfs_mount(struct file_system_type *fs_type,
567 int flags, const char *dev_name, void *data)
569 return mount_bdev(fs_type, flags, dev_name, data, cramfs_fill_super);
572 static struct file_system_type cramfs_fs_type = {
573 .owner = THIS_MODULE,
574 .name = "cramfs",
575 .mount = cramfs_mount,
576 .kill_sb = kill_block_super,
577 .fs_flags = FS_REQUIRES_DEV,
580 static int __init init_cramfs_fs(void)
582 int rv;
584 rv = cramfs_uncompress_init();
585 if (rv < 0)
586 return rv;
587 rv = register_filesystem(&cramfs_fs_type);
588 if (rv < 0)
589 cramfs_uncompress_exit();
590 return rv;
593 static void __exit exit_cramfs_fs(void)
595 cramfs_uncompress_exit();
596 unregister_filesystem(&cramfs_fs_type);
599 module_init(init_cramfs_fs)
600 module_exit(exit_cramfs_fs)
601 MODULE_LICENSE("GPL");