openfs.c revision 57bde59a067c21ed924de4194344948f3c3ecb9a 
1/*
2 * openfs.c --- open an ext2 filesystem
3 *
4 * Copyright (C) 1993, 1994, 1995, 1996 Theodore Ts'o.
5 *
6 * %Begin-Header%
7 * This file may be redistributed under the terms of the GNU Library
8 * General Public License, version 2.
9 * %End-Header%
10 */
11
12#include "config.h"
13#include <stdio.h>
14#include <string.h>
15#if HAVE_UNISTD_H
16#include <unistd.h>
17#endif
18#include <fcntl.h>
19#include <time.h>
20#if HAVE_SYS_STAT_H
21#include <sys/stat.h>
22#endif
23#if HAVE_SYS_TYPES_H
24#include <sys/types.h>
25#endif
26#ifdef HAVE_ERRNO_H
27#include <errno.h>
28#endif
29
30#include "ext2_fs.h"
31
32
33#include "ext2fs.h"
34#include "e2image.h"
35
36blk64_t ext2fs_descriptor_block_loc2(ext2_filsys fs, blk64_t group_block,
37				     dgrp_t i)
38{
39	int	bg;
40	int	has_super = 0;
41	blk64_t	ret_blk;
42
43	if (!(fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) ||
44	    (i < fs->super->s_first_meta_bg))
45		return (group_block + i + 1);
46
47	bg = EXT2_DESC_PER_BLOCK(fs->super) * i;
48	if (ext2fs_bg_has_super(fs, bg))
49		has_super = 1;
50	ret_blk = ext2fs_group_first_block2(fs, bg) + has_super;
51	/*
52	 * If group_block is not the normal value, we're trying to use
53	 * the backup group descriptors and superblock --- so use the
54	 * alternate location of the second block group in the
55	 * metablock group.  Ideally we should be testing each bg
56	 * descriptor block individually for correctness, but we don't
57	 * have the infrastructure in place to do that.
58	 */
59	if (group_block != fs->super->s_first_data_block &&
60	    ((ret_blk + fs->super->s_blocks_per_group) <
61	     ext2fs_blocks_count(fs->super)))
62		ret_blk += fs->super->s_blocks_per_group;
63	return ret_blk;
64}
65
66blk_t ext2fs_descriptor_block_loc(ext2_filsys fs, blk_t group_block, dgrp_t i)
67{
68	return ext2fs_descriptor_block_loc2(fs, group_block, i);
69}
70
71errcode_t ext2fs_open(const char *name, int flags, int superblock,
72		      unsigned int block_size, io_manager manager,
73		      ext2_filsys *ret_fs)
74{
75	return ext2fs_open2(name, 0, flags, superblock, block_size,
76			    manager, ret_fs);
77}
78
79/*
80 *  Note: if superblock is non-zero, block-size must also be non-zero.
81 * 	Superblock and block_size can be zero to use the default size.
82 *
83 * Valid flags for ext2fs_open()
84 *
85 * 	EXT2_FLAG_RW	- Open the filesystem for read/write.
86 * 	EXT2_FLAG_FORCE - Open the filesystem even if some of the
87 *				features aren't supported.
88 *	EXT2_FLAG_JOURNAL_DEV_OK - Open an ext3 journal device
89 *	EXT2_FLAG_SKIP_MMP - Open without multi-mount protection check.
90 *	EXT2_FLAG_64BITS - Allow 64-bit bitfields (needed for large
91 *				filesystems)
92 */
93errcode_t ext2fs_open2(const char *name, const char *io_options,
94		       int flags, int superblock,
95		       unsigned int block_size, io_manager manager,
96		       ext2_filsys *ret_fs)
97{
98	ext2_filsys	fs;
99	errcode_t	retval;
100	unsigned long	i, first_meta_bg;
101	__u32		features;
102	unsigned int	blocks_per_group, io_flags;
103	blk64_t		group_block, blk;
104	char		*dest, *cp;
105#ifdef WORDS_BIGENDIAN
106	unsigned int	groups_per_block;
107	struct ext2_group_desc *gdp;
108	int		j;
109#endif
110
111	EXT2_CHECK_MAGIC(manager, EXT2_ET_MAGIC_IO_MANAGER);
112
113	retval = ext2fs_get_mem(sizeof(struct struct_ext2_filsys), &fs);
114	if (retval)
115		return retval;
116
117	memset(fs, 0, sizeof(struct struct_ext2_filsys));
118	fs->magic = EXT2_ET_MAGIC_EXT2FS_FILSYS;
119	fs->flags = flags;
120	/* don't overwrite sb backups unless flag is explicitly cleared */
121	fs->flags |= EXT2_FLAG_MASTER_SB_ONLY;
122	fs->umask = 022;
123	retval = ext2fs_get_mem(strlen(name)+1, &fs->device_name);
124	if (retval)
125		goto cleanup;
126	strcpy(fs->device_name, name);
127	cp = strchr(fs->device_name, '?');
128	if (!io_options && cp) {
129		*cp++ = 0;
130		io_options = cp;
131	}
132
133	io_flags = 0;
134	if (flags & EXT2_FLAG_RW)
135		io_flags |= IO_FLAG_RW;
136	if (flags & EXT2_FLAG_EXCLUSIVE)
137		io_flags |= IO_FLAG_EXCLUSIVE;
138	if (flags & EXT2_FLAG_DIRECT_IO)
139		io_flags |= IO_FLAG_DIRECT_IO;
140	retval = manager->open(fs->device_name, io_flags, &fs->io);
141	if (retval)
142		goto cleanup;
143	if (io_options &&
144	    (retval = io_channel_set_options(fs->io, io_options)))
145		goto cleanup;
146	fs->image_io = fs->io;
147	fs->io->app_data = fs;
148	retval = io_channel_alloc_buf(fs->io, -SUPERBLOCK_SIZE, &fs->super);
149	if (retval)
150		goto cleanup;
151	if (flags & EXT2_FLAG_IMAGE_FILE) {
152		retval = ext2fs_get_mem(sizeof(struct ext2_image_hdr),
153					&fs->image_header);
154		if (retval)
155			goto cleanup;
156		retval = io_channel_read_blk(fs->io, 0,
157					     -(int)sizeof(struct ext2_image_hdr),
158					     fs->image_header);
159		if (retval)
160			goto cleanup;
161		if (fs->image_header->magic_number != EXT2_ET_MAGIC_E2IMAGE)
162			return EXT2_ET_MAGIC_E2IMAGE;
163		superblock = 1;
164		block_size = fs->image_header->fs_blocksize;
165	}
166
167	/*
168	 * If the user specifies a specific block # for the
169	 * superblock, then he/she must also specify the block size!
170	 * Otherwise, read the master superblock located at offset
171	 * SUPERBLOCK_OFFSET from the start of the partition.
172	 *
173	 * Note: we only save a backup copy of the superblock if we
174	 * are reading the superblock from the primary superblock location.
175	 */
176	if (superblock) {
177		if (!block_size) {
178			retval = EXT2_ET_INVALID_ARGUMENT;
179			goto cleanup;
180		}
181		io_channel_set_blksize(fs->io, block_size);
182		group_block = superblock;
183		fs->orig_super = 0;
184	} else {
185		io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
186		superblock = 1;
187		group_block = 0;
188		retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->orig_super);
189		if (retval)
190			goto cleanup;
191	}
192	retval = io_channel_read_blk(fs->io, superblock, -SUPERBLOCK_SIZE,
193				     fs->super);
194	if (retval)
195		goto cleanup;
196	if (fs->orig_super)
197		memcpy(fs->orig_super, fs->super, SUPERBLOCK_SIZE);
198
199#ifdef WORDS_BIGENDIAN
200	fs->flags |= EXT2_FLAG_SWAP_BYTES;
201	ext2fs_swap_super(fs->super);
202#else
203	if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
204		retval = EXT2_ET_UNIMPLEMENTED;
205		goto cleanup;
206	}
207#endif
208
209	if (fs->super->s_magic != EXT2_SUPER_MAGIC) {
210		retval = EXT2_ET_BAD_MAGIC;
211		goto cleanup;
212	}
213	if (fs->super->s_rev_level > EXT2_LIB_CURRENT_REV) {
214		retval = EXT2_ET_REV_TOO_HIGH;
215		goto cleanup;
216	}
217
218	/*
219	 * Check for feature set incompatibility
220	 */
221	if (!(flags & EXT2_FLAG_FORCE)) {
222		features = fs->super->s_feature_incompat;
223#ifdef EXT2_LIB_SOFTSUPP_INCOMPAT
224		if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
225			features &= ~EXT2_LIB_SOFTSUPP_INCOMPAT;
226#endif
227		if (features & ~EXT2_LIB_FEATURE_INCOMPAT_SUPP) {
228			retval = EXT2_ET_UNSUPP_FEATURE;
229			goto cleanup;
230		}
231
232		features = fs->super->s_feature_ro_compat;
233#ifdef EXT2_LIB_SOFTSUPP_RO_COMPAT
234		if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
235			features &= ~EXT2_LIB_SOFTSUPP_RO_COMPAT;
236#endif
237		if ((flags & EXT2_FLAG_RW) &&
238		    (features & ~EXT2_LIB_FEATURE_RO_COMPAT_SUPP)) {
239			retval = EXT2_ET_RO_UNSUPP_FEATURE;
240			goto cleanup;
241		}
242
243		if (!(flags & EXT2_FLAG_JOURNAL_DEV_OK) &&
244		    (fs->super->s_feature_incompat &
245		     EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)) {
246			retval = EXT2_ET_UNSUPP_FEATURE;
247			goto cleanup;
248		}
249	}
250
251	if ((fs->super->s_log_block_size + EXT2_MIN_BLOCK_LOG_SIZE) >
252	    EXT2_MAX_BLOCK_LOG_SIZE) {
253		retval = EXT2_ET_CORRUPT_SUPERBLOCK;
254		goto cleanup;
255	}
256
257	/*
258	 * bigalloc requires cluster-aware bitfield operations, which at the
259	 * moment means we need EXT2_FLAG_64BITS.
260	 */
261	if (EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
262				       EXT4_FEATURE_RO_COMPAT_BIGALLOC) &&
263	    !(flags & EXT2_FLAG_64BITS)) {
264		retval = EXT2_ET_CANT_USE_LEGACY_BITMAPS;
265		goto cleanup;
266	}
267
268	if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
269					EXT4_FEATURE_RO_COMPAT_BIGALLOC) &&
270	    (fs->super->s_log_block_size != fs->super->s_log_cluster_size)) {
271		retval = EXT2_ET_CORRUPT_SUPERBLOCK;
272		goto cleanup;
273	}
274	fs->fragsize = fs->blocksize = EXT2_BLOCK_SIZE(fs->super);
275	if (EXT2_INODE_SIZE(fs->super) < EXT2_GOOD_OLD_INODE_SIZE) {
276		retval = EXT2_ET_CORRUPT_SUPERBLOCK;
277		goto cleanup;
278	}
279	fs->cluster_ratio_bits = fs->super->s_log_cluster_size -
280		fs->super->s_log_block_size;
281	if (EXT2_BLOCKS_PER_GROUP(fs->super) !=
282	    EXT2_CLUSTERS_PER_GROUP(fs->super) << fs->cluster_ratio_bits) {
283		retval = EXT2_ET_CORRUPT_SUPERBLOCK;
284		goto cleanup;
285	}
286	fs->inode_blocks_per_group = ((EXT2_INODES_PER_GROUP(fs->super) *
287				       EXT2_INODE_SIZE(fs->super) +
288				       EXT2_BLOCK_SIZE(fs->super) - 1) /
289				      EXT2_BLOCK_SIZE(fs->super));
290	if (block_size) {
291		if (block_size != fs->blocksize) {
292			retval = EXT2_ET_UNEXPECTED_BLOCK_SIZE;
293			goto cleanup;
294		}
295	}
296	/*
297	 * Set the blocksize to the filesystem's blocksize.
298	 */
299	io_channel_set_blksize(fs->io, fs->blocksize);
300
301	/*
302	 * If this is an external journal device, don't try to read
303	 * the group descriptors, because they're not there.
304	 */
305	if (fs->super->s_feature_incompat &
306	    EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) {
307		fs->group_desc_count = 0;
308		*ret_fs = fs;
309		return 0;
310	}
311
312	if (EXT2_INODES_PER_GROUP(fs->super) == 0) {
313		retval = EXT2_ET_CORRUPT_SUPERBLOCK;
314		goto cleanup;
315	}
316
317	/*
318	 * Read group descriptors
319	 */
320	blocks_per_group = EXT2_BLOCKS_PER_GROUP(fs->super);
321	if (blocks_per_group == 0 ||
322	    blocks_per_group > EXT2_MAX_BLOCKS_PER_GROUP(fs->super) ||
323	    fs->inode_blocks_per_group > EXT2_MAX_INODES_PER_GROUP(fs->super) ||
324           EXT2_DESC_PER_BLOCK(fs->super) == 0 ||
325           fs->super->s_first_data_block >= ext2fs_blocks_count(fs->super)) {
326		retval = EXT2_ET_CORRUPT_SUPERBLOCK;
327		goto cleanup;
328	}
329	fs->group_desc_count = ext2fs_div64_ceil(ext2fs_blocks_count(fs->super) -
330						 fs->super->s_first_data_block,
331						 blocks_per_group);
332	if (fs->group_desc_count * EXT2_INODES_PER_GROUP(fs->super) !=
333	    fs->super->s_inodes_count) {
334		retval = EXT2_ET_CORRUPT_SUPERBLOCK;
335		goto cleanup;
336	}
337	fs->desc_blocks = ext2fs_div_ceil(fs->group_desc_count,
338					  EXT2_DESC_PER_BLOCK(fs->super));
339	retval = ext2fs_get_array(fs->desc_blocks, fs->blocksize,
340				&fs->group_desc);
341	if (retval)
342		goto cleanup;
343	if (!group_block)
344		group_block = fs->super->s_first_data_block;
345	if (group_block == 0 && fs->blocksize == 1024)
346		group_block = 1; /* Deal with 1024 blocksize && bigalloc */
347	dest = (char *) fs->group_desc;
348#ifdef WORDS_BIGENDIAN
349	groups_per_block = EXT2_DESC_PER_BLOCK(fs->super);
350#endif
351	if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
352		first_meta_bg = fs->super->s_first_meta_bg;
353	else
354		first_meta_bg = fs->desc_blocks;
355	if (first_meta_bg) {
356		retval = io_channel_read_blk(fs->io, group_block+1,
357					     first_meta_bg, dest);
358		if (retval)
359			goto cleanup;
360#ifdef WORDS_BIGENDIAN
361		gdp = (struct ext2_group_desc *) dest;
362		for (j=0; j < groups_per_block*first_meta_bg; j++) {
363			gdp = ext2fs_group_desc(fs, fs->group_desc, j);
364			ext2fs_swap_group_desc2(fs, gdp);
365		}
366#endif
367		dest += fs->blocksize*first_meta_bg;
368	}
369	for (i=first_meta_bg ; i < fs->desc_blocks; i++) {
370		blk = ext2fs_descriptor_block_loc2(fs, group_block, i);
371		retval = io_channel_read_blk64(fs->io, blk, 1, dest);
372		if (retval)
373			goto cleanup;
374#ifdef WORDS_BIGENDIAN
375		for (j=0; j < groups_per_block; j++) {
376			gdp = ext2fs_group_desc(fs, fs->group_desc,
377						i * groups_per_block + j);
378			ext2fs_swap_group_desc2(fs, gdp);
379		}
380#endif
381		dest += fs->blocksize;
382	}
383
384	fs->stride = fs->super->s_raid_stride;
385
386	/*
387	 * If recovery is from backup superblock, Clear _UNININT flags &
388	 * reset bg_itable_unused to zero
389	 */
390	if (superblock > 1 && EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
391					EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) {
392		dgrp_t group;
393
394		for (group = 0; group < fs->group_desc_count; group++) {
395			ext2fs_bg_flags_clear(fs, group, EXT2_BG_BLOCK_UNINIT);
396			ext2fs_bg_flags_clear(fs, group, EXT2_BG_INODE_UNINIT);
397			ext2fs_bg_itable_unused_set(fs, group, 0);
398			/* The checksum will be reset later, but fix it here
399			 * anyway to avoid printing a lot of spurious errors. */
400			ext2fs_group_desc_csum_set(fs, group);
401		}
402		if (fs->flags & EXT2_FLAG_RW)
403			ext2fs_mark_super_dirty(fs);
404	}
405
406	if ((fs->super->s_feature_incompat & EXT4_FEATURE_INCOMPAT_MMP) &&
407	    !(flags & EXT2_FLAG_SKIP_MMP) &&
408	    (flags & (EXT2_FLAG_RW | EXT2_FLAG_EXCLUSIVE))) {
409		retval = ext2fs_mmp_start(fs);
410		if (retval) {
411			fs->flags |= EXT2_FLAG_SKIP_MMP; /* just do cleanup */
412			ext2fs_mmp_stop(fs);
413			goto cleanup;
414		}
415	}
416
417	fs->flags &= ~EXT2_FLAG_NOFREE_ON_ERROR;
418	*ret_fs = fs;
419
420	return 0;
421cleanup:
422	if (flags & EXT2_FLAG_NOFREE_ON_ERROR)
423		*ret_fs = fs;
424	else
425		ext2fs_free(fs);
426	return retval;
427}
428
429/*
430 * Set/get the filesystem data I/O channel.
431 *
432 * These functions are only valid if EXT2_FLAG_IMAGE_FILE is true.
433 */
434errcode_t ext2fs_get_data_io(ext2_filsys fs, io_channel *old_io)
435{
436	if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
437		return EXT2_ET_NOT_IMAGE_FILE;
438	if (old_io) {
439		*old_io = (fs->image_io == fs->io) ? 0 : fs->io;
440	}
441	return 0;
442}
443
444errcode_t ext2fs_set_data_io(ext2_filsys fs, io_channel new_io)
445{
446	if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
447		return EXT2_ET_NOT_IMAGE_FILE;
448	fs->io = new_io ? new_io : fs->image_io;
449	return 0;
450}
451
452errcode_t ext2fs_rewrite_to_io(ext2_filsys fs, io_channel new_io)
453{
454	if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
455		return EXT2_ET_NOT_IMAGE_FILE;
456	fs->io = fs->image_io = new_io;
457	fs->flags |= EXT2_FLAG_DIRTY | EXT2_FLAG_RW |
458		EXT2_FLAG_BB_DIRTY | EXT2_FLAG_IB_DIRTY;
459	fs->flags &= ~EXT2_FLAG_IMAGE_FILE;
460	return 0;
461}
462