summaryrefslogtreecommitdiffstats
path: root/fs/hfs/mdb.c
blob: 482081bcdf70c86da21f22ca1c443373b7327180 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
/*
 *  linux/fs/hfs/mdb.c
 *
 * Copyright (C) 1995-1997  Paul H. Hargrove
 * (C) 2003 Ardis Technologies <roman@ardistech.com>
 * This file may be distributed under the terms of the GNU General Public License.
 *
 * This file contains functions for reading/writing the MDB.
 */

#include <linux/cdrom.h>
#include <linux/genhd.h>
#include <linux/nls.h>
#include <linux/slab.h>

#include "hfs_fs.h"
#include "btree.h"

/*================ File-local data types ================*/

/*
 * The HFS Master Directory Block (MDB).
 *
 * Also known as the Volume Information Block (VIB), this structure is
 * the HFS equivalent of a superblock.
 *
 * Reference: _Inside Macintosh: Files_ pages 2-59 through 2-62
 *
 * modified for HFS Extended
 */

static int hfs_get_last_session(struct super_block *sb,
				sector_t *start, sector_t *size)
{
	struct cdrom_multisession ms_info;
	struct cdrom_tocentry te;
	int res;

	/* default values */
	*start = 0;
	*size = i_size_read(sb->s_bdev->bd_inode) >> 9;

	if (HFS_SB(sb)->session >= 0) {
		te.cdte_track = HFS_SB(sb)->session;
		te.cdte_format = CDROM_LBA;
		res = ioctl_by_bdev(sb->s_bdev, CDROMREADTOCENTRY, (unsigned long)&te);
		if (!res && (te.cdte_ctrl & CDROM_DATA_TRACK) == 4) {
			*start = (sector_t)te.cdte_addr.lba << 2;
			return 0;
		}
		pr_err("invalid session number or type of track\n");
		return -EINVAL;
	}
	ms_info.addr_format = CDROM_LBA;
	res = ioctl_by_bdev(sb->s_bdev, CDROMMULTISESSION, (unsigned long)&ms_info);
	if (!res && ms_info.xa_flag)
		*start = (sector_t)ms_info.addr.lba << 2;
	return 0;
}

/*
 * hfs_mdb_get()
 *
 * Build the in-core MDB for a filesystem, including
 * the B-trees and the volume bitmap.
 */
int hfs_mdb_get(struct super_block *sb)
{
	struct buffer_head *bh;
	struct hfs_mdb *mdb, *mdb2;
	unsigned int block;
	char *ptr;
	int off2, len, size, sect;
	sector_t part_start, part_size;
	loff_t off;
	__be16 attrib;

	/* set the device driver to 512-byte blocks */
	size = sb_min_blocksize(sb, HFS_SECTOR_SIZE);
	if (!size)
		return -EINVAL;

	if (hfs_get_last_session(sb, &part_start, &part_size))
		return -EINVAL;
	while (1) {
		/* See if this is an HFS filesystem */
		bh = sb_bread512(sb, part_start + HFS_MDB_BLK, mdb);
		if (!bh)
			goto out;

		if (mdb->drSigWord == cpu_to_be16(HFS_SUPER_MAGIC))
			break;
		brelse(bh);

		/* check for a partition block
		 * (should do this only for cdrom/loop though)
		 */
		if (hfs_part_find(sb, &part_start, &part_size))
			goto out;
	}

	HFS_SB(sb)->alloc_blksz = size = be32_to_cpu(mdb->drAlBlkSiz);
	if (!size || (size & (HFS_SECTOR_SIZE - 1))) {
		pr_err("bad allocation block size %d\n", size);
		goto out_bh;
	}

	size = min(HFS_SB(sb)->alloc_blksz, (u32)PAGE_SIZE);
	/* size must be a multiple of 512 */
	while (size & (size - 1))
		size -= HFS_SECTOR_SIZE;
	sect = be16_to_cpu(mdb->drAlBlSt) + part_start;
	/* align block size to first sector */
	while (sect & ((size - 1) >> HFS_SECTOR_SIZE_BITS))
		size >>= 1;
	/* align block size to weird alloc size */
	while (HFS_SB(sb)->alloc_blksz & (size - 1))
		size >>= 1;
	brelse(bh);
	if (!sb_set_blocksize(sb, size)) {
		pr_err("unable to set blocksize to %u\n", size);
		goto out;
	}

	bh = sb_bread512(sb, part_start + HFS_MDB_BLK, mdb);
	if (!bh)
		goto out;
	if (mdb->drSigWord != cpu_to_be16(HFS_SUPER_MAGIC))
		goto out_bh;

	HFS_SB(sb)->mdb_bh = bh;
	HFS_SB(sb)->mdb = mdb;

	/* These parameters are read from the MDB, and never written */
	HFS_SB(sb)->part_start = part_start;
	HFS_SB(sb)->fs_ablocks = be16_to_cpu(mdb->drNmAlBlks);
	HFS_SB(sb)->fs_div = HFS_SB(sb)->alloc_blksz >> sb->s_blocksize_bits;
	HFS_SB(sb)->clumpablks = be32_to_cpu(mdb->drClpSiz) /
				 HFS_SB(sb)->alloc_blksz;
	if (!HFS_SB(sb)->clumpablks)
		HFS_SB(sb)->clumpablks = 1;
	HFS_SB(sb)->fs_start = (be16_to_cpu(mdb->drAlBlSt) + part_start) >>
			       (sb->s_blocksize_bits - HFS_SECTOR_SIZE_BITS);

	/* These parameters are read from and written to the MDB */
	HFS_SB(sb)->free_ablocks = be16_to_cpu(mdb->drFreeBks);
	HFS_SB(sb)->next_id = be32_to_cpu(mdb->drNxtCNID);
	HFS_SB(sb)->root_files = be16_to_cpu(mdb->drNmFls);
	HFS_SB(sb)->root_dirs = be16_to_cpu(mdb->drNmRtDirs);
	HFS_SB(sb)->file_count = be32_to_cpu(mdb->drFilCnt);
	HFS_SB(sb)->folder_count = be32_to_cpu(mdb->drDirCnt);

	/* TRY to get the alternate (backup) MDB. */
	sect = part_start + part_size - 2;
	bh = sb_bread512(sb, sect, mdb2);
	if (bh) {
		if (mdb2->drSigWord == cpu_to_be16(HFS_SUPER_MAGIC)) {
			HFS_SB(sb)->alt_mdb_bh = bh;
			HFS_SB(sb)->alt_mdb = mdb2;
		} else
			brelse(bh);
	}

	if (!HFS_SB(sb)->alt_mdb) {
		pr_warn("unable to locate alternate MDB\n");
		pr_warn("continuing without an alternate MDB\n");
	}

	HFS_SB(sb)->bitmap = kmalloc(8192, GFP_KERNEL);
	if (!HFS_SB(sb)->bitmap)
		goto out;

	/* read in the bitmap */
	block = be16_to_cpu(mdb->drVBMSt) + part_start;
	off = (loff_t)block << HFS_SECTOR_SIZE_BITS;
	size = (HFS_SB(sb)->fs_ablocks + 8) / 8;
	ptr = (u8 *)HFS_SB(sb)->bitmap;
	while (size) {
		bh = sb_bread(sb, off >> sb->s_blocksize_bits);
		if (!bh) {
			pr_err("unable to read volume bitmap\n");
			goto out;
		}
		off2 = off & (sb->s_blocksize - 1);
		len = min((int)sb->s_blocksize - off2, size);
		memcpy(ptr, bh->b_data + off2, len);
		brelse(bh);
		ptr += len;
		off += len;
		size -= len;
	}

	HFS_SB(sb)->ext_tree = hfs_btree_open(sb, HFS_EXT_CNID, hfs_ext_keycmp);
	if (!HFS_SB(sb)->ext_tree) {
		pr_err("unable to open extent tree\n");
		goto out;
	}
	HFS_SB(sb)->cat_tree = hfs_btree_open(sb, HFS_CAT_CNID, hfs_cat_keycmp);
	if (!HFS_SB(sb)->cat_tree) {
		pr_err("unable to open catalog tree\n");
		goto out;
	}

	attrib = mdb->drAtrb;
	if (!(attrib & cpu_to_be16(HFS_SB_ATTRIB_UNMNT))) {
		pr_warn("filesystem was not cleanly unmounted, running fsck.hfs is recommended.  mounting read-only.\n");
		sb->s_flags |= MS_RDONLY;
	}
	if ((attrib & cpu_to_be16(HFS_SB_ATTRIB_SLOCK))) {
		pr_warn("filesystem is marked locked, mounting read-only.\n");
		sb->s_flags |= MS_RDONLY;
	}
	if (!(sb->s_flags & MS_RDONLY)) {
		/* Mark the volume uncleanly unmounted in case we crash */
		attrib &= cpu_to_be16(~HFS_SB_ATTRIB_UNMNT);
		attrib |= cpu_to_be16(HFS_SB_ATTRIB_INCNSTNT);
		mdb->drAtrb = attrib;
		be32_add_cpu(&mdb->drWrCnt, 1);
		mdb->drLsMod = hfs_mtime();

		mark_buffer_dirty(HFS_SB(sb)->mdb_bh);
		sync_dirty_buffer(HFS_SB(sb)->mdb_bh);
	}

	return 0;

out_bh:
	brelse(bh);
out:
	hfs_mdb_put(sb);
	return -EIO;
}

/*
 * hfs_mdb_commit()
 *
 * Description:
 *   This updates the MDB on disk.
 *   It does not check, if the superblock has been modified, or
 *   if the filesystem has been mounted read-only. It is mainly
 *   called by hfs_sync_fs() and flush_mdb().
 * Input Variable(s):
 *   struct hfs_mdb *mdb: Pointer to the hfs MDB
 *   int backup;
 * Output Variable(s):
 *   NONE
 * Returns:
 *   void
 * Preconditions:
 *   'mdb' points to a "valid" (struct hfs_mdb).
 * Postconditions:
 *   The HFS MDB and on disk will be updated, by copying the possibly
 *   modified fields from the in memory MDB (in native byte order) to
 *   the disk block buffer.
 *   If 'backup' is non-zero then the alternate MDB is also written
 *   and the function doesn't return until it is actually on disk.
 */
void hfs_mdb_commit(struct super_block *sb)
{
	struct hfs_mdb *mdb = HFS_SB(sb)->mdb;

	if (sb->s_flags & MS_RDONLY)
		return;

	lock_buffer(HFS_SB(sb)->mdb_bh);
	if (test_and_clear_bit(HFS_FLG_MDB_DIRTY, &HFS_SB(sb)->flags)) {
		/* These parameters may have been modified, so write them back */
		mdb->drLsMod = hfs_mtime();
		mdb->drFreeBks = cpu_to_be16(HFS_SB(sb)->free_ablocks);
		mdb->drNxtCNID = cpu_to_be32(HFS_SB(sb)->next_id);
		mdb->drNmFls = cpu_to_be16(HFS_SB(sb)->root_files);
		mdb->drNmRtDirs = cpu_to_be16(HFS_SB(sb)->root_dirs);
		mdb->drFilCnt = cpu_to_be32(HFS_SB(sb)->file_count);
		mdb->drDirCnt = cpu_to_be32(HFS_SB(sb)->folder_count);

		/* write MDB to disk */
		mark_buffer_dirty(HFS_SB(sb)->mdb_bh);
	}

	/* write the backup MDB, not returning until it is written.
	 * we only do this when either the catalog or extents overflow
	 * files grow. */
	if (test_and_clear_bit(HFS_FLG_ALT_MDB_DIRTY, &HFS_SB(sb)->flags) &&
	    HFS_SB(sb)->alt_mdb) {
		hfs_inode_write_fork(HFS_SB(sb)->ext_tree->inode, mdb->drXTExtRec,
				     &mdb->drXTFlSize, NULL);
		hfs_inode_write_fork(HFS_SB(sb)->cat_tree->inode, mdb->drCTExtRec,
				     &mdb->drCTFlSize, NULL);

		lock_buffer(HFS_SB(sb)->alt_mdb_bh);
		memcpy(HFS_SB(sb)->alt_mdb, HFS_SB(sb)->mdb, HFS_SECTOR_SIZE);
		HFS_SB(sb)->alt_mdb->drAtrb |= cpu_to_be16(HFS_SB_ATTRIB_UNMNT);
		HFS_SB(sb)->alt_mdb->drAtrb &= cpu_to_be16(~HFS_SB_ATTRIB_INCNSTNT);
		unlock_buffer(HFS_SB(sb)->alt_mdb_bh);

		mark_buffer_dirty(HFS_SB(sb)->alt_mdb_bh);
		sync_dirty_buffer(HFS_SB(sb)->alt_mdb_bh);
	}

	if (test_and_clear_bit(HFS_FLG_BITMAP_DIRTY, &HFS_SB(sb)->flags)) {
		struct buffer_head *bh;
		sector_t block;
		char *ptr;
		int off, size, len;

		block = be16_to_cpu(HFS_SB(sb)->mdb->drVBMSt) + HFS_SB(sb)->part_start;
		off = (block << HFS_SECTOR_SIZE_BITS) & (sb->s_blocksize - 1);
		block >>= sb->s_blocksize_bits - HFS_SECTOR_SIZE_BITS;
		size = (HFS_SB(sb)->fs_ablocks + 7) / 8;
		ptr = (u8 *)HFS_SB(sb)->bitmap;
		while (size) {
			bh = sb_bread(sb, block);
			if (!bh) {
				pr_err("unable to read volume bitmap\n");
				break;
			}
			len = min((int)sb->s_blocksize - off, size);

			lock_buffer(bh);
			memcpy(bh->b_data + off, ptr, len);
			unlock_buffer(bh);

			mark_buffer_dirty(bh);
			brelse(bh);
			block++;
			off = 0;
			ptr += len;
			size -= len;
		}
	}
	unlock_buffer(HFS_SB(sb)->mdb_bh);
}

void hfs_mdb_close(struct super_block *sb)
{
	/* update volume attributes */
	if (sb->s_flags & MS_RDONLY)
		return;
	HFS_SB(sb)->mdb->drAtrb |= cpu_to_be16(HFS_SB_ATTRIB_UNMNT);
	HFS_SB(sb)->mdb->drAtrb &= cpu_to_be16(~HFS_SB_ATTRIB_INCNSTNT);
	mark_buffer_dirty(HFS_SB(sb)->mdb_bh);
}

/*
 * hfs_mdb_put()
 *
 * Release the resources associated with the in-core MDB.  */
void hfs_mdb_put(struct super_block *sb)
{
	if (!HFS_SB(sb))
		return;
	/* free the B-trees */
	hfs_btree_close(HFS_SB(sb)->ext_tree);
	hfs_btree_close(HFS_SB(sb)->cat_tree);

	/* free the buffers holding the primary and alternate MDBs */
	brelse(HFS_SB(sb)->mdb_bh);
	brelse(HFS_SB(sb)->alt_mdb_bh);

	unload_nls(HFS_SB(sb)->nls_io);
	unload_nls(HFS_SB(sb)->nls_disk);

	kfree(HFS_SB(sb)->bitmap);
	kfree(HFS_SB(sb));
	sb->s_fs_info = NULL;
}
OpenPOWER on IntegriCloud