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authorAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>2008-01-28 23:58:27 -0500
committerTheodore Ts'o <tytso@mit.edu>2008-01-28 23:58:27 -0500
commitabcb2947c91130426539f209f7a473a67a1f6663 (patch)
tree4305e34c0a129c1351d9acabd254b0f896617470 /fs/ext4
parent389d1b083c767a360ec84b27a95da06244becec8 (diff)
ext4: add block bitmap validation
When a new block bitmap is read from disk in read_block_bitmap() there are a few bits that should ALWAYS be set. In particular, the blocks given corresponding to block bitmap, inode bitmap and inode tables. Validate the block bitmap against these blocks. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Diffstat (limited to 'fs/ext4')
-rw-r--r--fs/ext4/balloc.c99
1 files changed, 81 insertions, 18 deletions
diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index ff3428e195b4..d460223b8e1d 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -189,13 +189,65 @@ struct ext4_group_desc * ext4_get_group_desc(struct super_block * sb,
189 return desc; 189 return desc;
190} 190}
191 191
192static int ext4_valid_block_bitmap(struct super_block *sb,
193 struct ext4_group_desc *desc,
194 unsigned int block_group,
195 struct buffer_head *bh)
196{
197 ext4_grpblk_t offset;
198 ext4_grpblk_t next_zero_bit;
199 ext4_fsblk_t bitmap_blk;
200 ext4_fsblk_t group_first_block;
201
202 if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
203 /* with FLEX_BG, the inode/block bitmaps and itable
204 * blocks may not be in the group at all
205 * so the bitmap validation will be skipped for those groups
206 * or it has to also read the block group where the bitmaps
207 * are located to verify they are set.
208 */
209 return 1;
210 }
211 group_first_block = ext4_group_first_block_no(sb, block_group);
212
213 /* check whether block bitmap block number is set */
214 bitmap_blk = ext4_block_bitmap(sb, desc);
215 offset = bitmap_blk - group_first_block;
216 if (!ext4_test_bit(offset, bh->b_data))
217 /* bad block bitmap */
218 goto err_out;
219
220 /* check whether the inode bitmap block number is set */
221 bitmap_blk = ext4_inode_bitmap(sb, desc);
222 offset = bitmap_blk - group_first_block;
223 if (!ext4_test_bit(offset, bh->b_data))
224 /* bad block bitmap */
225 goto err_out;
226
227 /* check whether the inode table block number is set */
228 bitmap_blk = ext4_inode_table(sb, desc);
229 offset = bitmap_blk - group_first_block;
230 next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
231 offset + EXT4_SB(sb)->s_itb_per_group,
232 offset);
233 if (next_zero_bit >= offset + EXT4_SB(sb)->s_itb_per_group)
234 /* good bitmap for inode tables */
235 return 1;
236
237err_out:
238 ext4_error(sb, __FUNCTION__,
239 "Invalid block bitmap - "
240 "block_group = %d, block = %llu",
241 block_group, bitmap_blk);
242 return 0;
243}
192/** 244/**
193 * read_block_bitmap() 245 * read_block_bitmap()
194 * @sb: super block 246 * @sb: super block
195 * @block_group: given block group 247 * @block_group: given block group
196 * 248 *
197 * Read the bitmap for a given block_group, reading into the specified 249 * Read the bitmap for a given block_group,and validate the
198 * slot in the superblock's bitmap cache. 250 * bits for block/inode/inode tables are set in the bitmaps
199 * 251 *
200 * Return buffer_head on success or NULL in case of failure. 252 * Return buffer_head on success or NULL in case of failure.
201 */ 253 */
@@ -210,25 +262,36 @@ read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
210 if (!desc) 262 if (!desc)
211 return NULL; 263 return NULL;
212 bitmap_blk = ext4_block_bitmap(sb, desc); 264 bitmap_blk = ext4_block_bitmap(sb, desc);
265 bh = sb_getblk(sb, bitmap_blk);
266 if (unlikely(!bh)) {
267 ext4_error(sb, __FUNCTION__,
268 "Cannot read block bitmap - "
269 "block_group = %d, block_bitmap = %llu",
270 (int)block_group, (unsigned long long)bitmap_blk);
271 return NULL;
272 }
273 if (bh_uptodate_or_lock(bh))
274 return bh;
275
213 if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) { 276 if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
214 bh = sb_getblk(sb, bitmap_blk); 277 ext4_init_block_bitmap(sb, bh, block_group, desc);
215 if (!buffer_uptodate(bh)) { 278 set_buffer_uptodate(bh);
216 lock_buffer(bh); 279 unlock_buffer(bh);
217 if (!buffer_uptodate(bh)) { 280 return bh;
218 ext4_init_block_bitmap(sb, bh, block_group,
219 desc);
220 set_buffer_uptodate(bh);
221 }
222 unlock_buffer(bh);
223 }
224 } else {
225 bh = sb_bread(sb, bitmap_blk);
226 } 281 }
227 if (!bh) 282 if (bh_submit_read(bh) < 0) {
228 ext4_error (sb, __FUNCTION__, 283 put_bh(bh);
284 ext4_error(sb, __FUNCTION__,
229 "Cannot read block bitmap - " 285 "Cannot read block bitmap - "
230 "block_group = %lu, block_bitmap = %llu", 286 "block_group = %d, block_bitmap = %llu",
231 block_group, bitmap_blk); 287 (int)block_group, (unsigned long long)bitmap_blk);
288 return NULL;
289 }
290 if (!ext4_valid_block_bitmap(sb, desc, block_group, bh)) {
291 put_bh(bh);
292 return NULL;
293 }
294
232 return bh; 295 return bh;
233} 296}
234/* 297/*