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authorOGAWA Hirofumi <hirofumi@mail.parknet.co.jp>2008-11-06 15:53:57 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2008-11-06 18:41:21 -0500
commit2bdf67eb1631f30e2f3f5d49e4007c76e88877a8 (patch)
treed3d337e52516b3b61cdf4508cf445ef8dcaae2ed /fs/fat
parent0e75f5da06c05425f4b375eb981c4489fb2d9787 (diff)
fat: mmu_private race fix
mmu_private is 64bits value, hence it's not atomic to update. So, the access rule for mmu_private is we must hold ->i_mutex. But, fat_get_block() path doesn't follow the rule on non-allocation path. This fixes by using i_size instead if non-allocation path. Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/fat')
-rw-r--r--fs/fat/cache.c23
-rw-r--r--fs/fat/dir.c2
-rw-r--r--fs/fat/fat.h6
-rw-r--r--fs/fat/inode.c4
4 files changed, 25 insertions, 10 deletions
diff --git a/fs/fat/cache.c b/fs/fat/cache.c
index 589edde9053c..b42602298087 100644
--- a/fs/fat/cache.c
+++ b/fs/fat/cache.c
@@ -293,10 +293,12 @@ static int fat_bmap_cluster(struct inode *inode, int cluster)
293} 293}
294 294
295int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys, 295int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys,
296 unsigned long *mapped_blocks) 296 unsigned long *mapped_blocks, int create)
297{ 297{
298 struct super_block *sb = inode->i_sb; 298 struct super_block *sb = inode->i_sb;
299 struct msdos_sb_info *sbi = MSDOS_SB(sb); 299 struct msdos_sb_info *sbi = MSDOS_SB(sb);
300 const unsigned long blocksize = sb->s_blocksize;
301 const unsigned char blocksize_bits = sb->s_blocksize_bits;
300 sector_t last_block; 302 sector_t last_block;
301 int cluster, offset; 303 int cluster, offset;
302 304
@@ -309,10 +311,21 @@ int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys,
309 } 311 }
310 return 0; 312 return 0;
311 } 313 }
312 last_block = (MSDOS_I(inode)->mmu_private + (sb->s_blocksize - 1)) 314
313 >> sb->s_blocksize_bits; 315 last_block = (i_size_read(inode) + (blocksize - 1)) >> blocksize_bits;
314 if (sector >= last_block) 316 if (sector >= last_block) {
315 return 0; 317 if (!create)
318 return 0;
319
320 /*
321 * ->mmu_private can access on only allocation path.
322 * (caller must hold ->i_mutex)
323 */
324 last_block = (MSDOS_I(inode)->mmu_private + (blocksize - 1))
325 >> blocksize_bits;
326 if (sector >= last_block)
327 return 0;
328 }
316 329
317 cluster = sector >> (sbi->cluster_bits - sb->s_blocksize_bits); 330 cluster = sector >> (sbi->cluster_bits - sb->s_blocksize_bits);
318 offset = sector & (sbi->sec_per_clus - 1); 331 offset = sector & (sbi->sec_per_clus - 1);
diff --git a/fs/fat/dir.c b/fs/fat/dir.c
index 140fc39e2307..2ecaa17acdb5 100644
--- a/fs/fat/dir.c
+++ b/fs/fat/dir.c
@@ -77,7 +77,7 @@ next:
77 77
78 *bh = NULL; 78 *bh = NULL;
79 iblock = *pos >> sb->s_blocksize_bits; 79 iblock = *pos >> sb->s_blocksize_bits;
80 err = fat_bmap(dir, iblock, &phys, &mapped_blocks); 80 err = fat_bmap(dir, iblock, &phys, &mapped_blocks, 0);
81 if (err || !phys) 81 if (err || !phys)
82 return -1; /* beyond EOF or error */ 82 return -1; /* beyond EOF or error */
83 83
diff --git a/fs/fat/fat.h b/fs/fat/fat.h
index a69f7f9757c0..4efc5038ed29 100644
--- a/fs/fat/fat.h
+++ b/fs/fat/fat.h
@@ -91,7 +91,9 @@ struct msdos_inode_info {
91 /* for avoiding the race between fat_free() and fat_get_cluster() */ 91 /* for avoiding the race between fat_free() and fat_get_cluster() */
92 unsigned int cache_valid_id; 92 unsigned int cache_valid_id;
93 93
94 loff_t mmu_private; 94 /* NOTE: mmu_private is 64bits, so must hold ->i_mutex to access */
95 loff_t mmu_private; /* physically allocated size */
96
95 int i_start; /* first cluster or 0 */ 97 int i_start; /* first cluster or 0 */
96 int i_logstart; /* logical first cluster */ 98 int i_logstart; /* logical first cluster */
97 int i_attrs; /* unused attribute bits */ 99 int i_attrs; /* unused attribute bits */
@@ -222,7 +224,7 @@ extern void fat_cache_inval_inode(struct inode *inode);
222extern int fat_get_cluster(struct inode *inode, int cluster, 224extern int fat_get_cluster(struct inode *inode, int cluster,
223 int *fclus, int *dclus); 225 int *fclus, int *dclus);
224extern int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys, 226extern int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys,
225 unsigned long *mapped_blocks); 227 unsigned long *mapped_blocks, int create);
226 228
227/* fat/dir.c */ 229/* fat/dir.c */
228extern const struct file_operations fat_dir_operations; 230extern const struct file_operations fat_dir_operations;
diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index be88208b83a6..9e37ad93c730 100644
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -64,7 +64,7 @@ static inline int __fat_get_block(struct inode *inode, sector_t iblock,
64 sector_t phys; 64 sector_t phys;
65 int err, offset; 65 int err, offset;
66 66
67 err = fat_bmap(inode, iblock, &phys, &mapped_blocks); 67 err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create);
68 if (err) 68 if (err)
69 return err; 69 return err;
70 if (phys) { 70 if (phys) {
@@ -94,7 +94,7 @@ static inline int __fat_get_block(struct inode *inode, sector_t iblock,
94 *max_blocks = min(mapped_blocks, *max_blocks); 94 *max_blocks = min(mapped_blocks, *max_blocks);
95 MSDOS_I(inode)->mmu_private += *max_blocks << sb->s_blocksize_bits; 95 MSDOS_I(inode)->mmu_private += *max_blocks << sb->s_blocksize_bits;
96 96
97 err = fat_bmap(inode, iblock, &phys, &mapped_blocks); 97 err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create);
98 if (err) 98 if (err)
99 return err; 99 return err;
100 100