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-rw-r--r--fs/fat/cache.c23
1 files changed, 18 insertions, 5 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);