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| author | Sougata Santra <sougata@tuxera.com> | 2014-04-03 14:50:34 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-04-03 16:21:26 -0700 |
| commit | d7bdb996aef67ea24c62707ca4e29b07025e9683 (patch) | |
| tree | 619189c603f5ff8dca0f83880bc38382da61039d /fs/hfsplus | |
| parent | abfeb724b43f371ea70ec2c1290ed33e6f65db60 (diff) | |
| download | lwn-d7bdb996aef67ea24c62707ca4e29b07025e9683.tar.gz lwn-d7bdb996aef67ea24c62707ca4e29b07025e9683.zip | |
fs/hfsplus/extents.c: fix concurrent acess of alloc_blocks
Concurrent access to alloc_blocks in hfsplus_inode_info() is protected
by extents_lock mutex. This patch fixes two instances where
alloc_blocks modification was not protected with this lock.
This fixes possible allocation bitmap corruption in race conditions
while extending and truncating files.
[akpm@linux-foundation.org: take extents_lock before taking a copy of ->alloc_blocks]
[akpm@linux-foundation.org: remove now-unused label `out']
Signed-off-by: Sougata Santra <sougata@tuxera.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Vyacheslav Dubeyko <slava@dubeyko.com>
Cc: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/hfsplus')
| -rw-r--r-- | fs/hfsplus/extents.c | 14 |
1 files changed, 9 insertions, 5 deletions
diff --git a/fs/hfsplus/extents.c b/fs/hfsplus/extents.c index 136d860cd746..a7aafb35b624 100644 --- a/fs/hfsplus/extents.c +++ b/fs/hfsplus/extents.c @@ -496,11 +496,13 @@ int hfsplus_file_extend(struct inode *inode) goto insert_extent; } out: - mutex_unlock(&hip->extents_lock); if (!res) { hip->alloc_blocks += len; + mutex_unlock(&hip->extents_lock); hfsplus_mark_inode_dirty(inode, HFSPLUS_I_ALLOC_DIRTY); + return 0; } + mutex_unlock(&hip->extents_lock); return res; insert_extent: @@ -554,11 +556,13 @@ void hfsplus_file_truncate(struct inode *inode) blk_cnt = (inode->i_size + HFSPLUS_SB(sb)->alloc_blksz - 1) >> HFSPLUS_SB(sb)->alloc_blksz_shift; + + mutex_lock(&hip->extents_lock); + alloc_cnt = hip->alloc_blocks; if (blk_cnt == alloc_cnt) - goto out; + goto out_unlock; - mutex_lock(&hip->extents_lock); res = hfs_find_init(HFSPLUS_SB(sb)->ext_tree, &fd); if (res) { mutex_unlock(&hip->extents_lock); @@ -590,10 +594,10 @@ void hfsplus_file_truncate(struct inode *inode) hfs_brec_remove(&fd); } hfs_find_exit(&fd); - mutex_unlock(&hip->extents_lock); hip->alloc_blocks = blk_cnt; -out: +out_unlock: + mutex_unlock(&hip->extents_lock); hip->phys_size = inode->i_size; hip->fs_blocks = (inode->i_size + sb->s_blocksize - 1) >> sb->s_blocksize_bits; |