From: Sougata Santra <sougata@xxxxxxxxxx>
This patch has been added to the 3.12 stable tree. If you have any
objections, please let us know.
===============
commit d7bdb996aef67ea24c62707ca4e29b07025e9683 upstream.
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@xxxxxxxxxxxxxxxxxxxx: take extents_lock before taking a copy of ->alloc_blocks]
[akpm@xxxxxxxxxxxxxxxxxxxx: remove now-unused label `out']
Signed-off-by: Sougata Santra <sougata@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Cc: Vyacheslav Dubeyko <slava@xxxxxxxxxxx>
Cc: Alexey Khoroshilov <khoroshilov@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
fs/hfsplus/extents.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/fs/hfsplus/extents.c b/fs/hfsplus/extents.c
index fbb212fbb1ef..f0f601c83ad6 100644
--- a/fs/hfsplus/extents.c
+++ b/fs/hfsplus/extents.c
@@ -498,11 +498,13 @@ 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:
@@ -556,11 +558,13 @@ 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);
@@ -592,10 +596,10 @@ 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;
--
2.1.3
--
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