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>
diff --git a/fs/hfsplus/extents.c b/fs/hfsplus/extents.c
index 136d860..a7aafb35 100644
--- a/fs/hfsplus/extents.c
+++ b/fs/hfsplus/extents.c
@@ -496,11 +496,13 @@
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 @@
blk_cnt = (inode->i_size + HFSPLUS_SB(sb)->alloc_blksz - 1) >>
HFSPLUS_SB(sb)->alloc_blksz_shift;
- alloc_cnt = hip->alloc_blocks;
- if (blk_cnt == alloc_cnt)
- goto out;
mutex_lock(&hip->extents_lock);
+
+ alloc_cnt = hip->alloc_blocks;
+ if (blk_cnt == alloc_cnt)
+ goto out_unlock;
+
res = hfs_find_init(HFSPLUS_SB(sb)->ext_tree, &fd);
if (res) {
mutex_unlock(&hip->extents_lock);
@@ -590,10 +594,10 @@
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;