ext4: Fix buffer double free in ext4_alloc_branch()
commit c5c7b8ddfb
upstream.
Error recovery in ext4_alloc_branch() calls ext4_forget() even for
buffer corresponding to indirect block it did not allocate. This leads
to brelse() being called twice for that buffer (once from ext4_forget()
and once from cleanup in ext4_ind_map_blocks()) leading to buffer use
count misaccounting. Eventually (but often much later because there
are other users of the buffer) we will see messages like:
VFS: brelse: Trying to free free buffer
Another manifestation of this problem is an error:
JBD2 unexpected failure: jbd2_journal_revoke: !buffer_revoked(bh);
inconsistent data on disk
The fix is easy - don't forget buffer we did not allocate. Also add an
explanatory comment because the indexing at ext4_alloc_branch() is
somewhat subtle.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
parent
baa9dbe85a
commit
cbbe137036
|
@ -389,7 +389,13 @@ static int ext4_alloc_branch(handle_t *handle, struct inode *inode,
|
|||
return 0;
|
||||
failed:
|
||||
for (; i >= 0; i--) {
|
||||
if (i != indirect_blks && branch[i].bh)
|
||||
/*
|
||||
* We want to ext4_forget() only freshly allocated indirect
|
||||
* blocks. Buffer for new_blocks[i-1] is at branch[i].bh and
|
||||
* buffer at branch[0].bh is indirect block / inode already
|
||||
* existing before ext4_alloc_branch() was called.
|
||||
*/
|
||||
if (i > 0 && i != indirect_blks && branch[i].bh)
|
||||
ext4_forget(handle, 1, inode, branch[i].bh,
|
||||
branch[i].bh->b_blocknr);
|
||||
ext4_free_blocks(handle, inode, NULL, new_blocks[i],
|
||||
|
|
Loading…
Reference in New Issue