path: root/fs
diff options
authorDave Chinner <dchinner@redhat.com>2015-07-29 11:48:02 +1000
committerDave Chinner <david@fromorbit.com>2015-07-29 11:48:02 +1000
commitdf150ed102baa0e78c06e08e975dfb47147dd677 (patch)
tree17009e6cb40e45695db64014cc48356af53180bf /fs
parentxfs: remote attribute headers contain an invalid LSN (diff)
xfs: remote attributes need to be considered data
We don't log remote attribute contents, and instead write them synchronously before we commit the block allocation and attribute tree update transaction. As a result we are writing to the allocated space before the allcoation has been made permanent. As a result, we cannot consider this allocation to be a metadata allocation. Metadata allocation can take blocks from the free list and so reuse them before the transaction that freed the block is committed to disk. This behaviour is perfectly fine for journalled metadata changes as log recovery will ensure the free operation is replayed before the overwrite, but for remote attribute writes this is not the case. Hence we have to consider the remote attribute blocks to contain data and allocate accordingly. We do this by dropping the XFS_BMAPI_METADATA flag from the block allocation. This means the allocation will not use blocks that are on the busy list without first ensuring that the freeing transaction has been committed to disk and the blocks removed from the busy list. This ensures we will never overwrite a freed block without first ensuring that it is really free. cc: <stable@vger.kernel.org> Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Brian Foster <bfoster@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
Diffstat (limited to 'fs')
1 files changed, 11 insertions, 4 deletions
diff --git a/fs/xfs/libxfs/xfs_attr_remote.c b/fs/xfs/libxfs/xfs_attr_remote.c
index 2faec26962e8..dd714037c322 100644
--- a/fs/xfs/libxfs/xfs_attr_remote.c
+++ b/fs/xfs/libxfs/xfs_attr_remote.c
@@ -451,14 +451,21 @@ xfs_attr_rmtval_set(
* Allocate a single extent, up to the size of the value.
+ *
+ * Note that we have to consider this a data allocation as we
+ * write the remote attribute without logging the contents.
+ * Hence we must ensure that we aren't using blocks that are on
+ * the busy list so that we don't overwrite blocks which have
+ * recently been freed but their transactions are not yet
+ * committed to disk. If we overwrite the contents of a busy
+ * extent and then crash then the block may not contain the
+ * correct metadata after log recovery occurs.
xfs_bmap_init(args->flist, args->firstblock);
nmap = 1;
error = xfs_bmapi_write(args->trans, dp, (xfs_fileoff_t)lblkno,
- blkcnt,
- args->firstblock, args->total, &map, &nmap,
- args->flist);
+ blkcnt, XFS_BMAPI_ATTRFORK, args->firstblock,
+ args->total, &map, &nmap, args->flist);
if (!error) {
error = xfs_bmap_finish(&args->trans, args->flist,