diff options
| author | Liu Bo <bo.li.liu@oracle.com> | 2016-07-29 11:09:50 -0700 |
|---|---|---|
| committer | Chris Mason <clm@fb.com> | 2016-08-25 03:58:27 -0700 |
| commit | 28b737f6ede3661fe610937706c4a6f50e9ab769 (patch) | |
| tree | 6ea6240c269bc46e66dd87deef33e5ba7287deec /fs/btrfs | |
| parent | 9e7cc91a6d18a4973c6d2cc104871439c9e94f3d (diff) | |
Btrfs: clarify do_chunk_alloc()'s return value
Function start_transaction() can return ERR_PTR(1) when flush is
BTRFS_RESERVE_FLUSH_LIMIT, so the call graph is
start_transaction (return ERR_PTR(1))
-> btrfs_block_rsv_add (return 1)
-> reserve_metadata_bytes (return 1)
-> flush_space (return 1)
-> do_chunk_alloc (return 1)
With BTRFS_RESERVE_FLUSH_LIMIT, if flush_space is already on the
flush_state of ALLOC_CHUNK and it successfully allocates a new
chunk, then instead of trying to reserve space again,
reserve_metadata_bytes returns 1 immediately.
Eventually the callers who call start_transaction() usually just
do the IS_ERR() check which ERR_PTR(1) can pass, then it'll get
a panic when dereferencing a pointer which is ERR_PTR(1).
The following patch fixes the above problem.
"btrfs: flush_space: treat return value of do_chunk_alloc properly"
https://patchwork.kernel.org/patch/7778651/
This add comments to clarify do_chunk_alloc()'s return value.
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
Diffstat (limited to 'fs/btrfs')
| -rw-r--r-- | fs/btrfs/extent-tree.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 133c93b0a0f1..d5d3cfb1f66f 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -4457,6 +4457,15 @@ void check_system_chunk(struct btrfs_trans_handle *trans, } } +/* + * If force is CHUNK_ALLOC_FORCE: + * - return 1 if it successfully allocates a chunk, + * - return errors including -ENOSPC otherwise. + * If force is NOT CHUNK_ALLOC_FORCE: + * - return 0 if it doesn't need to allocate a new chunk, + * - return 1 if it successfully allocates a chunk, + * - return errors including -ENOSPC otherwise. + */ static int do_chunk_alloc(struct btrfs_trans_handle *trans, struct btrfs_root *extent_root, u64 flags, int force) { |