diff mbox series

[v2,03/11] xfs: skip small alloc cntbt logic on NULL cursor

Message ID 20190522180546.17063-4-bfoster@redhat.com (mailing list archive)
State Accepted
Headers show
Series xfs: rework extent allocation | expand

Commit Message

Brian Foster May 22, 2019, 6:05 p.m. UTC 
The small allocation helper is implemented in a way that is fairly
tightly integrated to the existing allocation algorithms. It expects
a cntbt cursor beyond the end of the tree, attempts to locate the
last record in the tree and only attempts an AGFL allocation if the
cntbt is empty.

The upcoming generic algorithm doesn't rely on the cntbt processing
of this function. It will only call this function when the cntbt
doesn't have a big enough extent or is empty and thus AGFL
allocation is the only remaining option. Tweak
xfs_alloc_ag_vextent_small() to handle a NULL cntbt cursor and skip
the cntbt logic. This facilitates use by the existing allocation
code and new code that only requires an AGFL allocation attempt.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/libxfs/xfs_alloc.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

Comments

Darrick J. Wong June 21, 2019, 11:58 p.m. UTC | #1 
On Wed, May 22, 2019 at 02:05:38PM -0400, Brian Foster wrote:
> The small allocation helper is implemented in a way that is fairly
> tightly integrated to the existing allocation algorithms. It expects
> a cntbt cursor beyond the end of the tree, attempts to locate the
> last record in the tree and only attempts an AGFL allocation if the
> cntbt is empty.
> 
> The upcoming generic algorithm doesn't rely on the cntbt processing
> of this function. It will only call this function when the cntbt
> doesn't have a big enough extent or is empty and thus AGFL
> allocation is the only remaining option. Tweak
> xfs_alloc_ag_vextent_small() to handle a NULL cntbt cursor and skip
> the cntbt logic. This facilitates use by the existing allocation
> code and new code that only requires an AGFL allocation attempt.
> 
> Signed-off-by: Brian Foster <bfoster@redhat.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>

Looks ok,
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

> ---
>  fs/xfs/libxfs/xfs_alloc.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
> index b345fe771c54..436f8eb0bc4c 100644
> --- a/fs/xfs/libxfs/xfs_alloc.c
> +++ b/fs/xfs/libxfs/xfs_alloc.c
> @@ -713,9 +713,16 @@ xfs_alloc_ag_vextent_small(
>  	int			error = 0;
>  	xfs_agblock_t		fbno = NULLAGBLOCK;
>  	xfs_extlen_t		flen = 0;
> -	int			i;
> +	int			i = 0;
>  
> -	error = xfs_btree_decrement(ccur, 0, &i);
> +	/*
> +	 * If a cntbt cursor is provided, try to allocate the largest record in
> +	 * the tree. Try the AGFL if the cntbt is empty, otherwise fail the
> +	 * allocation. Make sure to respect minleft even when pulling from the
> +	 * freelist.
> +	 */
> +	if (ccur)
> +		error = xfs_btree_decrement(ccur, 0, &i);
>  	if (error)
>  		goto error;
>  	if (i) {
> -- 
> 2.17.2
>
diff mbox series

Patch

diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
index b345fe771c54..436f8eb0bc4c 100644
--- a/fs/xfs/libxfs/xfs_alloc.c
+++ b/fs/xfs/libxfs/xfs_alloc.c
@@ -713,9 +713,16 @@  xfs_alloc_ag_vextent_small(
 	int			error = 0;
 	xfs_agblock_t		fbno = NULLAGBLOCK;
 	xfs_extlen_t		flen = 0;
-	int			i;
+	int			i = 0;
 
-	error = xfs_btree_decrement(ccur, 0, &i);
+	/*
+	 * If a cntbt cursor is provided, try to allocate the largest record in
+	 * the tree. Try the AGFL if the cntbt is empty, otherwise fail the
+	 * allocation. Make sure to respect minleft even when pulling from the
+	 * freelist.
+	 */
+	if (ccur)
+		error = xfs_btree_decrement(ccur, 0, &i);
 	if (error)
 		goto error;
 	if (i) {