diff options
| author | Dave Chinner <dchinner@redhat.com> | 2022-07-14 04:04:43 +0200 |
|---|---|---|
| committer | Dave Chinner <david@fromorbit.com> | 2022-07-14 04:04:43 +0200 |
| commit | 32dd4f9c506b1bf147c24cf05423cd893bc06e38 (patch) | |
| tree | 3609c32414136ae8fd8df7d812283b0d784332c0 /fs | |
| parent | xfs: reduce the number of atomic when locking a buffer after lookup (diff) | |
| download | linux-32dd4f9c506b1bf147c24cf05423cd893bc06e38.tar.xz linux-32dd4f9c506b1bf147c24cf05423cd893bc06e38.zip | |
xfs: remove a superflous hash lookup when inserting new buffers
Currently on the slow path insert we repeat the initial hash table
lookup before we attempt the insert, resulting in a two traversals
of the hash table to ensure the insert is valid. The rhashtable API
provides a method for an atomic lookup and insert operation, so we
can avoid one of the hash table traversals by using this method.
Adapted from a large patch containing this optimisation by Christoph
Hellwig.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/xfs/xfs_buf.c | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c index 374c4e508b12..1a6542e01bec 100644 --- a/fs/xfs/xfs_buf.c +++ b/fs/xfs/xfs_buf.c @@ -623,8 +623,15 @@ xfs_buf_find_insert( } spin_lock(&pag->pag_buf_lock); - bp = rhashtable_lookup(&pag->pag_buf_hash, cmap, xfs_buf_hash_params); + bp = rhashtable_lookup_get_insert_fast(&pag->pag_buf_hash, + &new_bp->b_rhash_head, xfs_buf_hash_params); + if (IS_ERR(bp)) { + error = PTR_ERR(bp); + spin_unlock(&pag->pag_buf_lock); + goto out_free_buf; + } if (bp) { + /* found an existing buffer */ atomic_inc(&bp->b_hold); spin_unlock(&pag->pag_buf_lock); error = xfs_buf_find_lock(bp, flags); @@ -635,10 +642,8 @@ xfs_buf_find_insert( goto out_free_buf; } - /* The buffer keeps the perag reference until it is freed. */ + /* The new buffer keeps the perag reference until it is freed. */ new_bp->b_pag = pag; - rhashtable_insert_fast(&pag->pag_buf_hash, &new_bp->b_rhash_head, - xfs_buf_hash_params); spin_unlock(&pag->pag_buf_lock); *bpp = new_bp; return 0; |