Patch "xfs: Reduce unnecessary searches when searching for the best extents" has been added to the 6.6-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    xfs: Reduce unnecessary searches when searching for the best extents

to the 6.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     xfs-reduce-unnecessary-searches-when-searching-for-the-best-extents.patch
and it can be found in the queue-6.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


From stable+bounces-113987-greg=kroah.com@vger.kernel.org Wed Feb  5 22:41:28 2025
From: Catherine Hoang <catherine.hoang@oracle.com>
Date: Wed,  5 Feb 2025 13:40:23 -0800
Subject: xfs: Reduce unnecessary searches when searching for the best extents
To: stable@vger.kernel.org
Cc: xfs-stable@lists.linux.dev
Message-ID: <20250205214025.72516-23-catherine.hoang@oracle.com>

From: Chi Zhiling <chizhiling@kylinos.cn>

commit 3ef22684038aa577c10972ee9c6a2455f5fac941 upstream.

Recently, we found that the CPU spent a lot of time in
xfs_alloc_ag_vextent_size when the filesystem has millions of fragmented
spaces.

The reason is that we conducted much extra searching for extents that
could not yield a better result, and these searches would cost a lot of
time when there were millions of extents to search through. Even if we
get the same result length, we don't switch our choice to the new one,
so we can definitely terminate the search early.

Since the result length cannot exceed the found length, when the found
length equals the best result length we already have, we can conclude
the search.

We did a test in that filesystem:
[root@localhost ~]# xfs_db -c freesp /dev/vdb
   from      to extents  blocks    pct
      1       1     215     215   0.01
      2       3  994476 1988952  99.99

Before this patch:
 0)               |  xfs_alloc_ag_vextent_size [xfs]() {
 0) * 15597.94 us |  }

After this patch:
 0)               |  xfs_alloc_ag_vextent_size [xfs]() {
 0)   19.176 us    |  }

Signed-off-by: Chi Zhiling <chizhiling@kylinos.cn>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Signed-off-by: Catherine Hoang <catherine.hoang@oracle.com>
Acked-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/xfs/libxfs/xfs_alloc.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/xfs/libxfs/xfs_alloc.c
+++ b/fs/xfs/libxfs/xfs_alloc.c
@@ -1783,7 +1783,7 @@ restart:
 				error = -EFSCORRUPTED;
 				goto error0;
 			}
-			if (flen < bestrlen)
+			if (flen <= bestrlen)
 				break;
 			busy = xfs_alloc_compute_aligned(args, fbno, flen,
 					&rbno, &rlen, &busy_gen);


Patches currently in stable-queue which might be from catherine.hoang@oracle.com are

queue-6.6/xfs-return-bool-from-xfs_attr3_leaf_add.patch
queue-6.6/xfs-fix-a-sloppy-memory-handling-bug-in-xfs_iroot_realloc.patch
queue-6.6/xfs-streamline-xfs_filestream_pick_ag.patch
queue-6.6/xfs-merge-xfs_attr_leaf_try_add-into-xfs_attr_leaf_addname.patch
queue-6.6/xfs-don-t-free-cowblocks-from-under-dirty-pagecache-on-unshare.patch
queue-6.6/xfs-pass-the-exact-range-to-initialize-to-xfs_initialize_perag.patch
queue-6.6/xfs-assert-a-valid-limit-in-xfs_rtfind_forw.patch
queue-6.6/xfs-don-t-use-__gfp_retry_mayfail-in-xfs_initialize_perag.patch
queue-6.6/xfs-use-try_cmpxchg-in-xlog_cil_insert_pcp_aggregate.patch
queue-6.6/xfs-don-t-ifdef-around-the-exact-minlen-allocations.patch
queue-6.6/xfs-reduce-unnecessary-searches-when-searching-for-the-best-extents.patch
queue-6.6/xfs-validate-inumber-in-xfs_iget.patch
queue-6.6/xfs-support-lowmode-allocations-in-xfs_bmap_exact_minlen_extent_alloc.patch
queue-6.6/xfs-skip-background-cowblock-trims-on-inodes-open-for-write.patch
queue-6.6/xfs-remove-empty-declartion-in-header-file.patch
queue-6.6/xfs-fold-xfs_bmap_alloc_userdata-into-xfs_bmapi_allocate.patch
queue-6.6/xfs-update-the-file-system-geometry-after-recoverying-superblock-buffers.patch
queue-6.6/xfs-call-xfs_bmap_exact_minlen_extent_alloc-from-xfs_bmap_btalloc.patch
queue-6.6/xfs-distinguish-extra-split-from-real-enospc-from-xfs_attr_node_try_addname.patch
queue-6.6/xfs-error-out-when-a-superblock-buffer-update-reduces-the-agcount.patch
queue-6.6/xfs-update-the-pag-for-the-last-ag-at-recovery-time.patch
queue-6.6/xfs-check-for-delayed-allocations-before-setting-extsize.patch
queue-6.6/xfs-fix-a-typo.patch
queue-6.6/xfs-distinguish-extra-split-from-real-enospc-from-xfs_attr3_leaf_split.patch