xfs: process free extents to busy list in FIFO order

When we're adding extents to the busy discard list, add them to the tail
of the list so that we get FIFO order.  For FITRIM commands, this means
that we send discard bios sorted in order from longest to shortest, like
we did before commit 89cfa899608fc.

For transactions that are freeing extents, this puts them in the
transaction's busy list in FIFO order as well, which shouldn't make any
noticeable difference.

Fixes: 89cfa899608fc ("xfs: reduce AGF hold times during fstrim operations")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

diff --git a/fs/xfs/xfs_extent_busy.c b/fs/xfs/xfs_extent_busy.c
index 746814815b1da7fb8b1092f6772a6d6b26c99f62..9ecfdcdc752f799a8dfe7a4bdede0ad39b127f4e 100644 (file)
--- a/fs/xfs/xfs_extent_busy.c
+++ b/fs/xfs/xfs_extent_busy.c
@@ -62,7 +62,8 @@ xfs_extent_busy_insert_list(
        rb_link_node(&new->rb_node, parent, rbp);
        rb_insert_color(&new->rb_node, &pag->pagb_tree);
 
-       list_add(&new->list, busy_list);
+       /* always process discard lists in fifo order */
+       list_add_tail(&new->list, busy_list);
        spin_unlock(&pag->pagb_lock);
 }