Revert "xfs: block allocation work needs to be kswapd aware"

This reverts commit 1f6d64829db78a7e1d63e15c9f48f0a5d2b5a679.

This commit resulted in regressions in performance in low
memory situations where kswapd was doing writeback of delayed
allocation blocks. It resulted in significant parallelism of the
kswapd work and with the special kswapd flags meant that hundreds of
active allocation could dip into kswapd specific memory reserves and
avoid being throttled. This cause a large amount of performance
variation, as well as random OOM-killer invocations that didn't
previously exist.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

1 files changed, 3 insertions, 13 deletions

diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index 703b3ec..057f671 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -258,23 +258,14 @@ xfs_bmapi_allocate_worker(
 	struct xfs_bmalloca	*args = container_of(work,
 						struct xfs_bmalloca, work);
 	unsigned long		pflags;
-	unsigned long		new_pflags = PF_FSTRANS;
 
-	/*
-	 * we are in a transaction context here, but may also be doing work
-	 * in kswapd context, and hence we may need to inherit that state
-	 * temporarily to ensure that we don't block waiting for memory reclaim
-	 * in any way.
-	 */
-	if (args->kswapd)
-		new_pflags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD;
-
-	current_set_flags_nested(&pflags, new_pflags);
+	/* we are in a transaction context here */
+	current_set_flags_nested(&pflags, PF_FSTRANS);
 
 	args->result = __xfs_bmapi_allocate(args);
 	complete(args->done);
 
-	current_restore_flags_nested(&pflags, new_pflags);
+	current_restore_flags_nested(&pflags, PF_FSTRANS);
 }
 
 /*
@@ -293,7 +284,6 @@ xfs_bmapi_allocate(
 
 
 	args->done = &done;
-	args->kswapd = current_is_kswapd();
 	INIT_WORK_ONSTACK(&args->work, xfs_bmapi_allocate_worker);
 	queue_work(xfs_alloc_wq, &args->work);
 	wait_for_completion(&done);