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[5/7] Btrfs: don't wait for all the async delalloc when shrinking delalloc

Message ID 1383578006-22691-6-git-send-email-miaox@cn.fujitsu.com (mailing list archive)
State Accepted, archived
Headers show

Commit Message

Miao Xie Nov. 4, 2013, 3:13 p.m. UTC 
It was very likely that there were lots of async delalloc pages in the
filesystem, if we waited until all the pages were flushed, we would be
blocked for a long time, and the performance would also drop down.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
---
 fs/btrfs/extent-tree.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)
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Patch

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index c48fde1..d691e15 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -4061,9 +4061,19 @@  static void shrink_delalloc(struct btrfs_root *root, u64 to_reclaim, u64 orig,
 		 * We need to wait for the async pages to actually start before
 		 * we do anything.
 		 */
-		wait_event(root->fs_info->async_submit_wait,
-			   !atomic_read(&root->fs_info->async_delalloc_pages));
+		max_reclaim = atomic_read(&root->fs_info->async_delalloc_pages);
+		if (!max_reclaim)
+			goto skip_async;
+
+		if (max_reclaim <= nr_pages)
+			max_reclaim = 0;
+		else
+			max_reclaim -= nr_pages;
 
+		wait_event(root->fs_info->async_submit_wait,
+			   atomic_read(&root->fs_info->async_delalloc_pages) <=
+			   (int)max_reclaim);
+skip_async:
 		if (!trans)
 			flush = BTRFS_RESERVE_FLUSH_ALL;
 		else