linux-kernel - [PATCH AUTOSEL for 4.9 092/293] Btrfs: skip commit transaction if we don't have enough pinned bytes

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Date:   Mon, 9 Apr 2018 00:24:06 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Liu Bo <bo.li.liu@...cle.com>, David Sterba <dsterba@...e.com>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL for 4.9 092/293] Btrfs: skip commit transaction if we
 don't have enough pinned bytes

From: Liu Bo <bo.li.liu@...cle.com>

[ Upstream commit 28785f70ef882e4798cd5706066a55dbf7adf80e ]

We commit transaction in order to reclaim space from pinned bytes because
it could process delayed refs, and in may_commit_transaction(), we check
first if pinned bytes are enough for the required space, we then check if
that plus bytes reserved for delayed insert are enough for the required
space.

This changes the code to the above logic.

Fixes: b150a4f10d87 ("Btrfs: use a percpu to keep track of possibly pinned bytes")
Tested-by: Nikolay Borisov <nborisov@...e.com>
Reported-by: Nikolay Borisov <nborisov@...e.com>
Reviewed-by: Nikolay Borisov <nborisov@...e.com>
Signed-off-by: Liu Bo <bo.li.liu@...cle.com>
Signed-off-by: David Sterba <dsterba@...e.com>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
 fs/btrfs/extent-tree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index a29730c44850..f9d87903ef48 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -4818,7 +4818,7 @@ static int may_commit_transaction(struct btrfs_root *root,
 
 	spin_lock(&delayed_rsv->lock);
 	if (percpu_counter_compare(&space_info->total_bytes_pinned,
-				   bytes - delayed_rsv->size) >= 0) {
+				   bytes - delayed_rsv->size) < 0) {
 		spin_unlock(&delayed_rsv->lock);
 		return -ENOSPC;
 	}
-- 
2.15.1