linux-kernel - [PATCH AUTOSEL 4.19 34/38] btrfs: file: reserve qgroup space after the hole punch range is locked

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Date:   Fri, 21 Aug 2020 12:18:03 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Qu Wenruo <wqu@...e.com>, Josef Bacik <josef@...icpanda.com>,
        David Sterba <dsterba@...e.com>,
        Sasha Levin <sashal@...nel.org>, linux-btrfs@...r.kernel.org
Subject: [PATCH AUTOSEL 4.19 34/38] btrfs: file: reserve qgroup space after the hole punch range is locked

From: Qu Wenruo <wqu@...e.com>

[ Upstream commit a7f8b1c2ac21bf081b41264c9cfd6260dffa6246 ]

The incoming qgroup reserved space timing will move the data reservation
to ordered extent completely.

However in btrfs_punch_hole_lock_range() will call
btrfs_invalidate_page(), which will clear QGROUP_RESERVED bit for the
range.

In current stage it's OK, but if we're making ordered extents handle the
reserved space, then btrfs_punch_hole_lock_range() can clear the
QGROUP_RESERVED bit before we submit ordered extent, leading to qgroup
reserved space leakage.

So here change the timing to make reserve data space after
btrfs_punch_hole_lock_range().
The new timing is fine for either current code or the new code.

Reviewed-by: Josef Bacik <josef@...icpanda.com>
Signed-off-by: Qu Wenruo <wqu@...e.com>
Reviewed-by: David Sterba <dsterba@...e.com>
Signed-off-by: David Sterba <dsterba@...e.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/btrfs/file.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index dc1841855a69a..646152f305843 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -3010,14 +3010,14 @@ static int btrfs_zero_range(struct inode *inode,
 		if (ret < 0)
 			goto out;
 		space_reserved = true;
-		ret = btrfs_qgroup_reserve_data(inode, &data_reserved,
-						alloc_start, bytes_to_reserve);
-		if (ret)
-			goto out;
 		ret = btrfs_punch_hole_lock_range(inode, lockstart, lockend,
 						  &cached_state);
 		if (ret)
 			goto out;
+		ret = btrfs_qgroup_reserve_data(inode, &data_reserved,
+						alloc_start, bytes_to_reserve);
+		if (ret)
+			goto out;
 		ret = btrfs_prealloc_file_range(inode, mode, alloc_start,
 						alloc_end - alloc_start,
 						i_blocksize(inode),
-- 
2.25.1