linux-kernel - [PATCH 4.14 118/159] btrfs: Fix quota reservation leak on preallocated files

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Date:   Fri, 23 Feb 2018 19:27:06 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Justin Maggard <jmaggard@...gear.com>,
        Qu Wenruo <wqu@...e.com>, David Sterba <dsterba@...e.com>,
        Sasha Levin <alexander.levin@...izon.com>
Subject: [PATCH 4.14 118/159] btrfs: Fix quota reservation leak on preallocated files

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Justin Maggard <jmaggard10@...il.com>

[ Upstream commit b430b7751286b3acff2d324553c8cec4f1e87764 ]

Commit c6887cd11149 ("Btrfs: don't do nocow check unless we have to")
changed the behavior of __btrfs_buffered_write() so that it first tries
to get a data space reservation, and then skips the relatively expensive
nocow check if the reservation succeeded.

If we have quotas enabled, the data space reservation also includes a
quota reservation.  But in the rewrite case, the space has already been
accounted for in qgroups.  So btrfs_check_data_free_space() increases
the quota reservation, but it never gets decreased when the data
actually gets written and overwrites the pre-existing data.  So we're
left with both the qgroup and qgroup reservation accounting for the same
space.

This commit adds the missing btrfs_qgroup_free_data() call in the case
of BTRFS_ORDERED_PREALLOC extents.

Fixes: c6887cd11149 ("Btrfs: don't do nocow check unless we have to")
Signed-off-by: Justin Maggard <jmaggard@...gear.com>
Reviewed-by: Qu Wenruo <wqu@...e.com>
Signed-off-by: David Sterba <dsterba@...e.com>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/btrfs/inode.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -3016,6 +3016,8 @@ static int btrfs_finish_ordered_io(struc
 		compress_type = ordered_extent->compress_type;
 	if (test_bit(BTRFS_ORDERED_PREALLOC, &ordered_extent->flags)) {
 		BUG_ON(compress_type);
+		btrfs_qgroup_free_data(inode, NULL, ordered_extent->file_offset,
+				       ordered_extent->len);
 		ret = btrfs_mark_extent_written(trans, BTRFS_I(inode),
 						ordered_extent->file_offset,
 						ordered_extent->file_offset +