linux-kernel - [PATCH 4.19 05/39] btrfs: unlock extents in btrfs_zero_range in case of quota reservation errors

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Message-Id: <20210310132319.897535962@linuxfoundation.org>
Date:   Wed, 10 Mar 2021 14:24:13 +0100
From:   gregkh@...uxfoundation.org
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Qu Wenruo <wqu@...e.com>,
        Nikolay Borisov <nborisov@...e.com>,
        David Sterba <dsterba@...e.com>
Subject: [PATCH 4.19 05/39] btrfs: unlock extents in btrfs_zero_range in case of quota reservation errors

From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

From: Nikolay Borisov <nborisov@...e.com>

commit 4f6a49de64fd1b1dba5229c02047376da7cf24fd upstream.

If btrfs_qgroup_reserve_data returns an error (i.e quota limit reached)
the handling logic directly goes to the 'out' label without first
unlocking the extent range between lockstart, lockend. This results in
deadlocks as other processes try to lock the same extent.

Fixes: a7f8b1c2ac21 ("btrfs: file: reserve qgroup space after the hole punch range is locked")
CC: stable@...r.kernel.org # 5.10+
Reviewed-by: Qu Wenruo <wqu@...e.com>
Signed-off-by: Nikolay Borisov <nborisov@...e.com>
Reviewed-by: David Sterba <dsterba@...e.com>
Signed-off-by: David Sterba <dsterba@...e.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/btrfs/file.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -3016,8 +3016,11 @@ reserve_space:
 			goto out;
 		ret = btrfs_qgroup_reserve_data(inode, &data_reserved,
 						alloc_start, bytes_to_reserve);
-		if (ret)
+		if (ret) {
+			unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart,
+					     lockend, &cached_state);
 			goto out;
+		}
 		ret = btrfs_prealloc_file_range(inode, mode, alloc_start,
 						alloc_end - alloc_start,
 						i_blocksize(inode),