linux-kernel - [PATCH 5.8 172/255] btrfs: reset compression level for lzo on remount

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Message-Id: <20200901151008.936048011@linuxfoundation.org>
Date:   Tue,  1 Sep 2020 17:10:28 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Marcos Paulo de Souza <mpdesouza@...e.com>,
        David Sterba <dsterba@...e.com>
Subject: [PATCH 5.8 172/255] btrfs: reset compression level for lzo on remount

From: Marcos Paulo de Souza <mpdesouza@...e.com>

commit 282dd7d7718444679b046b769d872b188818ca35 upstream.

Currently a user can set mount "-o compress" which will set the
compression algorithm to zlib, and use the default compress level for
zlib (3):

  relatime,compress=zlib:3,space_cache

If the user remounts the fs using "-o compress=lzo", then the old
compress_level is used:

  relatime,compress=lzo:3,space_cache

But lzo does not expose any tunable compression level. The same happens
if we set any compress argument with different level, also with zstd.

Fix this by resetting the compress_level when compress=lzo is
specified.  With the fix applied, lzo is shown without compress level:

  relatime,compress=lzo,space_cache

CC: stable@...r.kernel.org # 4.4+
Signed-off-by: Marcos Paulo de Souza <mpdesouza@...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/super.c |    1 +
 1 file changed, 1 insertion(+)

--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -558,6 +558,7 @@ int btrfs_parse_options(struct btrfs_fs_
 			} else if (strncmp(args[0].from, "lzo", 3) == 0) {
 				compress_type = "lzo";
 				info->compress_type = BTRFS_COMPRESS_LZO;
+				info->compress_level = 0;
 				btrfs_set_opt(info->mount_opt, COMPRESS);
 				btrfs_clear_opt(info->mount_opt, NODATACOW);
 				btrfs_clear_opt(info->mount_opt, NODATASUM);