6.11-stable review patch. If anyone has any objections, please let me know.
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From: Filipe Manana fdmanana@suse.com
commit 3510e684b8f6a569c2f8b86870da116e2ffeec2d upstream.
After the migration to use fs context for processing mount options we had a slight change in the semantics for remounting a filesystem that was mounted with compress-force. Before we could clear compress-force by passing only "-o compress[=algo]" during a remount, but after that change that does not work anymore, force-compress is still present and one needs to pass "-o compress-force=no,compress[=algo]" to the mount command.
Example, when running on a kernel 6.8+:
$ mount -o compress-force=zlib:9 /dev/sdi /mnt/sdi $ mount | grep sdi /dev/sdi on /mnt/sdi type btrfs (rw,relatime,compress-force=zlib:9,discard=async,space_cache=v2,subvolid=5,subvol=/)
$ mount -o remount,compress=zlib:5 /mnt/sdi $ mount | grep sdi /dev/sdi on /mnt/sdi type btrfs (rw,relatime,compress-force=zlib:5,discard=async,space_cache=v2,subvolid=5,subvol=/)
On a 6.7 kernel (or older):
$ mount -o compress-force=zlib:9 /dev/sdi /mnt/sdi $ mount | grep sdi /dev/sdi on /mnt/sdi type btrfs (rw,relatime,compress-force=zlib:9,discard=async,space_cache=v2,subvolid=5,subvol=/)
$ mount -o remount,compress=zlib:5 /mnt/sdi $ mount | grep sdi /dev/sdi on /mnt/sdi type btrfs (rw,relatime,compress=zlib:5,discard=async,space_cache=v2,subvolid=5,subvol=/)
So update btrfs_parse_param() to clear "compress-force" when "compress" is given, providing the same semantics as kernel 6.7 and older.
Reported-by: Roman Mamedov rm@romanrm.net Link: https://lore.kernel.org/linux-btrfs/20241014182416.13d0f8b0@nvm/ CC: stable@vger.kernel.org # 6.8+ Signed-off-by: Filipe Manana fdmanana@suse.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/btrfs/super.c | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 98fa0f382480..3f8673f97432 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -340,6 +340,15 @@ static int btrfs_parse_param(struct fs_context *fc, struct fs_parameter *param) fallthrough; case Opt_compress: case Opt_compress_type: + /* + * Provide the same semantics as older kernels that don't use fs + * context, specifying the "compress" option clears + * "force-compress" without the need to pass + * "compress-force=[no|none]" before specifying "compress". + */ + if (opt != Opt_compress_force && opt != Opt_compress_force_type) + btrfs_clear_opt(ctx->mount_opt, FORCE_COMPRESS); + if (opt == Opt_compress || opt == Opt_compress_force) { ctx->compress_type = BTRFS_COMPRESS_ZLIB; ctx->compress_level = BTRFS_ZLIB_DEFAULT_LEVEL;