Btrfs: allow mount -o remount,compress=no

Btrfs allows to turn on compression on a mounted and used filesystem
by issuing mount -o remount,compress=lzo.
This patch allows to turn compression off again
while the filesystem is mounted. As suggested by David Sterba
if the compress-force option was set, it is implicitly cleared
if compression is turned off.

Tested-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Arnd Hannemann <arnd@arndnet.de>

1 files changed, 8 insertions, 1 deletions

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index ddc2efdda1ab..88a2d2bb2d75 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -396,15 +396,22 @@ int btrfs_parse_options(struct btrfs_root *root, char *options)
                             strcmp(args[0].from, "zlib") == 0) {
                                 compress_type = "zlib";
                                 info->compress_type = BTRFS_COMPRESS_ZLIB;
+                                btrfs_set_opt(info->mount_opt, COMPRESS);
                         } else if (strcmp(args[0].from, "lzo") == 0) {
                                 compress_type = "lzo";
                                 info->compress_type = BTRFS_COMPRESS_LZO;
+                                btrfs_set_opt(info->mount_opt, COMPRESS);
+                        } else if (strncmp(args[0].from, "no", 2) == 0) {
+                                compress_type = "no";
+                                info->compress_type = BTRFS_COMPRESS_NONE;
+                                btrfs_clear_opt(info->mount_opt, COMPRESS);
+                                btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
+                                compress_force = false;
                         } else {
                                 ret = -EINVAL;
                                 goto out;
                         }
 
-                        btrfs_set_opt(info->mount_opt, COMPRESS);
                         if (compress_force) {
                                 btrfs_set_opt(info->mount_opt, FORCE_COMPRESS);
                                 pr_info("btrfs: force %s compression\n",