btrfs: fix messages after changing compression level by remount

Reported by Forza on IRC that remounting with compression options does
not reflect the change in level, or at least it does not appear to do so
according to the messages:

  mount -o compress=zstd:1 /dev/sda /mnt
  mount -o remount,compress=zstd:15 /mnt

does not print the change to the level to syslog:

  [   41.366060] BTRFS info (device vda): use zstd compression, level 1
  [   41.368254] BTRFS info (device vda): disk space caching is enabled
  [   41.390429] BTRFS info (device vda): disk space caching is enabled

What really happens is that the message is lost but the level is actualy
changed.

There's another weird output, if compression is reset to 'no':

  [   45.413776] BTRFS info (device vda): use no compression, level 4

To fix that, save the previous compression level and print the message
in that case too and use separate message for 'no' compression.

CC: stable@vger.kernel.org # 4.19+
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 5a9dc31d95c9836cb77822ecdadcb90a7f850854..aa73422b06785ea86cd0af88cb864c25d2174c30 100644 (file)
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -517,6 +517,7 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
        char *compress_type;
        bool compress_force = false;
        enum btrfs_compression_type saved_compress_type;
+       int saved_compress_level;
        bool saved_compress_force;
        int no_compress = 0;
 
@@ -598,6 +599,7 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
                                info->compress_type : BTRFS_COMPRESS_NONE;
                        saved_compress_force =
                                btrfs_test_opt(info, FORCE_COMPRESS);
+                       saved_compress_level = info->compress_level;
                        if (token == Opt_compress ||
                            token == Opt_compress_force ||
                            strncmp(args[0].from, "zlib", 4) == 0) {
@@ -642,6 +644,8 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
                                no_compress = 0;
                        } else if (strncmp(args[0].from, "no", 2) == 0) {
                                compress_type = "no";
+                               info->compress_level = 0;
+                               info->compress_type = 0;
                                btrfs_clear_opt(info->mount_opt, COMPRESS);
                                btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
                                compress_force = false;
@@ -662,11 +666,11 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
                                 */
                                btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
                        }
-                       if ((btrfs_test_opt(info, COMPRESS) &&
-                            (info->compress_type != saved_compress_type ||
-                             compress_force != saved_compress_force)) ||
-                           (!btrfs_test_opt(info, COMPRESS) &&
-                            no_compress == 1)) {
+                       if (no_compress == 1) {
+                               btrfs_info(info, "use no compression");
+                       } else if ((info->compress_type != saved_compress_type) ||
+                                  (compress_force != saved_compress_force) ||
+                                  (info->compress_level != saved_compress_level)) {
                                btrfs_info(info, "%s %s compression, level %d",
                                           (compress_force) ? "force" : "use",
                                           compress_type, info->compress_level);