Btrfs: make compress and nodatacow mount options mutually exclusive

If a filesystem is mounted with compression and then remounted by adding nodatacow,
the compression is disabled but the compress flag is still visible.
Also, if a filesystem is mounted with nodatacow and then remounted with compression,
nodatacow flag is still present but it's not active.
This patch:
- removes compress flags and notifies that the compression has been disabled if the
  filesystem is mounted with nodatacow
- removes nodatacow and nodatasum flags if mounted with compress.

Signed-off-by: Andrei Popa <andrei.popa@i-neo.ro>

1 files changed, 13 insertions, 1 deletions

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 0fadcdba8ce4..915ac14c2064 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -413,7 +413,15 @@ int btrfs_parse_options(struct btrfs_root *root, char *options)
                         btrfs_set_opt(info->mount_opt, NODATASUM);
                         break;
                 case Opt_nodatacow:
-                        printk(KERN_INFO "btrfs: setting nodatacow\n");
+                        if (!btrfs_test_opt(root, COMPRESS) ||
+                                !btrfs_test_opt(root, FORCE_COMPRESS)) {
+                                        printk(KERN_INFO "btrfs: setting nodatacow, compression disabled\n");
+                        } else {
+                                printk(KERN_INFO "btrfs: setting nodatacow\n");
+                        }
+                        info->compress_type = BTRFS_COMPRESS_NONE;
+                        btrfs_clear_opt(info->mount_opt, COMPRESS);
+                        btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
                         btrfs_set_opt(info->mount_opt, NODATACOW);
                         btrfs_set_opt(info->mount_opt, NODATASUM);
                         break;
@@ -428,10 +436,14 @@ int btrfs_parse_options(struct btrfs_root *root, char *options)
                                 compress_type = "zlib";
                                 info->compress_type = BTRFS_COMPRESS_ZLIB;
                                 btrfs_set_opt(info->mount_opt, COMPRESS);
+                                btrfs_clear_opt(info->mount_opt, NODATACOW);
+                                btrfs_clear_opt(info->mount_opt, NODATASUM);
                         } else if (strcmp(args[0].from, "lzo") == 0) {
                                 compress_type = "lzo";
                                 info->compress_type = BTRFS_COMPRESS_LZO;
                                 btrfs_set_opt(info->mount_opt, COMPRESS);
+                                btrfs_clear_opt(info->mount_opt, NODATACOW);
+                                btrfs_clear_opt(info->mount_opt, NODATASUM);
                                 btrfs_set_fs_incompat(info, COMPRESS_LZO);
                         } else if (strncmp(args[0].from, "no", 2) == 0) {
                                 compress_type = "no";