btrfs: Add noautodefrag mount option.

Btrfs has autodefrag mount option but no pairing noautodefrag option,
which makes it impossible to disable autodefrag without umount.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>

diff --git a/Documentation/filesystems/btrfs.txt b/Documentation/filesystems/btrfs.txt
index ce487a2..e87609a 100644 (file)
--- a/Documentation/filesystems/btrfs.txt
+++ b/Documentation/filesystems/btrfs.txt
@@ -46,10 +46,12 @@ Options with (*) are default options and will not show in the mount options.
        bytes, optionally with a K, M, or G suffix, case insensitive.
        Default is 1MB.
 
+  noautodefrag(*)
   autodefrag
-       Detect small random writes into files and queue them up for the
-       defrag process.  Works best for small files; Not well suited for
-       large database workloads.
+       Disable/enable auto defragmentation.
+       Auto defragmentation detects small random writes into files and queue
+       them up for the defrag process.  Works best for small files;
+       Not well suited for large database workloads.
 
   check_int
   check_int_data

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index b02d25a..44513f3 100644 (file)
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -323,7 +323,7 @@ enum {
        Opt_no_space_cache, Opt_recovery, Opt_skip_balance,
        Opt_check_integrity, Opt_check_integrity_including_extent_data,
        Opt_check_integrity_print_mask, Opt_fatal_errors, Opt_rescan_uuid_tree,
-       Opt_commit_interval, Opt_barrier,
+       Opt_commit_interval, Opt_barrier, Opt_nodefrag,
        Opt_err,
 };
 
@@ -357,6 +357,7 @@ static match_table_t tokens = {
        {Opt_enospc_debug, "enospc_debug"},
        {Opt_subvolrootid, "subvolrootid=%d"},
        {Opt_defrag, "autodefrag"},
+       {Opt_nodefrag, "noautodefrag"},
        {Opt_inode_cache, "inode_cache"},
        {Opt_no_space_cache, "nospace_cache"},
        {Opt_recovery, "recovery"},
@@ -602,6 +603,11 @@ int btrfs_parse_options(struct btrfs_root *root, char *options)
                        btrfs_info(root->fs_info, "enabling auto defrag");
                        btrfs_set_opt(info->mount_opt, AUTO_DEFRAG);
                        break;
+               case Opt_nodefrag:
+                       if (btrfs_test_opt(root, AUTO_DEFRAG))
+                               btrfs_info(root->fs_info, "disabling auto defrag");
+                       btrfs_clear_opt(info->mount_opt, AUTO_DEFRAG);
+                       break;
                case Opt_recovery:
                        btrfs_info(root->fs_info, "enabling auto recovery");
                        btrfs_set_opt(info->mount_opt, RECOVERY);