2 files changed, 12 insertions, 4 deletions

diff --git a/Documentation/filesystems/btrfs.txt b/Documentation/filesystems/btrfs.txt
index ce487a2a88f8..e87609a4e21c 100644
--- 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 b02d25a64b2e..44513f3fbdc1 100644
--- 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);