Btrfs: add mount -o auto_defrag

This will detect small random writes into files and
queue the up for an auto defrag process.  It isn't well suited to
database workloads yet, but works for smaller files such as rpm, sqlite
or bdb databases.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index cd0c7cd2c8fb..28e3cb2607ff 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -160,7 +160,7 @@ enum {
         Opt_compress_type, Opt_compress_force, Opt_compress_force_type,
         Opt_notreelog, Opt_ratio, Opt_flushoncommit, Opt_discard,
         Opt_space_cache, Opt_clear_cache, Opt_user_subvol_rm_allowed,
-        Opt_enospc_debug, Opt_subvolrootid, Opt_err,
+        Opt_enospc_debug, Opt_subvolrootid, Opt_defrag, Opt_err,
 };
 
 static match_table_t tokens = {
@@ -191,6 +191,7 @@ static match_table_t tokens = {
         {Opt_user_subvol_rm_allowed, "user_subvol_rm_allowed"},
         {Opt_enospc_debug, "enospc_debug"},
         {Opt_subvolrootid, "subvolrootid=%d"},
+        {Opt_defrag, "autodefrag"},
         {Opt_err, NULL},
 };
 
@@ -369,6 +370,10 @@ int btrfs_parse_options(struct btrfs_root *root, char *options)
                 case Opt_enospc_debug:
                         btrfs_set_opt(info->mount_opt, ENOSPC_DEBUG);
                         break;
+                case Opt_defrag:
+                        printk(KERN_INFO "btrfs: enabling auto defrag");
+                        btrfs_set_opt(info->mount_opt, AUTO_DEFRAG);
+                        break;
                 case Opt_err:
                         printk(KERN_INFO "btrfs: unrecognized mount option "
                                "'%s'\n", p);