btrfs: Add noinode_cache mount option

Add noinode_cache mount option for btrfs.

Since inode map cache involves all the btrfs_find_free_ino/return_ino
things and if just trigger the mount_opt,
an inode number get from inode map cache will not returned to inode map
cache.

To keep the find and return inode both in the same behavior,
a new bit in mount_opt, CHANGE_INODE_CACHE, is introduced for this idea.
CHANGE_INODE_CACHE is set/cleared in remounting, and the original
INODE_MAP_CACHE is set/cleared according to CHANGE_INODE_CACHE after a
success transaction.
Since find/return inode is all done between btrfs_start_transaction and
btrfs_commit_transaction, this will keep consistent behavior.

Also noinode_cache mount option will not stop the caching_kthread.

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

1 files changed, 8 insertions, 2 deletions

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index f44cc6a0eb27..362aef44a17b 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -327,7 +327,7 @@ enum {
         Opt_check_integrity_print_mask, Opt_fatal_errors, Opt_rescan_uuid_tree,
         Opt_commit_interval, Opt_barrier, Opt_nodefrag, Opt_nodiscard,
         Opt_noenospc_debug, Opt_noflushoncommit, Opt_acl, Opt_datacow,
-        Opt_datasum, Opt_treelog,
+        Opt_datasum, Opt_treelog, Opt_noinode_cache,
         Opt_err,
 };
 
@@ -370,6 +370,7 @@ static match_table_t tokens = {
         {Opt_defrag, "autodefrag"},
         {Opt_nodefrag, "noautodefrag"},
         {Opt_inode_cache, "inode_cache"},
+        {Opt_noinode_cache, "noinode_cache"},
         {Opt_no_space_cache, "nospace_cache"},
         {Opt_recovery, "recovery"},
         {Opt_skip_balance, "skip_balance"},
@@ -627,7 +628,12 @@ int btrfs_parse_options(struct btrfs_root *root, char *options)
                         break;
                 case Opt_inode_cache:
                         btrfs_info(root->fs_info, "enabling inode map caching");
-                        btrfs_set_opt(info->mount_opt, INODE_MAP_CACHE);
+                        btrfs_set_opt(info->mount_opt, CHANGE_INODE_CACHE);
+                        break;
+                case Opt_noinode_cache:
+                        if (btrfs_test_opt(root, CHANGE_INODE_CACHE))
+                                btrfs_info(root->fs_info, "disabling inode map caching");
+                        btrfs_clear_opt(info->mount_opt, CHANGE_INODE_CACHE);
                         break;
                 case Opt_clear_cache:
                         btrfs_info(root->fs_info, "force clearing of disk cache");