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, 9 insertions, 0 deletions

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 5e2bfdaf8d14..34cd83184c4a 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -1826,6 +1826,15 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
                 goto cleanup_transaction;
         }
 
+        /*
+         * Since the transaction is done, we should set the inode map cache flag
+         * before any other comming transaction.
+         */
+        if (btrfs_test_opt(root, CHANGE_INODE_CACHE))
+                btrfs_set_opt(root->fs_info->mount_opt, INODE_MAP_CACHE);
+        else
+                btrfs_clear_opt(root->fs_info->mount_opt, INODE_MAP_CACHE);
+
         /* commit_fs_roots gets rid of all the tree log roots, it is now
          * safe to free the root of tree log roots
          */