btrfs: open-code remount flag setting in btrfs_remount

When we're (re)mounting a btrfs filesystem we set the
BTRFS_FS_STATE_REMOUNTING state in fs_info to serialize against async
reclaim or defrags.

This flag is set in btrfs_remount_prepare() called by btrfs_remount().
As btrfs_remount_prepare() does nothing but setting this flag and
doesn't have a second caller, we can just open-code the flag setting in
btrfs_remount().

Similarly do for so clearing of the flag by moving it out of
btrfs_remount_cleanup() into btrfs_remount() to be symmetrical.

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/super.c

@@ -1782,11 +1782,6 @@ static void btrfs_resize_thread_pool(struct btrfs_fs_info *fs_info,
 				new_pool_size);
 }
 
-static inline void btrfs_remount_prepare(struct btrfs_fs_info *fs_info)
-{
-	set_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
-}
-
 static inline void btrfs_remount_begin(struct btrfs_fs_info *fs_info,
 				       unsigned long old_opts, int flags)
 {
@@ -1820,8 +1815,6 @@ static inline void btrfs_remount_cleanup(struct btrfs_fs_info *fs_info,
 	else if (btrfs_raw_test_opt(old_opts, DISCARD_ASYNC) &&
 		 !btrfs_test_opt(fs_info, DISCARD_ASYNC))
 		btrfs_discard_cleanup(fs_info);
-
-	clear_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
 }
 
 static int btrfs_remount(struct super_block *sb, int *flags, char *data)
@@ -1837,7 +1830,7 @@ static int btrfs_remount(struct super_block *sb, int *flags, char *data)
 	int ret;
 
 	sync_filesystem(sb);
-	btrfs_remount_prepare(fs_info);
+	set_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
 
 	if (data) {
 		void *new_sec_opts = NULL;
@@ -1959,6 +1952,8 @@ static int btrfs_remount(struct super_block *sb, int *flags, char *data)
 out:
 	wake_up_process(fs_info->transaction_kthread);
 	btrfs_remount_cleanup(fs_info, old_opts);
+	clear_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
+
 	return 0;
 
 restore:
@@ -1973,6 +1968,8 @@ restore:
 		old_thread_pool_size, fs_info->thread_pool_size);
 	fs_info->metadata_ratio = old_metadata_ratio;
 	btrfs_remount_cleanup(fs_info, old_opts);
+	clear_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
+
 	return ret;
 }