f2fs: add a rw_sem to cover quota flag changes

Two paths to update quota and f2fs_lock_op:

1.
 - lock_op
 |  - quota_update
 `- unlock_op

2.
 - quota_update
 - lock_op
 `- unlock_op

But, we need to make a transaction on quota_update + lock_op in #2 case.
So, this patch introduces:
1. lock_op
2. down_write
3. check __need_flush
4. up_write
5. if there is dirty quota entries, flush them
6. otherwise, good to go

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

1 files changed, 19 insertions, 22 deletions

diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index 2d23671d2034..a0eef95b9e0e 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -1133,17 +1133,24 @@ static void __prepare_cp_block(struct f2fs_sb_info *sbi)
 
 static bool __need_flush_quota(struct f2fs_sb_info *sbi)
 {
+	bool ret = false;
+
 	if (!is_journalled_quota(sbi))
 		return false;
-	if (is_sbi_flag_set(sbi, SBI_QUOTA_SKIP_FLUSH))
-		return false;
-	if (is_sbi_flag_set(sbi, SBI_QUOTA_NEED_REPAIR))
-		return false;
-	if (is_sbi_flag_set(sbi, SBI_QUOTA_NEED_FLUSH))
-		return true;
-	if (get_pages(sbi, F2FS_DIRTY_QDATA))
-		return true;
-	return false;
+
+	down_write(&sbi->quota_sem);
+	if (is_sbi_flag_set(sbi, SBI_QUOTA_SKIP_FLUSH)) {
+		ret = false;
+	} else if (is_sbi_flag_set(sbi, SBI_QUOTA_NEED_REPAIR)) {
+		ret = false;
+	} else if (is_sbi_flag_set(sbi, SBI_QUOTA_NEED_FLUSH)) {
+		clear_sbi_flag(sbi, SBI_QUOTA_NEED_FLUSH);
+		ret = true;
+	} else if (get_pages(sbi, F2FS_DIRTY_QDATA)) {
+		ret = true;
+	}
+	up_write(&sbi->quota_sem);
+	return ret;
 }
 
 /*
@@ -1162,26 +1169,22 @@ static int block_operations(struct f2fs_sb_info *sbi)
 	blk_start_plug(&plug);
 
 retry_flush_quotas:
+	f2fs_lock_all(sbi);
 	if (__need_flush_quota(sbi)) {
 		int locked;
 
 		if (++cnt > DEFAULT_RETRY_QUOTA_FLUSH_COUNT) {
 			set_sbi_flag(sbi, SBI_QUOTA_SKIP_FLUSH);
-			f2fs_lock_all(sbi);
+			set_sbi_flag(sbi, SBI_QUOTA_NEED_FLUSH);
 			goto retry_flush_dents;
 		}
-		clear_sbi_flag(sbi, SBI_QUOTA_NEED_FLUSH);
+		f2fs_unlock_all(sbi);
 
 		/* only failed during mount/umount/freeze/quotactl */
 		locked = down_read_trylock(&sbi->sb->s_umount);
 		f2fs_quota_sync(sbi->sb, -1);
 		if (locked)
 			up_read(&sbi->sb->s_umount);
-	}
-
-	f2fs_lock_all(sbi);
-	if (__need_flush_quota(sbi)) {
-		f2fs_unlock_all(sbi);
 		cond_resched();
 		goto retry_flush_quotas;
 	}
@@ -1203,12 +1206,6 @@ retry_flush_dents:
 	 */
 	down_write(&sbi->node_change);
 
-	if (__need_flush_quota(sbi)) {
-		up_write(&sbi->node_change);
-		f2fs_unlock_all(sbi);
-		goto retry_flush_quotas;
-	}
-
 	if (get_pages(sbi, F2FS_DIRTY_IMETA)) {
 		up_write(&sbi->node_change);
 		f2fs_unlock_all(sbi);