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, 33 insertions, 5 deletions

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 3ac706506ca2..1d33ca1a8c09 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1919,6 +1919,18 @@ int f2fs_quota_sync(struct super_block *sb, int type)
 	int cnt;
 	int ret;
 
+	/*
+	 * do_quotactl
+	 *  f2fs_quota_sync
+	 *  down_read(quota_sem)
+	 *  dquot_writeback_dquots()
+	 *  f2fs_dquot_commit
+	 *                            block_operation
+	 *                            down_read(quota_sem)
+	 */
+	f2fs_lock_op(sbi);
+
+	down_read(&sbi->quota_sem);
 	ret = dquot_writeback_dquots(sb, type);
 	if (ret)
 		goto out;
@@ -1956,6 +1968,8 @@ int f2fs_quota_sync(struct super_block *sb, int type)
 out:
 	if (ret)
 		set_sbi_flag(F2FS_SB(sb), SBI_QUOTA_NEED_REPAIR);
+	up_read(&sbi->quota_sem);
+	f2fs_unlock_op(sbi);
 	return ret;
 }
 
@@ -2047,32 +2061,40 @@ static void f2fs_truncate_quota_inode_pages(struct super_block *sb)
 
 static int f2fs_dquot_commit(struct dquot *dquot)
 {
+	struct f2fs_sb_info *sbi = F2FS_SB(dquot->dq_sb);
 	int ret;
 
+	down_read(&sbi->quota_sem);
 	ret = dquot_commit(dquot);
 	if (ret < 0)
-		set_sbi_flag(F2FS_SB(dquot->dq_sb), SBI_QUOTA_NEED_REPAIR);
+		set_sbi_flag(sbi, SBI_QUOTA_NEED_REPAIR);
+	up_read(&sbi->quota_sem);
 	return ret;
 }
 
 static int f2fs_dquot_acquire(struct dquot *dquot)
 {
+	struct f2fs_sb_info *sbi = F2FS_SB(dquot->dq_sb);
 	int ret;
 
+	down_read(&sbi->quota_sem);
 	ret = dquot_acquire(dquot);
 	if (ret < 0)
-		set_sbi_flag(F2FS_SB(dquot->dq_sb), SBI_QUOTA_NEED_REPAIR);
-
+		set_sbi_flag(sbi, SBI_QUOTA_NEED_REPAIR);
+	up_read(&sbi->quota_sem);
 	return ret;
 }
 
 static int f2fs_dquot_release(struct dquot *dquot)
 {
+	struct f2fs_sb_info *sbi = F2FS_SB(dquot->dq_sb);
 	int ret;
 
+	down_read(&sbi->quota_sem);
 	ret = dquot_release(dquot);
 	if (ret < 0)
-		set_sbi_flag(F2FS_SB(dquot->dq_sb), SBI_QUOTA_NEED_REPAIR);
+		set_sbi_flag(sbi, SBI_QUOTA_NEED_REPAIR);
+	up_read(&sbi->quota_sem);
 	return ret;
 }
 
@@ -2082,22 +2104,27 @@ static int f2fs_dquot_mark_dquot_dirty(struct dquot *dquot)
 	struct f2fs_sb_info *sbi = F2FS_SB(sb);
 	int ret;
 
+	down_read(&sbi->quota_sem);
 	ret = dquot_mark_dquot_dirty(dquot);
 
 	/* if we are using journalled quota */
 	if (is_journalled_quota(sbi))
 		set_sbi_flag(sbi, SBI_QUOTA_NEED_FLUSH);
 
+	up_read(&sbi->quota_sem);
 	return ret;
 }
 
 static int f2fs_dquot_commit_info(struct super_block *sb, int type)
 {
+	struct f2fs_sb_info *sbi = F2FS_SB(sb);
 	int ret;
 
+	down_read(&sbi->quota_sem);
 	ret = dquot_commit_info(sb, type);
 	if (ret < 0)
-		set_sbi_flag(F2FS_SB(sb), SBI_QUOTA_NEED_REPAIR);
+		set_sbi_flag(sbi, SBI_QUOTA_NEED_REPAIR);
+	up_read(&sbi->quota_sem);
 	return ret;
 }
 
@@ -3167,6 +3194,7 @@ try_onemore:
 	}
 
 	init_rwsem(&sbi->cp_rwsem);
+	init_rwsem(&sbi->quota_sem);
 	init_waitqueue_head(&sbi->cp_wait);
 	init_sb_info(sbi);