f2fs: fix potential deadlock due to unpaired node_write lock use

If S_NOQUOTA is cleared from inode during data page writeback of quota
file, it may miss to unlock node_write lock, result in potential
deadlock, fix to use the lock in paired.

Kworker					Thread
- writepage
 if (IS_NOQUOTA())
   f2fs_down_read(&sbi->node_write);
					- vfs_cleanup_quota_inode
					 - inode->i_flags &= ~S_NOQUOTA;
 if (IS_NOQUOTA())
   f2fs_up_read(&sbi->node_write);

Fixes: 79963d967b49 ("f2fs: shrink node_write lock coverage")
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

1 files changed, 4 insertions, 3 deletions

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 0990d7f05366..3fad7a23a507 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -2832,6 +2832,7 @@ int f2fs_write_single_data_page(struct page *page, int *submitted,
 	loff_t psize = (loff_t)(page->index + 1) << PAGE_SHIFT;
 	unsigned offset = 0;
 	bool need_balance_fs = false;
+	bool quota_inode = IS_NOQUOTA(inode);
 	int err = 0;
 	struct f2fs_io_info fio = {
 		.sbi = sbi,
@@ -2893,19 +2894,19 @@ write:
 		goto out;
 
 	/* Dentry/quota blocks are controlled by checkpoint */
-	if (S_ISDIR(inode->i_mode) || IS_NOQUOTA(inode)) {
+	if (S_ISDIR(inode->i_mode) || quota_inode) {
 		/*
 		 * We need to wait for node_write to avoid block allocation during
 		 * checkpoint. This can only happen to quota writes which can cause
 		 * the below discard race condition.
 		 */
-		if (IS_NOQUOTA(inode))
+		if (quota_inode)
 			f2fs_down_read(&sbi->node_write);
 
 		fio.need_lock = LOCK_DONE;
 		err = f2fs_do_write_data_page(&fio);
 
-		if (IS_NOQUOTA(inode))
+		if (quota_inode)
 			f2fs_up_read(&sbi->node_write);
 
 		goto done;