[PATCH] f2fs: fix potential deadlock due to unpaired node_write lock use

[Chao Yu]

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@xxxxxxxxxx>
---
 fs/f2fs/compress.c | 7 ++++---
 fs/f2fs/data.c     | 7 ++++---
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
index 11653fa79289..2ec7cf454418 100644
--- a/fs/f2fs/compress.c
+++ b/fs/f2fs/compress.c
@@ -1215,6 +1215,7 @@ static int f2fs_write_compressed_pages(struct compress_ctx *cc,
 	unsigned int last_index = cc->cluster_size - 1;
 	loff_t psize;
 	int i, err;
+	bool quota_inode = IS_NOQUOTA(inode);
 
 	/* we should bypass data pages to proceed the kworker jobs */
 	if (unlikely(f2fs_cp_error(sbi))) {
@@ -1222,7 +1223,7 @@ static int f2fs_write_compressed_pages(struct compress_ctx *cc,
 		goto out_free;
 	}
 
-	if (IS_NOQUOTA(inode)) {
+	if (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
@@ -1344,7 +1345,7 @@ static int f2fs_write_compressed_pages(struct compress_ctx *cc,
 		set_inode_flag(inode, FI_FIRST_BLOCK_WRITTEN);
 
 	f2fs_put_dnode(&dn);
-	if (IS_NOQUOTA(inode))
+	if (quota_inode)
 		f2fs_up_read(&sbi->node_write);
 	else
 		f2fs_unlock_op(sbi);
@@ -1370,7 +1371,7 @@ static int f2fs_write_compressed_pages(struct compress_ctx *cc,
 out_put_dnode:
 	f2fs_put_dnode(&dn);
 out_unlock_op:
-	if (IS_NOQUOTA(inode))
+	if (quota_inode)
 		f2fs_up_read(&sbi->node_write);
 	else
 		f2fs_unlock_op(sbi);
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 7165b1202f53..4a0ee9cc43b5 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -2775,6 +2775,7 @@ 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,
@@ -2832,19 +2833,19 @@ int f2fs_write_single_data_page(struct page *page, int *submitted,
 		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;
-- 
2.36.1