f2fs: wait IO writeback in commit_inmem_pages()

From: Chao Yu <[email protected]>

Thread A Thread B
- f2fs_ioc_commit_atomic_write
- commit_inmem_pages
- f2fs_submit_merged_write_cond
: write data
- write_checkpoint
- do_checkpoint : commit all node within CP -> SPO
- f2fs_do_sync_file
- file_write_and_wait_range
: wait data writeback

In above race condition, data/node can be flushed in reversed order when coming a checkpoint before f2fs_do_sync_file, after SPOR, it results in atomic written data being corrupted.

This patch adds filemap_fdatawait() in commit_inmem_pages() to keep data and node of atomic file being flushed orderly.

Signed-off-by Chao Yu <[email protected]>

---
v2:
- clean up codes suggested by Jaegeuk.

 fs/f2fs/file.c    | 4 ++++
 fs/f2fs/segment.c | 2 ++
 2 files changed, 6 insertions(+)

fs/f2fs/file.c +4 -0

index bac059474342..0cfa65c21d3f 100644
@@ -217,6 +217,9 @@ static int f2fs_do_sync_file(struct file *file, loff_t start, loff_t end,
 
 	trace_f2fs_sync_file_enter(inode);
 
+	if (atomic)
+		goto write_done;
+
 	/* if fdatasync is triggered, let's do in-place-update */
 	if (datasync || get_dirty_pages(inode) <= SM_I(sbi)->min_fsync_blocks)
 		set_inode_flag(inode, FI_NEED_IPU);

@@ -228,6 +231,7 @@ static int f2fs_do_sync_file(struct file *file, loff_t start, loff_t end,
 		return ret;
 	}
 
+write_done:
 	/* if the inode is dirty, let's recover all the time */
 	if (!f2fs_skip_inode_update(inode, datasync)) {
 		f2fs_write_inode(inode, NULL);

fs/f2fs/segment.c +2 -0

index 710d817c4350..31336fc54d8e 100644
@@ -419,6 +419,8 @@ static int __commit_inmem_pages(struct inode *inode)
 		__revoke_inmem_pages(inode, &fi->inmem_pages, true, false);
 	} else {
 		__revoke_inmem_pages(inode, &revoke_list, false, false);
+
+		err = filemap_fdatawait(inode->i_mapping);
 	}
 
 	return err;