--- /dev/null
+From 31867b23d7d1ee3535136c6a410a6cf56f666bfc Mon Sep 17 00:00:00 2001
+From: Jaegeuk Kim <jaegeuk@kernel.org>
+Date: Fri, 28 Dec 2018 11:00:38 -0800
+Subject: f2fs: wait on atomic writes to count F2FS_CP_WB_DATA
+
+From: Jaegeuk Kim <jaegeuk@kernel.org>
+
+commit 31867b23d7d1ee3535136c6a410a6cf56f666bfc upstream.
+
+Otherwise, we can get wrong counts incurring checkpoint hang.
+
+IO_W (CP: -24, Data: 24, Flush: ( 0 0 1), Discard: ( 0 0))
+
+Thread A Thread B
+- f2fs_write_data_pages
+ - __write_data_page
+ - f2fs_submit_page_write
+ - inc_page_count(F2FS_WB_DATA)
+ type is F2FS_WB_DATA due to file is non-atomic one
+- f2fs_ioc_start_atomic_write
+ - set_inode_flag(FI_ATOMIC_FILE)
+ - f2fs_write_end_io
+ - dec_page_count(F2FS_WB_CP_DATA)
+ type is F2FS_WB_DATA due to file becomes
+ atomic one
+
+Cc: <stable@vger.kernel.org>
+Reviewed-by: Chao Yu <yuchao0@huawei.com>
+Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ fs/f2fs/file.c | 12 +++++++-----
+ 1 file changed, 7 insertions(+), 5 deletions(-)
+
+--- a/fs/f2fs/file.c
++++ b/fs/f2fs/file.c
+@@ -1736,10 +1736,12 @@ static int f2fs_ioc_start_atomic_write(s
+
+ down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
+
+- if (!get_dirty_pages(inode))
+- goto skip_flush;
+-
+- f2fs_msg(F2FS_I_SB(inode)->sb, KERN_WARNING,
++ /*
++ * Should wait end_io to count F2FS_WB_CP_DATA correctly by
++ * f2fs_is_atomic_file.
++ */
++ if (get_dirty_pages(inode))
++ f2fs_msg(F2FS_I_SB(inode)->sb, KERN_WARNING,
+ "Unexpected flush for atomic writes: ino=%lu, npages=%u",
+ inode->i_ino, get_dirty_pages(inode));
+ ret = filemap_write_and_wait_range(inode->i_mapping, 0, LLONG_MAX);
+@@ -1747,7 +1749,7 @@ static int f2fs_ioc_start_atomic_write(s
+ up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
+ goto out;
+ }
+-skip_flush:
++
+ set_inode_flag(inode, FI_ATOMIC_FILE);
+ clear_inode_flag(inode, FI_ATOMIC_REVOKE_REQUEST);
+ up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);