[PATCH 4.14 169/246] f2fs: avoid fsync() failure caused by EAGAIN in writepage()

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jaegeuk Kim <jaegeuk@kernel.org>

[ Upstream commit 5b19d284f5195a925dd015a6397bfce184097378 ]

pageout() in MM traslates EAGAIN, so calls handle_write_error()
 -> mapping_set_error() -> set_bit(AS_EIO, ...).
 file_write_and_wait_range() will see EIO error, which is critical
 to return value of fsync() followed by atomic_write failure to user.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Sasha Levin <redacted>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/f2fs/data.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c

@@ -1601,7 +1601,13 @@ out:
 
 redirty_out:
 	redirty_page_for_writepage(wbc, page);
-	if (!err)
+	/*
+	 * pageout() in MM traslates EAGAIN, so calls handle_write_error()
+	 * -> mapping_set_error() -> set_bit(AS_EIO, ...).
+	 * file_write_and_wait_range() will see EIO error, which is critical
+	 * to return value of fsync() followed by atomic_write failure to user.
+	 */
+	if (!err || wbc->for_reclaim)
 		return AOP_WRITEPAGE_ACTIVATE;
 	unlock_page(page);
 	return err;