Replace racy xfs_wait_for_freeze() check with reliable sb_start_write()
- sb_end_write() locking. Due to lock ranking dictated by the page fault
code we have to call sb_start_write() after we acquire ilock.

CC: Ben Myers <redacted>
CC: Alex Elder <elder@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/xfs/xfs_file.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 753ed9b..c5f879b 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c

@@ -862,9 +862,11 @@ xfs_file_dio_aio_write(
 		*iolock = XFS_IOLOCK_SHARED;
 	}
 
+	sb_start_write(inode->i_sb);
 	trace_xfs_file_direct_write(ip, count, iocb->ki_pos, 0);
 	ret = generic_file_direct_write(iocb, iovp,
 			&nr_segs, pos, &iocb->ki_pos, count, ocount);
+	sb_end_write(inode->i_sb);