[PATCH 2/3] fs: block_page_mkwrite should wait for writeback to finish

For filesystems such as nilfs2 and xfs that use block_page_mkwrite, modify that
function to wait for pending writeback before allowing the page to become
writable.  This is needed to stabilize pages during writeback for those two
filesystems.

Signed-off-by: Darrick J. Wong <redacted>
---
 fs/buffer.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index a08bb8e..0e7fa16 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c

@@ -2367,8 +2367,10 @@ block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
 			ret = VM_FAULT_OOM;
 		else /* -ENOSPC, -EIO, etc */
 			ret = VM_FAULT_SIGBUS;
-	} else
+	} else {
+		wait_on_page_writeback(page);
 		ret = VM_FAULT_LOCKED;
+	}
 
 out:
 	return ret;

--

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