[PATCH 2/4] fs: return writeback errors for IOCB_DONTCACHE in generic_write_sync

[Christoph Hellwig <hch@lst.de>]

Currently generic_write_sync only kicks of writeback for IOCB_DONTCACHE
writes, but never looks at the writeback errors.  When using
IOCB_DONTCACHE as a fallback for IOCB_DIRECT for devcies that require
stable writes, this breaks a few xfstests test cases that expect instant
errors like removed devices to be directly propagated to the writer.
While I don't know of real applications that would expect this, trying to
keep the behavior as similar as possible sounds useful and can be
trivially done by checking for and returning writeback errors in
generic_write_sync.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/linux/fs.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 09b47effc55e..34a843cf4c1c 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3047,9 +3047,13 @@ static inline ssize_t generic_write_sync(struct kiocb *iocb, ssize_t count)
 			return ret;
 	} else if (iocb->ki_flags & IOCB_DONTCACHE) {
 		struct address_space *mapping = iocb->ki_filp->f_mapping;
+		int err;
 
 		filemap_fdatawrite_range_kick(mapping, iocb->ki_pos - count,
 					      iocb->ki_pos - 1);
+		err = file_check_and_advance_wb_err(iocb->ki_filp);
+		if (err)
+			return err;
 	}
 
 	return count;
-- 
2.47.3