Patch "netfs: Fix writethrough-mode error handling" has been added to the 6.8-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    netfs: Fix writethrough-mode error handling

to the 6.8-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     netfs-fix-writethrough-mode-error-handling.patch
and it can be found in the queue-6.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 170c66c57fd246d0b67b94a7a98196ef700f11f8
Author: David Howells <dhowells@xxxxxxxxxx>
Date:   Wed Apr 17 09:47:19 2024 +0100

    netfs: Fix writethrough-mode error handling
    
    [ Upstream commit 619606a7b8d5e54b71578ecc988d3f8e1896bbc6 ]
    
    Fix the error return in netfs_perform_write() acting in writethrough-mode
    to return any cached error in the case that netfs_end_writethrough()
    returns 0.
    
    This can affect the use of O_SYNC/O_DSYNC/RWF_SYNC/RWF_DSYNC in 9p and afs.
    
    Fixes: 41d8e7673a77 ("netfs: Implement a write-through caching option")
    Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/6736.1713343639@xxxxxxxxxxxxxxxxxxxxxx
    Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
    cc: Eric Van Hensbergen <ericvh@xxxxxxxxxx>
    cc: Latchesar Ionkov <lucho@xxxxxxxxxx>
    cc: Dominique Martinet <asmadeus@xxxxxxxxxxxxx>
    cc: Christian Schoenebeck <linux_oss@xxxxxxxxxxxxx>
    cc: Marc Dionne <marc.dionne@xxxxxxxxxxxx>
    cc: netfs@xxxxxxxxxxxxxxx
    cc: linux-fsdevel@xxxxxxxxxxxxxxx
    cc: v9fs@xxxxxxxxxxxxxxx
    cc: linux-afs@xxxxxxxxxxxxxxxxxxx
    Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/fs/netfs/buffered_write.c b/fs/netfs/buffered_write.c
index 9a0d32e4b422a..8f13ca8fbc74d 100644
--- a/fs/netfs/buffered_write.c
+++ b/fs/netfs/buffered_write.c
@@ -164,7 +164,7 @@ ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter,
 	enum netfs_how_to_modify howto;
 	enum netfs_folio_trace trace;
 	unsigned int bdp_flags = (iocb->ki_flags & IOCB_SYNC) ? 0: BDP_ASYNC;
-	ssize_t written = 0, ret;
+	ssize_t written = 0, ret, ret2;
 	loff_t i_size, pos = iocb->ki_pos, from, to;
 	size_t max_chunk = PAGE_SIZE << MAX_PAGECACHE_ORDER;
 	bool maybe_trouble = false;
@@ -395,10 +395,12 @@ ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter,
 
 out:
 	if (unlikely(wreq)) {
-		ret = netfs_end_writethrough(wreq, iocb);
+		ret2 = netfs_end_writethrough(wreq, iocb);
 		wbc_detach_inode(&wbc);
-		if (ret == -EIOCBQUEUED)
-			return ret;
+		if (ret2 == -EIOCBQUEUED)
+			return ret2;
+		if (ret == 0)
+			ret = ret2;
 	}
 
 	iocb->ki_pos += written;