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From: Joel Stanley <joel@jms.id.au>
To: David Woodhouse <dwmw2@infradead.org>,
	Richard Weinberger <richard@nod.at>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Kees Cook <keescook@chromium.org>, Christoph Hellwig <hch@lst.de>
Cc: "William A . Kennington III" <wak@google.com>,
	Lei YU <mine260309@gmail.com>,
	linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: [PATCH] jffs2: Hook up splice_write callback
Date: Wed, 31 Mar 2021 00:15:37 +1030	[thread overview]
Message-ID: <20210330134537.423447-1-joel@jms.id.au> (raw)

overlayfs using jffs2 as the upper filesystem would fail in some cases
since moving to v5.10. The test case used was to run 'touch' on a file
that exists in the lower fs, causing the modification time to be
updated. It returns EINVAL when the bug is triggered.

A bisection showed this was introduced in v5.9-rc1, with commit
36e2c7421f02 ("fs: don't allow splice read/write without explicit ops").
Reverting that commit restores the expected behaviour.

Some digging showed that this was due to jffs2 lacking an implementation
of splice_write. (For unknown reasons the warn_unsupported that should
trigger was not displaying any output).

Adding this patch resolved the issue and the test now passes.

Fixes: 36e2c7421f02 ("fs: don't allow splice read/write without explicit ops")
Signed-off-by: Joel Stanley <joel@jms.id.au>
---
 fs/jffs2/file.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/jffs2/file.c b/fs/jffs2/file.c
index f8fb89b10227..4fc8cd698d1a 100644
--- a/fs/jffs2/file.c
+++ b/fs/jffs2/file.c
@@ -57,6 +57,7 @@ const struct file_operations jffs2_file_operations =
 	.mmap =		generic_file_readonly_mmap,
 	.fsync =	jffs2_fsync,
 	.splice_read =	generic_file_splice_read,
+	.splice_write = iter_file_splice_write,
 };
 
 /* jffs2_file_inode_operations */
-- 
2.30.2


             reply	other threads:[~2021-03-30 13:46 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-30 13:45 Joel Stanley [this message]
2021-03-30 16:17 ` [PATCH] jffs2: Hook up splice_write callback Christoph Hellwig
2021-03-30 18:31   ` Al Viro
2021-03-30 18:38     ` Al Viro
2021-03-31 14:44     ` Christoph Hellwig
2021-03-31  4:55 ` Lei YU

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