From: Joel Stanley joel@jms.id.au
commit 42984af09afc414d540fcc8247f42894b0378a91 upstream.
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.
Cc: stable@vger.kernel.org Fixes: 36e2c7421f02 ("fs: don't allow splice read/write without explicit ops") Signed-off-by: Joel Stanley joel@jms.id.au Reviewed-by: Christoph Hellwig hch@lst.de Tested-by: Lei YU yulei.sh@bytedance.com Signed-off-by: Richard Weinberger richard@nod.at Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/jffs2/file.c | 1 + 1 file changed, 1 insertion(+)
--- a/fs/jffs2/file.c +++ b/fs/jffs2/file.c @@ -57,6 +57,7 @@ const struct file_operations jffs2_file_ .mmap = generic_file_readonly_mmap, .fsync = jffs2_fsync, .splice_read = generic_file_splice_read, + .splice_write = iter_file_splice_write, };
/* jffs2_file_inode_operations */