From 2d1b3bbc3dd56fc8364350eb93e5d67a05cb2c23 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Mon, 25 Sep 2023 00:21:35 -0600 Subject: [PATCH] ovl: disable IOCB_DIO_CALLER_COMP overlayfs copies the kiocb flags when it sets up a new kiocb to handle a write, but it doesn't properly support dealing with the deferred caller completions of the kiocb. This means it doesn't get the final write completion value, and hence will complete the write with '0' as the result. We could support the caller completions in overlayfs, but for now let's just disable them in the generated write kiocb. Reported-by: Zorro Lang Link: https://lore.kernel.org/io-uring/20230924142754.ejwsjen5pvyc32l4@dell-per750-06-vm-08.rhts.eng.pek2.redhat.com/ Fixes: 8c052fb3002e ("iomap: support IOCB_DIO_CALLER_COMP") Signed-off-by: Jens Axboe Message-Id: <71897125-e570-46ce-946a-d4729725e28f@kernel.dk> Signed-off-by: Christian Brauner --- fs/overlayfs/file.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c index 3b4cc63..ca18db7 100644 --- a/fs/overlayfs/file.c +++ b/fs/overlayfs/file.c @@ -393,6 +393,12 @@ static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter) if (!ovl_should_sync(OVL_FS(inode->i_sb))) ifl &= ~(IOCB_DSYNC | IOCB_SYNC); + /* + * Overlayfs doesn't support deferred completions, don't copy + * this property in case it is set by the issuer. + */ + ifl &= ~IOCB_DIO_CALLER_COMP; + old_cred = ovl_override_creds(file_inode(file)->i_sb); if (is_sync_kiocb(iocb)) { file_start_write(real.file); -- 2.7.4