[Devel] [PATCH hci-8.1 0/2] fs/fuse kio: two fixes for the sockio transmit refactor

[Devel] [PATCH hci-8.1 0/2] fs/fuse kio: two fixes for the sockio transmit refactor

[Liu Kui]

Follow-up to the sockio refactor, fixing two issues found in review:
a latent infinite loop on an empty iter in do_sockio_sendmsg(), and
iov_iter_sendpages_ok() missing the last page of a bvec with an
unaligned bv_offset.

https://virtuozzo.atlassian.net/browse/VSTOR-142167

---
Liu Kui (2):
      fs/fuse kio: don't spin on an empty iter in do_sockio_sendmsg()
      fs/fuse kio: check every touched page in iov_iter_sendpages_ok()

 fs/fuse/kio/pcs/pcs_sock_io.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)
---
base-commit: 06ad1cd8ca1cd811287ca06c378547202fcca4ee
change-id: 20261001-sockio-sendmsg-empty-iter-405f96a2db01

Best regards,
--  
Liu Kui <kui.liu@virtuozzo.com>

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[Devel] [PATCH hci-8.1 1/2] fs/fuse kio: don't spin on an empty iter in do_sockio_sendmsg()

[Liu Kui]

If msg->get_iter() ever returns an empty iterator, do_sockio_sendmsg()
spins forever. Restore the old do_send_one_seg() behavior: warn and
fail the msg.

https://virtuozzo.atlassian.net/browse/VSTOR-142167

Fixes: 32b44dc7ba67 ("fs/fuse kio: refactor transmit path in pcs_sockio_send()")
Signed-off-by: Liu Kui <kui.liu@virtuozzo.com>
---
 fs/fuse/kio/pcs/pcs_sock_io.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fs/fuse/kio/pcs/pcs_sock_io.c b/fs/fuse/kio/pcs/pcs_sock_io.c
index 2da6d51c898b..b4a2ceeb331c 100644
--- a/fs/fuse/kio/pcs/pcs_sock_io.c
+++ b/fs/fuse/kio/pcs/pcs_sock_io.c
@@ -307,6 +307,11 @@ static int do_sockio_sendmsg(struct pcs_sockio *sio, struct pcs_msg *msg)
 		if (!iov_iter_count(it)) {
 			/* Current iter is exhausted, init new one */
 			msg->get_iter(msg, sio->write_offset, it, WRITE);
+			/* An empty iter here would spin this loop forever */
+			if (WARN_ON(!iov_iter_count(it))) {
+				clear_and_wake_up_bit(PCS_MSG_BUSY, &msg->flags);
+				return -PCS_ERR_NET_ABORT;
+			}
 		}
 
 		BUG_ON(iov_iter_count(it) > left);

-- 
Git-155)

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[Devel] [PATCH hci-8.1 2/2] fs/fuse kio: check every touched page in iov_iter_sendpages_ok()

[Liu Kui]

A bvec with an unaligned bv_offset can cross into one more page than
sendpages_ok() checks, so fold the intra-page offset into len. Pure
hardening: today the skipped page can never fail sendpage_ok().

https://virtuozzo.atlassian.net/browse/VSTOR-142167

Fixes: 32b44dc7ba67 ("fs/fuse kio: refactor transmit path in pcs_sockio_send()")
Signed-off-by: Liu Kui <kui.liu@virtuozzo.com>
---
 fs/fuse/kio/pcs/pcs_sock_io.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/fs/fuse/kio/pcs/pcs_sock_io.c b/fs/fuse/kio/pcs/pcs_sock_io.c
index b4a2ceeb331c..753a85a560bc 100644
--- a/fs/fuse/kio/pcs/pcs_sock_io.c
+++ b/fs/fuse/kio/pcs/pcs_sock_io.c
@@ -272,7 +272,13 @@ static bool iov_iter_sendpages_ok(struct iov_iter *it)
 		return false;
 
 	while (bvec < (it->bvec + it->nr_segs)) {
-		if (!sendpages_ok(bvec->bv_page, bvec->bv_len, bvec->bv_offset))
+		/*
+		 * Fold the intra-page offset into len so sendpages_ok()
+		 * checks every page the range touches.
+		 */
+		if (!sendpages_ok(bvec->bv_page,
+				  (bvec->bv_offset & ~PAGE_MASK) + bvec->bv_len,
+				  bvec->bv_offset & PAGE_MASK))
 			return false;
 		bvec++;
 	}

-- 
Git-155)

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Re: [Devel] [PATCH hci-8.1 2/2] fs/fuse kio: check every touched page in iov_iter_sendpages_ok()

[no-reply]

> A bvec with an unaligned bv_offset can cross into one more page than
> sendpages_ok() checks, so fold the intra-page offset into len. Pure
> hardening: today the skipped page can never fail sendpage_ok().
> 
> https://virtuozzo.atlassian.net/browse/VSTOR-142167
> 
> Fixes: 32b44dc7ba67 ("fs/fuse kio: refactor transmit path in pcs_sockio_send()")
> Signed-off-by: Liu Kui <kui.liu@virtuozzo.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.vzint.dev/#/patchset/20261001-sockio-sendmsg-empty-iter-v1-0-b876f4fbb9c7@virtuozzo.com?part=2


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Re: [Devel] [PATCH hci-8.1 1/2] fs/fuse kio: don't spin on an empty iter in do_sockio_sendmsg()

[no-reply]

> If msg->get_iter() ever returns an empty iterator, do_sockio_sendmsg()
> spins forever. Restore the old do_send_one_seg() behavior: warn and
> fail the msg.
> 
> https://virtuozzo.atlassian.net/browse/VSTOR-142167
> 
> Fixes: 32b44dc7ba67 ("fs/fuse kio: refactor transmit path in pcs_sockio_send()")
> Signed-off-by: Liu Kui <kui.liu@virtuozzo.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.vzint.dev/#/patchset/20261001-sockio-sendmsg-empty-iter-v1-0-b876f4fbb9c7@virtuozzo.com?part=1


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Re: [Devel] [PATCH hci-8.1 0/2] fs/fuse kio: two fixes for the sockio transmit refactor

[Konstantin Khorenko]

On Thu, 01 Oct 2026 11:23:40 +0800, Liu Kui wrote:
> fs/fuse kio: two fixes for the sockio transmit refactor
> 
> Follow-up to the sockio refactor, fixing two issues found in review:
> a latent infinite loop on an empty iter in do_sockio_sendmsg(), and
> iov_iter_sendpages_ok() missing the last page of a bvec with an
> unaligned bv_offset.
> 
> [...]

Applied to branch-rh10-6.12.0-211.52.1.22.x.vz10-ovz, will be released in rh10-6.12.0-211.52.1.22.7.vz10, thanks!

[1/2] fs/fuse kio: don't spin on an empty iter in do_sockio_sendmsg()
      https://bitbucket.org/virtuozzocore/vzkernel.vzs/commits/668fd929529e
[2/2] fs/fuse kio: check every touched page in iov_iter_sendpages_ok()
      https://bitbucket.org/virtuozzocore/vzkernel.vzs/commits/0750a95935c5

-- 
Konstantin Khorenko <khorenko@virtuozzo.com>

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