[Bug 2093871] Re: Using sendpages_ok() in nvme_tcp_try_send_data()

** Also affects: linux (Ubuntu Noble)
Importance: Undecided
Status: New

** Also affects: linux (Ubuntu Oracular)
Importance: Undecided
Status: New

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https://bugs.launchpad.net/bugs/2093871

Title:
Using sendpages_ok() in nvme_tcp_try_send_data()

Status in linux package in Ubuntu:
New
Status in linux source package in Noble:
New
Status in linux source package in Oracular:
New

Bug description:
Can you please cherry-pick those 2 important commits from upstream?

1. net: introduce helper sendpages_ok()
(https://github.com/torvalds/linux/commit/23a55f44)

Network drivers are using sendpage_ok() to check the first page of an
iterator in order to disable MSG_SPLICE_PAGES. The iterator can
represent list of contiguous pages.

When MSG_SPLICE_PAGES is enabled skb_splice_from_iter() is being used,
it requires all pages in the iterator to be sendable. Therefore it needs
to check that each page is sendable.

The patch introduces a helper sendpages_ok(), it returns true if all the
contiguous pages are sendable.

Drivers who want to send contiguous pages with MSG_SPLICE_PAGES may use
this helper to check whether the page list is OK. If the helper does not
return true, the driver should remove MSG_SPLICE_PAGES flag.


2. nvme-tcp: use sendpages_ok() instead of sendpage_ok() (https://github.com/torvalds/linux/commit/6af7331a)

Currently nvme_tcp_try_send_data() use sendpage_ok() in order to disable
MSG_SPLICE_PAGES, it check the first page of the iterator, the iterator
may represent contiguous pages.

MSG_SPLICE_PAGES enables skb_splice_from_iter() which checks all the
pages it sends with sendpage_ok().

When nvme_tcp_try_send_data() sends an iterator that the first page is
sendable, but one of the other pages isn't skb_splice_from_iter() warns
and aborts the data transfer.

Using the new helper sendpages_ok() in order to disable MSG_SPLICE_PAGES
solves the issue.

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