Searched hist:"7 d58fe73" (Results 1 – 2 of 2) sorted by relevance
| /openbmc/linux/include/linux/ |
| H A D | uio.h | 7d58fe73 Fri Oct 28 15:50:30 CDT 2022 David Howells <dhowells@redhat.com> iov_iter: Add a function to extract a page list from an iterator
Add a function, iov_iter_extract_pages(), to extract a list of pages from
an iterator. The pages may be returned with a pin added or nothing,
depending on the type of iterator.
Add a second function, iov_iter_extract_will_pin(), to determine how the
cleanup should be done.
There are two cases:
(1) ITER_IOVEC or ITER_UBUF iterator.
Extracted pages will have pins (FOLL_PIN) obtained on them so that a
concurrent fork() will forcibly copy the page so that DMA is done
to/from the parent's buffer and is unavailable to/unaffected by the
child process.
iov_iter_extract_will_pin() will return true for this case. The
caller should use something like unpin_user_page() to dispose of the
page.
(2) Any other sort of iterator.
No refs or pins are obtained on the page, the assumption is made that
the caller will manage page retention.
iov_iter_extract_will_pin() will return false. The pages don't need
additional disposal.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: John Hubbard <jhubbard@nvidia.com>
cc: David Hildenbrand <david@redhat.com>
cc: Matthew Wilcox <willy@infradead.org>
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org
Signed-off-by: Steve French <stfrench@microsoft.com>
|
| /openbmc/linux/lib/ |
| H A D | iov_iter.c | 7d58fe73 Fri Oct 28 15:50:30 CDT 2022 David Howells <dhowells@redhat.com> iov_iter: Add a function to extract a page list from an iterator
Add a function, iov_iter_extract_pages(), to extract a list of pages from
an iterator. The pages may be returned with a pin added or nothing,
depending on the type of iterator.
Add a second function, iov_iter_extract_will_pin(), to determine how the
cleanup should be done.
There are two cases:
(1) ITER_IOVEC or ITER_UBUF iterator.
Extracted pages will have pins (FOLL_PIN) obtained on them so that a
concurrent fork() will forcibly copy the page so that DMA is done
to/from the parent's buffer and is unavailable to/unaffected by the
child process.
iov_iter_extract_will_pin() will return true for this case. The
caller should use something like unpin_user_page() to dispose of the
page.
(2) Any other sort of iterator.
No refs or pins are obtained on the page, the assumption is made that
the caller will manage page retention.
iov_iter_extract_will_pin() will return false. The pages don't need
additional disposal.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: John Hubbard <jhubbard@nvidia.com>
cc: David Hildenbrand <david@redhat.com>
cc: Matthew Wilcox <willy@infradead.org>
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org
Signed-off-by: Steve French <stfrench@microsoft.com>
|