Commit d9736929 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Andrew Morton
Browse files

iov: remove copy_page_from_iter_atomic() 

All callers now use copy_folio_from_iter_atomic(), so convert
copy_page_from_iter_atomic().  While I'm in there, use kmap_local_folio()
and pagefault_disable() instead of kmap_atomic().  That allows preemption
and/or task migration to happen during the copy_from_user().  Also use the
new folio_test_partial_kmap() predicate instead of open-coding it.

Link: https://lkml.kernel.org/r/20250514170607.3000994-4-willy@infradead.org


Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Hugh Dickins <hughd@google.com>
Cc: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 80ae99c5

include/linux/uio.h

+2 −8
Original line number Diff line number Diff line
@@ -176,8 +176,6 @@ static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs) 
	return ret;

}



size_t copy_page_from_iter_atomic(struct page *page, size_t offset,

				  size_t bytes, struct iov_iter *i);

void iov_iter_advance(struct iov_iter *i, size_t bytes);

void iov_iter_revert(struct iov_iter *i, size_t bytes);

size_t fault_in_iov_iter_readable(const struct iov_iter *i, size_t bytes);
@@ -187,6 +185,8 @@ size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes, 
			 struct iov_iter *i);

size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,

			 struct iov_iter *i);

size_t copy_folio_from_iter_atomic(struct folio *folio, size_t offset,

		size_t bytes, struct iov_iter *i);



size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i);

size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i);
@@ -204,12 +204,6 @@ static inline size_t copy_folio_from_iter(struct folio *folio, size_t offset, 
	return copy_page_from_iter(&folio->page, offset, bytes, i);

}



static inline size_t copy_folio_from_iter_atomic(struct folio *folio,

		size_t offset, size_t bytes, struct iov_iter *i)

{

	return copy_page_from_iter_atomic(&folio->page, offset, bytes, i);

}



size_t copy_page_to_iter_nofault(struct page *page, unsigned offset,

				 size_t bytes, struct iov_iter *i);

lib/iov_iter.c

+13 −16
Original line number Diff line number Diff line
@@ -457,38 +457,35 @@ size_t iov_iter_zero(size_t bytes, struct iov_iter *i) 
}

EXPORT_SYMBOL(iov_iter_zero);



size_t copy_page_from_iter_atomic(struct page *page, size_t offset,

size_t copy_folio_from_iter_atomic(struct folio *folio, size_t offset,

		size_t bytes, struct iov_iter *i)

{

	size_t n, copied = 0;

	bool uses_kmap = IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP) ||

			 PageHighMem(page);



	if (!page_copy_sane(page, offset, bytes))

	if (!page_copy_sane(&folio->page, offset, bytes))

		return 0;

	if (WARN_ON_ONCE(!i->data_source))

		return 0;



	do {

		char *p;

		char *to = kmap_local_folio(folio, offset);



		n = bytes - copied;

		if (uses_kmap) {

			page += offset / PAGE_SIZE;

			offset %= PAGE_SIZE;

			n = min_t(size_t, n, PAGE_SIZE - offset);

		}



		p = kmap_atomic(page) + offset;

		n = __copy_from_iter(p, n, i);

		kunmap_atomic(p);

		if (folio_test_partial_kmap(folio) &&

		    n > PAGE_SIZE - offset_in_page(offset))

			n = PAGE_SIZE - offset_in_page(offset);



		pagefault_disable();

		n = __copy_from_iter(to, n, i);

		pagefault_enable();

		kunmap_local(to);

		copied += n;

		offset += n;

	} while (uses_kmap && copied != bytes && n > 0);

	} while (copied != bytes && n > 0);



	return copied;

}

EXPORT_SYMBOL(copy_page_from_iter_atomic);

EXPORT_SYMBOL(copy_folio_from_iter_atomic);



static void iov_iter_bvec_advance(struct iov_iter *i, size_t size)

{