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iov: remove copy_page_from_iter_atomic()

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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: Matthew 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: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Matthew Wilcox (Oracle)
2025-05-14 18:06:04 +01:00
committed by Andrew Morton
parent 80ae99c572
commit d973692944
2 changed files with 14 additions and 23 deletions
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10
include/linux/uio.h
View File

@@ -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);

27
lib/iov_iter.c
View File

@@ -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);
}
if (folio_test_partial_kmap(folio) &&
n > PAGE_SIZE - offset_in_page(offset))
n = PAGE_SIZE - offset_in_page(offset);
p = kmap_atomic(page) + offset;
n = __copy_from_iter(p, n, i);
kunmap_atomic(p);
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)
{