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copy_page_to_iter(): don't split high-order page in case of ITER_PIPE

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... just shove it into one pipe_buffer.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2022-06-23 17:21:37 -04:00
parent 310d9d5a50
commit f0f6b614f8
1 changed files with 6 additions and 15 deletions
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21
lib/iov_iter.c
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@ -706,30 +706,21 @@ static inline bool page_copy_sane(struct page *page, size_t offset, size_t n)
return false;
}
static size_t __copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i)
{
if (unlikely(iov_iter_is_pipe(i))) {
return copy_page_to_iter_pipe(page, offset, bytes, i);
} else {
void *kaddr = kmap_local_page(page);
size_t wanted = _copy_to_iter(kaddr + offset, bytes, i);
kunmap_local(kaddr);
return wanted;
}
}
size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i)
{
size_t res = 0;
if (unlikely(!page_copy_sane(page, offset, bytes)))
return 0;
if (unlikely(iov_iter_is_pipe(i)))
return copy_page_to_iter_pipe(page, offset, bytes, i);
page += offset / PAGE_SIZE; // first subpage
offset %= PAGE_SIZE;
while (1) {
size_t n = __copy_page_to_iter(page, offset,
min(bytes, (size_t)PAGE_SIZE - offset), i);
void *kaddr = kmap_local_page(page);
size_t n = min(bytes, (size_t)PAGE_SIZE - offset);
n = _copy_to_iter(kaddr + offset, n, i);
kunmap_local(kaddr);
res += n;
bytes -= n;
if (!bytes || !n)