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iov_iter: Handle compound highmem pages in copy_page_from_iter_atomic()

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copy_page_from_iter_atomic() already handles !highmem compound
pages correctly, but if we are passed a highmem compound page,
each base page needs to be mapped & unmapped individually.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kent Overstreet <kent.overstreet@linux.dev>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Tested-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Matthew Wilcox (Oracle) 2023-06-06 16:43:32 -04:00
parent f7f9a0c873
commit 908a1ad894
1 changed files with 23 additions and 10 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

33
lib/iov_iter.c
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@ -566,24 +566,37 @@ 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, unsigned offset, size_t bytes,
struct iov_iter *i)
size_t copy_page_from_iter_atomic(struct page *page, unsigned offset,
size_t bytes, struct iov_iter *i)
{
char *p;
size_t n, copied = 0;
if (!page_copy_sane(page, offset, bytes))
return 0;
if (WARN_ON_ONCE(!i->data_source))
return 0;
p = kmap_atomic(page) + offset;
iterate_and_advance(i, bytes, base, len, off,
copyin(p + off, base, len),
memcpy_from_iter(i, p + off, base, len)
)
kunmap_atomic(p);
do {
char *p;
return bytes;
n = bytes - copied;
if (PageHighMem(page)) {
page += offset / PAGE_SIZE;
offset %= PAGE_SIZE;
n = min_t(size_t, n, PAGE_SIZE - offset);
}
p = kmap_atomic(page) + offset;
iterate_and_advance(i, n, base, len, off,
copyin(p + off, base, len),
memcpy_from_iter(i, p + off, base, len)
)
kunmap_atomic(p);
copied += n;
offset += n;
} while (PageHighMem(page) && copied != bytes && n > 0);
return copied;
}
EXPORT_SYMBOL(copy_page_from_iter_atomic);