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authorAl Viro <viro@zeniv.linux.org.uk>2022-07-29 12:54:53 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2022-08-08 22:37:26 -0400
commitc03f05f183cd15f4259684ab658fbc3d23797d99 (patch)
tree0913d63d42f83b6fc80113446df4b3891acbcdae /lib/iov_iter.c
parentc7d57ab1632d29e256e3ae68f925751142330d88 (diff)
fix copy_page_from_iter() for compound destinations
had been broken for ITER_BVEC et.al. since ever (OK, v3.17 when ITER_BVEC had first appeared)... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'lib/iov_iter.c')
-rw-r--r--lib/iov_iter.c22
1 files changed, 18 insertions, 4 deletions
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 4e3696d349a4..4b7fce72e3e5 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -738,13 +738,27 @@ EXPORT_SYMBOL(copy_page_to_iter);
size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i)
{
- if (page_copy_sane(page, offset, bytes)) {
+ size_t res = 0;
+ if (!page_copy_sane(page, offset, bytes))
+ return 0;
+ page += offset / PAGE_SIZE; // first subpage
+ offset %= PAGE_SIZE;
+ while (1) {
void *kaddr = kmap_local_page(page);
- size_t wanted = _copy_from_iter(kaddr + offset, bytes, i);
+ size_t n = min(bytes, (size_t)PAGE_SIZE - offset);
+ n = _copy_from_iter(kaddr + offset, n, i);
kunmap_local(kaddr);
- return wanted;
+ res += n;
+ bytes -= n;
+ if (!bytes || !n)
+ break;
+ offset += n;
+ if (offset == PAGE_SIZE) {
+ page++;
+ offset = 0;
+ }
}
- return 0;
+ return res;
}
EXPORT_SYMBOL(copy_page_from_iter);