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iov_iter: teach csum_and_copy_to_iter() to handle pipe-backed ones

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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2018-11-25 16:24:16 -05:00
parent 2084ac6c50
commit 78e1f38617
1 changed files with 37 additions and 1 deletions
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38
lib/iov_iter.c
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@ -560,6 +560,38 @@ static size_t copy_pipe_to_iter(const void *addr, size_t bytes,
return bytes;
}
static size_t csum_and_copy_to_pipe_iter(const void *addr, size_t bytes,
__wsum *csum, struct iov_iter *i)
{
struct pipe_inode_info *pipe = i->pipe;
size_t n, r;
size_t off = 0;
__wsum sum = *csum, next;
int idx;
if (!sanity(i))
return 0;
bytes = n = push_pipe(i, bytes, &idx, &r);
if (unlikely(!n))
return 0;
for ( ; n; idx = next_idx(idx, pipe), r = 0) {
size_t chunk = min_t(size_t, n, PAGE_SIZE - r);
char *p = kmap_atomic(pipe->bufs[idx].page);
next = csum_partial_copy_nocheck(addr, p + r, chunk, 0);
sum = csum_block_add(sum, next, off);
kunmap_atomic(p);
i->idx = idx;
i->iov_offset = r + chunk;
n -= chunk;
off += chunk;
addr += chunk;
}
i->count -= bytes;
*csum = sum;
return bytes;
}
size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
{
const char *from = addr;
@ -1438,8 +1470,12 @@ size_t csum_and_copy_to_iter(const void *addr, size_t bytes, __wsum *csum,
const char *from = addr;
__wsum sum, next;
size_t off = 0;
if (unlikely(iov_iter_is_pipe(i)))
return csum_and_copy_to_pipe_iter(addr, bytes, csum, i);
sum = *csum;
if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
if (unlikely(iov_iter_is_discard(i))) {
WARN_ON(1); /* for now */
return 0;
}