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iov_iter: clean csum_and_copy_...() primitives up a bit 

1) kmap_atomic() is not needed here, kmap_local_page() is enough.
2) No need to make sum = csum_block_add(sum, next, off); conditional
upon next != 0 - adding 0 is a no-op as far as csum_block_add()
is concerned.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2021-04-30 13:40:48 -04:00
parent 55ca375c5d
commit 2495bdcc86
1 changed files with 4 additions and 6 deletions
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10
lib/iov_iter.c
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@ -600,9 +600,9 @@ static size_t csum_and_copy_to_pipe_iter(const void *addr, size_t bytes,
return 0;
do {
size_t chunk = min_t(size_t, n, PAGE_SIZE - r);
char *p = kmap_atomic(pipe->bufs[i_head & p_mask].page);
char *p = kmap_local_page(pipe->bufs[i_head & p_mask].page);
sum = csum_and_memcpy(p + r, addr, chunk, sum, off);
kunmap_atomic(p);
kunmap_local(p);
i->head = i_head;
i->iov_offset = r + chunk;
n -= chunk;
@ -1665,8 +1665,7 @@ size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum,
}
iterate_and_advance(i, bytes, base, len, off, ({
next = csum_and_copy_from_user(base, addr + off, len);
if (next)
sum = csum_block_add(sum, next, off);
sum = csum_block_add(sum, next, off);
next ? 0 : len;
}), ({
sum = csum_and_memcpy(addr + off, base, len, sum, off);
@ -1693,8 +1692,7 @@ size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *_csstate,
}
iterate_and_advance(i, bytes, base, len, off, ({
next = csum_and_copy_to_user(addr + off, base, len);
if (next)
sum = csum_block_add(sum, next, off);
sum = csum_block_add(sum, next, off);
next ? 0 : len;
}), ({
sum = csum_and_memcpy(base, addr + off, len, sum, off);