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iov_iter: replace iov_iter_copy_from_user_atomic() with iterator-advancing variant

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Replacement is called copy_page_from_iter_atomic(); unlike the old primitive the
callers do *not* need to do iov_iter_advance() after it.  In case when they end
up consuming less than they'd been given they need to do iov_iter_revert() on
everything they had not consumed.  That, however, needs to be done only on slow
paths.

All in-tree callers converted.  And that kills the last user of iterate_all_kinds()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro
2021-04-30 10:26:41 -04:00
parent e4f8df8679
commit f0b65f39ac
8 changed files with 43 additions and 60 deletions
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30
lib/iov_iter.c
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@@ -114,28 +114,6 @@
n = wanted - n; \
}
#define iterate_all_kinds(i, n, v, I, B, K, X) { \
if (likely(n)) { \
size_t skip = i->iov_offset; \
if (likely(iter_is_iovec(i))) { \
const struct iovec *iov; \
struct iovec v; \
iterate_iovec(i, n, v, iov, skip, (I)) \
} else if (iov_iter_is_bvec(i)) { \
struct bio_vec v; \
struct bvec_iter __bi; \
iterate_bvec(i, n, v, __bi, skip, (B)) \
} else if (iov_iter_is_kvec(i)) { \
const struct kvec *kvec; \
struct kvec v; \
iterate_kvec(i, n, v, kvec, skip, (K)) \
} else if (iov_iter_is_xarray(i)) { \
struct bio_vec v; \
iterate_xarray(i, n, v, skip, (X)); \
} \
} \
}
#define iterate_and_advance(i, n, v, I, B, K, X) { \
if (unlikely(i->count < n)) \
n = i->count; \
@@ -1009,8 +987,8 @@ size_t iov_iter_zero(size_t bytes, struct iov_iter *i)
}
EXPORT_SYMBOL(iov_iter_zero);
size_t iov_iter_copy_from_user_atomic(struct page *page,
struct iov_iter *i, unsigned long offset, size_t bytes)
size_t copy_page_from_iter_atomic(struct page *page, unsigned offset, size_t bytes,
struct iov_iter *i)
{
char *kaddr = kmap_atomic(page), *p = kaddr + offset;
if (unlikely(!page_copy_sane(page, offset, bytes))) {
@@ -1022,7 +1000,7 @@ size_t iov_iter_copy_from_user_atomic(struct page *page,
WARN_ON(1);
return 0;
}
iterate_all_kinds(i, bytes, v,
iterate_and_advance(i, bytes, v,
copyin((p += v.iov_len) - v.iov_len, v.iov_base, v.iov_len),
memcpy_from_page((p += v.bv_len) - v.bv_len, v.bv_page,
v.bv_offset, v.bv_len),
@@ -1033,7 +1011,7 @@ size_t iov_iter_copy_from_user_atomic(struct page *page,
kunmap_atomic(kaddr);
return bytes;
}
EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
EXPORT_SYMBOL(copy_page_from_iter_atomic);
static inline void pipe_truncate(struct iov_iter *i)
{