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[iov_iter] new primitives - copy_from_iter_full() and friends

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copy_from_iter_full(), copy_from_iter_full_nocache() and
csum_and_copy_from_iter_full() - counterparts of copy_from_iter()
et.al., advancing iterator only in case of successful full copy
and returning whether it had been successful or not.

Convert some obvious users.  *NOTE* - do not blindly assume that
something is a good candidate for those unless you are sure that
not advancing iov_iter in failure case is the right thing in
this case.  Anything that does short read/short write kind of
stuff (or is in a loop, etc.) is unlikely to be a good one.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2016-11-01 22:09:04 -04:00
parent e5517c2a5a
commit cbbd26b8b1
17 changed files with 121 additions and 39 deletions
Download patch file Download diff file Expand all files Collapse all files

98
lib/iov_iter.c
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@ -568,6 +568,31 @@ size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
}
EXPORT_SYMBOL(copy_from_iter);
bool copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i)
{
char *to = addr;
if (unlikely(i->type & ITER_PIPE)) {
WARN_ON(1);
return false;
}
if (unlikely(i->count < bytes)) \
return false;
iterate_all_kinds(i, bytes, v, ({
if (__copy_from_user((to += v.iov_len) - v.iov_len,
v.iov_base, v.iov_len))
return false;
0;}),
memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
v.bv_offset, v.bv_len),
memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
)
iov_iter_advance(i, bytes);
return true;
}
EXPORT_SYMBOL(copy_from_iter_full);
size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
{
char *to = addr;
@ -587,6 +612,30 @@ size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
}
EXPORT_SYMBOL(copy_from_iter_nocache);
bool copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i)
{
char *to = addr;
if (unlikely(i->type & ITER_PIPE)) {
WARN_ON(1);
return false;
}
if (unlikely(i->count < bytes)) \
return false;
iterate_all_kinds(i, bytes, v, ({
if (__copy_from_user_nocache((to += v.iov_len) - v.iov_len,
v.iov_base, v.iov_len))
return false;
0;}),
memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
v.bv_offset, v.bv_len),
memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
)
iov_iter_advance(i, bytes);
return true;
}
EXPORT_SYMBOL(copy_from_iter_full_nocache);
size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i)
{
@ -1008,7 +1057,7 @@ size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum,
}
iterate_and_advance(i, bytes, v, ({
int err = 0;
next = csum_and_copy_from_user(v.iov_base,
next = csum_and_copy_from_user(v.iov_base,
(to += v.iov_len) - v.iov_len,
v.iov_len, 0, &err);
if (!err) {
@ -1037,6 +1086,51 @@ size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum,
}
EXPORT_SYMBOL(csum_and_copy_from_iter);
bool csum_and_copy_from_iter_full(void *addr, size_t bytes, __wsum *csum,
struct iov_iter *i)
{
char *to = addr;
__wsum sum, next;
size_t off = 0;
sum = *csum;
if (unlikely(i->type & ITER_PIPE)) {
WARN_ON(1);
return false;
}
if (unlikely(i->count < bytes))
return false;
iterate_all_kinds(i, bytes, v, ({
int err = 0;
next = csum_and_copy_from_user(v.iov_base,
(to += v.iov_len) - v.iov_len,
v.iov_len, 0, &err);
if (err)
return false;
sum = csum_block_add(sum, next, off);
off += v.iov_len;
0;
}), ({
char *p = kmap_atomic(v.bv_page);
next = csum_partial_copy_nocheck(p + v.bv_offset,
(to += v.bv_len) - v.bv_len,
v.bv_len, 0);
kunmap_atomic(p);
sum = csum_block_add(sum, next, off);
off += v.bv_len;
}),({
next = csum_partial_copy_nocheck(v.iov_base,
(to += v.iov_len) - v.iov_len,
v.iov_len, 0);
sum = csum_block_add(sum, next, off);
off += v.iov_len;
})
)
*csum = sum;
iov_iter_advance(i, bytes);
return true;
}
EXPORT_SYMBOL(csum_and_copy_from_iter_full);
size_t csum_and_copy_to_iter(const void *addr, size_t bytes, __wsum *csum,
struct iov_iter *i)
{
@ -1051,7 +1145,7 @@ size_t csum_and_copy_to_iter(const void *addr, size_t bytes, __wsum *csum,
iterate_and_advance(i, bytes, v, ({
int err = 0;
next = csum_and_copy_to_user((from += v.iov_len) - v.iov_len,
v.iov_base,
v.iov_base,
v.iov_len, 0, &err);
if (!err) {
sum = csum_block_add(sum, next, off);