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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
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4
drivers/net/macvtap.c
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@@ -673,7 +673,6 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m,
int depth;
bool zerocopy = false;
size_t linear;
ssize_t n;
if (q->flags & IFF_VNET_HDR) {
vnet_hdr_len = q->vnet_hdr_sz;
@@ -684,8 +683,7 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m,
len -= vnet_hdr_len;
err = -EFAULT;
n = copy_from_iter(&vnet_hdr, sizeof(vnet_hdr), from);
if (n != sizeof(vnet_hdr))
if (!copy_from_iter_full(&vnet_hdr, sizeof(vnet_hdr), from))
goto err;
iov_iter_advance(from, vnet_hdr_len - sizeof(vnet_hdr));
if ((vnet_hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&