Merge tag 'vfs-6.7.iov_iter' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs

Pull iov_iter updates from Christian Brauner:
 "This contain's David's iov_iter cleanup work to convert the iov_iter
  iteration macros to inline functions:

   - Remove last_offset from iov_iter as it was only used by ITER_PIPE

   - Add a __user tag on copy_mc_to_user()'s dst argument on x86 to
     match that on powerpc and get rid of a sparse warning

   - Convert iter->user_backed to user_backed_iter() in the sound PCM
     driver

   - Convert iter->user_backed to user_backed_iter() in a couple of
     infiniband drivers

   - Renumber the type enum so that the ITER_* constants match the order
     in iterate_and_advance*()

   - Since the preceding patch puts UBUF and IOVEC at 0 and 1, change
     user_backed_iter() to just use the type value and get rid of the
     extra flag

   - Convert the iov_iter iteration macros to always-inline functions to
     make the code easier to follow. It uses function pointers, but they
     get optimised away

   - Move the check for ->copy_mc to _copy_from_iter() and
     copy_page_from_iter_atomic() rather than in memcpy_from_iter_mc()
     where it gets repeated for every segment. Instead, we check once
     and invoke a side function that can use iterate_bvec() rather than
     iterate_and_advance() and supply a different step function

   - Move the copy-and-csum code to net/ where it can be in proximity
     with the code that uses it

   - Fold memcpy_and_csum() in to its two users

   - Move csum_and_copy_from_iter_full() out of line and merge in
     csum_and_copy_from_iter() since the former is the only caller of
     the latter

   - Move hash_and_copy_to_iter() to net/ where it can be with its only
     caller"

* tag 'vfs-6.7.iov_iter' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs:
  iov_iter, net: Move hash_and_copy_to_iter() to net/
  iov_iter, net: Merge csum_and_copy_from_iter{,_full}() together
  iov_iter, net: Fold in csum_and_memcpy()
  iov_iter, net: Move csum_and_copy_to/from_iter() to net/
  iov_iter: Don't deal with iter->copy_mc in memcpy_from_iter_mc()
  iov_iter: Convert iterate*() to inline funcs
  iov_iter: Derive user-backedness from the iterator type
  iov_iter: Renumber ITER_* constants
  infiniband: Use user_backed_iter() to see if iterator is UBUF/IOVEC
  sound: Fix snd_pcm_readv()/writev() to use iov access functions
  iov_iter, x86: Be consistent about the __user tag on copy_mc_to_user()
  iov_iter: Remove last_offset from iov_iter as it was for ITER_PIPE

2 files changed, 114 insertions, 1 deletions

diff --git a/net/core/datagram.c b/net/core/datagram.c
index 176eb5834746..103d46fa0eeb 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -50,7 +50,7 @@
 #include <linux/spinlock.h>
 #include <linux/slab.h>
 #include <linux/pagemap.h>
-#include <linux/uio.h>
+#include <linux/iov_iter.h>
 #include <linux/indirect_call_wrapper.h>
 
 #include <net/protocol.h>
@@ -61,6 +61,7 @@
 #include <net/tcp_states.h>
 #include <trace/events/skb.h>
 #include <net/busy_poll.h>
+#include <crypto/hash.h>
 
 /*
  *	Is a socket 'connection oriented' ?
@@ -489,6 +490,24 @@ short_copy:
 	return 0;
 }
 
+static size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp,
+				    struct iov_iter *i)
+{
+#ifdef CONFIG_CRYPTO_HASH
+	struct ahash_request *hash = hashp;
+	struct scatterlist sg;
+	size_t copied;
+
+	copied = copy_to_iter(addr, bytes, i);
+	sg_init_one(&sg, addr, copied);
+	ahash_request_set_crypt(hash, &sg, NULL, copied);
+	crypto_ahash_update(hash);
+	return copied;
+#else
+	return 0;
+#endif
+}
+
 /**
  *	skb_copy_and_hash_datagram_iter - Copy datagram to an iovec iterator
  *          and update a hash.
@@ -716,6 +735,60 @@ int zerocopy_sg_from_iter(struct sk_buff *skb, struct iov_iter *from)
 }
 EXPORT_SYMBOL(zerocopy_sg_from_iter);
 
+static __always_inline
+size_t copy_to_user_iter_csum(void __user *iter_to, size_t progress,
+			      size_t len, void *from, void *priv2)
+{
+	__wsum next, *csum = priv2;
+
+	next = csum_and_copy_to_user(from + progress, iter_to, len);
+	*csum = csum_block_add(*csum, next, progress);
+	return next ? 0 : len;
+}
+
+static __always_inline
+size_t memcpy_to_iter_csum(void *iter_to, size_t progress,
+			   size_t len, void *from, void *priv2)
+{
+	__wsum *csum = priv2;
+	__wsum next = csum_partial_copy_nocheck(from, iter_to, len);
+
+	*csum = csum_block_add(*csum, next, progress);
+	return 0;
+}
+
+struct csum_state {
+	__wsum csum;
+	size_t off;
+};
+
+static size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *_csstate,
+				    struct iov_iter *i)
+{
+	struct csum_state *csstate = _csstate;
+	__wsum sum;
+
+	if (WARN_ON_ONCE(i->data_source))
+		return 0;
+	if (unlikely(iov_iter_is_discard(i))) {
+		// can't use csum_memcpy() for that one - data is not copied
+		csstate->csum = csum_block_add(csstate->csum,
+					       csum_partial(addr, bytes, 0),
+					       csstate->off);
+		csstate->off += bytes;
+		return bytes;
+	}
+
+	sum = csum_shift(csstate->csum, csstate->off);
+
+	bytes = iterate_and_advance2(i, bytes, (void *)addr, &sum,
+				     copy_to_user_iter_csum,
+				     memcpy_to_iter_csum);
+	csstate->csum = csum_shift(sum, csstate->off);
+	csstate->off += bytes;
+	return bytes;
+}
+
 /**
  *	skb_copy_and_csum_datagram - Copy datagram to an iovec iterator
  *          and update a checksum.
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 4eaf7ed0d1f4..2bfa6a7ba244 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -62,6 +62,7 @@
 #include <linux/if_vlan.h>
 #include <linux/mpls.h>
 #include <linux/kcov.h>
+#include <linux/iov_iter.h>
 
 #include <net/protocol.h>
 #include <net/dst.h>
@@ -6931,3 +6932,42 @@ out:
 	return spliced ?: ret;
 }
 EXPORT_SYMBOL(skb_splice_from_iter);
+
+static __always_inline
+size_t memcpy_from_iter_csum(void *iter_from, size_t progress,
+			     size_t len, void *to, void *priv2)
+{
+	__wsum *csum = priv2;
+	__wsum next = csum_partial_copy_nocheck(iter_from, to + progress, len);
+
+	*csum = csum_block_add(*csum, next, progress);
+	return 0;
+}
+
+static __always_inline
+size_t copy_from_user_iter_csum(void __user *iter_from, size_t progress,
+				size_t len, void *to, void *priv2)
+{
+	__wsum next, *csum = priv2;
+
+	next = csum_and_copy_from_user(iter_from, to + progress, len);
+	*csum = csum_block_add(*csum, next, progress);
+	return next ? 0 : len;
+}
+
+bool csum_and_copy_from_iter_full(void *addr, size_t bytes,
+				  __wsum *csum, struct iov_iter *i)
+{
+	size_t copied;
+
+	if (WARN_ON_ONCE(!i->data_source))
+		return false;
+	copied = iterate_and_advance2(i, bytes, addr, csum,
+				      copy_from_user_iter_csum,
+				      memcpy_from_iter_csum);
+	if (likely(copied == bytes))
+		return true;
+	iov_iter_revert(i, copied);
+	return false;
+}
+EXPORT_SYMBOL(csum_and_copy_from_iter_full);