[PATCH v6 00/34] iov_iter: Improve page extraction (ref, pin or just list)

[PATCH v6 00/34] iov_iter: Improve page extraction (ref, pin or just list)

[David Howells]

Hi Al, Christoph,

Here are patches clean up some use of READ/WRITE and ITER_SOURCE/DEST,
patches to provide support for extracting pages from an iov_iter and a
patch to use the primary extraction function in the block layer bio code.
I've also added a bunch of other conversions and had a tentative stab at
the networking code.

The patches make the following changes:

 (1) Deal with switching from using the iterator data_source to indicate
     the I/O direction to deriving this from other information, eg.:
     IOCB_WRITE, IOMAP_WRITE and the REQ_OP_* number.  This allows
     iov_iter_rw() to be removed eventually.

 (2) Define FOLL_SOURCE_BUF and FOLL_DEST_BUF and pass these into
     iov_iter_get_pages*() to indicate the I/O direction with regards to
     how the buffer described by the iterator is to be used.  This is
     included in the gup_flags passed in with Logan's patches.

     Calls to iov_iter_get_pages*2() are replaced with calls to
     iov_iter_get_pages*() and the former is removed.

 (3) Add a function, iov_iter_extract_pages() to replace
     iov_iter_get_pages*() that gets refs, pins or just lists the pages as
     appropriate to the iterator type and the I/O direction.

     Add a function, iov_iter_extract_mode() that will indicate from the
     iterator type and the I/O direction how the cleanup is to be
     performed, returning FOLL_GET, FOLL_PIN or 0.

     Add a function, folio_put_unpin(), and a wrapper, page_put_unpin(),
     that take a page and the return from iov_iter_extract_mode() and do
     the right thing to clean up the page.

 (4) Make the bio struct carry a pair of flags to indicate the cleanup
     mode.  BIO_NO_PAGE_REF is replaced with BIO_PAGE_REFFED (equivalent to
     FOLL_GET) and BIO_PAGE_PINNED (equivalent to BIO_PAGE_PINNED) is
     added.  These are forced to have the same value as the FOLL_* flags so
     they can be passed to the previously mentioned cleanup function.

 (5) Make the iter-to-bio code use iov_iter_extract_pages() to
     appropriately retain the pages and clean them up later.

 (6) Fix bio_flagged() so that it doesn't prevent a gcc optimisation.

 (7) Add a function in netfslib, netfs_extract_user_iter(), to extract a
     UBUF- or IOVEC-type iterator to a page list in a BVEC-type iterator,
     with all the pages suitably ref'd or pinned.

 (8) Add a function in netfslib, netfs_extract_iter_to_sg(), to extract a
     UBUF-, IOVEC-, BVEC-, XARRAY- or KVEC-type iterator to a scatterlist.
     The first two types appropriately ref or pin pages; the latter three
     don't perform any retention, leaving that to the caller.

     Note that I can make use of this in the SCSI and AF_ALG code and
     possibly the networking code, so this might merit being moved to core
     code.

 (9) Make AF_ALG use iov_iter_extract_pages() and possibly go further and
     make it use netfs_extract_iter_to_sg() instead.

(10) Make SCSI vhost use netfs_extract_iter_to_sg().

(11) Make fs/direct-io.c use iov_iter_extract_pages().

(13) Make splice-to-pipe use iov_iter_extract_pages(), but limit the usage
     to a cleanup mode of FOLL_GET.

(13) Make the 9P, FUSE and NFS filesystems use iov_iter_extract_pages().

(14) Make the CIFS filesystem use iterators from the top all the way down
     to the socket on the simple path.  Make it use
     netfs_extract_user_iter() to use an XARRAY-type iterator or to build a
     BVEC-type iterator in the top layers from a UBUF- or IOVEC-type
     iterator and attach the iterator to the operation descriptors.

     netfs_extract_iter_to_sg() is used to build scatterlists for doing
     transport crypto and a function, smb_extract_iter_to_rdma(), is
     provided to build an RDMA SGE list directly from an iterator without
     going via a page list and then a scatter list.

(15) A couple of work-in-progress patches to try and make sk_buff fragments
     record the information needed to clean them up in the lowest two bits
     of the page pointer in the fragment struct.

This leaves:

 (*) Four calls to iov_iter_get_pages() in CEPH.  That will be helped by
     patches to pass an iterator down to the transport layer instead of
     converting to a page list high up and passing that down, but the
     transport layer could do with some massaging so that it doesn't covert
     the iterator to a page list and then the pages individually back to
     iterators to pass to the socket.

 (*) One call to iov_iter_get_pages() each in the networking core, RDS and
     TLS, all related to zero-copy.  TLS seems to do zerocopy-read (or
     maybe decrypt-offload) and should be doing FOLL_PIN, not FOLL_GET for
     user-provided buffers.


Changes:
========
ver #6)
 - Fix write() syscall and co. not setting IOCB_WRITE.
 - Added iocb_is_read() and iocb_is_write() to check IOCB_WRITE.
 - Use op_is_write() in bio_copy_user_iov().
 - Drop the iterator direction checks from smbd_recv().
 - Define FOLL_SOURCE_BUF and FOLL_DEST_BUF and pass them in as part of
   gup_flags to iov_iter_get/extract_pages*().
 - Replace iov_iter_get_pages*2() with iov_iter_get_pages*() and remove.
 - Add back the function to indicate the cleanup mode.
 - Drop the cleanup_mode return arg to iov_iter_extract_pages().
 - Provide a helper to clean up a page.
 - Renumbered FOLL_GET and FOLL_PIN and made BIO_PAGE_REFFED/PINNED have
   the same numerical values, enforced with an assertion.
 - Converted AF_ALG, SCSI vhost, generic DIO, FUSE, splice to pipe, 9P and
   NFS.
 - Added in the patches to make CIFS do top-to-bottom iterators and use
   various of the added extraction functions.
 - Added a pair of work-in-progess patches to make sk_buff fragments store
   FOLL_GET and FOLL_PIN.

ver #5)
 - Replace BIO_NO_PAGE_REF with BIO_PAGE_REFFED and split into own patch.
 - Transcribe FOLL_GET/PIN into BIO_PAGE_REFFED/PINNED flags.
 - Add patch to allow bio_flagged() to be combined by gcc.

ver #4)
 - Drop the patch to move the FOLL_* flags to linux/mm_types.h as they're
   no longer referenced by linux/uio.h.
 - Add ITER_SOURCE/DEST cleanup patches.
 - Make iov_iter/netfslib iter extraction patches use ITER_SOURCE/DEST.
 - Allow additional gup_flags to be passed into iov_iter_extract_pages().
 - Add struct bio patch.

ver #3)
 - Switch to using EXPORT_SYMBOL_GPL to prevent indirect 3rd-party access
   to get/pin_user_pages_fast()[1].

ver #2)
 - Rolled the extraction cleanup mode query function into the extraction
   function, returning the indication through the argument list.
 - Fixed patch 4 (extract to scatterlist) to actually use the new
   extraction API.

I've pushed the patches (excluding the two WIP networking patches) here
also:

	https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/log/?h=iov-extract

David

Link: https://lore.kernel.org/r/Y3zFzdWnWlEJ8X8/@infradead.org/ [1]
Link: https://lore.kernel.org/r/166697254399.61150.1256557652599252121.stgit@warthog.procyon.org.uk/ # rfc
Link: https://lore.kernel.org/r/166722777223.2555743.162508599131141451.stgit@warthog.procyon.org.uk/ # rfc
Link: https://lore.kernel.org/r/166732024173.3186319.18204305072070871546.stgit@warthog.procyon.org.uk/ # rfc
Link: https://lore.kernel.org/r/166869687556.3723671.10061142538708346995.stgit@warthog.procyon.org.uk/ # rfc
Link: https://lore.kernel.org/r/166920902005.1461876.2786264600108839814.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/166997419665.9475.15014699817597102032.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/167305160937.1521586.133299343565358971.stgit@warthog.procyon.org.uk/ # v4
Link: https://lore.kernel.org/r/167344725490.2425628.13771289553670112965.stgit@warthog.procyon.org.uk/ # v5

Previous versions of the CIFS patch sets can be found here:
Link: https://lore.kernel.org/r/164311902471.2806745.10187041199819525677.stgit@warthog.procyon.org.uk/ # rfc
Link: https://lore.kernel.org/r/164928615045.457102.10607899252434268982.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/165211416682.3154751.17287804906832979514.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/165348876794.2106726.9240233279581920208.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/165364823513.3334034.11209090728654641458.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/166126392703.708021.14465850073772688008.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/166697254399.61150.1256557652599252121.stgit@warthog.procyon.org.uk/ # rfc
Link: https://lore.kernel.org/r/166732024173.3186319.18204305072070871546.stgit@warthog.procyon.org.uk/ # rfc


---
David Howells (34):
      vfs: Unconditionally set IOCB_WRITE in call_write_iter()
      iov_iter: Use IOCB/IOMAP_WRITE/op_is_write rather than iterator direction
      iov_iter: Pass I/O direction into iov_iter_get_pages*()
      iov_iter: Remove iov_iter_get_pages2/pages_alloc2()
      iov_iter: Change the direction macros into an enum
      iov_iter: Use the direction in the iterator functions
      iov_iter: Add a function to extract a page list from an iterator
      mm: Provide a helper to drop a pin/ref on a page
      bio: Rename BIO_NO_PAGE_REF to BIO_PAGE_REFFED and invert the meaning
      mm, block: Make BIO_PAGE_REFFED/PINNED the same as FOLL_GET/PIN numerically
      iov_iter, block: Make bio structs pin pages rather than ref'ing if appropriate
      bio: Fix bio_flagged() so that gcc can better optimise it
      netfs: Add a function to extract a UBUF or IOVEC into a BVEC iterator
      netfs: Add a function to extract an iterator into a scatterlist
      af_alg: Pin pages rather than ref'ing if appropriate
      af_alg: [RFC] Use netfs_extract_iter_to_sg() to create scatterlists
      scsi: [RFC] Use netfs_extract_iter_to_sg()
      dio: Pin pages rather than ref'ing if appropriate
      fuse:  Pin pages rather than ref'ing if appropriate
      vfs: Make splice use iov_iter_extract_pages()
      9p: Pin pages rather than ref'ing if appropriate
      nfs: Pin pages rather than ref'ing if appropriate
      cifs: Implement splice_read to pass down ITER_BVEC not ITER_PIPE
      cifs: Add a function to build an RDMA SGE list from an iterator
      cifs: Add a function to Hash the contents of an iterator
      cifs: Add some helper functions
      cifs: Add a function to read into an iter from a socket
      cifs: Change the I/O paths to use an iterator rather than a page list
      cifs: Build the RDMA SGE list directly from an iterator
      cifs: Remove unused code
      cifs: Fix problem with encrypted RDMA data read
      cifs: DIO to/from KVEC-type iterators should now work
      net: [RFC][WIP] Mark each skb_frags as to how they should be cleaned up
      net: [RFC][WIP] Make __zerocopy_sg_from_iter() correctly pin or leave pages unref'd


 block/bio.c               |   48 +-
 block/blk-map.c           |   26 +-
 block/blk.h               |   25 +
 block/fops.c              |    8 +-
 crypto/af_alg.c           |   57 +-
 crypto/algif_hash.c       |   20 +-
 drivers/net/tun.c         |    2 +-
 drivers/vhost/scsi.c      |   75 +-
 fs/9p/vfs_addr.c          |    2 +-
 fs/affs/file.c            |    4 +-
 fs/ceph/addr.c            |    2 +-
 fs/ceph/file.c            |   16 +-
 fs/cifs/Kconfig           |    1 +
 fs/cifs/cifsencrypt.c     |  172 +++-
 fs/cifs/cifsfs.c          |   12 +-
 fs/cifs/cifsfs.h          |    6 +
 fs/cifs/cifsglob.h        |   66 +-
 fs/cifs/cifsproto.h       |   11 +-
 fs/cifs/cifssmb.c         |   13 +-
 fs/cifs/connect.c         |   16 +
 fs/cifs/file.c            | 1851 +++++++++++++++++--------------------
 fs/cifs/fscache.c         |   22 +-
 fs/cifs/fscache.h         |   10 +-
 fs/cifs/misc.c            |  132 +--
 fs/cifs/smb2ops.c         |  374 ++++----
 fs/cifs/smb2pdu.c         |   45 +-
 fs/cifs/smbdirect.c       |  511 ++++++----
 fs/cifs/smbdirect.h       |    4 +-
 fs/cifs/transport.c       |   57 +-
 fs/dax.c                  |    6 +-
 fs/direct-io.c            |   77 +-
 fs/exfat/inode.c          |    6 +-
 fs/ext2/inode.c           |    2 +-
 fs/f2fs/file.c            |   10 +-
 fs/fat/inode.c            |    4 +-
 fs/fuse/dax.c             |    2 +-
 fs/fuse/dev.c             |   24 +-
 fs/fuse/file.c            |   34 +-
 fs/fuse/fuse_i.h          |    1 +
 fs/hfs/inode.c            |    2 +-
 fs/hfsplus/inode.c        |    2 +-
 fs/iomap/direct-io.c      |    6 +-
 fs/jfs/inode.c            |    2 +-
 fs/netfs/Makefile         |    1 +
 fs/netfs/iterator.c       |  371 ++++++++
 fs/nfs/direct.c           |   32 +-
 fs/nilfs2/inode.c         |    2 +-
 fs/ntfs3/inode.c          |    2 +-
 fs/ocfs2/aops.c           |    2 +-
 fs/orangefs/inode.c       |    2 +-
 fs/reiserfs/inode.c       |    2 +-
 fs/splice.c               |   10 +-
 fs/udf/inode.c            |    2 +-
 include/crypto/if_alg.h   |    7 +-
 include/linux/bio.h       |   23 +-
 include/linux/blk_types.h |    3 +-
 include/linux/fs.h        |   11 +
 include/linux/mm.h        |   32 +-
 include/linux/netfs.h     |    6 +
 include/linux/skbuff.h    |  124 ++-
 include/linux/uio.h       |   83 +-
 io_uring/net.c            |    2 +-
 lib/iov_iter.c            |  428 ++++++++-
 mm/gup.c                  |   47 +
 mm/vmalloc.c              |    1 +
 net/9p/trans_common.c     |    6 +-
 net/9p/trans_common.h     |    3 +-
 net/9p/trans_virtio.c     |   91 +-
 net/bpf/test_run.c        |    2 +-
 net/core/datagram.c       |   23 +-
 net/core/gro.c            |    2 +-
 net/core/skbuff.c         |   16 +-
 net/core/skmsg.c          |    4 +-
 net/ipv4/ip_output.c      |    2 +-
 net/ipv4/tcp.c            |    4 +-
 net/ipv6/esp6.c           |    5 +-
 net/ipv6/ip6_output.c     |    2 +-
 net/packet/af_packet.c    |    2 +-
 net/rds/message.c         |    4 +-
 net/tls/tls_sw.c          |    5 +-
 net/xfrm/xfrm_ipcomp.c    |    2 +-
 81 files changed, 3006 insertions(+), 2126 deletions(-)
 create mode 100644 fs/netfs/iterator.c

[PATCH v6 15/34] af_alg: Pin pages rather than ref'ing if appropriate

[David Howells]

Convert AF_ALG to use iov_iter_extract_pages() instead of
iov_iter_get_pages().  This will pin pages or leave them unaltered rather
than getting a ref on them as appropriate to the iterator.

The pages need to be pinned for DIO-read rather than having refs taken on
them to prevent VM copy-on-write from malfunctioning during a concurrent
fork() (the result of the I/O would otherwise end up only visible to the
child process and not the parent).

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Herbert Xu <herbert@gondor.apana.org.au>
cc: linux-crypto@vger.kernel.org
---

 crypto/af_alg.c         |    9 ++++++---
 include/crypto/if_alg.h |    1 +
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/crypto/af_alg.c b/crypto/af_alg.c
index 7a68db157fae..c99e09fce71f 100644
--- a/crypto/af_alg.c
+++ b/crypto/af_alg.c
@@ -534,15 +534,18 @@ static const struct net_proto_family alg_family = {
 int af_alg_make_sg(struct af_alg_sgl *sgl, struct iov_iter *iter, int len,
 		   unsigned int gup_flags)
 {
+	struct page **pages = sgl->pages;
 	size_t off;
 	ssize_t n;
 	int npages, i;
 
-	n = iov_iter_get_pages(iter, sgl->pages, len, ALG_MAX_PAGES, &off,
-			       gup_flags);
+	n = iov_iter_extract_pages(iter, &pages, len, ALG_MAX_PAGES,
+				   gup_flags, &off);
 	if (n < 0)
 		return n;
 
+	sgl->cleanup_mode = iov_iter_extract_mode(iter, gup_flags);
+
 	npages = DIV_ROUND_UP(off + n, PAGE_SIZE);
 	if (WARN_ON(npages == 0))
 		return -EINVAL;
@@ -576,7 +579,7 @@ void af_alg_free_sg(struct af_alg_sgl *sgl)
 	int i;
 
 	for (i = 0; i < sgl->npages; i++)
-		put_page(sgl->pages[i]);
+		page_put_unpin(sgl->pages[i], sgl->cleanup_mode);
 }
 EXPORT_SYMBOL_GPL(af_alg_free_sg);
 
diff --git a/include/crypto/if_alg.h b/include/crypto/if_alg.h
index 12058ab6cad9..95b3b7517d3f 100644
--- a/include/crypto/if_alg.h
+++ b/include/crypto/if_alg.h
@@ -61,6 +61,7 @@ struct af_alg_sgl {
 	struct scatterlist sg[ALG_MAX_PAGES + 1];
 	struct page *pages[ALG_MAX_PAGES];
 	unsigned int npages;
+	unsigned int cleanup_mode;
 };
 
 /* TX SGL entry */

[PATCH v6 16/34] af_alg: [RFC] Use netfs_extract_iter_to_sg() to create scatterlists

[David Howells]

Use netfs_extract_iter_to_sg() to decant the destination iterator into a
scatterlist in af_alg_get_rsgl().  af_alg_make_sg() can then be removed.

Note that if this fits, netfs_extract_iter_to_sg() should move to core
code.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Herbert Xu <herbert@gondor.apana.org.au>
cc: linux-crypto@vger.kernel.org
---

 crypto/af_alg.c         |   63 +++++++++++++----------------------------------
 crypto/algif_hash.c     |   21 +++++++++++-----
 include/crypto/if_alg.h |    7 +----
 3 files changed, 35 insertions(+), 56 deletions(-)

diff --git a/crypto/af_alg.c b/crypto/af_alg.c
index c99e09fce71f..c5fbe39366ff 100644
--- a/crypto/af_alg.c
+++ b/crypto/af_alg.c
@@ -22,6 +22,7 @@
 #include <linux/sched/signal.h>
 #include <linux/security.h>
 #include <linux/string.h>
+#include <linux/netfs.h>
 #include <keys/user-type.h>
 #include <keys/trusted-type.h>
 #include <keys/encrypted-type.h>
@@ -531,55 +532,22 @@ static const struct net_proto_family alg_family = {
 	.owner	=	THIS_MODULE,
 };
 
-int af_alg_make_sg(struct af_alg_sgl *sgl, struct iov_iter *iter, int len,
-		   unsigned int gup_flags)
-{
-	struct page **pages = sgl->pages;
-	size_t off;
-	ssize_t n;
-	int npages, i;
-
-	n = iov_iter_extract_pages(iter, &pages, len, ALG_MAX_PAGES,
-				   gup_flags, &off);
-	if (n < 0)
-		return n;
-
-	sgl->cleanup_mode = iov_iter_extract_mode(iter, gup_flags);
-
-	npages = DIV_ROUND_UP(off + n, PAGE_SIZE);
-	if (WARN_ON(npages == 0))
-		return -EINVAL;
-	/* Add one extra for linking */
-	sg_init_table(sgl->sg, npages + 1);
-
-	for (i = 0, len = n; i < npages; i++) {
-		int plen = min_t(int, len, PAGE_SIZE - off);
-
-		sg_set_page(sgl->sg + i, sgl->pages[i], plen, off);
-
-		off = 0;
-		len -= plen;
-	}
-	sg_mark_end(sgl->sg + npages - 1);
-	sgl->npages = npages;
-
-	return n;
-}
-EXPORT_SYMBOL_GPL(af_alg_make_sg);
-
 static void af_alg_link_sg(struct af_alg_sgl *sgl_prev,
 			   struct af_alg_sgl *sgl_new)
 {
-	sg_unmark_end(sgl_prev->sg + sgl_prev->npages - 1);
-	sg_chain(sgl_prev->sg, sgl_prev->npages + 1, sgl_new->sg);
+	sg_unmark_end(sgl_prev->sgt.sgl + sgl_prev->sgt.nents - 1);
+	sg_chain(sgl_prev->sgt.sgl, sgl_prev->sgt.nents + 1, sgl_new->sgt.sgl);
 }
 
 void af_alg_free_sg(struct af_alg_sgl *sgl)
 {
 	int i;
 
-	for (i = 0; i < sgl->npages; i++)
-		page_put_unpin(sgl->pages[i], sgl->cleanup_mode);
+	if (!(sgl->cleanup_mode & (FOLL_PIN | FOLL_GET)))
+		return;
+
+	for (i = 0; i < sgl->sgt.nents; i++)
+		page_put_unpin(sg_page(&sgl->sgt.sgl[i]), sgl->cleanup_mode);
 }
 EXPORT_SYMBOL_GPL(af_alg_free_sg);
 
@@ -1293,8 +1261,8 @@ int af_alg_get_rsgl(struct sock *sk, struct msghdr *msg, int flags,
 
 	while (maxsize > len && msg_data_left(msg)) {
 		struct af_alg_rsgl *rsgl;
+		ssize_t err;
 		size_t seglen;
-		int err;
 
 		/* limit the amount of readable buffers */
 		if (!af_alg_readable(sk))
@@ -1311,17 +1279,22 @@ int af_alg_get_rsgl(struct sock *sk, struct msghdr *msg, int flags,
 				return -ENOMEM;
 		}
 
-		rsgl->sgl.npages = 0;
+		rsgl->sgl.sgt.sgl = rsgl->sgl.sgl;
+		rsgl->sgl.sgt.nents = 0;
+		rsgl->sgl.sgt.orig_nents = 0;
 		list_add_tail(&rsgl->list, &areq->rsgl_list);
 
-		/* make one iovec available as scatterlist */
-		err = af_alg_make_sg(&rsgl->sgl, &msg->msg_iter, seglen,
-				     FOLL_DEST_BUF);
+		err = netfs_extract_iter_to_sg(&msg->msg_iter, seglen,
+					       &rsgl->sgl.sgt, ALG_MAX_PAGES,
+					       FOLL_DEST_BUF);
 		if (err < 0) {
 			rsgl->sg_num_bytes = 0;
 			return err;
 		}
 
+		rsgl->sgl.cleanup_mode = iov_iter_extract_mode(&msg->msg_iter,
+							       FOLL_DEST_BUF);
+
 		/* chain the new scatterlist with previous one */
 		if (areq->last_rsgl)
 			af_alg_link_sg(&areq->last_rsgl->sgl, &rsgl->sgl);
diff --git a/crypto/algif_hash.c b/crypto/algif_hash.c
index fe3d2258145f..5aef6818a9ff 100644
--- a/crypto/algif_hash.c
+++ b/crypto/algif_hash.c
@@ -14,6 +14,7 @@
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/net.h>
+#include <linux/netfs.h>
 #include <net/sock.h>
 
 struct hash_ctx {
@@ -91,14 +92,22 @@ static int hash_sendmsg(struct socket *sock, struct msghdr *msg,
 		if (len > limit)
 			len = limit;
 
-		len = af_alg_make_sg(&ctx->sgl, &msg->msg_iter, len,
-				     FOLL_SOURCE_BUF);
+		ctx->sgl.sgt.sgl = ctx->sgl.sgl;
+		ctx->sgl.sgt.nents = 0;
+		ctx->sgl.sgt.orig_nents = 0;
+
+		len = netfs_extract_iter_to_sg(&msg->msg_iter, len,
+					       &ctx->sgl.sgt, ALG_MAX_PAGES,
+					       FOLL_SOURCE_BUF);
 		if (len < 0) {
 			err = copied ? 0 : len;
 			goto unlock;
 		}
 
-		ahash_request_set_crypt(&ctx->req, ctx->sgl.sg, NULL, len);
+		ctx->sgl.cleanup_mode = iov_iter_extract_mode(&msg->msg_iter,
+							      FOLL_SOURCE_BUF);
+
+		ahash_request_set_crypt(&ctx->req, ctx->sgl.sgt.sgl, NULL, len);
 
 		err = crypto_wait_req(crypto_ahash_update(&ctx->req),
 				      &ctx->wait);
@@ -142,8 +151,8 @@ static ssize_t hash_sendpage(struct socket *sock, struct page *page,
 		flags |= MSG_MORE;
 
 	lock_sock(sk);
-	sg_init_table(ctx->sgl.sg, 1);
-	sg_set_page(ctx->sgl.sg, page, size, offset);
+	sg_init_table(ctx->sgl.sgl, 1);
+	sg_set_page(ctx->sgl.sgl, page, size, offset);
 
 	if (!(flags & MSG_MORE)) {
 		err = hash_alloc_result(sk, ctx);
@@ -152,7 +161,7 @@ static ssize_t hash_sendpage(struct socket *sock, struct page *page,
 	} else if (!ctx->more)
 		hash_free_result(sk, ctx);
 
-	ahash_request_set_crypt(&ctx->req, ctx->sgl.sg, ctx->result, size);
+	ahash_request_set_crypt(&ctx->req, ctx->sgl.sgl, ctx->result, size);
 
 	if (!(flags & MSG_MORE)) {
 		if (ctx->more)
diff --git a/include/crypto/if_alg.h b/include/crypto/if_alg.h
index 95b3b7517d3f..424a2071705d 100644
--- a/include/crypto/if_alg.h
+++ b/include/crypto/if_alg.h
@@ -58,9 +58,8 @@ struct af_alg_type {
 };
 
 struct af_alg_sgl {
-	struct scatterlist sg[ALG_MAX_PAGES + 1];
-	struct page *pages[ALG_MAX_PAGES];
-	unsigned int npages;
+	struct sg_table sgt;
+	struct scatterlist sgl[ALG_MAX_PAGES + 1];
 	unsigned int cleanup_mode;
 };
 
@@ -166,8 +165,6 @@ int af_alg_release(struct socket *sock);
 void af_alg_release_parent(struct sock *sk);
 int af_alg_accept(struct sock *sk, struct socket *newsock, bool kern);
 
-int af_alg_make_sg(struct af_alg_sgl *sgl, struct iov_iter *iter, int len,
-		   unsigned int gup_flags);
 void af_alg_free_sg(struct af_alg_sgl *sgl);
 
 static inline struct alg_sock *alg_sk(struct sock *sk)

[PATCH v6 25/34] cifs: Add a function to Hash the contents of an iterator

[David Howells]

Add a function to push the contents of a BVEC-, KVEC- or XARRAY-type
iterator into a symmetric hash algorithm.

UBUF- and IOBUF-type iterators are not supported on the assumption that
either we're doing buffered I/O, in which case we won't see them, or we're
doing direct I/O, in which case the iterator will have been extracted into
a BVEC-type iterator higher up.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Steve French <sfrench@samba.org>
cc: Shyam Prasad N <nspmangalore@gmail.com>
cc: Rohith Surabattula <rohiths.msft@gmail.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: linux-cifs@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
cc: linux-crypto@vger.kernel.org

Link: https://lore.kernel.org/r/166697257423.61150.12070648579830206483.stgit@warthog.procyon.org.uk/ # rfc
Link: https://lore.kernel.org/r/166732029577.3186319.17162612653237909961.stgit@warthog.procyon.org.uk/ # rfc
---

 fs/cifs/cifsencrypt.c |  144 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 144 insertions(+)

diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c
index 5db73c0f792a..e13f26371540 100644
--- a/fs/cifs/cifsencrypt.c
+++ b/fs/cifs/cifsencrypt.c
@@ -24,6 +24,150 @@
 #include "../smbfs_common/arc4.h"
 #include <crypto/aead.h>
 
+/*
+ * Hash data from a BVEC-type iterator.
+ */
+static int cifs_shash_bvec(const struct iov_iter *iter, ssize_t maxsize,
+			   struct shash_desc *shash)
+{
+	const struct bio_vec *bv = iter->bvec;
+	unsigned long start = iter->iov_offset;
+	unsigned int i;
+	void *p;
+	int ret;
+
+	for (i = 0; i < iter->nr_segs; i++) {
+		size_t off, len;
+
+		len = bv[i].bv_len;
+		if (start >= len) {
+			start -= len;
+			continue;
+		}
+
+		len = min_t(size_t, maxsize, len - start);
+		off = bv[i].bv_offset + start;
+
+		p = kmap_local_page(bv[i].bv_page);
+		ret = crypto_shash_update(shash, p + off, len);
+		kunmap_local(p);
+		if (ret < 0)
+			return ret;
+
+		maxsize -= len;
+		if (maxsize <= 0)
+			break;
+		start = 0;
+	}
+
+	return 0;
+}
+
+/*
+ * Hash data from a KVEC-type iterator.
+ */
+static int cifs_shash_kvec(const struct iov_iter *iter, ssize_t maxsize,
+			   struct shash_desc *shash)
+{
+	const struct kvec *kv = iter->kvec;
+	unsigned long start = iter->iov_offset;
+	unsigned int i;
+	int ret;
+
+	for (i = 0; i < iter->nr_segs; i++) {
+		size_t len;
+
+		len = kv[i].iov_len;
+		if (start >= len) {
+			start -= len;
+			continue;
+		}
+
+		len = min_t(size_t, maxsize, len - start);
+		ret = crypto_shash_update(shash, kv[i].iov_base + start, len);
+		if (ret < 0)
+			return ret;
+		maxsize -= len;
+
+		if (maxsize <= 0)
+			break;
+		start = 0;
+	}
+
+	return 0;
+}
+
+/*
+ * Hash data from an XARRAY-type iterator.
+ */
+static ssize_t cifs_shash_xarray(const struct iov_iter *iter, ssize_t maxsize,
+				 struct shash_desc *shash)
+{
+	struct folio *folios[16], *folio;
+	unsigned int nr, i, j, npages;
+	loff_t start = iter->xarray_start + iter->iov_offset;
+	pgoff_t last, index = start / PAGE_SIZE;
+	ssize_t ret = 0;
+	size_t len, offset, foffset;
+	void *p;
+
+	if (maxsize == 0)
+		return 0;
+
+	last = (start + maxsize - 1) / PAGE_SIZE;
+	do {
+		nr = xa_extract(iter->xarray, (void **)folios, index, last,
+				ARRAY_SIZE(folios), XA_PRESENT);
+		if (nr == 0)
+			return -EIO;
+
+		for (i = 0; i < nr; i++) {
+			folio = folios[i];
+			npages = folio_nr_pages(folio);
+			foffset = start - folio_pos(folio);
+			offset = foffset % PAGE_SIZE;
+			for (j = foffset / PAGE_SIZE; j < npages; j++) {
+				len = min_t(size_t, maxsize, PAGE_SIZE - offset);
+				p = kmap_local_page(folio_page(folio, j));
+				ret = crypto_shash_update(shash, p, len);
+				kunmap_local(p);
+				if (ret < 0)
+					return ret;
+				maxsize -= len;
+				if (maxsize <= 0)
+					return 0;
+				start += len;
+				offset = 0;
+				index++;
+			}
+		}
+	} while (nr == ARRAY_SIZE(folios));
+	return 0;
+}
+
+/*
+ * Pass the data from an iterator into a hash.
+ */
+static int cifs_shash_iter(const struct iov_iter *iter, size_t maxsize,
+			   struct shash_desc *shash)
+{
+	if (maxsize == 0)
+		return 0;
+
+	switch (iov_iter_type(iter)) {
+	case ITER_BVEC:
+		return cifs_shash_bvec(iter, maxsize, shash);
+	case ITER_KVEC:
+		return cifs_shash_kvec(iter, maxsize, shash);
+	case ITER_XARRAY:
+		return cifs_shash_xarray(iter, maxsize, shash);
+	default:
+		pr_err("cifs_shash_iter(%u) unsupported\n", iov_iter_type(iter));
+		WARN_ON_ONCE(1);
+		return -EIO;
+	}
+}
+
 int __cifs_calc_signature(struct smb_rqst *rqst,
 			struct TCP_Server_Info *server, char *signature,
 			struct shash_desc *shash)

Re: [PATCH v6 00/34] iov_iter: Improve page extraction (ref, pin or just list)

[Christoph Hellwig]

First off the liver comment:  can we cut down things for a first
round?  Maybe just convert everything using the bio based helpers
and then chunk it up?  Reviewing 34 patches across a dozen subsystems
isn't going to be easy and it will be hard to come up with a final
positive conclusion.