[RFC 00/13] smb3: Use iov_iters down to the network transport and fix DIO page pinning

[RFC 00/13] smb3: Use iov_iters down to the network transport and fix DIO page pinning

[David Howells]

Hi Steve,

Here's an updated version of my patchset to make the cifs/smb3 driver pass
iov_iters down to the lowest layers where they can be passed directly to
the network transport rather than passing lists of pages around.

The series also deals with some other issues:

 (*) By pinning pages, it fixes the race between concurrent DIO read and
     fork, whereby the pages containing the DIO read buffer may end up
     belonging to the child process and not the parent - with the result
     that the parent might not see the retrieved data.

 (*) cifs shouldn't take refs on pages extracted from non-user-backed
     iterators (eg. KVEC).  With these changes, cifs will apply the
     appropriate cleanup.  Note that there is the possibility the network
     transport might, but that's beyond the scope of this patchset.

 (*) Making it easier to transition to using folios in cifs rather than
     pages by dealing with them through BVEC and XARRAY iterators.


The first couple of patches to provide function to pin or leave unpinned
the pages from an iterator (and not take a ref on them).

 (1) Define qualifying flags for extraction functions.

 (2) Define iov_iter_extract_pages() to do the extraction and
     iov_iter_extract_will_pin() to indicate how it should be cleaned up.

Then there are a couple of patches that add stuff to netfslib that I want
to use there as well as in cifs:

 (3) Add a netfslib function to extract and pin pages from an ITER_IOBUF or
     ITER_UBUF iterator into an ITER_BVEC iterator.

 (4) Add a netfslib function to extract pages from an iterator that's of
     type ITER_UBUF/IOVEC/BVEC/KVEC/XARRAY and add them to a scatterlist.
     The cleanup will need to be done as for iov_iter_extract_pages().

     BVEC, KVEC and XARRAY iterators can be rendered into elements that
     span multiple pages.

Then a fix:

 (5) Fix oops due to uncleared server->smbd_conn in reconnect

Then there are some cifs helpers that work with iterators:

 (6) Implement cifs_splice_read() to use an ITER_BVEC rather than an
     ITER_PIPE, bulk-allocating the pages, attaching them to the bvec,
     doing the I/O and then pushing the pages into the pipe.  This avoids
     the problem with cifs wanting to split the pipe iterator in a later
     patch.

 (7) Add a function to walk through an ITER_BVEC/KVEC/XARRAY iterator and
     add elements to an RDMA SGE list.  Only the DMA addresses are stored,
     and an element may span multiple pages (say if an xarray contains a
     multipage folio).

 (8) Add a function to walk through an ITER_BVEC/KVEC/XARRAY iterator and
     pass the contents into a shash function.

 (9) Add functions to walk through an ITER_XARRAY iterator and perform
     various sorts of cleanup on the folios held therein, to be used on I/O
     completion.

(10) Add a function to read from the transport TCP socket directly into an
     iterator.

Then come the patches that actually do the work of iteratorising cifs:

(11) The main patch.  Replace page lists with iterators.  It extracts the
     pages from ITER_UBUF and ITER_IOVEC iterators to an ITER_BVEC
     iterator, pinning or getting refs on them, before passing them down as
     the I/O may be done from a worker thread.

     The iterator is extracted into a scatterlist in order to talk to the
     crypto interface or to do RDMA.

(12) In the cifs RDMA code, extract the iterator into an RDMA SGE[] list,
     removing the scatterlist intermediate - at least for smbd_send().
     There appear to be other ways for cifs to talk to the RDMA layer that
     don't go through that that I haven't managed to work out.

(13) Remove a chunk of now-unused code.

(14) Fix a problem with encrypted RDMA data read.

(15) Allow DIO to/from KVEC-type iterators.

Note also that I haven't managed to test all the combinations of transport.
Samba doesn't support RDMA and ksmbd doesn't support encryption.  I can
test them separately, but not together.  That said, rdma, sign, seal and
sign+seal seem to work.

I've pushed the patches here also:

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

David

Link: https://lore.kernel.org/r/166697254399.61150.1256557652599252121.stgit@warthog.procyon.org.uk/

David Howells (13):
  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
  cifs: Fix oops due to uncleared server->smbd_conn in reconnect
  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

 fs/cifs/Kconfig       |    1 +
 fs/cifs/cifsencrypt.c |  172 +++-
 fs/cifs/cifsfs.c      |   12 +-
 fs/cifs/cifsfs.h      |    6 +
 fs/cifs/cifsglob.h    |   65 +-
 fs/cifs/cifsproto.h   |   11 +-
 fs/cifs/cifssmb.c     |   13 +-
 fs/cifs/connect.c     |   16 +
 fs/cifs/file.c        | 1847 +++++++++++++++++++----------------------
 fs/cifs/fscache.c     |   22 +-
 fs/cifs/fscache.h     |   10 +-
 fs/cifs/misc.c        |  128 +--
 fs/cifs/smb2ops.c     |  371 ++++-----
 fs/cifs/smb2pdu.c     |   50 +-
 fs/cifs/smbdirect.c   |  536 +++++++-----
 fs/cifs/smbdirect.h   |    7 +-
 fs/cifs/transport.c   |   57 +-
 fs/netfs/Makefile     |    1 +
 fs/netfs/iterator.c   |  371 +++++++++
 fs/splice.c           |    1 +
 include/linux/netfs.h |    6 +
 mm/vmalloc.c          |    1 +
 22 files changed, 2014 insertions(+), 1690 deletions(-)
 create mode 100644 fs/netfs/iterator.c

[RFC 01/13] netfs: Add a function to extract a UBUF or IOVEC into a BVEC iterator

[David Howells]

Add a function to extract the pages from a user-space supplied iterator
(UBUF- or IOVEC-type) into a BVEC-type iterator, retaining the pages by
getting a pin on them (as FOLL_PIN) as we go.

This is useful in three situations:

 (1) A userspace thread may have a sibling that unmaps or remaps the
     process's VM during the operation, changing the assignment of the
     pages and potentially causing an error.  Retaining the pages keeps
     some pages around, even if this occurs; futher, we find out at the
     point of extraction if EFAULT is going to be incurred.

 (2) Pages might get swapped out/discarded if not retained, so we want to
     retain them to avoid the reload causing a deadlock due to a DIO
     from/to an mmapped region on the same file.

 (3) The iterator may get passed to sendmsg() by the filesystem.  If a
     fault occurs, we may get a short write to a TCP stream that's then
     tricky to recover from.

We don't deal with other types of iterator here, leaving it to other
mechanisms to retain the pages (eg. PG_locked, PG_writeback and the pipe
lock).

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: Steve French <sfrench@samba.org>
cc: Shyam Prasad N <nspmangalore@gmail.com>
cc: Rohith Surabattula <rohiths.msft@gmail.com>
cc: linux-cachefs@redhat.com
cc: linux-cifs@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
---
 fs/netfs/Makefile     |   1 +
 fs/netfs/iterator.c   | 102 ++++++++++++++++++++++++++++++++++++++++++
 include/linux/netfs.h |   2 +
 3 files changed, 105 insertions(+)
 create mode 100644 fs/netfs/iterator.c

diff --git a/fs/netfs/Makefile b/fs/netfs/Makefile
index f684c0cd1ec5..386d6fb92793 100644
--- a/fs/netfs/Makefile
+++ b/fs/netfs/Makefile
@@ -3,6 +3,7 @@
 netfs-y := \
 	buffered_read.o \
 	io.o \
+	iterator.o \
 	main.o \
 	objects.o
 
diff --git a/fs/netfs/iterator.c b/fs/netfs/iterator.c
new file mode 100644
index 000000000000..7b7cdc2863fc
--- /dev/null
+++ b/fs/netfs/iterator.c
@@ -0,0 +1,102 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Iterator helpers.
+ *
+ * Copyright (C) 2022 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#include <linux/export.h>
+#include <linux/slab.h>
+#include <linux/uio.h>
+#include <linux/netfs.h>
+#include "internal.h"
+
+/**
+ * netfs_extract_user_iter - Extract the pages from a user iterator into a bvec
+ * @orig: The original iterator
+ * @orig_len: The amount of iterator to copy
+ * @new: The iterator to be set up
+ * @extract_flags: Flags to qualify the request
+ *
+ * Extract the page fragments from the given amount of the source iterator and
+ * build up a second iterator that refers to all of those bits.  This allows
+ * the original iterator to disposed of.
+ *
+ * @extract_flags can have ITER_ALLOW_P2PDMA set to request peer-to-peer DMA be
+ * allowed on the pages extracted.
+ *
+ * On success, the number of elements in the bvec is returned, the original
+ * iterator will have been advanced by the amount extracted.
+ *
+ * The iov_iter_extract_mode() function should be used to query how cleanup
+ * should be performed.
+ */
+ssize_t netfs_extract_user_iter(struct iov_iter *orig, size_t orig_len,
+				struct iov_iter *new, unsigned int extract_flags)
+{
+	struct bio_vec *bv = NULL;
+	struct page **pages;
+	unsigned int cur_npages;
+	unsigned int max_pages;
+	unsigned int npages = 0;
+	unsigned int i;
+	ssize_t ret;
+	size_t count = orig_len, offset, len;
+	size_t bv_size, pg_size;
+
+	if (WARN_ON_ONCE(!iter_is_ubuf(orig) && !iter_is_iovec(orig)))
+		return -EIO;
+
+	max_pages = iov_iter_npages(orig, INT_MAX);
+	bv_size = array_size(max_pages, sizeof(*bv));
+	bv = kvmalloc(bv_size, GFP_KERNEL);
+	if (!bv)
+		return -ENOMEM;
+
+	/* Put the page list at the end of the bvec list storage.  bvec
+	 * elements are larger than page pointers, so as long as we work
+	 * 0->last, we should be fine.
+	 */
+	pg_size = array_size(max_pages, sizeof(*pages));
+	pages = (void *)bv + bv_size - pg_size;
+
+	while (count && npages < max_pages) {
+		ret = iov_iter_extract_pages(orig, &pages, count,
+					     max_pages - npages, extract_flags,
+					     &offset);
+		if (ret < 0) {
+			pr_err("Couldn't get user pages (rc=%zd)\n", ret);
+			break;
+		}
+
+		if (ret > count) {
+			pr_err("get_pages rc=%zd more than %zu\n", ret, count);
+			break;
+		}
+
+		count -= ret;
+		ret += offset;
+		cur_npages = DIV_ROUND_UP(ret, PAGE_SIZE);
+
+		if (npages + cur_npages > max_pages) {
+			pr_err("Out of bvec array capacity (%u vs %u)\n",
+			       npages + cur_npages, max_pages);
+			break;
+		}
+
+		for (i = 0; i < cur_npages; i++) {
+			len = ret > PAGE_SIZE ? PAGE_SIZE : ret;
+			bv[npages + i].bv_page	 = *pages++;
+			bv[npages + i].bv_offset = offset;
+			bv[npages + i].bv_len	 = len - offset;
+			ret -= len;
+			offset = 0;
+		}
+
+		npages += cur_npages;
+	}
+
+	iov_iter_bvec(new, orig->data_source, bv, npages, orig_len - count);
+	return npages;
+}
+EXPORT_SYMBOL_GPL(netfs_extract_user_iter);
diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index 4c76ddfb6a67..e8c560131170 100644
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h
@@ -296,6 +296,8 @@ void netfs_get_subrequest(struct netfs_io_subrequest *subreq,
 void netfs_put_subrequest(struct netfs_io_subrequest *subreq,
 			  bool was_async, enum netfs_sreq_ref_trace what);
 void netfs_stats_show(struct seq_file *);
+ssize_t netfs_extract_user_iter(struct iov_iter *orig, size_t orig_len,
+				struct iov_iter *new, unsigned int extract_flags);
 
 /**
  * netfs_inode - Get the netfs inode context from the inode

[RFC 02/13] netfs: Add a function to extract an iterator into a scatterlist

[David Howells]

Provide a function for filling in a scatterlist from the list of pages
contained in an iterator.

If the iterator is UBUF- or IOBUF-type, the pages have a pin taken on them
(as FOLL_PIN).

If the iterator is BVEC-, KVEC- or XARRAY-type, no pin is taken on the
pages and it is left to the caller to manage their lifetime.  It cannot be
assumed that a ref can be validly taken, particularly in the case of a KVEC
iterator.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: Steve French <sfrench@samba.org>
cc: Shyam Prasad N <nspmangalore@gmail.com>
cc: Rohith Surabattula <rohiths.msft@gmail.com>
cc: linux-cachefs@redhat.com
cc: linux-cifs@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
---
 fs/netfs/iterator.c   | 269 ++++++++++++++++++++++++++++++++++++++++++
 include/linux/netfs.h |   4 +
 mm/vmalloc.c          |   1 +
 3 files changed, 274 insertions(+)

diff --git a/fs/netfs/iterator.c b/fs/netfs/iterator.c
index 7b7cdc2863fc..9d198d0a5503 100644
--- a/fs/netfs/iterator.c
+++ b/fs/netfs/iterator.c
@@ -7,7 +7,9 @@
 
 #include <linux/export.h>
 #include <linux/slab.h>
+#include <linux/mm.h>
 #include <linux/uio.h>
+#include <linux/scatterlist.h>
 #include <linux/netfs.h>
 #include "internal.h"
 
@@ -100,3 +102,270 @@ ssize_t netfs_extract_user_iter(struct iov_iter *orig, size_t orig_len,
 	return npages;
 }
 EXPORT_SYMBOL_GPL(netfs_extract_user_iter);
+
+/*
+ * Extract and pin a list of up to sg_max pages from UBUF- or IOVEC-class
+ * iterators, and add them to the scatterlist.
+ */
+static ssize_t netfs_extract_user_to_sg(struct iov_iter *iter,
+					ssize_t maxsize,
+					struct sg_table *sgtable,
+					unsigned int sg_max,
+					unsigned int extract_flags)
+{
+	struct scatterlist *sg = sgtable->sgl + sgtable->nents;
+	struct page **pages;
+	unsigned int npages;
+	ssize_t ret = 0, res;
+	size_t len, off;
+
+	/* We decant the page list into the tail of the scatterlist */
+	pages = (void *)sgtable->sgl + array_size(sg_max, sizeof(struct scatterlist));
+	pages -= sg_max;
+
+	do {
+		res = iov_iter_extract_pages(iter, &pages, maxsize, sg_max,
+					     extract_flags, &off);
+		if (res < 0)
+			goto failed;
+
+		len = res;
+		maxsize -= len;
+		ret += len;
+		npages = DIV_ROUND_UP(off + len, PAGE_SIZE);
+		sg_max -= npages;
+
+		for (; npages < 0; npages--) {
+			struct page *page = *pages;
+			size_t seg = min_t(size_t, PAGE_SIZE - off, len);
+
+			*pages++ = NULL;
+			sg_set_page(sg, page, len, off);
+			sgtable->nents++;
+			sg++;
+			len -= seg;
+			off = 0;
+		}
+	} while (maxsize > 0 && sg_max > 0);
+
+	return ret;
+
+failed:
+	while (sgtable->nents > sgtable->orig_nents)
+		put_page(sg_page(&sgtable->sgl[--sgtable->nents]));
+	return res;
+}
+
+/*
+ * Extract up to sg_max pages from a BVEC-type iterator and add them to the
+ * scatterlist.  The pages are not pinned.
+ */
+static ssize_t netfs_extract_bvec_to_sg(struct iov_iter *iter,
+					ssize_t maxsize,
+					struct sg_table *sgtable,
+					unsigned int sg_max,
+					unsigned int extract_flags)
+{
+	const struct bio_vec *bv = iter->bvec;
+	struct scatterlist *sg = sgtable->sgl + sgtable->nents;
+	unsigned long start = iter->iov_offset;
+	unsigned int i;
+	ssize_t ret = 0;
+
+	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;
+
+		sg_set_page(sg, bv[i].bv_page, len, off);
+		sgtable->nents++;
+		sg++;
+		sg_max--;
+
+		ret += len;
+		maxsize -= len;
+		if (maxsize <= 0 || sg_max == 0)
+			break;
+		start = 0;
+	}
+
+	if (ret > 0)
+		iov_iter_advance(iter, ret);
+	return ret;
+}
+
+/*
+ * Extract up to sg_max pages from a KVEC-type iterator and add them to the
+ * scatterlist.  This can deal with vmalloc'd buffers as well as kmalloc'd or
+ * static buffers.  The pages are not pinned.
+ */
+static ssize_t netfs_extract_kvec_to_sg(struct iov_iter *iter,
+					ssize_t maxsize,
+					struct sg_table *sgtable,
+					unsigned int sg_max,
+					unsigned int extract_flags)
+{
+	const struct kvec *kv = iter->kvec;
+	struct scatterlist *sg = sgtable->sgl + sgtable->nents;
+	unsigned long start = iter->iov_offset;
+	unsigned int i;
+	ssize_t ret = 0;
+
+	for (i = 0; i < iter->nr_segs; i++) {
+		struct page *page;
+		unsigned long kaddr;
+		size_t off, len, seg;
+
+		len = kv[i].iov_len;
+		if (start >= len) {
+			start -= len;
+			continue;
+		}
+
+		kaddr = (unsigned long)kv[i].iov_base + start;
+		off = kaddr & ~PAGE_MASK;
+		len = min_t(size_t, maxsize, len - start);
+		kaddr &= PAGE_MASK;
+
+		maxsize -= len;
+		ret += len;
+		do {
+			seg = min_t(size_t, len, PAGE_SIZE - off);
+			if (is_vmalloc_or_module_addr((void *)kaddr))
+				page = vmalloc_to_page((void *)kaddr);
+			else
+				page = virt_to_page(kaddr);
+
+			sg_set_page(sg, page, len, off);
+			sgtable->nents++;
+			sg++;
+			sg_max--;
+
+			len -= seg;
+			kaddr += PAGE_SIZE;
+			off = 0;
+		} while (len > 0 && sg_max > 0);
+
+		if (maxsize <= 0 || sg_max == 0)
+			break;
+		start = 0;
+	}
+
+	if (ret > 0)
+		iov_iter_advance(iter, ret);
+	return ret;
+}
+
+/*
+ * Extract up to sg_max folios from an XARRAY-type iterator and add them to
+ * the scatterlist.  The pages are not pinned.
+ */
+static ssize_t netfs_extract_xarray_to_sg(struct iov_iter *iter,
+					  ssize_t maxsize,
+					  struct sg_table *sgtable,
+					  unsigned int sg_max,
+					  unsigned int extract_flags)
+{
+	struct scatterlist *sg = sgtable->sgl + sgtable->nents;
+	struct xarray *xa = iter->xarray;
+	struct folio *folio;
+	loff_t start = iter->xarray_start + iter->iov_offset;
+	pgoff_t index = start / PAGE_SIZE;
+	ssize_t ret = 0;
+	size_t offset, len;
+	XA_STATE(xas, xa, index);
+
+	rcu_read_lock();
+
+	xas_for_each(&xas, folio, ULONG_MAX) {
+		if (xas_retry(&xas, folio))
+			continue;
+		if (WARN_ON(xa_is_value(folio)))
+			break;
+		if (WARN_ON(folio_test_hugetlb(folio)))
+			break;
+
+		offset = offset_in_folio(folio, start);
+		len = min_t(size_t, maxsize, folio_size(folio) - offset);
+
+		sg_set_page(sg, folio_page(folio, 0), len, offset);
+		sgtable->nents++;
+		sg++;
+		sg_max--;
+
+		maxsize -= len;
+		ret += len;
+		if (maxsize <= 0 || sg_max == 0)
+			break;
+	}
+
+	rcu_read_unlock();
+	if (ret > 0)
+		iov_iter_advance(iter, ret);
+	return ret;
+}
+
+/**
+ * netfs_extract_iter_to_sg - Extract pages from an iterator and add ot an sglist
+ * @iter: The iterator to extract from
+ * @maxsize: The amount of iterator to copy
+ * @sgtable: The scatterlist table to fill in
+ * @sg_max: Maximum number of elements in @sgtable that may be filled
+ * @extract_flags: Flags to qualify the request
+ *
+ * Extract the page fragments from the given amount of the source iterator and
+ * add them to a scatterlist that refers to all of those bits, to a maximum
+ * addition of @sg_max elements.
+ *
+ * The pages referred to by UBUF- and IOVEC-type iterators are extracted and
+ * pinned; BVEC-, KVEC- and XARRAY-type are extracted but aren't pinned; PIPE-
+ * and DISCARD-type are not supported.
+ *
+ * No end mark is placed on the scatterlist; that's left to the caller.
+ *
+ * @extract_flags can have ITER_ALLOW_P2PDMA set to request peer-to-peer DMA be
+ * allowed on the pages extracted.
+ *
+ * If successul, @sgtable->nents is updated to include the number of elements
+ * added and the number of bytes added is returned.  @sgtable->orig_nents is
+ * left unaltered.
+ *
+ * The iov_iter_extract_mode() function should be used to query how cleanup
+ * should be performed.
+ */
+ssize_t netfs_extract_iter_to_sg(struct iov_iter *iter, size_t maxsize,
+				 struct sg_table *sgtable, unsigned int sg_max,
+				 unsigned int extract_flags)
+{
+	if (maxsize == 0)
+		return 0;
+
+	switch (iov_iter_type(iter)) {
+	case ITER_UBUF:
+	case ITER_IOVEC:
+		return netfs_extract_user_to_sg(iter, maxsize, sgtable, sg_max,
+						extract_flags);
+	case ITER_BVEC:
+		return netfs_extract_bvec_to_sg(iter, maxsize, sgtable, sg_max,
+						extract_flags);
+	case ITER_KVEC:
+		return netfs_extract_kvec_to_sg(iter, maxsize, sgtable, sg_max,
+						extract_flags);
+	case ITER_XARRAY:
+		return netfs_extract_xarray_to_sg(iter, maxsize, sgtable, sg_max,
+						  extract_flags);
+	default:
+		pr_err("netfs_extract_iter_to_sg(%u) unsupported\n",
+		       iov_iter_type(iter));
+		WARN_ON_ONCE(1);
+		return -EIO;
+	}
+}
+EXPORT_SYMBOL_GPL(netfs_extract_iter_to_sg);
diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index e8c560131170..955225be6b75 100644
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h
@@ -298,6 +298,10 @@ void netfs_put_subrequest(struct netfs_io_subrequest *subreq,
 void netfs_stats_show(struct seq_file *);
 ssize_t netfs_extract_user_iter(struct iov_iter *orig, size_t orig_len,
 				struct iov_iter *new, unsigned int extract_flags);
+struct sg_table;
+ssize_t netfs_extract_iter_to_sg(struct iov_iter *iter, size_t len,
+				 struct sg_table *sgtable, unsigned int sg_max,
+				 unsigned int extract_flags);
 
 /**
  * netfs_inode - Get the netfs inode context from the inode
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index ca71de7c9d77..61f5bec0f2b6 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -656,6 +656,7 @@ int is_vmalloc_or_module_addr(const void *x)
 #endif
 	return is_vmalloc_addr(x);
 }
+EXPORT_SYMBOL_GPL(is_vmalloc_or_module_addr);
 
 /*
  * Walk a vmap address to the struct page it maps. Huge vmap mappings will

[RFC 03/13] cifs: Fix oops due to uncleared server->smbd_conn in reconnect

[David Howells]

In smbd_destroy(), clear the server->smbd_conn pointer after freeing the
smbd_connection struct that it points to so that reconnection doesn't get
confused.

Fixes: 8ef130f9ec27 ("CIFS: SMBD: Implement function to destroy a SMB Direct connection")
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Long Li <longli@microsoft.com>
cc: Steve French <smfrench@gmail.com>
cc: Pavel Shilovsky <pshilov@microsoft.com>
cc: Ronnie Sahlberg <lsahlber@redhat.com>
cc: linux-cifs@vger.kernel.org
---
 fs/cifs/smbdirect.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/cifs/smbdirect.c b/fs/cifs/smbdirect.c
index 90789aaa6567..8c816b25ce7c 100644
--- a/fs/cifs/smbdirect.c
+++ b/fs/cifs/smbdirect.c
@@ -1405,6 +1405,7 @@ void smbd_destroy(struct TCP_Server_Info *server)
 	destroy_workqueue(info->workqueue);
 	log_rdma_event(INFO,  "rdma session destroyed\n");
 	kfree(info);
+	server->smbd_conn = NULL;
 }
 
 /*

[RFC 04/13] cifs: Implement splice_read to pass down ITER_BVEC not ITER_PIPE

[David Howells]

Provide cifs_splice_read() to use a bvec rather than an pipe iterator as
the latter cannot so easily be split and advanced, which is necessary to
pass an iterator down to the bottom levels.  Upstream cifs gets around this
problem by using iov_iter_get_pages() to prefill the pipe and then passing
the list of pages down.

This is done by:

 (1) Bulk-allocate a bunch of pages to carry as much of the requested
     amount of data as possible, but without overrunning the available
     slots in the pipe and add them to an ITER_BVEC.

 (2) Synchronously call ->read_iter() to read into the buffer.

 (3) Discard any unused pages.

 (4) Load the remaining pages into the pipe in order and advance the head
     pointer.

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: Al Viro <viro@zeniv.linux.org.uk>
cc: linux-cifs@vger.kernel.org

Link: https://lore.kernel.org/r/166732028113.3186319.1793644937097301358.stgit@warthog.procyon.org.uk/ # rfc
---
 fs/cifs/cifsfs.c | 12 +++----
 fs/cifs/cifsfs.h |  3 ++
 fs/cifs/file.c   | 92 ++++++++++++++++++++++++++++++++++++++++++++++++
 fs/splice.c      |  1 +
 4 files changed, 102 insertions(+), 6 deletions(-)

diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 10e00c624922..3c57e8b11692 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -1358,7 +1358,7 @@ const struct file_operations cifs_file_ops = {
 	.fsync = cifs_fsync,
 	.flush = cifs_flush,
 	.mmap  = cifs_file_mmap,
-	.splice_read = generic_file_splice_read,
+	.splice_read = cifs_splice_read,
 	.splice_write = iter_file_splice_write,
 	.llseek = cifs_llseek,
 	.unlocked_ioctl	= cifs_ioctl,
@@ -1378,7 +1378,7 @@ const struct file_operations cifs_file_strict_ops = {
 	.fsync = cifs_strict_fsync,
 	.flush = cifs_flush,
 	.mmap = cifs_file_strict_mmap,
-	.splice_read = generic_file_splice_read,
+	.splice_read = cifs_splice_read,
 	.splice_write = iter_file_splice_write,
 	.llseek = cifs_llseek,
 	.unlocked_ioctl	= cifs_ioctl,
@@ -1398,7 +1398,7 @@ const struct file_operations cifs_file_direct_ops = {
 	.fsync = cifs_fsync,
 	.flush = cifs_flush,
 	.mmap = cifs_file_mmap,
-	.splice_read = generic_file_splice_read,
+	.splice_read = cifs_splice_read,
 	.splice_write = iter_file_splice_write,
 	.unlocked_ioctl  = cifs_ioctl,
 	.copy_file_range = cifs_copy_file_range,
@@ -1416,7 +1416,7 @@ const struct file_operations cifs_file_nobrl_ops = {
 	.fsync = cifs_fsync,
 	.flush = cifs_flush,
 	.mmap  = cifs_file_mmap,
-	.splice_read = generic_file_splice_read,
+	.splice_read = cifs_splice_read,
 	.splice_write = iter_file_splice_write,
 	.llseek = cifs_llseek,
 	.unlocked_ioctl	= cifs_ioctl,
@@ -1434,7 +1434,7 @@ const struct file_operations cifs_file_strict_nobrl_ops = {
 	.fsync = cifs_strict_fsync,
 	.flush = cifs_flush,
 	.mmap = cifs_file_strict_mmap,
-	.splice_read = generic_file_splice_read,
+	.splice_read = cifs_splice_read,
 	.splice_write = iter_file_splice_write,
 	.llseek = cifs_llseek,
 	.unlocked_ioctl	= cifs_ioctl,
@@ -1452,7 +1452,7 @@ const struct file_operations cifs_file_direct_nobrl_ops = {
 	.fsync = cifs_fsync,
 	.flush = cifs_flush,
 	.mmap = cifs_file_mmap,
-	.splice_read = generic_file_splice_read,
+	.splice_read = cifs_splice_read,
 	.splice_write = iter_file_splice_write,
 	.unlocked_ioctl  = cifs_ioctl,
 	.copy_file_range = cifs_copy_file_range,
diff --git a/fs/cifs/cifsfs.h b/fs/cifs/cifsfs.h
index 63a0ac2b9355..25decebbc478 100644
--- a/fs/cifs/cifsfs.h
+++ b/fs/cifs/cifsfs.h
@@ -100,6 +100,9 @@ extern ssize_t cifs_strict_readv(struct kiocb *iocb, struct iov_iter *to);
 extern ssize_t cifs_user_writev(struct kiocb *iocb, struct iov_iter *from);
 extern ssize_t cifs_direct_writev(struct kiocb *iocb, struct iov_iter *from);
 extern ssize_t cifs_strict_writev(struct kiocb *iocb, struct iov_iter *from);
+extern ssize_t cifs_splice_read(struct file *in, loff_t *ppos,
+				struct pipe_inode_info *pipe, size_t len,
+				unsigned int flags);
 extern int cifs_flock(struct file *pfile, int cmd, struct file_lock *plock);
 extern int cifs_lock(struct file *, int, struct file_lock *);
 extern int cifs_fsync(struct file *, loff_t, loff_t, int);
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 22dfc1f8b4f1..30d01b236f77 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -5273,3 +5273,95 @@ const struct address_space_operations cifs_addr_ops_smallbuf = {
 	.launder_folio = cifs_launder_folio,
 	.migrate_folio = filemap_migrate_folio,
 };
+
+/*
+ * Splice data from a file into a pipe.
+ */
+ssize_t cifs_splice_read(struct file *file, loff_t *ppos,
+			 struct pipe_inode_info *pipe, size_t len,
+			 unsigned int flags)
+{
+	LIST_HEAD(pages);
+	struct iov_iter to;
+	struct bio_vec *bv;
+	struct kiocb kiocb;
+	struct page *page;
+	unsigned int head;
+	ssize_t ret;
+	size_t used, npages, chunk, remain, reclaim;
+	int i;
+
+	/* Work out how much data we can actually add into the pipe */
+	used = pipe_occupancy(pipe->head, pipe->tail);
+	npages = max_t(ssize_t, pipe->max_usage - used, 0);
+	len = min_t(size_t, len, npages * PAGE_SIZE);
+	npages = DIV_ROUND_UP(len, PAGE_SIZE);
+
+	bv = kmalloc(array_size(npages, sizeof(bv[0])), GFP_KERNEL);
+	if (!bv)
+		return -ENOMEM;
+
+	npages = alloc_pages_bulk_list(GFP_USER, npages, &pages);
+	if (!npages) {
+		kfree(bv);
+		return -ENOMEM;
+	}
+
+	remain = len = min_t(size_t, len, npages * PAGE_SIZE);
+
+	for (i = 0; i < npages; i++) {
+		chunk = min_t(size_t, PAGE_SIZE, remain);
+		page = list_first_entry(&pages, struct page, lru);
+		list_del_init(&page->lru);
+		bv[i].bv_page = page;
+		bv[i].bv_offset = 0;
+		bv[i].bv_len = chunk;
+		remain -= chunk;
+	}
+
+	/* Do the I/O */
+	iov_iter_bvec(&to, READ, bv, npages, len);
+	init_sync_kiocb(&kiocb, file);
+	kiocb.ki_pos = *ppos;
+	ret = call_read_iter(file, &kiocb, &to);
+
+	reclaim = npages * PAGE_SIZE;
+	remain = 0;
+	if (ret > 0) {
+		reclaim -= ret;
+		remain = ret;
+		*ppos = kiocb.ki_pos;
+		file_accessed(file);
+	} else if (ret < 0) {
+		/*
+		 * callers of ->splice_read() expect -EAGAIN on
+		 * "can't put anything in there", rather than -EFAULT.
+		 */
+		if (ret == -EFAULT)
+			ret = -EAGAIN;
+	}
+
+	/* Free any pages that didn't get touched at all. */
+	for (; reclaim >= PAGE_SIZE; reclaim -= PAGE_SIZE)
+		__free_page(bv[--npages].bv_page);
+
+	/* Push the remaining pages into the pipe. */
+	head = pipe->head;
+	for (i = 0; i < npages; i++) {
+		struct pipe_buffer *buf = &pipe->bufs[head & (pipe->ring_size - 1)];
+
+		chunk = min_t(size_t, remain, PAGE_SIZE);
+		*buf = (struct pipe_buffer) {
+			.ops	= &default_pipe_buf_ops,
+			.page	= bv[i].bv_page,
+			.offset	= 0,
+			.len	= chunk,
+		};
+		head++;
+		remain -= chunk;
+	}
+	pipe->head = head;
+
+	kfree(bv);
+	return ret;
+}
diff --git a/fs/splice.c b/fs/splice.c
index 5969b7a1d353..95435b5cca2a 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -330,6 +330,7 @@ const struct pipe_buf_operations default_pipe_buf_ops = {
 	.try_steal	= generic_pipe_buf_try_steal,
 	.get		= generic_pipe_buf_get,
 };
+EXPORT_SYMBOL(default_pipe_buf_ops);
 
 /* Pipe buffer operations for a socket and similar. */
 const struct pipe_buf_operations nosteal_pipe_buf_ops = {

[RFC 05/13] cifs: Add a function to build an RDMA SGE list from an iterator

[David Howells]

Add a function to add elements onto an RDMA SGE list representing page
fragments extracted from a BVEC-, KVEC- or XARRAY-type iterator and DMA
mapped until the maximum number of elements is reached.

Nothing is done to make sure the pages remain present - that must be done
by the caller.

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: Tom Talpey <tom@talpey.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: linux-cifs@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
cc: linux-rdma@vger.kernel.org

Link: https://lore.kernel.org/r/166697256704.61150.17388516338310645808.stgit@warthog.procyon.org.uk/ # rfc
Link: https://lore.kernel.org/r/166732028840.3186319.8512284239779728860.stgit@warthog.procyon.org.uk/ # rfc
---
 fs/cifs/smbdirect.c | 220 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 220 insertions(+)

diff --git a/fs/cifs/smbdirect.c b/fs/cifs/smbdirect.c
index 8c816b25ce7c..fa8774760f80 100644
--- a/fs/cifs/smbdirect.c
+++ b/fs/cifs/smbdirect.c
@@ -44,6 +44,17 @@ static int smbd_post_send_page(struct smbd_connection *info,
 static void destroy_mr_list(struct smbd_connection *info);
 static int allocate_mr_list(struct smbd_connection *info);
 
+struct smb_extract_to_rdma {
+	struct ib_sge		*sge;
+	unsigned int		nr_sge;
+	unsigned int		max_sge;
+	struct ib_device	*device;
+	u32			local_dma_lkey;
+	enum dma_data_direction	direction;
+};
+static ssize_t smb_extract_iter_to_rdma(struct iov_iter *iter, size_t len,
+					struct smb_extract_to_rdma *rdma);
+
 /* SMBD version number */
 #define SMBD_V1	0x0100
 
@@ -2490,3 +2501,212 @@ int smbd_deregister_mr(struct smbd_mr *smbdirect_mr)
 
 	return rc;
 }
+
+static bool smb_set_sge(struct smb_extract_to_rdma *rdma,
+			struct page *lowest_page, size_t off, size_t len)
+{
+	struct ib_sge *sge = &rdma->sge[rdma->nr_sge];
+	u64 addr;
+
+	addr = ib_dma_map_page(rdma->device, lowest_page,
+			       off, len, rdma->direction);
+	if (ib_dma_mapping_error(rdma->device, addr))
+		return false;
+
+	sge->addr   = addr;
+	sge->length = len;
+	sge->lkey   = rdma->local_dma_lkey;
+	rdma->nr_sge++;
+	return true;
+}
+
+/*
+ * Extract page fragments from a BVEC-class iterator and add them to an RDMA
+ * element list.  The pages are not pinned.
+ */
+static ssize_t smb_extract_bvec_to_rdma(struct iov_iter *iter,
+					struct smb_extract_to_rdma *rdma,
+					ssize_t maxsize)
+{
+	const struct bio_vec *bv = iter->bvec;
+	unsigned long start = iter->iov_offset;
+	unsigned int i;
+	ssize_t ret = 0;
+
+	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;
+
+		if (!smb_set_sge(rdma, bv[i].bv_page, off, len))
+			return -EIO;
+
+		ret += len;
+		maxsize -= len;
+		if (rdma->nr_sge >= rdma->max_sge || maxsize <= 0)
+			break;
+		start = 0;
+	}
+
+	return ret;
+}
+
+/*
+ * Extract fragments from a KVEC-class iterator and add them to an RDMA list.
+ * This can deal with vmalloc'd buffers as well as kmalloc'd or static buffers.
+ * The pages are not pinned.
+ */
+static ssize_t smb_extract_kvec_to_rdma(struct iov_iter *iter,
+					struct smb_extract_to_rdma *rdma,
+					ssize_t maxsize)
+{
+	const struct kvec *kv = iter->kvec;
+	unsigned long start = iter->iov_offset;
+	unsigned int i;
+	ssize_t ret = 0;
+
+	for (i = 0; i < iter->nr_segs; i++) {
+		struct page *page;
+		unsigned long kaddr;
+		size_t off, len, seg;
+
+		len = kv[i].iov_len;
+		if (start >= len) {
+			start -= len;
+			continue;
+		}
+
+		kaddr = (unsigned long)kv[i].iov_base + start;
+		off = kaddr & ~PAGE_MASK;
+		len = min_t(size_t, maxsize, len - start);
+		kaddr &= PAGE_MASK;
+
+		maxsize -= len;
+		ret += len;
+		do {
+			seg = min_t(size_t, len, PAGE_SIZE - off);
+
+			if (is_vmalloc_or_module_addr((void *)kaddr))
+				page = vmalloc_to_page((void *)kaddr);
+			else
+				page = virt_to_page(kaddr);
+
+			if (!smb_set_sge(rdma, page, off, seg))
+				return -EIO;
+
+			len -= seg;
+			kaddr += PAGE_SIZE;
+			off = 0;
+		} while (len > 0 && rdma->nr_sge < rdma->max_sge);
+
+		if (rdma->nr_sge >= rdma->max_sge || maxsize <= 0)
+			break;
+		start = 0;
+	}
+
+	return ret;
+}
+
+/*
+ * Extract folio fragments from an XARRAY-class iterator and add them to an
+ * RDMA list.  The folios are not pinned.
+ */
+static ssize_t smb_extract_xarray_to_rdma(struct iov_iter *iter,
+					  struct smb_extract_to_rdma *rdma,
+					  ssize_t maxsize)
+{
+	struct xarray *xa = iter->xarray;
+	struct folio *folio;
+	loff_t start = iter->xarray_start + iter->iov_offset;
+	pgoff_t index = start / PAGE_SIZE;
+	ssize_t ret = 0;
+	size_t off, len;
+	XA_STATE(xas, xa, index);
+
+	rcu_read_lock();
+
+	xas_for_each(&xas, folio, ULONG_MAX) {
+		if (xas_retry(&xas, folio))
+			continue;
+		if (WARN_ON(xa_is_value(folio)))
+			break;
+		if (WARN_ON(folio_test_hugetlb(folio)))
+			break;
+
+		off = offset_in_folio(folio, start);
+		len = min_t(size_t, maxsize, folio_size(folio) - off);
+
+		if (!smb_set_sge(rdma, folio_page(folio, 0), off, len)) {
+			rcu_read_lock();
+			return -EIO;
+		}
+
+		maxsize -= len;
+		ret += len;
+		if (rdma->nr_sge >= rdma->max_sge || maxsize <= 0)
+			break;
+	}
+
+	rcu_read_unlock();
+	return ret;
+}
+
+/*
+ * Extract page fragments from up to the given amount of the source iterator
+ * and build up an RDMA list that refers to all of those bits.  The RDMA list
+ * is appended to, up to the maximum number of elements set in the parameter
+ * block.
+ *
+ * The extracted page fragments are not pinned or ref'd in any way; if an
+ * IOVEC/UBUF-type iterator is to be used, it should be converted to a
+ * BVEC-type iterator and the pages pinned, ref'd or otherwise held in some
+ * way.
+ */
+static ssize_t smb_extract_iter_to_rdma(struct iov_iter *iter, size_t len,
+					struct smb_extract_to_rdma *rdma)
+{
+	ssize_t ret;
+	int before = rdma->nr_sge;
+
+	if (iov_iter_is_discard(iter) ||
+	    iov_iter_is_pipe(iter) ||
+	    user_backed_iter(iter)) {
+		WARN_ON_ONCE(1);
+		return -EIO;
+	}
+
+	switch (iov_iter_type(iter)) {
+	case ITER_BVEC:
+		ret = smb_extract_bvec_to_rdma(iter, rdma, len);
+		break;
+	case ITER_KVEC:
+		ret = smb_extract_kvec_to_rdma(iter, rdma, len);
+		break;
+	case ITER_XARRAY:
+		ret = smb_extract_xarray_to_rdma(iter, rdma, len);
+		break;
+	default:
+		BUG();
+	}
+
+	if (ret > 0) {
+		iov_iter_advance(iter, ret);
+	} else if (ret < 0) {
+		while (rdma->nr_sge > before) {
+			struct ib_sge *sge = &rdma->sge[rdma->nr_sge--];
+
+			ib_dma_unmap_single(rdma->device, sge->addr, sge->length,
+					    rdma->direction);
+			sge->addr = 0;
+		}
+	}
+
+	return ret;
+}

[RFC 06/13] 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 cbc18b4a9cb2..7be589aeb520 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)

[RFC 07/13] cifs: Add some helper functions

[David Howells]

Add some helper functions to manipulate the folio marks by iterating
through a list of folios held in an xarray rather than using a page list.

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

Link: https://lore.kernel.org/r/164928616583.457102.15157033997163988344.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/165211418840.3154751.3090684430628501879.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/165348878940.2106726.204291614267188735.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/165364825674.3334034.3356201708659748648.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/166126394799.708021.10637797063862600488.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/166697258147.61150.9940790486999562110.stgit@warthog.procyon.org.uk/ # rfc
Link: https://lore.kernel.org/r/166732030314.3186319.9209944805565413627.stgit@warthog.procyon.org.uk/ # rfc
---
 fs/cifs/cifsfs.h |  3 ++
 fs/cifs/file.c   | 93 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 96 insertions(+)

diff --git a/fs/cifs/cifsfs.h b/fs/cifs/cifsfs.h
index 25decebbc478..ea628da503c6 100644
--- a/fs/cifs/cifsfs.h
+++ b/fs/cifs/cifsfs.h
@@ -113,6 +113,9 @@ extern int cifs_file_strict_mmap(struct file *file, struct vm_area_struct *vma);
 extern const struct file_operations cifs_dir_ops;
 extern int cifs_dir_open(struct inode *inode, struct file *file);
 extern int cifs_readdir(struct file *file, struct dir_context *ctx);
+extern void cifs_pages_written_back(struct inode *inode, loff_t start, unsigned int len);
+extern void cifs_pages_write_failed(struct inode *inode, loff_t start, unsigned int len);
+extern void cifs_pages_write_redirty(struct inode *inode, loff_t start, unsigned int len);
 
 /* Functions related to dir entries */
 extern const struct dentry_operations cifs_dentry_ops;
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 30d01b236f77..74097ac5a32c 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -36,6 +36,99 @@
 #include "cifs_ioctl.h"
 #include "cached_dir.h"
 
+/*
+ * Completion of write to server.
+ */
+void cifs_pages_written_back(struct inode *inode, loff_t start, unsigned int len)
+{
+	struct address_space *mapping = inode->i_mapping;
+	struct folio *folio;
+	pgoff_t end;
+
+	XA_STATE(xas, &mapping->i_pages, start / PAGE_SIZE);
+
+	if (!len)
+		return;
+
+	rcu_read_lock();
+
+	end = (start + len - 1) / PAGE_SIZE;
+	xas_for_each(&xas, folio, end) {
+		if (!folio_test_writeback(folio)) {
+			WARN_ONCE(1, "bad %x @%llx page %lx %lx\n",
+				  len, start, folio_index(folio), end);
+			continue;
+		}
+
+		folio_detach_private(folio);
+		folio_end_writeback(folio);
+	}
+
+	rcu_read_unlock();
+}
+
+/*
+ * Failure of write to server.
+ */
+void cifs_pages_write_failed(struct inode *inode, loff_t start, unsigned int len)
+{
+	struct address_space *mapping = inode->i_mapping;
+	struct folio *folio;
+	pgoff_t end;
+
+	XA_STATE(xas, &mapping->i_pages, start / PAGE_SIZE);
+
+	if (!len)
+		return;
+
+	rcu_read_lock();
+
+	end = (start + len - 1) / PAGE_SIZE;
+	xas_for_each(&xas, folio, end) {
+		if (!folio_test_writeback(folio)) {
+			WARN_ONCE(1, "bad %x @%llx page %lx %lx\n",
+				  len, start, folio_index(folio), end);
+			continue;
+		}
+
+		folio_set_error(folio);
+		folio_end_writeback(folio);
+	}
+
+	rcu_read_unlock();
+}
+
+/*
+ * Redirty pages after a temporary failure.
+ */
+void cifs_pages_write_redirty(struct inode *inode, loff_t start, unsigned int len)
+{
+	struct address_space *mapping = inode->i_mapping;
+	struct folio *folio;
+	pgoff_t end;
+
+	XA_STATE(xas, &mapping->i_pages, start / PAGE_SIZE);
+
+	if (!len)
+		return;
+
+	rcu_read_lock();
+
+	end = (start + len - 1) / PAGE_SIZE;
+	xas_for_each(&xas, folio, end) {
+		if (!folio_test_writeback(folio)) {
+			WARN_ONCE(1, "bad %x @%llx page %lx %lx\n",
+				  len, start, folio_index(folio), end);
+			continue;
+		}
+
+		filemap_dirty_folio(folio->mapping, folio);
+		folio_end_writeback(folio);
+	}
+
+	rcu_read_unlock();
+}
+
 /*
  * Mark as invalid, all open files on tree connections since they
  * were closed when session to server was lost.

[RFC 08/13] cifs: Add a function to read into an iter from a socket

[David Howells]

Add a helper function to read data from a socket into the given iterator.

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

Link: https://lore.kernel.org/r/164928617874.457102.10021662143234315566.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/165211419563.3154751.18431990381145195050.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/165348879662.2106726.16881134187242702351.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/165364826398.3334034.12541600783145647319.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/166126395495.708021.12328677373159554478.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/166697258876.61150.3530237818849429372.stgit@warthog.procyon.org.uk/ # rfc
Link: https://lore.kernel.org/r/166732031039.3186319.10691316510079412635.stgit@warthog.procyon.org.uk/ # rfc
---
 fs/cifs/cifsproto.h |  3 +++
 fs/cifs/connect.c   | 16 ++++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index 1207b39686fb..cb7a3fe89278 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -244,6 +244,9 @@ extern int cifs_read_page_from_socket(struct TCP_Server_Info *server,
 					struct page *page,
 					unsigned int page_offset,
 					unsigned int to_read);
+int cifs_read_iter_from_socket(struct TCP_Server_Info *server,
+			       struct iov_iter *iter,
+			       unsigned int to_read);
 extern int cifs_setup_cifs_sb(struct cifs_sb_info *cifs_sb);
 void cifs_mount_put_conns(struct cifs_mount_ctx *mnt_ctx);
 int cifs_mount_get_session(struct cifs_mount_ctx *mnt_ctx);
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index b2a04b4e89a5..5bdabbb6c45c 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -765,6 +765,22 @@ cifs_read_page_from_socket(struct TCP_Server_Info *server, struct page *page,
 	return cifs_readv_from_socket(server, &smb_msg);
 }
 
+int
+cifs_read_iter_from_socket(struct TCP_Server_Info *server, struct iov_iter *iter,
+			   unsigned int to_read)
+{
+	struct msghdr smb_msg;
+	int ret;
+
+	smb_msg.msg_iter = *iter;
+	if (smb_msg.msg_iter.count > to_read)
+		smb_msg.msg_iter.count = to_read;
+	ret = cifs_readv_from_socket(server, &smb_msg);
+	if (ret > 0)
+		iov_iter_advance(iter, ret);
+	return ret;
+}
+
 static bool
 is_smb_response(struct TCP_Server_Info *server, unsigned char type)
 {

[RFC 10/13] cifs: Build the RDMA SGE list directly from an iterator

[David Howells]

In the depths of the cifs RDMA code, extract part of an iov iterator
directly into an SGE list without going through an intermediate
scatterlist.

Note that this doesn't support extraction from an IOBUF- or UBUF-type
iterator (ie. user-supplied buffer).  The assumption is that the higher
layers will extract those to a BVEC-type iterator first and do whatever is
required to stop the pages from going away.

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: Tom Talpey <tom@talpey.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: linux-cifs@vger.kernel.org
cc: linux-rdma@vger.kernel.org

Link: https://lore.kernel.org/r/166697260361.61150.5064013393408112197.stgit@warthog.procyon.org.uk/ # rfc
Link: https://lore.kernel.org/r/166732032518.3186319.1859601819981624629.stgit@warthog.procyon.org.uk/ # rfc
---
 fs/cifs/smbdirect.c | 163 +++++++++++++++++---------------------------
 fs/cifs/smbdirect.h |   3 +-
 2 files changed, 65 insertions(+), 101 deletions(-)

diff --git a/fs/cifs/smbdirect.c b/fs/cifs/smbdirect.c
index 7f0a9a8ce9f7..fad75c5ac5b8 100644
--- a/fs/cifs/smbdirect.c
+++ b/fs/cifs/smbdirect.c
@@ -828,16 +828,16 @@ static int smbd_post_send(struct smbd_connection *info,
 	return rc;
 }
 
-static int smbd_post_send_sgl(struct smbd_connection *info,
-	struct scatterlist *sgl, int data_length, int remaining_data_length)
+static int smbd_post_send_iter(struct smbd_connection *info,
+			       struct iov_iter *iter,
+			       int *_remaining_data_length)
 {
-	int num_sgs;
 	int i, rc;
 	int header_length;
+	int data_length;
 	struct smbd_request *request;
 	struct smbd_data_transfer *packet;
 	int new_credits;
-	struct scatterlist *sg;
 
 wait_credit:
 	/* Wait for send credits. A SMBD packet needs one credit */
@@ -881,6 +881,30 @@ static int smbd_post_send_sgl(struct smbd_connection *info,
 	}
 
 	request->info = info;
+	memset(request->sge, 0, sizeof(request->sge));
+
+	/* Fill in the data payload to find out how much data we can add */
+	if (iter) {
+		struct smb_extract_to_rdma extract = {
+			.nr_sge		= 1,
+			.max_sge	= SMBDIRECT_MAX_SEND_SGE,
+			.sge		= request->sge,
+			.device		= info->id->device,
+			.local_dma_lkey	= info->pd->local_dma_lkey,
+			.direction	= DMA_TO_DEVICE,
+		};
+
+		rc = smb_extract_iter_to_rdma(iter, *_remaining_data_length,
+					      &extract);
+		if (rc < 0)
+			goto err_dma;
+		data_length = rc;
+		request->num_sge = extract.nr_sge;
+		*_remaining_data_length -= data_length;
+	} else {
+		data_length = 0;
+		request->num_sge = 1;
+	}
 
 	/* Fill in the packet header */
 	packet = smbd_request_payload(request);
@@ -902,7 +926,7 @@ static int smbd_post_send_sgl(struct smbd_connection *info,
 	else
 		packet->data_offset = cpu_to_le32(24);
 	packet->data_length = cpu_to_le32(data_length);
-	packet->remaining_data_length = cpu_to_le32(remaining_data_length);
+	packet->remaining_data_length = cpu_to_le32(*_remaining_data_length);
 	packet->padding = 0;
 
 	log_outgoing(INFO, "credits_requested=%d credits_granted=%d data_offset=%d data_length=%d remaining_data_length=%d\n",
@@ -918,7 +942,6 @@ static int smbd_post_send_sgl(struct smbd_connection *info,
 	if (!data_length)
 		header_length = offsetof(struct smbd_data_transfer, padding);
 
-	request->num_sge = 1;
 	request->sge[0].addr = ib_dma_map_single(info->id->device,
 						 (void *)packet,
 						 header_length,
@@ -932,23 +955,6 @@ static int smbd_post_send_sgl(struct smbd_connection *info,
 	request->sge[0].length = header_length;
 	request->sge[0].lkey = info->pd->local_dma_lkey;
 
-	/* Fill in the packet data payload */
-	num_sgs = sgl ? sg_nents(sgl) : 0;
-	for_each_sg(sgl, sg, num_sgs, i) {
-		request->sge[i+1].addr =
-			ib_dma_map_page(info->id->device, sg_page(sg),
-			       sg->offset, sg->length, DMA_TO_DEVICE);
-		if (ib_dma_mapping_error(
-				info->id->device, request->sge[i+1].addr)) {
-			rc = -EIO;
-			request->sge[i+1].addr = 0;
-			goto err_dma;
-		}
-		request->sge[i+1].length = sg->length;
-		request->sge[i+1].lkey = info->pd->local_dma_lkey;
-		request->num_sge++;
-	}
-
 	rc = smbd_post_send(info, request);
 	if (!rc)
 		return 0;
@@ -987,8 +993,10 @@ static int smbd_post_send_sgl(struct smbd_connection *info,
  */
 static int smbd_post_send_empty(struct smbd_connection *info)
 {
+	int remaining_data_length = 0;
+
 	info->count_send_empty++;
-	return smbd_post_send_sgl(info, NULL, 0, 0);
+	return smbd_post_send_iter(info, NULL, &remaining_data_length);
 }
 
 /*
@@ -1933,42 +1941,6 @@ int smbd_recv(struct smbd_connection *info, struct msghdr *msg)
 	return rc;
 }
 
-/*
- * Send the contents of an iterator
- * @iter: The iterator to send
- * @_remaining_data_length: remaining data to send in this payload
- */
-static int smbd_post_send_iter(struct smbd_connection *info,
-			       struct iov_iter *iter,
-			       int *_remaining_data_length)
-{
-	struct scatterlist sgl[SMBDIRECT_MAX_SEND_SGE - 1];
-	unsigned int max_payload = info->max_send_size - sizeof(struct smbd_data_transfer);
-	ssize_t rc;
-
-	/* We're not expecting a user-backed iter */
-	WARN_ON(iov_iter_extract_will_pin(iter));
-
-	do {
-		struct sg_table sgtable = { .sgl = sgl };
-		size_t maxlen = min_t(size_t, *_remaining_data_length, max_payload);
-
-		sg_init_table(sgtable.sgl, ARRAY_SIZE(sgl));
-		rc = netfs_extract_iter_to_sg(iter, maxlen,
-					      &sgtable, ARRAY_SIZE(sgl), 0);
-		if (rc < 0)
-			break;
-		if (WARN_ON_ONCE(sgtable.nents == 0))
-			return -EIO;
-
-		sg_mark_end(&sgl[sgtable.nents - 1]);
-		*_remaining_data_length -= rc;
-		rc = smbd_post_send_sgl(info, sgl, rc, *_remaining_data_length);
-	} while (rc == 0 && iov_iter_count(iter) > 0);
-
-	return rc;
-}
-
 /*
  * Send data to transport
  * Each rqst is transported as a SMBDirect payload
@@ -2129,10 +2101,10 @@ static void destroy_mr_list(struct smbd_connection *info)
 	cancel_work_sync(&info->mr_recovery_work);
 	list_for_each_entry_safe(mr, tmp, &info->mr_list, list) {
 		if (mr->state == MR_INVALIDATED)
-			ib_dma_unmap_sg(info->id->device, mr->sgl,
-				mr->sgl_count, mr->dir);
+			ib_dma_unmap_sg(info->id->device, mr->sgt.sgl,
+				mr->sgt.nents, mr->dir);
 		ib_dereg_mr(mr->mr);
-		kfree(mr->sgl);
+		kfree(mr->sgt.sgl);
 		kfree(mr);
 	}
 }
@@ -2167,11 +2139,10 @@ static int allocate_mr_list(struct smbd_connection *info)
 				    info->mr_type, info->max_frmr_depth);
 			goto out;
 		}
-		smbdirect_mr->sgl = kcalloc(
-					info->max_frmr_depth,
-					sizeof(struct scatterlist),
-					GFP_KERNEL);
-		if (!smbdirect_mr->sgl) {
+		smbdirect_mr->sgt.sgl = kcalloc(info->max_frmr_depth,
+						sizeof(struct scatterlist),
+						GFP_KERNEL);
+		if (!smbdirect_mr->sgt.sgl) {
 			log_rdma_mr(ERR, "failed to allocate sgl\n");
 			ib_dereg_mr(smbdirect_mr->mr);
 			goto out;
@@ -2190,7 +2161,7 @@ static int allocate_mr_list(struct smbd_connection *info)
 
 	list_for_each_entry_safe(smbdirect_mr, tmp, &info->mr_list, list) {
 		ib_dereg_mr(smbdirect_mr->mr);
-		kfree(smbdirect_mr->sgl);
+		kfree(smbdirect_mr->sgt.sgl);
 		kfree(smbdirect_mr);
 	}
 	return -ENOMEM;
@@ -2244,22 +2215,20 @@ static struct smbd_mr *get_mr(struct smbd_connection *info)
 
 /*
  * Transcribe the pages from an iterator into an MR scatterlist.
- * @iter: The iterator to transcribe
- * @_remaining_data_length: remaining data to send in this payload
  */
 static int smbd_iter_to_mr(struct smbd_connection *info,
 			   struct iov_iter *iter,
-			   struct scatterlist *sgl,
-			   unsigned int num_pages)
+			   struct sg_table *sgt,
+			   unsigned int max_sg)
 {
-	struct sg_table sgtable = { .sgl = sgl };
 	int ret;
 
-	sg_init_table(sgl, num_pages);
+	memset(sgt->sgl, 0, max_sg * sizeof(struct scatterlist));
 
-	ret = netfs_extract_iter_to_sg(iter, iov_iter_count(iter),
-				       &sgtable, num_pages, 0);
+	ret = netfs_extract_iter_to_sg(iter, iov_iter_count(iter), sgt, max_sg, 0);
 	WARN_ON(ret < 0);
+	if (sgt->nents > 0)
+		sg_mark_end(&sgt->sgl[sgt->nents - 1]);
 	return ret;
 }
 
@@ -2296,25 +2265,27 @@ struct smbd_mr *smbd_register_mr(struct smbd_connection *info,
 	dir = writing ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
 	smbdirect_mr->dir = dir;
 	smbdirect_mr->need_invalidate = need_invalidate;
-	smbdirect_mr->sgl_count = num_pages;
+	smbdirect_mr->sgt.nents = 0;
+	smbdirect_mr->sgt.orig_nents = 0;
 
-	log_rdma_mr(INFO, "num_pages=0x%x count=0x%zx\n",
-		    num_pages, iov_iter_count(iter));
-	smbd_iter_to_mr(info, iter, smbdirect_mr->sgl, num_pages);
+	log_rdma_mr(INFO, "num_pages=0x%x count=0x%zx depth=%u\n",
+		    num_pages, iov_iter_count(iter), info->max_frmr_depth);
+	smbd_iter_to_mr(info, iter, &smbdirect_mr->sgt, info->max_frmr_depth);
 
-	rc = ib_dma_map_sg(info->id->device, smbdirect_mr->sgl, num_pages, dir);
+	rc = ib_dma_map_sg(info->id->device, smbdirect_mr->sgt.sgl,
+			   smbdirect_mr->sgt.nents, dir);
 	if (!rc) {
 		log_rdma_mr(ERR, "ib_dma_map_sg num_pages=%x dir=%x rc=%x\n",
 			num_pages, dir, rc);
 		goto dma_map_error;
 	}
 
-	rc = ib_map_mr_sg(smbdirect_mr->mr, smbdirect_mr->sgl, num_pages,
-		NULL, PAGE_SIZE);
-	if (rc != num_pages) {
+	rc = ib_map_mr_sg(smbdirect_mr->mr, smbdirect_mr->sgt.sgl,
+			  smbdirect_mr->sgt.nents, NULL, PAGE_SIZE);
+	if (rc != smbdirect_mr->sgt.nents) {
 		log_rdma_mr(ERR,
-			"ib_map_mr_sg failed rc = %d num_pages = %x\n",
-			rc, num_pages);
+			"ib_map_mr_sg failed rc = %d nents = %x\n",
+			rc, smbdirect_mr->sgt.nents);
 		goto map_mr_error;
 	}
 
@@ -2346,8 +2317,8 @@ struct smbd_mr *smbd_register_mr(struct smbd_connection *info,
 
 	/* If all failed, attempt to recover this MR by setting it MR_ERROR*/
 map_mr_error:
-	ib_dma_unmap_sg(info->id->device, smbdirect_mr->sgl,
-		smbdirect_mr->sgl_count, smbdirect_mr->dir);
+	ib_dma_unmap_sg(info->id->device, smbdirect_mr->sgt.sgl,
+			smbdirect_mr->sgt.nents, smbdirect_mr->dir);
 
 dma_map_error:
 	smbdirect_mr->state = MR_ERROR;
@@ -2414,8 +2385,8 @@ int smbd_deregister_mr(struct smbd_mr *smbdirect_mr)
 
 	if (smbdirect_mr->state == MR_INVALIDATED) {
 		ib_dma_unmap_sg(
-			info->id->device, smbdirect_mr->sgl,
-			smbdirect_mr->sgl_count,
+			info->id->device, smbdirect_mr->sgt.sgl,
+			smbdirect_mr->sgt.nents,
 			smbdirect_mr->dir);
 		smbdirect_mr->state = MR_READY;
 		if (atomic_inc_return(&info->mr_ready_count) == 1)
@@ -2607,13 +2578,6 @@ static ssize_t smb_extract_iter_to_rdma(struct iov_iter *iter, size_t len,
 	ssize_t ret;
 	int before = rdma->nr_sge;
 
-	if (iov_iter_is_discard(iter) ||
-	    iov_iter_is_pipe(iter) ||
-	    user_backed_iter(iter)) {
-		WARN_ON_ONCE(1);
-		return -EIO;
-	}
-
 	switch (iov_iter_type(iter)) {
 	case ITER_BVEC:
 		ret = smb_extract_bvec_to_rdma(iter, rdma, len);
@@ -2625,7 +2589,8 @@ static ssize_t smb_extract_iter_to_rdma(struct iov_iter *iter, size_t len,
 		ret = smb_extract_xarray_to_rdma(iter, rdma, len);
 		break;
 	default:
-		BUG();
+		WARN_ON_ONCE(1);
+		return -EIO;
 	}
 
 	if (ret > 0) {
diff --git a/fs/cifs/smbdirect.h b/fs/cifs/smbdirect.h
index be2cf18b7fec..83f239f376f0 100644
--- a/fs/cifs/smbdirect.h
+++ b/fs/cifs/smbdirect.h
@@ -288,8 +288,7 @@ struct smbd_mr {
 	struct list_head	list;
 	enum mr_state		state;
 	struct ib_mr		*mr;
-	struct scatterlist	*sgl;
-	int			sgl_count;
+	struct sg_table		sgt;
 	enum dma_data_direction	dir;
 	union {
 		struct ib_reg_wr	wr;

[RFC 11/13] cifs: Remove unused code

[David Howells]

Remove a bunch of functions that are no longer used and are commented out
after the conversion to use iterators throughout the I/O path.

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

Link: https://lore.kernel.org/r/164928621823.457102.8777804402615654773.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/165211421039.3154751.15199634443157779005.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/165348881165.2106726.2993852968344861224.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/165364827876.3334034.9331465096417303889.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/166126396915.708021.2010212654244139442.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/166697261080.61150.17513116912567922274.stgit@warthog.procyon.org.uk/ # rfc
Link: https://lore.kernel.org/r/166732033255.3186319.5527423437137895940.stgit@warthog.procyon.org.uk/ # rfc
---
 fs/cifs/file.c | 606 -------------------------------------------------
 1 file changed, 606 deletions(-)

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 8cf8ff2fc97b..89d59723bda8 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2603,314 +2603,6 @@ static int cifs_partialpagewrite(struct page *page, unsigned from, unsigned to)
 	return rc;
 }
 
-#if 0 // TODO: Remove for iov_iter support
-static struct cifs_writedata *
-wdata_alloc_and_fillpages(pgoff_t tofind, struct address_space *mapping,
-			  pgoff_t end, pgoff_t *index,
-			  unsigned int *found_pages)
-{
-	struct cifs_writedata *wdata;
-
-	wdata = cifs_writedata_alloc((unsigned int)tofind,
-				     cifs_writev_complete);
-	if (!wdata)
-		return NULL;
-
-	*found_pages = find_get_pages_range_tag(mapping, index, end,
-				PAGECACHE_TAG_DIRTY, tofind, wdata->pages);
-	return wdata;
-}
-
-static unsigned int
-wdata_prepare_pages(struct cifs_writedata *wdata, unsigned int found_pages,
-		    struct address_space *mapping,
-		    struct writeback_control *wbc,
-		    pgoff_t end, pgoff_t *index, pgoff_t *next, bool *done)
-{
-	unsigned int nr_pages = 0, i;
-	struct page *page;
-
-	for (i = 0; i < found_pages; i++) {
-		page = wdata->pages[i];
-		/*
-		 * At this point we hold neither the i_pages lock nor the
-		 * page lock: the page may be truncated or invalidated
-		 * (changing page->mapping to NULL), or even swizzled
-		 * back from swapper_space to tmpfs file mapping
-		 */
-
-		if (nr_pages == 0)
-			lock_page(page);
-		else if (!trylock_page(page))
-			break;
-
-		if (unlikely(page->mapping != mapping)) {
-			unlock_page(page);
-			break;
-		}
-
-		if (!wbc->range_cyclic && page->index > end) {
-			*done = true;
-			unlock_page(page);
-			break;
-		}
-
-		if (*next && (page->index != *next)) {
-			/* Not next consecutive page */
-			unlock_page(page);
-			break;
-		}
-
-		if (wbc->sync_mode != WB_SYNC_NONE)
-			wait_on_page_writeback(page);
-
-		if (PageWriteback(page) ||
-				!clear_page_dirty_for_io(page)) {
-			unlock_page(page);
-			break;
-		}
-
-		/*
-		 * This actually clears the dirty bit in the radix tree.
-		 * See cifs_writepage() for more commentary.
-		 */
-		set_page_writeback(page);
-		if (page_offset(page) >= i_size_read(mapping->host)) {
-			*done = true;
-			unlock_page(page);
-			end_page_writeback(page);
-			break;
-		}
-
-		wdata->pages[i] = page;
-		*next = page->index + 1;
-		++nr_pages;
-	}
-
-	/* reset index to refind any pages skipped */
-	if (nr_pages == 0)
-		*index = wdata->pages[0]->index + 1;
-
-	/* put any pages we aren't going to use */
-	for (i = nr_pages; i < found_pages; i++) {
-		put_page(wdata->pages[i]);
-		wdata->pages[i] = NULL;
-	}
-
-	return nr_pages;
-}
-
-static int
-wdata_send_pages(struct cifs_writedata *wdata, unsigned int nr_pages,
-		 struct address_space *mapping, struct writeback_control *wbc)
-{
-	int rc;
-
-	wdata->sync_mode = wbc->sync_mode;
-	wdata->nr_pages = nr_pages;
-	wdata->offset = page_offset(wdata->pages[0]);
-	wdata->pagesz = PAGE_SIZE;
-	wdata->tailsz = min(i_size_read(mapping->host) -
-			page_offset(wdata->pages[nr_pages - 1]),
-			(loff_t)PAGE_SIZE);
-	wdata->bytes = ((nr_pages - 1) * PAGE_SIZE) + wdata->tailsz;
-	wdata->pid = wdata->cfile->pid;
-
-	rc = adjust_credits(wdata->server, &wdata->credits, wdata->bytes);
-	if (rc)
-		return rc;
-
-	if (wdata->cfile->invalidHandle)
-		rc = -EAGAIN;
-	else
-		rc = wdata->server->ops->async_writev(wdata,
-						      cifs_writedata_release);
-
-	return rc;
-}
-
-static int
-cifs_writepage_locked(struct page *page, struct writeback_control *wbc);
-
-static int cifs_write_one_page(struct page *page, struct writeback_control *wbc,
-		void *data)
-{
-	struct address_space *mapping = data;
-	int ret;
-
-	ret = cifs_writepage_locked(page, wbc);
-	unlock_page(page);
-	mapping_set_error(mapping, ret);
-	return ret;
-}
-
-static int cifs_writepages(struct address_space *mapping,
-			   struct writeback_control *wbc)
-{
-	struct inode *inode = mapping->host;
-	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
-	struct TCP_Server_Info *server;
-	bool done = false, scanned = false, range_whole = false;
-	pgoff_t end, index;
-	struct cifs_writedata *wdata;
-	struct cifsFileInfo *cfile = NULL;
-	int rc = 0;
-	int saved_rc = 0;
-	unsigned int xid;
-
-	/*
-	 * If wsize is smaller than the page cache size, default to writing
-	 * one page at a time.
-	 */
-	if (cifs_sb->ctx->wsize < PAGE_SIZE)
-		return write_cache_pages(mapping, wbc, cifs_write_one_page,
-				mapping);
-
-	xid = get_xid();
-	if (wbc->range_cyclic) {
-		index = mapping->writeback_index; /* Start from prev offset */
-		end = -1;
-	} else {
-		index = wbc->range_start >> PAGE_SHIFT;
-		end = wbc->range_end >> PAGE_SHIFT;
-		if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
-			range_whole = true;
-		scanned = true;
-	}
-	server = cifs_pick_channel(cifs_sb_master_tcon(cifs_sb)->ses);
-
-retry:
-	while (!done && index <= end) {
-		unsigned int i, nr_pages, found_pages, wsize;
-		pgoff_t next = 0, tofind, saved_index = index;
-		struct cifs_credits credits_on_stack;
-		struct cifs_credits *credits = &credits_on_stack;
-		int get_file_rc = 0;
-
-		if (cfile)
-			cifsFileInfo_put(cfile);
-
-		rc = cifs_get_writable_file(CIFS_I(inode), FIND_WR_ANY, &cfile);
-
-		/* in case of an error store it to return later */
-		if (rc)
-			get_file_rc = rc;
-
-		rc = server->ops->wait_mtu_credits(server, cifs_sb->ctx->wsize,
-						   &wsize, credits);
-		if (rc != 0) {
-			done = true;
-			break;
-		}
-
-		tofind = min((wsize / PAGE_SIZE) - 1, end - index) + 1;
-
-		wdata = wdata_alloc_and_fillpages(tofind, mapping, end, &index,
-						  &found_pages);
-		if (!wdata) {
-			rc = -ENOMEM;
-			done = true;
-			add_credits_and_wake_if(server, credits, 0);
-			break;
-		}
-
-		if (found_pages == 0) {
-			kref_put(&wdata->refcount, cifs_writedata_release);
-			add_credits_and_wake_if(server, credits, 0);
-			break;
-		}
-
-		nr_pages = wdata_prepare_pages(wdata, found_pages, mapping, wbc,
-					       end, &index, &next, &done);
-
-		/* nothing to write? */
-		if (nr_pages == 0) {
-			kref_put(&wdata->refcount, cifs_writedata_release);
-			add_credits_and_wake_if(server, credits, 0);
-			continue;
-		}
-
-		wdata->credits = credits_on_stack;
-		wdata->cfile = cfile;
-		wdata->server = server;
-		cfile = NULL;
-
-		if (!wdata->cfile) {
-			cifs_dbg(VFS, "No writable handle in writepages rc=%d\n",
-				 get_file_rc);
-			if (is_retryable_error(get_file_rc))
-				rc = get_file_rc;
-			else
-				rc = -EBADF;
-		} else
-			rc = wdata_send_pages(wdata, nr_pages, mapping, wbc);
-
-		for (i = 0; i < nr_pages; ++i)
-			unlock_page(wdata->pages[i]);
-
-		/* send failure -- clean up the mess */
-		if (rc != 0) {
-			add_credits_and_wake_if(server, &wdata->credits, 0);
-			for (i = 0; i < nr_pages; ++i) {
-				if (is_retryable_error(rc))
-					redirty_page_for_writepage(wbc,
-							   wdata->pages[i]);
-				else
-					SetPageError(wdata->pages[i]);
-				end_page_writeback(wdata->pages[i]);
-				put_page(wdata->pages[i]);
-			}
-			if (!is_retryable_error(rc))
-				mapping_set_error(mapping, rc);
-		}
-		kref_put(&wdata->refcount, cifs_writedata_release);
-
-		if (wbc->sync_mode == WB_SYNC_ALL && rc == -EAGAIN) {
-			index = saved_index;
-			continue;
-		}
-
-		/* Return immediately if we received a signal during writing */
-		if (is_interrupt_error(rc)) {
-			done = true;
-			break;
-		}
-
-		if (rc != 0 && saved_rc == 0)
-			saved_rc = rc;
-
-		wbc->nr_to_write -= nr_pages;
-		if (wbc->nr_to_write <= 0)
-			done = true;
-
-		index = next;
-	}
-
-	if (!scanned && !done) {
-		/*
-		 * We hit the last page and there is more work to be done: wrap
-		 * back to the start of the file
-		 */
-		scanned = true;
-		index = 0;
-		goto retry;
-	}
-
-	if (saved_rc != 0)
-		rc = saved_rc;
-
-	if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
-		mapping->writeback_index = index;
-
-	if (cfile)
-		cifsFileInfo_put(cfile);
-	free_xid(xid);
-	/* Indication to update ctime and mtime as close is deferred */
-	set_bit(CIFS_INO_MODIFIED_ATTR, &CIFS_I(inode)->flags);
-	return rc;
-}
-#endif
-
 /*
  * Extend the region to be written back to include subsequent contiguously
  * dirty pages if possible, but don't sleep while doing so.
@@ -3505,49 +3197,6 @@ int cifs_flush(struct file *file, fl_owner_t id)
 	return rc;
 }
 
-#if 0 // TODO: Remove for iov_iter support
-static int
-cifs_write_allocate_pages(struct page **pages, unsigned long num_pages)
-{
-	int rc = 0;
-	unsigned long i;
-
-	for (i = 0; i < num_pages; i++) {
-		pages[i] = alloc_page(GFP_KERNEL|__GFP_HIGHMEM);
-		if (!pages[i]) {
-			/*
-			 * save number of pages we have already allocated and
-			 * return with ENOMEM error
-			 */
-			num_pages = i;
-			rc = -ENOMEM;
-			break;
-		}
-	}
-
-	if (rc) {
-		for (i = 0; i < num_pages; i++)
-			put_page(pages[i]);
-	}
-	return rc;
-}
-
-static inline
-size_t get_numpages(const size_t wsize, const size_t len, size_t *cur_len)
-{
-	size_t num_pages;
-	size_t clen;
-
-	clen = min_t(const size_t, len, wsize);
-	num_pages = DIV_ROUND_UP(clen, PAGE_SIZE);
-
-	if (cur_len)
-		*cur_len = clen;
-
-	return num_pages;
-}
-#endif
-
 static void
 cifs_uncached_writedata_release(struct kref *refcount)
 {
@@ -3580,50 +3229,6 @@ cifs_uncached_writev_complete(struct work_struct *work)
 	kref_put(&wdata->refcount, cifs_uncached_writedata_release);
 }
 
-#if 0 // TODO: Remove for iov_iter support
-static int
-wdata_fill_from_iovec(struct cifs_writedata *wdata, struct iov_iter *from,
-		      size_t *len, unsigned long *num_pages)
-{
-	size_t save_len, copied, bytes, cur_len = *len;
-	unsigned long i, nr_pages = *num_pages;
-
-	save_len = cur_len;
-	for (i = 0; i < nr_pages; i++) {
-		bytes = min_t(const size_t, cur_len, PAGE_SIZE);
-		copied = copy_page_from_iter(wdata->pages[i], 0, bytes, from);
-		cur_len -= copied;
-		/*
-		 * If we didn't copy as much as we expected, then that
-		 * may mean we trod into an unmapped area. Stop copying
-		 * at that point. On the next pass through the big
-		 * loop, we'll likely end up getting a zero-length
-		 * write and bailing out of it.
-		 */
-		if (copied < bytes)
-			break;
-	}
-	cur_len = save_len - cur_len;
-	*len = cur_len;
-
-	/*
-	 * If we have no data to send, then that probably means that
-	 * the copy above failed altogether. That's most likely because
-	 * the address in the iovec was bogus. Return -EFAULT and let
-	 * the caller free anything we allocated and bail out.
-	 */
-	if (!cur_len)
-		return -EFAULT;
-
-	/*
-	 * i + 1 now represents the number of pages we actually used in
-	 * the copy phase above.
-	 */
-	*num_pages = i + 1;
-	return 0;
-}
-#endif
-
 static int
 cifs_resend_wdata(struct cifs_writedata *wdata, struct list_head *wdata_list,
 	struct cifs_aio_ctx *ctx)
@@ -4210,83 +3815,6 @@ cifs_uncached_readv_complete(struct work_struct *work)
 	kref_put(&rdata->refcount, cifs_readdata_release);
 }
 
-#if 0 // TODO: Remove for iov_iter support
-
-static int
-uncached_fill_pages(struct TCP_Server_Info *server,
-		    struct cifs_readdata *rdata, struct iov_iter *iter,
-		    unsigned int len)
-{
-	int result = 0;
-	unsigned int i;
-	unsigned int nr_pages = rdata->nr_pages;
-	unsigned int page_offset = rdata->page_offset;
-
-	rdata->got_bytes = 0;
-	rdata->tailsz = PAGE_SIZE;
-	for (i = 0; i < nr_pages; i++) {
-		struct page *page = rdata->pages[i];
-		size_t n;
-		unsigned int segment_size = rdata->pagesz;
-
-		if (i == 0)
-			segment_size -= page_offset;
-		else
-			page_offset = 0;
-
-
-		if (len <= 0) {
-			/* no need to hold page hostage */
-			rdata->pages[i] = NULL;
-			rdata->nr_pages--;
-			put_page(page);
-			continue;
-		}
-
-		n = len;
-		if (len >= segment_size)
-			/* enough data to fill the page */
-			n = segment_size;
-		else
-			rdata->tailsz = len;
-		len -= n;
-
-		if (iter)
-			result = copy_page_from_iter(
-					page, page_offset, n, iter);
-#ifdef CONFIG_CIFS_SMB_DIRECT
-		else if (rdata->mr)
-			result = n;
-#endif
-		else
-			result = cifs_read_page_from_socket(
-					server, page, page_offset, n);
-		if (result < 0)
-			break;
-
-		rdata->got_bytes += result;
-	}
-
-	return rdata->got_bytes > 0 && result != -ECONNABORTED ?
-						rdata->got_bytes : result;
-}
-
-static int
-cifs_uncached_read_into_pages(struct TCP_Server_Info *server,
-			      struct cifs_readdata *rdata, unsigned int len)
-{
-	return uncached_fill_pages(server, rdata, NULL, len);
-}
-
-static int
-cifs_uncached_copy_into_pages(struct TCP_Server_Info *server,
-			      struct cifs_readdata *rdata,
-			      struct iov_iter *iter)
-{
-	return uncached_fill_pages(server, rdata, iter, iter->count);
-}
-#endif
-
 static int cifs_resend_rdata(struct cifs_readdata *rdata,
 			struct list_head *rdata_list,
 			struct cifs_aio_ctx *ctx)
@@ -4897,140 +4425,6 @@ int cifs_file_mmap(struct file *file, struct vm_area_struct *vma)
 	return rc;
 }
 
-#if 0 // TODO: Remove for iov_iter support
-
-static void
-cifs_readv_complete(struct work_struct *work)
-{
-	unsigned int i, got_bytes;
-	struct cifs_readdata *rdata = container_of(work,
-						struct cifs_readdata, work);
-
-	got_bytes = rdata->got_bytes;
-	for (i = 0; i < rdata->nr_pages; i++) {
-		struct page *page = rdata->pages[i];
-
-		if (rdata->result == 0 ||
-		    (rdata->result == -EAGAIN && got_bytes)) {
-			flush_dcache_page(page);
-			SetPageUptodate(page);
-		} else
-			SetPageError(page);
-
-		if (rdata->result == 0 ||
-		    (rdata->result == -EAGAIN && got_bytes))
-			cifs_readpage_to_fscache(rdata->mapping->host, page);
-
-		unlock_page(page);
-
-		got_bytes -= min_t(unsigned int, PAGE_SIZE, got_bytes);
-
-		put_page(page);
-		rdata->pages[i] = NULL;
-	}
-	kref_put(&rdata->refcount, cifs_readdata_release);
-}
-
-static int
-readpages_fill_pages(struct TCP_Server_Info *server,
-		     struct cifs_readdata *rdata, struct iov_iter *iter,
-		     unsigned int len)
-{
-	int result = 0;
-	unsigned int i;
-	u64 eof;
-	pgoff_t eof_index;
-	unsigned int nr_pages = rdata->nr_pages;
-	unsigned int page_offset = rdata->page_offset;
-
-	/* determine the eof that the server (probably) has */
-	eof = CIFS_I(rdata->mapping->host)->server_eof;
-	eof_index = eof ? (eof - 1) >> PAGE_SHIFT : 0;
-	cifs_dbg(FYI, "eof=%llu eof_index=%lu\n", eof, eof_index);
-
-	rdata->got_bytes = 0;
-	rdata->tailsz = PAGE_SIZE;
-	for (i = 0; i < nr_pages; i++) {
-		struct page *page = rdata->pages[i];
-		unsigned int to_read = rdata->pagesz;
-		size_t n;
-
-		if (i == 0)
-			to_read -= page_offset;
-		else
-			page_offset = 0;
-
-		n = to_read;
-
-		if (len >= to_read) {
-			len -= to_read;
-		} else if (len > 0) {
-			/* enough for partial page, fill and zero the rest */
-			zero_user(page, len + page_offset, to_read - len);
-			n = rdata->tailsz = len;
-			len = 0;
-		} else if (page->index > eof_index) {
-			/*
-			 * The VFS will not try to do readahead past the
-			 * i_size, but it's possible that we have outstanding
-			 * writes with gaps in the middle and the i_size hasn't
-			 * caught up yet. Populate those with zeroed out pages
-			 * to prevent the VFS from repeatedly attempting to
-			 * fill them until the writes are flushed.
-			 */
-			zero_user(page, 0, PAGE_SIZE);
-			flush_dcache_page(page);
-			SetPageUptodate(page);
-			unlock_page(page);
-			put_page(page);
-			rdata->pages[i] = NULL;
-			rdata->nr_pages--;
-			continue;
-		} else {
-			/* no need to hold page hostage */
-			unlock_page(page);
-			put_page(page);
-			rdata->pages[i] = NULL;
-			rdata->nr_pages--;
-			continue;
-		}
-
-		if (iter)
-			result = copy_page_from_iter(
-					page, page_offset, n, iter);
-#ifdef CONFIG_CIFS_SMB_DIRECT
-		else if (rdata->mr)
-			result = n;
-#endif
-		else
-			result = cifs_read_page_from_socket(
-					server, page, page_offset, n);
-		if (result < 0)
-			break;
-
-		rdata->got_bytes += result;
-	}
-
-	return rdata->got_bytes > 0 && result != -ECONNABORTED ?
-						rdata->got_bytes : result;
-}
-
-static int
-cifs_readpages_read_into_pages(struct TCP_Server_Info *server,
-			       struct cifs_readdata *rdata, unsigned int len)
-{
-	return readpages_fill_pages(server, rdata, NULL, len);
-}
-
-static int
-cifs_readpages_copy_into_pages(struct TCP_Server_Info *server,
-			       struct cifs_readdata *rdata,
-			       struct iov_iter *iter)
-{
-	return readpages_fill_pages(server, rdata, iter, iter->count);
-}
-#endif
-
 /*
  * Unlock a bunch of folios in the pagecache.
  */

[RFC 12/13] cifs: Fix problem with encrypted RDMA data read

[David Howells]

When the cifs client is talking to the ksmbd server by RDMA and the ksmbd
server has "smb3 encryption = yes" in its config file, the normal PDU
stream is encrypted, but the directly-delivered data isn't in the stream
(and isn't encrypted), but is rather delivered by DDP/RDMA packets (at
least with IWarp).

Currently, the direct delivery fails with:

   buf can not contain only a part of read data
   WARNING: CPU: 0 PID: 4619 at fs/cifs/smb2ops.c:4731 handle_read_data+0x393/0x405
   ...
   RIP: 0010:handle_read_data+0x393/0x405
   ...
    smb3_handle_read_data+0x30/0x37
    receive_encrypted_standard+0x141/0x224
    cifs_demultiplex_thread+0x21a/0x63b
    kthread+0xe7/0xef
    ret_from_fork+0x22/0x30

The problem apparently stemming from the fact that it's trying to manage
the decryption, but the data isn't in the smallbuf, the bigbuf or the page
array).

This can be fixed simply by inserting an extra case into handle_read_data()
that checks to see if use_rdma_mr is true, and if it is, just setting
rdata->got_bytes to the length of data delivered and allowing normal
continuation.

This can be seen in an IWarp packet trace.  With the upstream code, it does
a DDP/RDMA packet, which produces the warning above and then retries,
retrieving the data inline, spread across several SMBDirect messages that
get glued together into a single PDU.  With the patch applied, only the
DDP/RDMA packet is seen.

Note that this doesn't happen if the server isn't told to encrypt stuff and
it does also happen with softRoCE.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Steve French <smfrench@gmail.com>
cc: Tom Talpey <tom@talpey.com>
cc: Long Li <longli@microsoft.com>
cc: Namjae Jeon <linkinjeon@kernel.org>
cc: Stefan Metzmacher <metze@samba.org>
cc: linux-cifs@vger.kernel.org

Link: https://lore.kernel.org/r/166855224228.1998592.2212551359609792175.stgit@warthog.procyon.org.uk/ # v1
---
 fs/cifs/smb2ops.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 335080893ebc..aba6643e0869 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -4721,6 +4721,9 @@ handle_read_data(struct TCP_Server_Info *server, struct mid_q_entry *mid,
 		if (length < 0)
 			return length;
 		rdata->got_bytes = data_len;
+	} else if (use_rdma_mr) {
+		/* The data was delivered directly by RDMA. */
+		rdata->got_bytes = data_len;
 	} else {
 		/* read response payload cannot be in both buf and pages */
 		WARN_ONCE(1, "buf can not contain only a part of read data");

[RFC 13/13] cifs: DIO to/from KVEC-type iterators should now work

[David Howells]

DIO to/from KVEC-type iterators should now work as the iterator is passed
down to the socket in non-RDMA/non-crypto mode and in RDMA or crypto mode
care is taken to handle vmap/vmalloc correctly and not take page refs when
building a scatterlist.

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: Tom Talpey <tom@talpey.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: linux-cifs@vger.kernel.org
---
 fs/cifs/file.c | 20 --------------------
 1 file changed, 20 deletions(-)

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 89d59723bda8..98d3ad86995d 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -3545,16 +3545,6 @@ static ssize_t __cifs_writev(
 	struct cifs_aio_ctx *ctx;
 	int rc;
 
-	/*
-	 * iov_iter_get_pages_alloc doesn't work with ITER_KVEC.
-	 * In this case, fall back to non-direct write function.
-	 * this could be improved by getting pages directly in ITER_KVEC
-	 */
-	if (direct && iov_iter_is_kvec(from)) {
-		cifs_dbg(FYI, "use non-direct cifs_writev for kvec I/O\n");
-		direct = false;
-	}
-
 	rc = generic_write_checks(iocb, from);
 	if (rc <= 0)
 		return rc;
@@ -4088,16 +4078,6 @@ static ssize_t __cifs_readv(
 	loff_t offset = iocb->ki_pos;
 	struct cifs_aio_ctx *ctx;
 
-	/*
-	 * iov_iter_get_pages_alloc() doesn't work with ITER_KVEC,
-	 * fall back to data copy read path
-	 * this could be improved by getting pages directly in ITER_KVEC
-	 */
-	if (direct && iov_iter_is_kvec(to)) {
-		cifs_dbg(FYI, "use non-direct cifs_user_readv for kvec I/O\n");
-		direct = false;
-	}
-
 	len = iov_iter_count(to);
 	if (!len)
 		return 0;

RE: [RFC 08/13] cifs: Add a function to read into an iter from a socket

[David Laight]

From: David Howells
> Sent: 25 January 2023 21:46

> Add a helper function to read data from a socket into the given iterator.
...
> +int
> +cifs_read_iter_from_socket(struct TCP_Server_Info *server, struct iov_iter *iter,
> +			   unsigned int to_read)
> +{
> +	struct msghdr smb_msg;
> +	int ret;
> +
> +	smb_msg.msg_iter = *iter;
> +	if (smb_msg.msg_iter.count > to_read)
> +		smb_msg.msg_iter.count = to_read;
> +	ret = cifs_readv_from_socket(server, &smb_msg);
> +	if (ret > 0)
> +		iov_iter_advance(iter, ret);
> +	return ret;
> +}

On the face of it that passes a largely uninitialised 'struct msghdr'
to cifs_readv_from_socket() in order to pass an iov_iter.
That seems to be asking for trouble.

I'm also not 100% sure that taking a copy of an iov_iter is a good idea.

If cifs_readv_from_socket() only needs the iov_iter then wouldn't
it be better to do the wrapper the other way around?
(Probably as an inline function)
Something like:

int
cifs_readv_from_socket(struct TCP_Server_Info *server, struct msghdr *smb_msg)
{
	return cifs_read_iter_from_socket(server, &smb_msg->msg_iter, smb_msg->msg_iter.count);
}

and then changing cifs_readv_from_socket() to just use the iov_iter.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)

Re: [RFC 08/13] cifs: Add a function to read into an iter from a socket

[David Howells]

David Laight <David.Laight@ACULAB.COM> wrote:

> On the face of it that passes a largely uninitialised 'struct msghdr'
> to cifs_readv_from_socket() in order to pass an iov_iter.
> That seems to be asking for trouble.
> 
> If cifs_readv_from_socket() only needs the iov_iter then wouldn't
> it be better to do the wrapper the other way around?
> (Probably as an inline function)
> Something like:
> 
> int
> cifs_readv_from_socket(struct TCP_Server_Info *server, struct msghdr *smb_msg)
> {
> 	return cifs_read_iter_from_socket(server, &smb_msg->msg_iter, smb_msg->msg_iter.count);
> }
> 
> and then changing cifs_readv_from_socket() to just use the iov_iter.

Yeah.  And smbd_recv() only cares about the iterator too.

> I'm also not 100% sure that taking a copy of an iov_iter is a good idea.

It shouldn't matter as the only problematic iterator is ITER_PIPE (advancing
that has side effects) - and splice_read is handled specially by patch 4.  The
problem with splice_read with the way cifs works is that it likes to subdivide
its read/write requests across multiple reqs and then subsubdivide them if
certain types of failure occur.  But you can't do that with ITER_PIPE.

I build an ITER_BVEC from ITER_PIPE, ITER_UBUF and ITER_IOVEC in the top
levels with pins inserted as appropriate and hand the ITER_BVEC down.  For
user-backed iterators it has to be done this way because the I/O may get
shuffled off to a different thread.

Reqs can then just copy the BVEC/XARRAY/KVEC and narrow the region because the
master request at the top does holds the vector list and the top cifs level or
the caller above the vfs (eg. sys_execve) does what is necessary to retain the
pages.

David

RE: [RFC 08/13] cifs: Add a function to read into an iter from a socket

[David Laight]

From: David Howells
> Sent: 26 January 2023 15:44
...
> > I'm also not 100% sure that taking a copy of an iov_iter is a good idea.
> 
> It shouldn't matter as the only problematic iterator is ITER_PIPE (advancing
> that has side effects) - and splice_read is handled specially by patch 4.  The
> problem with splice_read with the way cifs works is that it likes to subdivide
> its read/write requests across multiple reqs and then subsubdivide them if
> certain types of failure occur.  But you can't do that with ITER_PIPE.

I was thinking that even if ok at the moment it might be troublesome later.
Somewhere I started writing a patch to put the iov_cache[] for user
requests into the same structure as the iterator.
Copying those might cause oddities.

> I build an ITER_BVEC from ITER_PIPE, ITER_UBUF and ITER_IOVEC in the top
> levels with pins inserted as appropriate and hand the ITER_BVEC down.  For
> user-backed iterators it has to be done this way because the I/O may get
> shuffled off to a different thread.

For sub-page sided transfers it is probably worth doing a bounce buffer
copy of user requests - just to save all the complex page pinning code.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)

Re: [RFC 08/13] cifs: Add a function to read into an iter from a socket

[David Howells]

David Laight <David.Laight@ACULAB.COM> wrote:

> > It shouldn't matter as the only problematic iterator is ITER_PIPE
> > (advancing that has side effects) - and splice_read is handled specially
> > by patch 4.  The problem with splice_read with the way cifs works is that
> > it likes to subdivide its read/write requests across multiple reqs and
> > then subsubdivide them if certain types of failure occur.  But you can't
> > do that with ITER_PIPE.
> 
> I was thinking that even if ok at the moment it might be troublesome later.
> Somewhere I started writing a patch to put the iov_cache[] for user
> requests into the same structure as the iterator.
> Copying those might cause oddities.

Well, there is dup_iter(), but that copies the vector table, which isn't what
we want in a number of cases.  You probably need to come up with a wrapper for
that.

But we copy iters by assignment in a lot of places.  With regards to msg_hdr,
it might be worth giving it an iterator pointer rather than its own iterator.

I've just had a go at attempting to modify the code.
cifs_read_iter_from_socket() wants to copy the iterator and truncate the copy,
which makes things slightly trickier.  For both of the call sites,
receive_encrypted_read() and cifs_readv_receive(), it can do the truncation
before calling cifs_read_iter_from_socket(), I think - but it may have to undo
the truncation afterwards.

> > I build an ITER_BVEC from ITER_PIPE, ITER_UBUF and ITER_IOVEC in the top
> > levels with pins inserted as appropriate and hand the ITER_BVEC down.  For
> > user-backed iterators it has to be done this way because the I/O may get
> > shuffled off to a different thread.
> 
> For sub-page sided transfers it is probably worth doing a bounce buffer
> copy of user requests - just to save all the complex page pinning code.

You can't avoid it for async DIO reads.  But that sort of thing I'm intending
to do in netfslib.

David

Re: [RFC 06/13] cifs: Add a function to Hash the contents of an iterator

[Herbert Xu]

David Howells <dhowells@redhat.com> wrote:
>
> diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c
> index cbc18b4a9cb2..7be589aeb520 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);

Please convert this to ahash.  The whole point of shash is to
process *small* amounts of data that is not on an SG list.

Cheers,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

Re: [RFC 06/13] cifs: Add a function to Hash the contents of an iterator

[David Howells]

Herbert Xu <herbert@gondor.apana.org.au> wrote:

> Please convert this to ahash.  The whole point of shash is to
> process *small* amounts of data that is not on an SG list.

Is ahash offloaded to another thread or hardware?

David

Re: [RFC 06/13] cifs: Add a function to Hash the contents of an iterator

[Herbert Xu]

On Fri, Jan 27, 2023 at 10:33:58AM +0000, David Howells wrote:
> Herbert Xu <herbert@gondor.apana.org.au> wrote:
> 
> > Please convert this to ahash.  The whole point of shash is to
> > process *small* amounts of data that is not on an SG list.
> 
> Is ahash offloaded to another thread or hardware?

That's something you can control when you allocate the ahash
object? You could even restrict it to sync algorithms by setting
type to 0 and mask to CRYPTO_ALG_SYNC.

Cheers,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt