Merge tag '6.3-rc-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6

Pull cifs client updates from Steve French:
 "The largest subset of this is from David Howells et al: making the
  cifs/smb3 driver pass iov_iters down to the lowest layers, directly to
  the network transport rather than passing lists of pages around,
  helping multiple areas:

   - Pin user pages, thereby fixing the race between concurrent DIO read
     and fork, where 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.

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

   - Allowing cifs to use the new splice function

  The remainder are:

   - fixes for stable, including various fixes for uninitialized memory,
     wrong length field causing mount issue to very old servers,
     important directory lease fixes and reconnect fixes

   - cleanups (unused code removal, change one element array usage, and
     a change form strtobool to kstrtobool, and Kconfig cleanups)

   - SMBDIRECT (RDMA) fixes including iov_iter integration and UAF fixes

   - reconnect fixes

   - multichannel fixes, including improving channel allocation (to
     least used channel)

   - remove the last use of lock_page_killable by moving to
     folio_lock_killable"

* tag '6.3-rc-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6: (46 commits)
  update internal module version number for cifs.ko
  cifs: update ip_addr for ses only for primary chan setup
  cifs: use tcon allocation functions even for dummy tcon
  cifs: use the least loaded channel for sending requests
  cifs: DIO to/from KVEC-type iterators should now work
  cifs: Remove unused code
  cifs: Build the RDMA SGE list directly from an iterator
  cifs: Change the I/O paths to use an iterator rather than a page list
  cifs: Add a function to read into an iter from a socket
  cifs: Add some helper functions
  cifs: Add a function to Hash the contents of an iterator
  cifs: Add a function to build an RDMA SGE list from an iterator
  netfs: Add a function to extract an iterator into a scatterlist
  netfs: Add a function to extract a UBUF or IOVEC into a BVEC iterator
  cifs: Implement splice_read to pass down ITER_BVEC not ITER_PIPE
  splice: Export filemap/direct_splice_read()
  iov_iter: Add a function to extract a page list from an iterator
  iov_iter: Define flags to qualify page extraction.
  splice: Add a func to do a splice from an O_DIRECT file without ITER_PIPE
  splice: Add a func to do a splice from a buffered file without ITER_PIPE
  ...

3 files changed, 151 insertions, 13 deletions

diff --git a/mm/filemap.c b/mm/filemap.c
index 0e20a8d6dd93..b794943bce76 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -42,6 +42,8 @@
 #include <linux/ramfs.h>
 #include <linux/page_idle.h>
 #include <linux/migrate.h>
+#include <linux/pipe_fs_i.h>
+#include <linux/splice.h>
 #include <asm/pgalloc.h>
 #include <asm/tlbflush.h>
 #include "internal.h"
@@ -2440,21 +2442,19 @@ static int filemap_read_folio(struct file *file, filler_t filler,
 }
 
 static bool filemap_range_uptodate(struct address_space *mapping,
-		loff_t pos, struct iov_iter *iter, struct folio *folio)
+		loff_t pos, size_t count, struct folio *folio,
+		bool need_uptodate)
 {
-	int count;
-
 	if (folio_test_uptodate(folio))
 		return true;
 	/* pipes can't handle partially uptodate pages */
-	if (iov_iter_is_pipe(iter))
+	if (need_uptodate)
 		return false;
 	if (!mapping->a_ops->is_partially_uptodate)
 		return false;
 	if (mapping->host->i_blkbits >= folio_shift(folio))
 		return false;
 
-	count = iter->count;
 	if (folio_pos(folio) > pos) {
 		count -= folio_pos(folio) - pos;
 		pos = 0;
@@ -2466,8 +2466,8 @@ static bool filemap_range_uptodate(struct address_space *mapping,
 }
 
 static int filemap_update_page(struct kiocb *iocb,
-		struct address_space *mapping, struct iov_iter *iter,
-		struct folio *folio)
+		struct address_space *mapping, size_t count,
+		struct folio *folio, bool need_uptodate)
 {
 	int error;
 
@@ -2501,7 +2501,8 @@ static int filemap_update_page(struct kiocb *iocb,
 		goto unlock;
 
 	error = 0;
-	if (filemap_range_uptodate(mapping, iocb->ki_pos, iter, folio))
+	if (filemap_range_uptodate(mapping, iocb->ki_pos, count, folio,
+				   need_uptodate))
 		goto unlock;
 
 	error = -EAGAIN;
@@ -2577,8 +2578,8 @@ static int filemap_readahead(struct kiocb *iocb, struct file *file,
 	return 0;
 }
 
-static int filemap_get_pages(struct kiocb *iocb, struct iov_iter *iter,
-		struct folio_batch *fbatch)
+static int filemap_get_pages(struct kiocb *iocb, size_t count,
+		struct folio_batch *fbatch, bool need_uptodate)
 {
 	struct file *filp = iocb->ki_filp;
 	struct address_space *mapping = filp->f_mapping;
@@ -2589,7 +2590,7 @@ static int filemap_get_pages(struct kiocb *iocb, struct iov_iter *iter,
 	int err = 0;
 
 	/* "last_index" is the index of the page beyond the end of the read */
-	last_index = DIV_ROUND_UP(iocb->ki_pos + iter->count, PAGE_SIZE);
+	last_index = DIV_ROUND_UP(iocb->ki_pos + count, PAGE_SIZE);
 retry:
 	if (fatal_signal_pending(current))
 		return -EINTR;
@@ -2622,7 +2623,8 @@ retry:
 		if ((iocb->ki_flags & IOCB_WAITQ) &&
 		    folio_batch_count(fbatch) > 1)
 			iocb->ki_flags |= IOCB_NOWAIT;
-		err = filemap_update_page(iocb, mapping, iter, folio);
+		err = filemap_update_page(iocb, mapping, count, folio,
+					  need_uptodate);
 		if (err)
 			goto err;
 	}
@@ -2692,7 +2694,8 @@ ssize_t filemap_read(struct kiocb *iocb, struct iov_iter *iter,
 		if (unlikely(iocb->ki_pos >= i_size_read(inode)))
 			break;
 
-		error = filemap_get_pages(iocb, iter, &fbatch);
+		error = filemap_get_pages(iocb, iter->count, &fbatch,
+					  iov_iter_is_pipe(iter));
 		if (error < 0)
 			break;
 
@@ -2842,6 +2845,134 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
 }
 EXPORT_SYMBOL(generic_file_read_iter);
 
+/*
+ * Splice subpages from a folio into a pipe.
+ */
+size_t splice_folio_into_pipe(struct pipe_inode_info *pipe,
+			      struct folio *folio, loff_t fpos, size_t size)
+{
+	struct page *page;
+	size_t spliced = 0, offset = offset_in_folio(folio, fpos);
+
+	page = folio_page(folio, offset / PAGE_SIZE);
+	size = min(size, folio_size(folio) - offset);
+	offset %= PAGE_SIZE;
+
+	while (spliced < size &&
+	       !pipe_full(pipe->head, pipe->tail, pipe->max_usage)) {
+		struct pipe_buffer *buf = pipe_head_buf(pipe);
+		size_t part = min_t(size_t, PAGE_SIZE - offset, size - spliced);
+
+		*buf = (struct pipe_buffer) {
+			.ops	= &page_cache_pipe_buf_ops,
+			.page	= page,
+			.offset	= offset,
+			.len	= part,
+		};
+		folio_get(folio);
+		pipe->head++;
+		page++;
+		spliced += part;
+		offset = 0;
+	}
+
+	return spliced;
+}
+
+/*
+ * Splice folios from the pagecache of a buffered (ie. non-O_DIRECT) file into
+ * a pipe.
+ */
+ssize_t filemap_splice_read(struct file *in, loff_t *ppos,
+			    struct pipe_inode_info *pipe,
+			    size_t len, unsigned int flags)
+{
+	struct folio_batch fbatch;
+	struct kiocb iocb;
+	size_t total_spliced = 0, used, npages;
+	loff_t isize, end_offset;
+	bool writably_mapped;
+	int i, error = 0;
+
+	init_sync_kiocb(&iocb, in);
+	iocb.ki_pos = *ppos;
+
+	/* 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);
+
+	folio_batch_init(&fbatch);
+
+	do {
+		cond_resched();
+
+		if (*ppos >= i_size_read(file_inode(in)))
+			break;
+
+		iocb.ki_pos = *ppos;
+		error = filemap_get_pages(&iocb, len, &fbatch, true);
+		if (error < 0)
+			break;
+
+		/*
+		 * i_size must be checked after we know the pages are Uptodate.
+		 *
+		 * Checking i_size after the check allows us to calculate
+		 * the correct value for "nr", which means the zero-filled
+		 * part of the page is not copied back to userspace (unless
+		 * another truncate extends the file - this is desired though).
+		 */
+		isize = i_size_read(file_inode(in));
+		if (unlikely(*ppos >= isize))
+			break;
+		end_offset = min_t(loff_t, isize, *ppos + len);
+
+		/*
+		 * Once we start copying data, we don't want to be touching any
+		 * cachelines that might be contended:
+		 */
+		writably_mapped = mapping_writably_mapped(in->f_mapping);
+
+		for (i = 0; i < folio_batch_count(&fbatch); i++) {
+			struct folio *folio = fbatch.folios[i];
+			size_t n;
+
+			if (folio_pos(folio) >= end_offset)
+				goto out;
+			folio_mark_accessed(folio);
+
+			/*
+			 * If users can be writing to this folio using arbitrary
+			 * virtual addresses, take care of potential aliasing
+			 * before reading the folio on the kernel side.
+			 */
+			if (writably_mapped)
+				flush_dcache_folio(folio);
+
+			n = min_t(loff_t, len, isize - *ppos);
+			n = splice_folio_into_pipe(pipe, folio, *ppos, n);
+			if (!n)
+				goto out;
+			len -= n;
+			total_spliced += n;
+			*ppos += n;
+			in->f_ra.prev_pos = *ppos;
+			if (pipe_full(pipe->head, pipe->tail, pipe->max_usage))
+				goto out;
+		}
+
+		folio_batch_release(&fbatch);
+	} while (len);
+
+out:
+	folio_batch_release(&fbatch);
+	file_accessed(in);
+
+	return total_spliced ? total_spliced : error;
+}
+EXPORT_SYMBOL(filemap_splice_read);
+
 static inline loff_t folio_seek_hole_data(struct xa_state *xas,
 		struct address_space *mapping, struct folio *folio,
 		loff_t start, loff_t end, bool seek_data)
diff --git a/mm/internal.h b/mm/internal.h
index bcf75a8b032d..6d4ca98f3844 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -795,6 +795,12 @@ struct migration_target_control {
 };
 
 /*
+ * mm/filemap.c
+ */
+size_t splice_folio_into_pipe(struct pipe_inode_info *pipe,
+			      struct folio *folio, loff_t fpos, size_t size);
+
+/*
  * mm/vmalloc.c
  */
 #ifdef CONFIG_MMU
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