netfs: Use new folio_queue data type and iterator instead of xarray iter

Make the netfs write-side routines use the new folio_queue struct to hold a
rolling buffer of folios, with the issuer adding folios at the tail and the
collector removing them from the head as they're processed instead of using
an xarray.

This will allow a subsequent patch to simplify the write collector.

The primary mark (as tested by folioq_is_marked()) is used to note if the
corresponding folio needs putting.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/20240814203850.2240469-16-dhowells@redhat.com/ # v2
Signed-off-by: Christian Brauner <brauner@kernel.org>

1 files changed, 13 insertions, 15 deletions

diff --git a/fs/netfs/write_issue.c b/fs/netfs/write_issue.c
index 7880a586343f..a75b62b202c5 100644
--- a/fs/netfs/write_issue.c
+++ b/fs/netfs/write_issue.c
@@ -213,9 +213,11 @@ static void netfs_prepare_write(struct netfs_io_request *wreq,
  * netfs_write_subrequest_terminated() when complete.
  */
 static void netfs_do_issue_write(struct netfs_io_stream *stream,
-				 struct netfs_io_subrequest *subreq)
+				 struct netfs_io_subrequest *subreq,
+				 struct iov_iter *source)
 {
 	struct netfs_io_request *wreq = subreq->rreq;
+	size_t size = subreq->len - subreq->transferred;
 
 	_enter("R=%x[%x],%zx", wreq->debug_id, subreq->debug_index, subreq->len);
 
@@ -223,27 +225,20 @@ static void netfs_do_issue_write(struct netfs_io_stream *stream,
 		return netfs_write_subrequest_terminated(subreq, subreq->error, false);
 
 	// TODO: Use encrypted buffer
-	if (test_bit(NETFS_RREQ_USE_IO_ITER, &wreq->flags)) {
-		subreq->io_iter = wreq->io_iter;
-		iov_iter_advance(&subreq->io_iter,
-				 subreq->start + subreq->transferred - wreq->start);
-		iov_iter_truncate(&subreq->io_iter,
-				 subreq->len - subreq->transferred);
-	} else {
-		iov_iter_xarray(&subreq->io_iter, ITER_SOURCE, &wreq->mapping->i_pages,
-				subreq->start + subreq->transferred,
-				subreq->len   - subreq->transferred);
-	}
+	subreq->io_iter = *source;
+	iov_iter_advance(source, size);
+	iov_iter_truncate(&subreq->io_iter, size);
 
 	trace_netfs_sreq(subreq, netfs_sreq_trace_submit);
 	stream->issue_write(subreq);
 }
 
 void netfs_reissue_write(struct netfs_io_stream *stream,
-			 struct netfs_io_subrequest *subreq)
+			 struct netfs_io_subrequest *subreq,
+			 struct iov_iter *source)
 {
 	__set_bit(NETFS_SREQ_IN_PROGRESS, &subreq->flags);
-	netfs_do_issue_write(stream, subreq);
+	netfs_do_issue_write(stream, subreq, source);
 }
 
 static void netfs_issue_write(struct netfs_io_request *wreq,
@@ -257,7 +252,7 @@ static void netfs_issue_write(struct netfs_io_request *wreq,
 
 	if (subreq->start + subreq->len > wreq->start + wreq->submitted)
 		WRITE_ONCE(wreq->submitted, subreq->start + subreq->len - wreq->start);
-	netfs_do_issue_write(stream, subreq);
+	netfs_do_issue_write(stream, subreq, &wreq->io_iter);
 }
 
 /*
@@ -422,6 +417,9 @@ static int netfs_write_folio(struct netfs_io_request *wreq,
 		trace_netfs_folio(folio, netfs_folio_trace_store_plus);
 	}
 
+	/* Attach the folio to the rolling buffer. */
+	netfs_buffer_append_folio(wreq, folio, false);
+
 	/* Move the submission point forward to allow for write-streaming data
 	 * not starting at the front of the page.  We don't do write-streaming
 	 * with the cache as the cache requires DIO alignment.