netfs: Refactor arguments for netfs_alloc_read_request

Pass start and len to the rreq allocator. This should ensure that the
fields are set so that ->init_request() can use them.

Also add a parameter to indicates the origin of the request.  Ceph can use
this to tell whether to get caps.

Changes
=======
ver #3)
 - Change the author to me as Jeff feels that most of the patch is my
   changes now.

ver #2)
 - Show the request origin in the netfs_rreq tracepoint.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Co-developed-by: David Howells <dhowells@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-cachefs@redhat.com

Link: https://lore.kernel.org/r/164622989020.3564931.17517006047854958747.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/164678208569.1200972.12153682697842916557.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/164692904155.2099075.14717645623034355995.stgit@warthog.procyon.org.uk/ # v3

2 files changed, 17 insertions, 1 deletions

diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index c702bd8ea8da..7dc741d9b21b 100644
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h
@@ -150,6 +150,12 @@ struct netfs_io_subrequest {
 #define NETFS_SREQ_NO_PROGRESS		4	/* Set if we didn't manage to read any data */
 };
 
+enum netfs_io_origin {
+	NETFS_READAHEAD,		/* This read was triggered by readahead */
+	NETFS_READPAGE,			/* This read is a synchronous read */
+	NETFS_READ_FOR_WRITE,		/* This read is to prepare a write */
+} __mode(byte);
+
 /*
  * Descriptor for an I/O helper request.  This is used to make multiple I/O
  * operations to a variety of data stores and then stitch the result together.
@@ -167,6 +173,7 @@ struct netfs_io_request {
 	size_t			submitted;	/* Amount submitted for I/O so far */
 	size_t			len;		/* Length of the request */
 	short			error;		/* 0 or error that occurred */
+	enum netfs_io_origin	origin;		/* Origin of the request */
 	loff_t			i_size;		/* Size of the file */
 	loff_t			start;		/* Start position */
 	pgoff_t			no_unlock_folio; /* Don't unlock this folio after read */
diff --git a/include/trace/events/netfs.h b/include/trace/events/netfs.h
index 556859b0f107..f00e3e1821c8 100644
--- a/include/trace/events/netfs.h
+++ b/include/trace/events/netfs.h
@@ -21,6 +21,11 @@
 	EM(netfs_read_trace_readpage,		"READPAGE ")	\
 	E_(netfs_read_trace_write_begin,	"WRITEBEGN")
 
+#define netfs_rreq_origins					\
+	EM(NETFS_READAHEAD,			"RA")		\
+	EM(NETFS_READPAGE,			"RP")		\
+	E_(NETFS_READ_FOR_WRITE,		"RW")
+
 #define netfs_rreq_traces					\
 	EM(netfs_rreq_trace_assess,		"ASSESS ")	\
 	EM(netfs_rreq_trace_copy,		"COPY   ")	\
@@ -101,6 +106,7 @@ enum netfs_sreq_ref_trace { netfs_sreq_ref_traces } __mode(byte);
 #define E_(a, b) TRACE_DEFINE_ENUM(a);
 
 netfs_read_traces;
+netfs_rreq_origins;
 netfs_rreq_traces;
 netfs_sreq_sources;
 netfs_sreq_traces;
@@ -159,17 +165,20 @@ TRACE_EVENT(netfs_rreq,
 	    TP_STRUCT__entry(
 		    __field(unsigned int,		rreq		)
 		    __field(unsigned int,		flags		)
+		    __field(enum netfs_io_origin,	origin		)
 		    __field(enum netfs_rreq_trace,	what		)
 			     ),
 
 	    TP_fast_assign(
 		    __entry->rreq	= rreq->debug_id;
 		    __entry->flags	= rreq->flags;
+		    __entry->origin	= rreq->origin;
 		    __entry->what	= what;
 			   ),
 
-	    TP_printk("R=%08x %s f=%02x",
+	    TP_printk("R=%08x %s %s f=%02x",
 		      __entry->rreq,
+		      __print_symbolic(__entry->origin, netfs_rreq_origins),
 		      __print_symbolic(__entry->what, netfs_rreq_traces),
 		      __entry->flags)
 	    );