GFS2: Implement iomap for block_map

This patch implements iomap for block mapping, and switches the
block_map function to use it under the covers.

The additional IOMAP_F_BOUNDARY iomap flag indicates when iomap has
reached a "metadata boundary" and fetching the next mapping is likely to
incur an additional I/O.  This flag is used for setting the bh buffer
boundary flag.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

fs/gfs2/bmap.h

@@ -10,6 +10,8 @@
 #ifndef __BMAP_DOT_H__
 #define __BMAP_DOT_H__
 
+#include <linux/iomap.h>
+
 #include "inode.h"
 
 struct inode;
@@ -47,6 +49,8 @@ static inline void gfs2_write_calc_reserv(const struct gfs2_inode *ip,
 extern int gfs2_unstuff_dinode(struct gfs2_inode *ip, struct page *page);
 extern int gfs2_block_map(struct inode *inode, sector_t lblock,
 			  struct buffer_head *bh, int create);
+extern int gfs2_iomap_begin(struct inode *inode, loff_t pos, loff_t length,
+			    unsigned flags, struct iomap *iomap);
 extern int gfs2_extent_map(struct inode *inode, u64 lblock, int *new,
 			   u64 *dblock, unsigned *extlen);
 extern int gfs2_setattr_size(struct inode *inode, u64 size);

fs/gfs2/trace_gfs2.h

@@ -12,6 +12,7 @@
 #include <linux/gfs2_ondisk.h>
 #include <linux/writeback.h>
 #include <linux/ktime.h>
+#include <linux/iomap.h>
 #include "incore.h"
 #include "glock.h"
 #include "rgrp.h"
@@ -469,6 +470,70 @@ TRACE_EVENT(gfs2_bmap,
 		  __entry->errno)
 );
 
+TRACE_EVENT(gfs2_iomap_start,
+
+	TP_PROTO(const struct gfs2_inode *ip, loff_t pos, ssize_t length,
+		 u16 flags),
+
+	TP_ARGS(ip, pos, length, flags),
+
+	TP_STRUCT__entry(
+		__field(        dev_t,  dev                     )
+		__field(	u64,	inum			)
+		__field(	loff_t, pos			)
+		__field(	ssize_t, length			)
+		__field(	u16,	flags			)
+	),
+
+	TP_fast_assign(
+		__entry->dev            = ip->i_gl->gl_name.ln_sbd->sd_vfs->s_dev;
+		__entry->inum		= ip->i_no_addr;
+		__entry->pos		= pos;
+		__entry->length		= length;
+		__entry->flags		= flags;
+	),
+
+	TP_printk("%u,%u bmap %llu iomap start %llu/%lu flags:%08x",
+		  MAJOR(__entry->dev), MINOR(__entry->dev),
+		  (unsigned long long)__entry->inum,
+		  (unsigned long long)__entry->pos,
+		  (unsigned long)__entry->length, (u16)__entry->flags)
+);
+
+TRACE_EVENT(gfs2_iomap_end,
+
+	TP_PROTO(const struct gfs2_inode *ip, struct iomap *iomap, int ret),
+
+	TP_ARGS(ip, iomap, ret),
+
+	TP_STRUCT__entry(
+		__field(        dev_t,  dev                     )
+		__field(	u64,	inum			)
+		__field(	loff_t, offset			)
+		__field(	ssize_t, length			)
+		__field(	u16,	flags			)
+		__field(	u16,	type			)
+		__field(	int,	ret			)
+	),
+
+	TP_fast_assign(
+		__entry->dev            = ip->i_gl->gl_name.ln_sbd->sd_vfs->s_dev;
+		__entry->inum		= ip->i_no_addr;
+		__entry->offset		= iomap->offset;
+		__entry->length		= iomap->length;
+		__entry->flags		= iomap->flags;
+		__entry->type		= iomap->type;
+		__entry->ret		= ret;
+	),
+
+	TP_printk("%u,%u bmap %llu iomap end %llu/%lu ty:%d flags:%08x rc:%d",
+		  MAJOR(__entry->dev), MINOR(__entry->dev),
+		  (unsigned long long)__entry->inum,
+		  (unsigned long long)__entry->offset,
+		  (unsigned long)__entry->length, (u16)__entry->type,
+		  (u16)__entry->flags, __entry->ret)
+);
+
 /* Keep track of blocks as they are allocated/freed */
 TRACE_EVENT(gfs2_block_alloc,
 

include/linux/iomap.h

@@ -22,6 +22,7 @@ struct vm_fault;
  * Flags for all iomap mappings:
  */
 #define IOMAP_F_NEW		0x01	/* blocks have been newly allocated */
+#define IOMAP_F_BOUNDARY	0x02	/* mapping ends at metadata boundary */
 
 /*
  * Flags that only need to be reported for IOMAP_REPORT requests: