dax: add tracepoints to dax_pmd_insert_mapping()

Add tracepoints to dax_pmd_insert_mapping(), following the same logging
conventions as the tracepoints in dax_iomap_pmd_fault().

Here is an example PMD fault showing the new tracepoints:

big-1504  [001] ....   326.960743: xfs_filemap_pmd_fault: dev 259:0 ino 0x1003

big-1504  [001] ....   326.960753: dax_pmd_fault: dev 259:0 ino 0x1003 shared WRITE|ALLOW_RETRY|KILLABLE|USER address 0x10505000 vm_start 0x10200000 vm_end 0x10700000 pgoff 0x200 max_pgoff 0x1400

big-1504  [001] ....   326.960981: dax_pmd_insert_mapping: dev 259:0 ino 0x1003 shared write address 0x10505000 length 0x200000 pfn 0x100600 DEV|MAP radix_entry 0xc000e

big-1504  [001] ....   326.960986: dax_pmd_fault_done: dev 259:0 ino 0x1003 shared WRITE|ALLOW_RETRY|KILLABLE|USER address 0x10505000 vm_start 0x10200000 vm_end 0x10700000 pgoff 0x200 max_pgoff 0x1400 NOPAGE

Link: http://lkml.kernel.org/r/1484085142-2297-6-git-send-email-ross.zwisler@linux.intel.com
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/dax.c

@@ -1262,15 +1262,16 @@ static int dax_pmd_insert_mapping(struct vm_area_struct *vma, pmd_t *pmd,
 {
 	struct address_space *mapping = vma->vm_file->f_mapping;
 	struct block_device *bdev = iomap->bdev;
+	struct inode *inode = mapping->host;
 	struct blk_dax_ctl dax = {
 		.sector = dax_iomap_sector(iomap, pos),
 		.size = PMD_SIZE,
 	};
 	long length = dax_map_atomic(bdev, &dax);
-	void *ret;
+	void *ret = NULL;
 
 	if (length < 0) /* dax_map_atomic() failed */
-		return VM_FAULT_FALLBACK;
+		goto fallback;
 	if (length < PMD_SIZE)
 		goto unmap_fallback;
 	if (pfn_t_to_pfn(dax.pfn) & PG_PMD_COLOUR)
@@ -1283,13 +1284,18 @@ static int dax_pmd_insert_mapping(struct vm_area_struct *vma, pmd_t *pmd,
 	ret = dax_insert_mapping_entry(mapping, vmf, *entryp, dax.sector,
 			RADIX_DAX_PMD);
 	if (IS_ERR(ret))
-		return VM_FAULT_FALLBACK;
+		goto fallback;
 	*entryp = ret;
 
+	trace_dax_pmd_insert_mapping(inode, vma, address, write, length,
+			dax.pfn, ret);
 	return vmf_insert_pfn_pmd(vma, address, pmd, dax.pfn, write);
 
  unmap_fallback:
 	dax_unmap_atomic(bdev, &dax);
+fallback:
+	trace_dax_pmd_insert_mapping_fallback(inode, vma, address, write,
+			length, dax.pfn, ret);
 	return VM_FAULT_FALLBACK;
 }
 

include/linux/pfn_t.h

@@ -15,6 +15,12 @@
 #define PFN_DEV (1ULL << (BITS_PER_LONG_LONG - 3))
 #define PFN_MAP (1ULL << (BITS_PER_LONG_LONG - 4))
 
+#define PFN_FLAGS_TRACE \
+	{ PFN_SG_CHAIN,	"SG_CHAIN" }, \
+	{ PFN_SG_LAST,	"SG_LAST" }, \
+	{ PFN_DEV,	"DEV" }, \
+	{ PFN_MAP,	"MAP" }
+
 static inline pfn_t __pfn_to_pfn_t(unsigned long pfn, u64 flags)
 {
 	pfn_t pfn_t = { .val = pfn | (flags & PFN_FLAGS_MASK), };

include/trace/events/fs_dax.h

@@ -104,6 +104,57 @@ DEFINE_EVENT(dax_pmd_load_hole_class, name, \
 DEFINE_PMD_LOAD_HOLE_EVENT(dax_pmd_load_hole);
 DEFINE_PMD_LOAD_HOLE_EVENT(dax_pmd_load_hole_fallback);
 
+DECLARE_EVENT_CLASS(dax_pmd_insert_mapping_class,
+	TP_PROTO(struct inode *inode, struct vm_area_struct *vma,
+		unsigned long address, int write, long length, pfn_t pfn,
+		void *radix_entry),
+	TP_ARGS(inode, vma, address, write, length, pfn, radix_entry),
+	TP_STRUCT__entry(
+		__field(unsigned long, ino)
+		__field(unsigned long, vm_flags)
+		__field(unsigned long, address)
+		__field(long, length)
+		__field(u64, pfn_val)
+		__field(void *, radix_entry)
+		__field(dev_t, dev)
+		__field(int, write)
+	),
+	TP_fast_assign(
+		__entry->dev = inode->i_sb->s_dev;
+		__entry->ino = inode->i_ino;
+		__entry->vm_flags = vma->vm_flags;
+		__entry->address = address;
+		__entry->write = write;
+		__entry->length = length;
+		__entry->pfn_val = pfn.val;
+		__entry->radix_entry = radix_entry;
+	),
+	TP_printk("dev %d:%d ino %#lx %s %s address %#lx length %#lx "
+			"pfn %#llx %s radix_entry %#lx",
+		MAJOR(__entry->dev),
+		MINOR(__entry->dev),
+		__entry->ino,
+		__entry->vm_flags & VM_SHARED ? "shared" : "private",
+		__entry->write ? "write" : "read",
+		__entry->address,
+		__entry->length,
+		__entry->pfn_val & ~PFN_FLAGS_MASK,
+		__print_flags_u64(__entry->pfn_val & PFN_FLAGS_MASK, "|",
+			PFN_FLAGS_TRACE),
+		(unsigned long)__entry->radix_entry
+	)
+)
+
+#define DEFINE_PMD_INSERT_MAPPING_EVENT(name) \
+DEFINE_EVENT(dax_pmd_insert_mapping_class, name, \
+	TP_PROTO(struct inode *inode, struct vm_area_struct *vma, \
+		unsigned long address, int write, long length, pfn_t pfn, \
+		void *radix_entry), \
+	TP_ARGS(inode, vma, address, write, length, pfn, radix_entry))
+
+DEFINE_PMD_INSERT_MAPPING_EVENT(dax_pmd_insert_mapping);
+DEFINE_PMD_INSERT_MAPPING_EVENT(dax_pmd_insert_mapping_fallback);
+
 #endif /* _TRACE_FS_DAX_H */
 
 /* This part must be outside protection */