commit c3ff68d7d1e6a24b7ad76d00ee583929858d4001
author Ross Zwisler <ross.zwisler@linux.intel.com> Mon May 08 16:00:03 2017 -0700
committer Linus Torvalds <torvalds@linux-foundation.org> Mon May 08 17:15:15 2017 -0700
tree e834b82b6fe8a37bc015dda345c4e60001acf57c
parent a9c42b33ed80968dd160e3be48c7e84ccf171cf9

dax: add tracepoints to dax_pfn_mkwrite()

Add tracepoints to dax_pfn_mkwrite(), following the same logging
conventions as the rest of DAX.

Here is an example PTE fault followed by a pfn_mkwrite:

  small_aligned-1094  [002] ....
   374.084998: dax_pte_fault: dev 259:0 ino 0x1003 shared WRITE|ALLOW_RETRY|KILLABLE|USER address 0x10400000 pgoff 0x200

  small_aligned-1094  [002] ....
   374.085145: dax_pte_fault_done: dev 259:0 ino 0x1003 shared WRITE|ALLOW_RETRY|KILLABLE|USER address 0x10400000 pgoff 0x200 MAJOR|NOPAGE

  small_aligned-1094  [002] ....
   374.085165: dax_pfn_mkwrite: dev 259:0 ino 0x1003 shared WRITE|MKWRITE|ALLOW_RETRY|KILLABLE|USER address 0x10400000 pgoff 0x200 NOPAGE

Link: http://lkml.kernel.org/r/20170221195116.13278-3-ross.zwisler@linux.intel.com
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/dax.c

diff --git a/fs/dax.c b/fs/dax.c
index f6c32d8..d10524a 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -927,6 +927,7 @@
 {
 	struct file *file = vmf->vma->vm_file;
 	struct address_space *mapping = file->f_mapping;
+	struct inode *inode = mapping->host;
 	void *entry, **slot;
 	pgoff_t index = vmf->pgoff;
 
@@ -936,6 +937,7 @@
 		if (entry)
 			put_unlocked_mapping_entry(mapping, index, entry);
 		spin_unlock_irq(&mapping->tree_lock);
+		trace_dax_pfn_mkwrite_no_entry(inode, vmf, VM_FAULT_NOPAGE);
 		return VM_FAULT_NOPAGE;
 	}
 	radix_tree_tag_set(&mapping->page_tree, index, PAGECACHE_TAG_DIRTY);
@@ -948,6 +950,7 @@
 	 */
 	finish_mkwrite_fault(vmf);
 	put_locked_mapping_entry(mapping, index, entry);
+	trace_dax_pfn_mkwrite(inode, vmf, VM_FAULT_NOPAGE);
 	return VM_FAULT_NOPAGE;
 }
 EXPORT_SYMBOL_GPL(dax_pfn_mkwrite);

include/trace/events/fs_dax.h

diff --git a/include/trace/events/fs_dax.h b/include/trace/events/fs_dax.h
index cbcd7d6..b5a5209 100644
--- a/include/trace/events/fs_dax.h
+++ b/include/trace/events/fs_dax.h
@@ -190,6 +190,8 @@
 
 DEFINE_PTE_FAULT_EVENT(dax_pte_fault);
 DEFINE_PTE_FAULT_EVENT(dax_pte_fault_done);
+DEFINE_PTE_FAULT_EVENT(dax_pfn_mkwrite_no_entry);
+DEFINE_PTE_FAULT_EVENT(dax_pfn_mkwrite);
 
 #endif /* _TRACE_FS_DAX_H */