dax: add tracepoint to dax_insert_mapping()

Add a tracepoint to dax_insert_mapping(), following the same logging
conventions as the rest of DAX.  This tracepoint, along with the one in
dax_load_hole(), lets us know how a DAX PTE fault was serviced.

Here is an example DAX fault that inserts a PTE mapping:

  small-1126  [007] ....
   145.451604: dax_pte_fault: dev 259:0 ino 0x1003 shared WRITE|ALLOW_RETRY|KILLABLE|USER address 0x10420000 pgoff 0x220

  small-1126  [007] ....
   145.452317: dax_insert_mapping: dev 259:0 ino 0x1003 shared write address 0x10420000 radix_entry 0x100006

  small-1126  [007] ....
   145.452399: dax_pte_fault_done: dev 259:0 ino 0x1003 shared WRITE|ALLOW_RETRY|KILLABLE|USER address 0x10420000 pgoff 0x220 MAJOR|NOPAGE

Link: http://lkml.kernel.org/r/20170221195116.13278-7-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>

diff --git a/fs/dax.c b/fs/dax.c
index 9bec30e062118c14499fb4af8d8236d3eba6fb92..66d79067eedfd25b942a37b2ba7188941df48cf2 100644 (file)
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -925,6 +925,7 @@ static int dax_insert_mapping(struct address_space *mapping,
                return PTR_ERR(ret);
        *entryp = ret;
 
+       trace_dax_insert_mapping(mapping->host, vmf, ret);
        return vm_insert_mixed(vma, vaddr, pfn);
 }
 

diff --git a/include/trace/events/fs_dax.h b/include/trace/events/fs_dax.h
index 292a4719edd011ceff950707dbc49f740d3a9100..08bb3ed18dcc213dbbdcfad0832a83a8fbb2ed4e 100644 (file)
--- a/include/trace/events/fs_dax.h
+++ b/include/trace/events/fs_dax.h
@@ -194,6 +194,36 @@ DEFINE_PTE_FAULT_EVENT(dax_pfn_mkwrite_no_entry);
 DEFINE_PTE_FAULT_EVENT(dax_pfn_mkwrite);
 DEFINE_PTE_FAULT_EVENT(dax_load_hole);
 
+TRACE_EVENT(dax_insert_mapping,
+       TP_PROTO(struct inode *inode, struct vm_fault *vmf, void *radix_entry),
+       TP_ARGS(inode, vmf, radix_entry),
+       TP_STRUCT__entry(
+               __field(unsigned long, ino)
+               __field(unsigned long, vm_flags)
+               __field(unsigned long, address)
+               __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 = vmf->vma->vm_flags;
+               __entry->address = vmf->address;
+               __entry->write = vmf->flags & FAULT_FLAG_WRITE;
+               __entry->radix_entry = radix_entry;
+       ),
+       TP_printk("dev %d:%d ino %#lx %s %s address %#lx radix_entry %#lx",
+               MAJOR(__entry->dev),
+               MINOR(__entry->dev),
+               __entry->ino,
+               __entry->vm_flags & VM_SHARED ? "shared" : "private",
+               __entry->write ? "write" : "read",
+               __entry->address,
+               (unsigned long)__entry->radix_entry
+       )
+)
+
 DECLARE_EVENT_CLASS(dax_writeback_range_class,
        TP_PROTO(struct inode *inode, pgoff_t start_index, pgoff_t end_index),
        TP_ARGS(inode, start_index, end_index),