nfsd: add new io class tracepoint

Add some new tracepoints in the nfsd read/write codepaths. The idea
is that this will give us the ability to measure how long each phase of
a read or write operation takes.

Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

3 files changed, 79 insertions, 0 deletions

diff --git a/fs/nfsd/nfsfh.h b/fs/nfsd/nfsfh.h
index 2087bae17582..0770bcb543c8 100644
--- a/fs/nfsd/nfsfh.h
+++ b/fs/nfsd/nfsfh.h
@@ -7,6 +7,7 @@
 #ifndef _LINUX_NFSD_NFSFH_H
 #define _LINUX_NFSD_NFSFH_H
 
+#include <linux/crc32.h>
 #include <linux/sunrpc/svc.h>
 #include <uapi/linux/nfsd/nfsfh.h>
 
@@ -205,6 +206,28 @@ static inline bool fh_fsid_match(struct knfsd_fh *fh1, struct knfsd_fh *fh2)
         return true;
 }
 
+#ifdef CONFIG_CRC32
+/**
+ * knfsd_fh_hash - calculate the crc32 hash for the filehandle
+ * @fh - pointer to filehandle
+ *
+ * returns a crc32 hash for the filehandle that is compatible with
+ * the one displayed by "wireshark".
+ */
+
+static inline u32
+knfsd_fh_hash(struct knfsd_fh *fh)
+{
+        return ~crc32_le(0xFFFFFFFF, (unsigned char *)&fh->fh_base, fh->fh_size);
+}
+#else
+static inline u32
+knfsd_fh_hash(struct knfsd_fh *fh)
+{
+        return 0;
+}
+#endif
+
 #ifdef CONFIG_NFSD_V3
 /*
  * The wcc data stored in current_fh should be cleared
diff --git a/fs/nfsd/trace.h b/fs/nfsd/trace.h
index 0befe762762b..3287041905da 100644
--- a/fs/nfsd/trace.h
+++ b/fs/nfsd/trace.h
@@ -8,6 +8,47 @@
 #define _NFSD_TRACE_H
 
 #include <linux/tracepoint.h>
+#include "nfsfh.h"
+
+DECLARE_EVENT_CLASS(nfsd_io_class,
+        TP_PROTO(struct svc_rqst *rqstp,
+                 struct svc_fh  *fhp,
+                 loff_t         offset,
+                 int            len),
+        TP_ARGS(rqstp, fhp, offset, len),
+        TP_STRUCT__entry(
+                __field(__be32, xid)
+                __field_struct(struct knfsd_fh, fh)
+                __field(loff_t, offset)
+                __field(int, len)
+        ),
+        TP_fast_assign(
+                __entry->xid = rqstp->rq_xid,
+                fh_copy_shallow(&__entry->fh, &fhp->fh_handle);
+                __entry->offset = offset;
+                __entry->len = len;
+        ),
+        TP_printk("xid=0x%x fh=0x%x offset=%lld len=%d",
+                  __be32_to_cpu(__entry->xid), knfsd_fh_hash(&__entry->fh),
+                  __entry->offset, __entry->len)
+)
+
+#define DEFINE_NFSD_IO_EVENT(name)              \
+DEFINE_EVENT(nfsd_io_class, name,               \
+        TP_PROTO(struct svc_rqst *rqstp,        \
+                 struct svc_fh  *fhp,           \
+                 loff_t         offset,         \
+                 int            len),           \
+        TP_ARGS(rqstp, fhp, offset, len))
+
+DEFINE_NFSD_IO_EVENT(read_start);
+DEFINE_NFSD_IO_EVENT(read_opened);
+DEFINE_NFSD_IO_EVENT(read_io_done);
+DEFINE_NFSD_IO_EVENT(read_done);
+DEFINE_NFSD_IO_EVENT(write_start);
+DEFINE_NFSD_IO_EVENT(write_opened);
+DEFINE_NFSD_IO_EVENT(write_io_done);
+DEFINE_NFSD_IO_EVENT(write_done);
 
 #include "state.h"
 
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 994d66fbb446..3257c59dc860 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -42,6 +42,7 @@
 
 #include "nfsd.h"
 #include "vfs.h"
+#include "trace.h"
 
 #define NFSDDBG_FACILITY                NFSDDBG_FILEOP
 
@@ -983,16 +984,23 @@ __be32 nfsd_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
         struct raparms  *ra;
         __be32 err;
 
+        trace_read_start(rqstp, fhp, offset, vlen);
         err = nfsd_open(rqstp, fhp, S_IFREG, NFSD_MAY_READ, &file);
         if (err)
                 return err;
 
         ra = nfsd_init_raparms(file);
+
+        trace_read_opened(rqstp, fhp, offset, vlen);
         err = nfsd_vfs_read(rqstp, file, offset, vec, vlen, count);
+        trace_read_io_done(rqstp, fhp, offset, vlen);
+
         if (ra)
                 nfsd_put_raparams(file, ra);
         fput(file);
 
+        trace_read_done(rqstp, fhp, offset, vlen);
+
         return err;
 }
 
@@ -1008,24 +1016,31 @@ nfsd_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file,
 {
         __be32                  err = 0;
 
+        trace_write_start(rqstp, fhp, offset, vlen);
+
         if (file) {
                 err = nfsd_permission(rqstp, fhp->fh_export, fhp->fh_dentry,
                                 NFSD_MAY_WRITE|NFSD_MAY_OWNER_OVERRIDE);
                 if (err)
                         goto out;
+                trace_write_opened(rqstp, fhp, offset, vlen);
                 err = nfsd_vfs_write(rqstp, fhp, file, offset, vec, vlen, cnt,
                                 stablep);
+                trace_write_io_done(rqstp, fhp, offset, vlen);
         } else {
                 err = nfsd_open(rqstp, fhp, S_IFREG, NFSD_MAY_WRITE, &file);
                 if (err)
                         goto out;
 
+                trace_write_opened(rqstp, fhp, offset, vlen);
                 if (cnt)
                         err = nfsd_vfs_write(rqstp, fhp, file, offset, vec, vlen,
                                              cnt, stablep);
+                trace_write_io_done(rqstp, fhp, offset, vlen);
                 fput(file);
         }
 out:
+        trace_write_done(rqstp, fhp, offset, vlen);
         return err;
 }