nfsd: Add I/O trace points in the NFSv4 read proc

NFSv4 read compound processing invokes nfsd_splice_read and
nfs_readv directly, so the trace points currently in nfsd_read are
not invoked for NFSv4 reads.

Move the NFSD READ trace points to common helpers so that NFSv4
reads are captured.

Also, record any local I/O error that occurs, the total count of
bytes that were actually returned, and whether splice or vectored
read was used.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

5 files changed, 39 insertions, 25 deletions

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index b773b314f599..250e0c550fd8 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -751,6 +751,9 @@ nfsd4_read(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
         if (read->rd_offset >= OFFSET_MAX)
                 return nfserr_inval;
 
+        trace_nfsd_read_start(rqstp, &cstate->current_fh,
+                              read->rd_offset, read->rd_length);
+
         /*
          * If we do a zero copy read, then a client will see read data
          * that reflects the state of the file *after* performing the
@@ -783,6 +786,8 @@ nfsd4_read_release(union nfsd4_op_u *u)
 {
         if (u->read.rd_filp)
                 fput(u->read.rd_filp);
+        trace_nfsd_read_done(u->read.rd_rqstp, u->read.rd_fhp,
+                             u->read.rd_offset, u->read.rd_length);
 }
 
 static __be32
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 9f8ef2c6e508..dd72cdf3662e 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -3427,8 +3427,9 @@ static __be32 nfsd4_encode_splice_read(
                 return nfserr_resource;
 
         len = maxcount;
-        nfserr = nfsd_splice_read(read->rd_rqstp, file,
-                                  read->rd_offset, &maxcount);
+        nfserr = nfsd_splice_read(read->rd_rqstp, read->rd_fhp,
+                                  file, read->rd_offset, &maxcount);
+        read->rd_length = maxcount;
         if (nfserr) {
                 /*
                  * nfsd_splice_actor may have already messed with the
@@ -3511,8 +3512,9 @@ static __be32 nfsd4_encode_readv(struct nfsd4_compoundres *resp,
         read->rd_vlen = v;
 
         len = maxcount;
-        nfserr = nfsd_readv(file, read->rd_offset, resp->rqstp->rq_vec,
-                        read->rd_vlen, &maxcount);
+        nfserr = nfsd_readv(resp->rqstp, read->rd_fhp, file, read->rd_offset,
+                            resp->rqstp->rq_vec, read->rd_vlen, &maxcount);
+        read->rd_length = maxcount;
         if (nfserr)
                 return nfserr;
         xdr_truncate_encode(xdr, starting_len + 8 + ((maxcount+3)&~3));
diff --git a/fs/nfsd/trace.h b/fs/nfsd/trace.h
index 653e9ee754d2..a8bbd9d00a9e 100644
--- a/fs/nfsd/trace.h
+++ b/fs/nfsd/trace.h
@@ -43,7 +43,8 @@ DEFINE_EVENT(nfsd_io_class, nfsd_##name,	\
         TP_ARGS(rqstp, fhp, offset, len))
 
 DEFINE_NFSD_IO_EVENT(read_start);
-DEFINE_NFSD_IO_EVENT(read_opened);
+DEFINE_NFSD_IO_EVENT(read_splice);
+DEFINE_NFSD_IO_EVENT(read_vector);
 DEFINE_NFSD_IO_EVENT(read_io_done);
 DEFINE_NFSD_IO_EVENT(read_done);
 DEFINE_NFSD_IO_EVENT(write_start);
@@ -82,6 +83,7 @@ DEFINE_EVENT(nfsd_err_class, nfsd_##name,	\
                  int            len),           \
         TP_ARGS(rqstp, fhp, offset, len))
 
+DEFINE_NFSD_ERR_EVENT(read_err);
 DEFINE_NFSD_ERR_EVENT(write_err);
 
 #include "state.h"
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index ee59a0b24fab..2410b093a2e6 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -881,20 +881,24 @@ static int nfsd_direct_splice_actor(struct pipe_inode_info *pipe,
         return __splice_from_pipe(pipe, sd, nfsd_splice_actor);
 }
 
-static __be32
-nfsd_finish_read(struct file *file, unsigned long *count, int host_err)
+static __be32 nfsd_finish_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
+                               struct file *file, loff_t offset,
+                               unsigned long *count, int host_err)
 {
         if (host_err >= 0) {
                 nfsdstats.io_read += host_err;
                 *count = host_err;
                 fsnotify_access(file);
+                trace_nfsd_read_io_done(rqstp, fhp, offset, *count);
                 return 0;
-        } else 
+        } else {
+                trace_nfsd_read_err(rqstp, fhp, offset, host_err);
                 return nfserrno(host_err);
+        }
 }
 
-__be32 nfsd_splice_read(struct svc_rqst *rqstp,
-                     struct file *file, loff_t offset, unsigned long *count)
+__be32 nfsd_splice_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
+                        struct file *file, loff_t offset, unsigned long *count)
 {
         struct splice_desc sd = {
                 .len            = 0,
@@ -904,21 +908,23 @@ __be32 nfsd_splice_read(struct svc_rqst *rqstp,
         };
         int host_err;
 
+        trace_nfsd_read_splice(rqstp, fhp, offset, *count);
         rqstp->rq_next_page = rqstp->rq_respages + 1;
         host_err = splice_direct_to_actor(file, &sd, nfsd_direct_splice_actor);
-        return nfsd_finish_read(file, count, host_err);
+        return nfsd_finish_read(rqstp, fhp, file, offset, count, host_err);
 }
 
-__be32 nfsd_readv(struct file *file, loff_t offset, struct kvec *vec, int vlen,
-                unsigned long *count)
+__be32 nfsd_readv(struct svc_rqst *rqstp, struct svc_fh *fhp,
+                  struct file *file, loff_t offset,
+                  struct kvec *vec, int vlen, unsigned long *count)
 {
         struct iov_iter iter;
         int host_err;
 
+        trace_nfsd_read_vector(rqstp, fhp, offset, *count);
         iov_iter_kvec(&iter, READ | ITER_KVEC, vec, vlen, *count);
         host_err = vfs_iter_read(file, &iter, &offset, 0);
-
-        return nfsd_finish_read(file, count, host_err);
+        return nfsd_finish_read(rqstp, fhp, file, offset, count, host_err);
 }
 
 /*
@@ -1034,14 +1040,10 @@ __be32 nfsd_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
 
         ra = nfsd_init_raparms(file);
 
-        trace_nfsd_read_opened(rqstp, fhp, offset, *count);
-
         if (file->f_op->splice_read && test_bit(RQ_SPLICE_OK, &rqstp->rq_flags))
-                err = nfsd_splice_read(rqstp, file, offset, count);
+                err = nfsd_splice_read(rqstp, fhp, file, offset, count);
         else
-                err = nfsd_readv(file, offset, vec, vlen, count);
-
-        trace_nfsd_read_io_done(rqstp, fhp, offset, *count);
+                err = nfsd_readv(rqstp, fhp, file, offset, vec, vlen, count);
 
         if (ra)
                 nfsd_put_raparams(file, ra);
diff --git a/fs/nfsd/vfs.h b/fs/nfsd/vfs.h
index be6d8e00453f..a7e107309f76 100644
--- a/fs/nfsd/vfs.h
+++ b/fs/nfsd/vfs.h
@@ -78,10 +78,13 @@ __be32		nfsd_commit(struct svc_rqst *, struct svc_fh *,
 __be32          nfsd_open(struct svc_rqst *, struct svc_fh *, umode_t,
                                 int, struct file **);
 struct raparms;
-__be32          nfsd_splice_read(struct svc_rqst *,
-                                struct file *, loff_t, unsigned long *);
-__be32          nfsd_readv(struct file *, loff_t, struct kvec *, int,
-                                unsigned long *);
+__be32          nfsd_splice_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
+                                struct file *file, loff_t offset,
+                                unsigned long *count);
+__be32          nfsd_readv(struct svc_rqst *rqstp, struct svc_fh *fhp,
+                                struct file *file, loff_t offset,
+                                struct kvec *vec, int vlen,
+                                unsigned long *count);
 __be32          nfsd_read(struct svc_rqst *, struct svc_fh *,
                                 loff_t, struct kvec *, int, unsigned long *);
 __be32          nfsd_write(struct svc_rqst *, struct svc_fh *, loff_t,