NFS: Add trace events to report non-zero NFS status codes

These can help field troubleshooting without needing the overhead
of a full network capture (ie, tcpdump).
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

fs/nfs/nfs2xdr.c

@@ -22,6 +22,7 @@
 #include <linux/nfs.h>
 #include <linux/nfs2.h>
 #include <linux/nfs_fs.h>
+#include "nfstrace.h"
 #include "internal.h"
 
 #define NFSDBG_FACILITY		NFSDBG_XDR
@@ -145,7 +146,13 @@ static int decode_stat(struct xdr_stream *xdr, enum nfs_stat *status)
 	p = xdr_inline_decode(xdr, 4);
 	if (unlikely(!p))
 		return -EIO;
+	if (unlikely(*p != cpu_to_be32(NFS_OK)))
+		goto out_status;
+	*status = 0;
+	return 0;
+out_status:
 	*status = be32_to_cpup(p);
+	trace_nfs_xdr_status((int)*status);
 	return 0;
 }
 

fs/nfs/nfs3xdr.c

@@ -21,6 +21,7 @@
 #include <linux/nfs3.h>
 #include <linux/nfs_fs.h>
 #include <linux/nfsacl.h>
+#include "nfstrace.h"
 #include "internal.h"
 
 #define NFSDBG_FACILITY		NFSDBG_XDR
@@ -337,7 +338,13 @@ static int decode_nfsstat3(struct xdr_stream *xdr, enum nfs_stat *status)
 	p = xdr_inline_decode(xdr, 4);
 	if (unlikely(!p))
 		return -EIO;
+	if (unlikely(*p != cpu_to_be32(NFS3_OK)))
+		goto out_status;
+	*status = 0;
+	return 0;
+out_status:
 	*status = be32_to_cpup(p);
+	trace_nfs_xdr_status((int)*status);
 	return 0;
 }
 

fs/nfs/nfs4trace.h

@@ -524,6 +524,31 @@ TRACE_EVENT(nfs4_setup_sequence,
 		)
 );
 
+TRACE_EVENT(nfs4_xdr_status,
+		TP_PROTO(
+			u32 op,
+			int error
+		),
+
+		TP_ARGS(op, error),
+
+		TP_STRUCT__entry(
+			__field(u32, op)
+			__field(int, error)
+		),
+
+		TP_fast_assign(
+			__entry->op = op;
+			__entry->error = -error;
+		),
+
+		TP_printk(
+			"operation %d: nfs status %d (%s)",
+			__entry->op,
+			__entry->error, show_nfsv4_errors(__entry->error)
+		)
+);
+
 DECLARE_EVENT_CLASS(nfs4_open_event,
 		TP_PROTO(
 			const struct nfs_open_context *ctx,

fs/nfs/nfs4xdr.c

@@ -54,6 +54,7 @@
 #include <linux/nfs_fs.h>
 
 #include "nfs4_fs.h"
+#include "nfs4trace.h"
 #include "internal.h"
 #include "nfs4idmap.h"
 #include "nfs4session.h"
@@ -3188,10 +3189,13 @@ static bool __decode_op_hdr(struct xdr_stream *xdr, enum nfs_opnum4 expected,
 	opnum = be32_to_cpup(p++);
 	if (unlikely(opnum != expected))
 		goto out_bad_operation;
-	nfserr = be32_to_cpup(p);
-	if (nfserr == NFS_OK)
+	if (unlikely(*p != cpu_to_be32(NFS_OK)))
+		goto out_status;
 	*nfs_retval = 0;
-	else
+	return true;
+out_status:
+	nfserr = be32_to_cpup(p);
+	trace_nfs4_xdr_status(opnum, nfserr);
 	*nfs_retval = nfs4_stat_to_errno(nfserr);
 	return true;
 out_bad_operation:

fs/nfs/nfstrace.c

@@ -11,3 +11,4 @@
 
 EXPORT_TRACEPOINT_SYMBOL_GPL(nfs_fsync_enter);
 EXPORT_TRACEPOINT_SYMBOL_GPL(nfs_fsync_exit);
+EXPORT_TRACEPOINT_SYMBOL_GPL(nfs_xdr_status);

fs/nfs/nfstrace.h

@@ -969,6 +969,91 @@ TRACE_EVENT(nfs_commit_done,
 		)
 );
 
+TRACE_DEFINE_ENUM(NFS_OK);
+TRACE_DEFINE_ENUM(NFSERR_PERM);
+TRACE_DEFINE_ENUM(NFSERR_NOENT);
+TRACE_DEFINE_ENUM(NFSERR_IO);
+TRACE_DEFINE_ENUM(NFSERR_NXIO);
+TRACE_DEFINE_ENUM(NFSERR_ACCES);
+TRACE_DEFINE_ENUM(NFSERR_EXIST);
+TRACE_DEFINE_ENUM(NFSERR_XDEV);
+TRACE_DEFINE_ENUM(NFSERR_NODEV);
+TRACE_DEFINE_ENUM(NFSERR_NOTDIR);
+TRACE_DEFINE_ENUM(NFSERR_ISDIR);
+TRACE_DEFINE_ENUM(NFSERR_INVAL);
+TRACE_DEFINE_ENUM(NFSERR_FBIG);
+TRACE_DEFINE_ENUM(NFSERR_NOSPC);
+TRACE_DEFINE_ENUM(NFSERR_ROFS);
+TRACE_DEFINE_ENUM(NFSERR_MLINK);
+TRACE_DEFINE_ENUM(NFSERR_NAMETOOLONG);
+TRACE_DEFINE_ENUM(NFSERR_NOTEMPTY);
+TRACE_DEFINE_ENUM(NFSERR_DQUOT);
+TRACE_DEFINE_ENUM(NFSERR_STALE);
+TRACE_DEFINE_ENUM(NFSERR_REMOTE);
+TRACE_DEFINE_ENUM(NFSERR_WFLUSH);
+TRACE_DEFINE_ENUM(NFSERR_BADHANDLE);
+TRACE_DEFINE_ENUM(NFSERR_NOT_SYNC);
+TRACE_DEFINE_ENUM(NFSERR_BAD_COOKIE);
+TRACE_DEFINE_ENUM(NFSERR_NOTSUPP);
+TRACE_DEFINE_ENUM(NFSERR_TOOSMALL);
+TRACE_DEFINE_ENUM(NFSERR_SERVERFAULT);
+TRACE_DEFINE_ENUM(NFSERR_BADTYPE);
+TRACE_DEFINE_ENUM(NFSERR_JUKEBOX);
+
+#define nfs_show_status(x) \
+	__print_symbolic(x, \
+			{ NFS_OK, "OK" }, \
+			{ NFSERR_PERM, "PERM" }, \
+			{ NFSERR_NOENT, "NOENT" }, \
+			{ NFSERR_IO, "IO" }, \
+			{ NFSERR_NXIO, "NXIO" }, \
+			{ NFSERR_ACCES, "ACCES" }, \
+			{ NFSERR_EXIST, "EXIST" }, \
+			{ NFSERR_XDEV, "XDEV" }, \
+			{ NFSERR_NODEV, "NODEV" }, \
+			{ NFSERR_NOTDIR, "NOTDIR" }, \
+			{ NFSERR_ISDIR, "ISDIR" }, \
+			{ NFSERR_INVAL, "INVAL" }, \
+			{ NFSERR_FBIG, "FBIG" }, \
+			{ NFSERR_NOSPC, "NOSPC" }, \
+			{ NFSERR_ROFS, "ROFS" }, \
+			{ NFSERR_MLINK, "MLINK" }, \
+			{ NFSERR_NAMETOOLONG, "NAMETOOLONG" }, \
+			{ NFSERR_NOTEMPTY, "NOTEMPTY" }, \
+			{ NFSERR_DQUOT, "DQUOT" }, \
+			{ NFSERR_STALE, "STALE" }, \
+			{ NFSERR_REMOTE, "REMOTE" }, \
+			{ NFSERR_WFLUSH, "WFLUSH" }, \
+			{ NFSERR_BADHANDLE, "BADHANDLE" }, \
+			{ NFSERR_NOT_SYNC, "NOTSYNC" }, \
+			{ NFSERR_BAD_COOKIE, "BADCOOKIE" }, \
+			{ NFSERR_NOTSUPP, "NOTSUPP" }, \
+			{ NFSERR_TOOSMALL, "TOOSMALL" }, \
+			{ NFSERR_SERVERFAULT, "REMOTEIO" }, \
+			{ NFSERR_BADTYPE, "BADTYPE" }, \
+			{ NFSERR_JUKEBOX, "JUKEBOX" })
+
+TRACE_EVENT(nfs_xdr_status,
+		TP_PROTO(
+			int error
+		),
+
+		TP_ARGS(error),
+
+		TP_STRUCT__entry(
+			__field(int, error)
+		),
+
+		TP_fast_assign(
+			__entry->error = error;
+		),
+
+		TP_printk(
+			"error=%d (%s)",
+			__entry->error, nfs_show_status(__entry->error)
+		)
+);
+
 #endif /* _TRACE_NFS_H */
 
 #undef TRACE_INCLUDE_PATH