NFS: Add a tracepoint in nfs_set_pgio_error()

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

fs/nfs/nfstrace.h

@@ -1008,6 +1008,50 @@ TRACE_EVENT(nfs_readpage_short,
 		)
 );
 
+TRACE_EVENT(nfs_pgio_error,
+	TP_PROTO(
+		const struct nfs_pgio_header *hdr,
+		int error,
+		loff_t pos
+	),
+
+	TP_ARGS(hdr, error, pos),
+
+	TP_STRUCT__entry(
+		__field(dev_t, dev)
+		__field(u32, fhandle)
+		__field(u64, fileid)
+		__field(loff_t, offset)
+		__field(u32, arg_count)
+		__field(u32, res_count)
+		__field(loff_t, pos)
+		__field(int, status)
+	),
+
+	TP_fast_assign(
+		const struct inode *inode = hdr->inode;
+		const struct nfs_inode *nfsi = NFS_I(inode);
+		const struct nfs_fh *fh = hdr->args.fh ?
+					  hdr->args.fh : &nfsi->fh;
+
+		__entry->status = error;
+		__entry->offset = hdr->args.offset;
+		__entry->arg_count = hdr->args.count;
+		__entry->res_count = hdr->res.count;
+		__entry->dev = inode->i_sb->s_dev;
+		__entry->fileid = nfsi->fileid;
+		__entry->fhandle = nfs_fhandle_hash(fh);
+	),
+
+	TP_printk("fileid=%02x:%02x:%llu fhandle=0x%08x "
+		  "offset=%lld count=%u res=%u pos=%llu status=%d",
+		MAJOR(__entry->dev), MINOR(__entry->dev),
+		(unsigned long long)__entry->fileid, __entry->fhandle,
+		(long long)__entry->offset, __entry->arg_count, __entry->res_count,
+		__entry->pos, __entry->status
+	)
+);
+
 TRACE_DEFINE_ENUM(NFS_UNSTABLE);
 TRACE_DEFINE_ENUM(NFS_DATA_SYNC);
 TRACE_DEFINE_ENUM(NFS_FILE_SYNC);

fs/nfs/pagelist.c

@@ -24,6 +24,7 @@
 
 #include "internal.h"
 #include "pnfs.h"
+#include "nfstrace.h"
 
 #define NFSDBG_FACILITY		NFSDBG_PAGECACHE
 
@@ -64,6 +65,7 @@ void nfs_set_pgio_error(struct nfs_pgio_header *hdr, int error, loff_t pos)
 {
 	unsigned int new = pos - hdr->io_start;
 
+	trace_nfs_pgio_error(hdr, error, pos);
 	if (hdr->good_bytes > new) {
 		hdr->good_bytes = new;
 		clear_bit(NFS_IOHDR_EOF, &hdr->flags);