NFS: Improve write error tracing

Don't leak request pointers, but use the "device:inode" labelling that
is used by all the other trace points. Furthermore, replace use of page
indexes with an offset, again in order to align behaviour with other
NFS trace points.
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

fs/nfs/nfstrace.h

@@ -1447,44 +1447,50 @@ TRACE_EVENT(nfs_writeback_done,
 
 DECLARE_EVENT_CLASS(nfs_page_error_class,
 		TP_PROTO(
+			const struct inode *inode,
 			const struct nfs_page *req,
 			int error
 		),
 
-		TP_ARGS(req, error),
+		TP_ARGS(inode, req, error),
 
 		TP_STRUCT__entry(
-			__field(const void *, req)
-			__field(pgoff_t, index)
-			__field(unsigned int, offset)
-			__field(unsigned int, pgbase)
-			__field(unsigned int, bytes)
+			__field(dev_t, dev)
+			__field(u32, fhandle)
+			__field(u64, fileid)
+			__field(loff_t, offset)
+			__field(unsigned int, count)
 			__field(int, error)
 		),
 
 		TP_fast_assign(
-			__entry->req = req;
-			__entry->index = req->wb_index;
-			__entry->offset = req->wb_offset;
-			__entry->pgbase = req->wb_pgbase;
-			__entry->bytes = req->wb_bytes;
+			const struct nfs_inode *nfsi = NFS_I(inode);
+			__entry->dev = inode->i_sb->s_dev;
+			__entry->fileid = nfsi->fileid;
+			__entry->fhandle = nfs_fhandle_hash(&nfsi->fh);
+			__entry->offset = req_offset(req);
+			__entry->count = req->wb_bytes;
 			__entry->error = error;
 		),
 
 		TP_printk(
-			"req=%p index=%lu offset=%u pgbase=%u bytes=%u error=%d",
-			__entry->req, __entry->index, __entry->offset,
-			__entry->pgbase, __entry->bytes, __entry->error
+			"error=%d fileid=%02x:%02x:%llu fhandle=0x%08x "
+			"offset=%lld count=%u", __entry->error,
+			MAJOR(__entry->dev), MINOR(__entry->dev),
+			(unsigned long long)__entry->fileid,
+			__entry->fhandle, __entry->offset,
+			__entry->count
 		)
 );
 
 #define DEFINE_NFS_PAGEERR_EVENT(name) \
 	DEFINE_EVENT(nfs_page_error_class, name, \
 			TP_PROTO( \
+				const struct inode *inode, \
 				const struct nfs_page *req, \
 				int error \
 			), \
-			TP_ARGS(req, error))
+			TP_ARGS(inode, req, error))
 
 DEFINE_NFS_PAGEERR_EVENT(nfs_write_error);
 DEFINE_NFS_PAGEERR_EVENT(nfs_comp_error);

fs/nfs/write.c

@@ -592,7 +592,8 @@ nfs_lock_and_join_requests(struct page *page)
 
 static void nfs_write_error(struct nfs_page *req, int error)
 {
-	trace_nfs_write_error(req, error);
+	trace_nfs_write_error(page_file_mapping(req->wb_page)->host, req,
+			      error);
 	nfs_mapping_set_error(req->wb_page, error);
 	nfs_inode_remove_request(req);
 	nfs_end_page_writeback(req);
@@ -1000,7 +1001,7 @@ static void nfs_write_completion(struct nfs_pgio_header *hdr)
 		nfs_list_remove_request(req);
 		if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) &&
 		    (hdr->good_bytes < bytes)) {
-			trace_nfs_comp_error(req, hdr->error);
+			trace_nfs_comp_error(hdr->inode, req, hdr->error);
 			nfs_mapping_set_error(req->wb_page, hdr->error);
 			goto remove_req;
 		}
@@ -1882,7 +1883,8 @@ static void nfs_commit_release_pages(struct nfs_commit_data *data)
 			(long long)req_offset(req));
 		if (status < 0) {
 			if (req->wb_page) {
-				trace_nfs_commit_error(req, status);
+				trace_nfs_commit_error(data->inode, req,
+						       status);
 				nfs_mapping_set_error(req->wb_page, status);
 				nfs_inode_remove_request(req);
 			}

include/linux/nfs_page.h

@@ -202,8 +202,7 @@ nfs_list_entry(struct list_head *head)
 	return list_entry(head, struct nfs_page, wb_list);
 }
 
-static inline
-loff_t req_offset(struct nfs_page *req)
+static inline loff_t req_offset(const struct nfs_page *req)
 {
 	return (((loff_t)req->wb_index) << PAGE_SHIFT) + req->wb_offset;
 }