afs: Add stats for data transfer operations

Add statistics to /proc/fs/afs/stats for data transfer RPC operations.  New
lines are added that look like:

	file-rd : n=55794 nb=10252282150
	file-wr : n=9789 nb=3247763645

where n= indicates the number of ops completed and nb= indicates the number
of bytes successfully transferred.  file-rd is the counts for read/fetch
operations and file-wr the counts for write/store operations.

Note that directory and symlink downloading are included in the file-rd
stats at the moment.
Signed-off-by: David Howells <dhowells@redhat.com>

fs/afs/file.c

@@ -242,6 +242,12 @@ int afs_fetch_data(struct afs_vnode *vnode, struct key *key, struct afs_read *de
 		ret = afs_end_vnode_operation(&fc);
 	}
 
+	if (ret == 0) {
+		afs_stat_v(vnode, n_fetches);
+		atomic_long_add(desc->actual_len,
+				&afs_v2net(vnode)->n_fetch_bytes);
+	}
+
 	_leave(" = %d", ret);
 	return ret;
 }

fs/afs/internal.h

@@ -273,6 +273,10 @@ struct afs_net {
 	atomic_t		n_read_dir;	/* Number of directory pages read */
 	atomic_t		n_dir_cr;	/* Number of directory entry creation edits */
 	atomic_t		n_dir_rm;	/* Number of directory entry removal edits */
+	atomic_t		n_stores;	/* Number of store ops */
+	atomic_long_t		n_store_bytes;	/* Number of bytes stored */
+	atomic_long_t		n_fetch_bytes;	/* Number of bytes fetched */
+	atomic_t		n_fetches;	/* Number of data fetch ops */
 };
 
 extern const char afs_init_sysname[];

fs/afs/proc.c

@@ -922,6 +922,13 @@ static int afs_proc_stats_show(struct seq_file *m, void *v)
 	seq_printf(m, "dir-edit: cr=%u rm=%u\n",
 		   atomic_read(&net->n_dir_cr),
 		   atomic_read(&net->n_dir_rm));
+
+	seq_printf(m, "file-rd : n=%u nb=%lu\n",
+		   atomic_read(&net->n_fetches),
+		   atomic_long_read(&net->n_fetch_bytes));
+	seq_printf(m, "file-wr : n=%u nb=%lu\n",
+		   atomic_read(&net->n_stores),
+		   atomic_long_read(&net->n_store_bytes));
 	return 0;
 }
 

fs/afs/write.c

@@ -356,6 +356,12 @@ static int afs_store_data(struct address_space *mapping,
 	}
 
 	switch (ret) {
+	case 0:
+		afs_stat_v(vnode, n_stores);
+		atomic_long_add((last * PAGE_SIZE + to) -
+				(first * PAGE_SIZE + offset),
+				&afs_v2net(vnode)->n_store_bytes);
+		break;
 	case -EACCES:
 	case -EPERM:
 	case -ENOKEY: