pnfs: client stats

A pNFS client auto-negotiates a lot of features (minorversion level,
pNFS layout type, etc.). This is convenient, but makes certain kinds of
failures hard for a user to detect.

For example, if the client falls back on 4.0, or falls back to MDS IO
because the user didn't connect to the right iscsi disks before
mounting, the only symptoms may be reduced performance, which may not be
noticed till long after the actual failure, and may be difficult for a
user to diagnose.

However, such "failures" may also be perfectly normal in some cases, so
we don't want to spam the system logs with them.

One approach would be to put some more information into
/proc/self/mountstats.

Signed-off-by: J. Bruce Fields <[e-mail]>
Signed-off-by: Benny Halevy <[e-mail]>
[pnfs: add commit client stats]
[fixup data types for "ret" variables in pnfs_try_to* inline funcs.]
Signed-off-by: Benny Halevy <[e-mail]>
[fix definition of show_pnfs for !CONFIG_PNFS]
Signed-off-by: Benny Halevy <[e-mail]>
[nfs41: Fix show_sessions in the not CONFIG_NFS_V4_1 case]
There is a build error when CONFIG_NFS_V4 is set but
CONFIG_NFS_V4_1 is *not* set. show_sessions() prototype
was unbalanced between the two cases.
Signed-off-by: Boaz Harrosh <[e-mail]>
[pnfs: super.c remove CONFIG_PNFS]
Signed-off-by: Andy Adamson <[e-mail]>
Signed-off-by: Benny Halevy <[e-mail]>

fs/nfs/super.c

···
 #include "iostat.h"
 #include "internal.h"
 #include "fscache.h"
+#include "pnfs.h"
 
 #define NFSDBG_FACILITY		NFSDBG_VFS
 
···
 
 	return 0;
 }
+#ifdef CONFIG_NFS_V4_1
+void show_sessions(struct seq_file *m, struct nfs_server *server)
+{
+	if (nfs4_has_session(server->nfs_client))
+		seq_printf(m, ",sessions");
+}
+#else
+void show_sessions(struct seq_file *m, struct nfs_server *server) {}
+#endif
+
+#ifdef CONFIG_NFS_V4_1
+void show_pnfs(struct seq_file *m, struct nfs_server *server)
+{
+	seq_printf(m, ",pnfs=");
+	if (server->pnfs_curr_ld)
+		seq_printf(m, "%s", server->pnfs_curr_ld->name);
+	else
+		seq_printf(m, "not configured");
+}
+#else  /* CONFIG_NFS_V4_1 */
+void show_pnfs(struct seq_file *m, struct nfs_server *server) {}
+#endif /* CONFIG_NFS_V4_1 */
 
 static int nfs_show_devname(struct seq_file *m, struct vfsmount *mnt)
 {
···
 		seq_printf(m, "bm0=0x%x", nfss->attr_bitmask[0]);
 		seq_printf(m, ",bm1=0x%x", nfss->attr_bitmask[1]);
 		seq_printf(m, ",acl=0x%x", nfss->acl_bitmask);
+		show_sessions(m, nfss);
+		show_pnfs(m, nfss);
 	}
 #endif