[RFC PATCH 1/4] nfs/blocklayout: SCSI layout trace points for reservation key reg/unreg

[cel@kernel.org]

From: Chuck Lever <chuck.lever@oracle.com>

An administrator cannot take action on these messages, but the
reported errors might be helpful for troubleshooting. Transition
them to trace points so these events appear in the trace log and
can be easily lined up with other traced NFS client operations.

Examples:

   append_writer-6147  [000]    80.247393: bl_pr_key_reg:        device=sdb key=0x666dcdabf29514fe
   append_writer-6147  [000]    80.247842: bl_pr_key_unreg:      device=sdb key=0x666dcdabf29514fe

     umount.nfs4-6172  [002]    84.950409: bl_pr_key_unreg_err:  device=sdb key=0x666dcdabf29514fe error=24

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/nfs/blocklayout/dev.c | 33 +++++++++++----------
 fs/nfs/nfs4trace.c       |  5 ++++
 fs/nfs/nfs4trace.h       | 62 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 85 insertions(+), 15 deletions(-)

diff --git a/fs/nfs/blocklayout/dev.c b/fs/nfs/blocklayout/dev.c
index 519c310c745d..b3828e5ee079 100644
--- a/fs/nfs/blocklayout/dev.c
+++ b/fs/nfs/blocklayout/dev.c
@@ -10,6 +10,7 @@
 #include <linux/pr.h>
 
 #include "blocklayout.h"
+#include "../nfs4trace.h"
 
 #define NFSDBG_FACILITY		NFSDBG_PNFS_LD
 
@@ -24,14 +25,17 @@ bl_free_device(struct pnfs_block_dev *dev)
 		kfree(dev->children);
 	} else {
 		if (dev->pr_registered) {
-			const struct pr_ops *ops =
-				file_bdev(dev->bdev_file)->bd_disk->fops->pr_ops;
+			struct block_device *bdev = file_bdev(dev->bdev_file);
+			const struct pr_ops *ops = bdev->bd_disk->fops->pr_ops;
 			int error;
 
-			error = ops->pr_register(file_bdev(dev->bdev_file),
-				dev->pr_key, 0, false);
+			error = ops->pr_register(bdev, dev->pr_key, 0, false);
 			if (error)
-				pr_err("failed to unregister PR key.\n");
+				trace_bl_pr_key_unreg_err(bdev->bd_disk->disk_name,
+							  dev->pr_key, error);
+			else
+				trace_bl_pr_key_unreg(bdev->bd_disk->disk_name,
+						      dev->pr_key);
 		}
 
 		if (dev->bdev_file)
@@ -327,8 +331,9 @@ bl_parse_scsi(struct nfs_server *server, struct pnfs_block_dev *d,
 		struct pnfs_block_volume *volumes, int idx, gfp_t gfp_mask)
 {
 	struct pnfs_block_volume *v = &volumes[idx];
-	struct file *bdev_file;
+	struct block_device *bdev;
 	const struct pr_ops *ops;
+	struct file *bdev_file;
 	int error;
 
 	if (!bl_validate_designator(v))
@@ -346,8 +351,9 @@ bl_parse_scsi(struct nfs_server *server, struct pnfs_block_dev *d,
 	if (IS_ERR(bdev_file))
 		return PTR_ERR(bdev_file);
 	d->bdev_file = bdev_file;
+	bdev = file_bdev(bdev_file);
 
-	d->len = bdev_nr_bytes(file_bdev(d->bdev_file));
+	d->len = bdev_nr_bytes(bdev);
 	d->map = bl_map_simple;
 	d->pr_key = v->scsi.pr_key;
 
@@ -356,23 +362,20 @@ bl_parse_scsi(struct nfs_server *server, struct pnfs_block_dev *d,
 		goto out_blkdev_put;
 	}
 
-	pr_info("pNFS: using block device %s (reservation key 0x%llx)\n",
-		file_bdev(d->bdev_file)->bd_disk->disk_name, d->pr_key);
-
-	ops = file_bdev(d->bdev_file)->bd_disk->fops->pr_ops;
+	ops = bdev->bd_disk->fops->pr_ops;
 	if (!ops) {
 		pr_err("pNFS: block device %s does not support reservations.",
-				file_bdev(d->bdev_file)->bd_disk->disk_name);
+				bdev->bd_disk->disk_name);
 		error = -EINVAL;
 		goto out_blkdev_put;
 	}
 
-	error = ops->pr_register(file_bdev(d->bdev_file), 0, d->pr_key, true);
+	error = ops->pr_register(bdev, 0, d->pr_key, true);
 	if (error) {
-		pr_err("pNFS: failed to register key for block device %s.",
-				file_bdev(d->bdev_file)->bd_disk->disk_name);
+		trace_bl_pr_key_reg_err(bdev->bd_disk->disk_name, d->pr_key, error);
 		goto out_blkdev_put;
 	}
+	trace_bl_pr_key_reg(bdev->bd_disk->disk_name, d->pr_key);
 
 	d->pr_registered = true;
 	return 0;
diff --git a/fs/nfs/nfs4trace.c b/fs/nfs/nfs4trace.c
index d22c6670f770..74eff35fbc90 100644
--- a/fs/nfs/nfs4trace.c
+++ b/fs/nfs/nfs4trace.c
@@ -29,5 +29,10 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(ff_layout_read_error);
 EXPORT_TRACEPOINT_SYMBOL_GPL(ff_layout_write_error);
 EXPORT_TRACEPOINT_SYMBOL_GPL(ff_layout_commit_error);
 
+EXPORT_TRACEPOINT_SYMBOL_GPL(bl_pr_key_reg);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bl_pr_key_reg_err);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bl_pr_key_unreg);
+EXPORT_TRACEPOINT_SYMBOL_GPL(bl_pr_key_unreg_err);
+
 EXPORT_TRACEPOINT_SYMBOL_GPL(fl_getdevinfo);
 #endif
diff --git a/fs/nfs/nfs4trace.h b/fs/nfs/nfs4trace.h
index 4de8780a7c48..2af75b8e018d 100644
--- a/fs/nfs/nfs4trace.h
+++ b/fs/nfs/nfs4trace.h
@@ -2153,6 +2153,68 @@ TRACE_EVENT(ff_layout_commit_error,
 		)
 );
 
+DECLARE_EVENT_CLASS(pnfs_bl_pr_key_class,
+	TP_PROTO(
+		const char *name,
+		u64 key
+	),
+	TP_ARGS(name, key),
+	TP_STRUCT__entry(
+		__string(name, name)
+		__field(u64, key)
+	),
+	TP_fast_assign(
+		__assign_str(name);
+		__entry->key = key;
+	),
+	TP_printk("device=%s key=0x%llx",
+		__get_str(name), __entry->key
+	)
+);
+
+#define DEFINE_NFS4_BLOCK_PRKEY_EVENT(name) \
+	DEFINE_EVENT(pnfs_bl_pr_key_class, name, \
+		TP_PROTO( \
+			const char *name, \
+			u64 key \
+		), \
+		TP_ARGS(name, key))
+DEFINE_NFS4_BLOCK_PRKEY_EVENT(bl_pr_key_reg);
+DEFINE_NFS4_BLOCK_PRKEY_EVENT(bl_pr_key_unreg);
+
+DECLARE_EVENT_CLASS(pnfs_bl_pr_key_err_class,
+	TP_PROTO(
+		const char *name,
+		u64 key,
+		int error
+	),
+	TP_ARGS(name, key, error),
+	TP_STRUCT__entry(
+		__string(name, name)
+		__field(u64, key)
+		__field(int, error)
+	),
+	TP_fast_assign(
+		__assign_str(name);
+		__entry->key = key;
+		__entry->error = error;
+	),
+	TP_printk("device=%s key=0x%llx error=%d",
+		__get_str(name), __entry->key, __entry->error
+	)
+);
+
+#define DEFINE_NFS4_BLOCK_PRKEY_ERR_EVENT(name) \
+	DEFINE_EVENT(pnfs_bl_pr_key_err_class, name, \
+		TP_PROTO( \
+			const char *name, \
+			u64 key, \
+			int error \
+		), \
+		TP_ARGS(name, key, error))
+DEFINE_NFS4_BLOCK_PRKEY_ERR_EVENT(bl_pr_key_reg_err);
+DEFINE_NFS4_BLOCK_PRKEY_ERR_EVENT(bl_pr_key_unreg_err);
+
 #ifdef CONFIG_NFS_V4_2
 TRACE_DEFINE_ENUM(NFS4_CONTENT_DATA);
 TRACE_DEFINE_ENUM(NFS4_CONTENT_HOLE);
-- 
2.45.1