scsi: core: add scsi_host_busy_iter()

Add an iterator scsi_host_busy_iter() to traverse all busy commands.  If
locking against concurrent command completions is required, it has to be
provided by the caller.

Link: https://lore.kernel.org/r/20200228075318.91255-11-hare@suse.de
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index 00ae9d4..7ec91c3 100644 (file)
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -678,3 +678,40 @@ void scsi_host_complete_all_commands(struct Scsi_Host *shost, int status)
                                &status);
 }
 EXPORT_SYMBOL_GPL(scsi_host_complete_all_commands);
+
+struct scsi_host_busy_iter_data {
+       bool (*fn)(struct scsi_cmnd *, void *, bool);
+       void *priv;
+};
+
+static bool __scsi_host_busy_iter_fn(struct request *req, void *priv,
+                                  bool reserved)
+{
+       struct scsi_host_busy_iter_data *iter_data = priv;
+       struct scsi_cmnd *sc = blk_mq_rq_to_pdu(req);
+
+       return iter_data->fn(sc, iter_data->priv, reserved);
+}
+
+/**
+ * scsi_host_busy_iter - Iterate over all busy commands
+ * @shost:     Pointer to Scsi_Host.
+ * @fn:                Function to call on each busy command
+ * @priv:      Data pointer passed to @fn
+ *
+ * If locking against concurrent command completions is required
+ * ithas to be provided by the caller
+ **/
+void scsi_host_busy_iter(struct Scsi_Host *shost,
+                        bool (*fn)(struct scsi_cmnd *, void *, bool),
+                        void *priv)
+{
+       struct scsi_host_busy_iter_data iter_data = {
+               .fn = fn,
+               .priv = priv,
+       };
+
+       blk_mq_tagset_busy_iter(&shost->tag_set, __scsi_host_busy_iter_fn,
+                               &iter_data);
+}
+EXPORT_SYMBOL_GPL(scsi_host_busy_iter);

diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 613c382..eff1244 100644 (file)
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -761,6 +761,9 @@ extern void scsi_block_requests(struct Scsi_Host *);
 extern int scsi_host_block(struct Scsi_Host *shost);
 extern int scsi_host_unblock(struct Scsi_Host *shost, int new_state);
 
+void scsi_host_busy_iter(struct Scsi_Host *,
+                        bool (*fn)(struct scsi_cmnd *, void *, bool), void *priv);
+
 struct class_container;
 
 /*