blk-mq: replace timeout synchronization with a RCU and generation based scheme

[linux.git] / include / linux / blkdev.h

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 46e606f5b44b3b7e5ec2cab1a476d3f46380ff67..ae563d01b29d7eb1f20b1f442fe0c31b57001b94 100644 (file)
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -27,6 +27,8 @@
 #include <linux/percpu-refcount.h>
 #include <linux/scatterlist.h>
 #include <linux/blkzoned.h>
+#include <linux/seqlock.h>
+#include <linux/u64_stats_sync.h>
 
 struct module;
 struct scsi_ioctl_command;
@@ -230,6 +232,27 @@ struct request {
 
        unsigned short write_hint;
 
+       /*
+        * On blk-mq, the lower bits of ->gstate (generation number and
+        * state) carry the MQ_RQ_* state value and the upper bits the
+        * generation number which is monotonically incremented and used to
+        * distinguish the reuse instances.
+        *
+        * ->gstate_seq allows updates to ->gstate and other fields
+        * (currently ->deadline) during request start to be read
+        * atomically from the timeout path, so that it can operate on a
+        * coherent set of information.
+        */
+       seqcount_t gstate_seq;
+       u64 gstate;
+
+       /*
+        * ->aborted_gstate is used by the timeout to claim a specific
+        * recycle instance of this request.  See blk_mq_timeout_work().
+        */
+       struct u64_stats_sync aborted_gstate_sync;
+       u64 aborted_gstate;
+
        unsigned long deadline;
        struct list_head timeout_list;