Add support to submit a bio per-path. In addition, for failover, add
support to requeue a failed bio.
NVMe has almost like-for-like equivalents here:
- nvme_available_path() -> mpath_available_path()
- nvme_requeue_work() -> mpath_requeue_work()
- nvme_ns_head_submit_bio() -> mpath_bdev_submit_bio()
For failover, a driver may want to re-submit a bio, so add support to
clone a bio prior to submission.
A bio which is submitted to a per-path device has flag REQ_MPATH set,
same as what is done for NVMe with REQ_NVME_MPATH.
Signed-off-by: John Garry<[email protected]>
---
include/linux/multipath.h | 15 +++++++
lib/multipath.c | 92 ++++++++++++++++++++++++++++++++++++++-
2 files changed, 106 insertions(+), 1 deletion(-)
diff --git a/include/linux/multipath.h b/include/linux/multipath.h
index c964a1aba9c42..d557fb9bab4c9 100644
--- a/include/linux/multipath.h
+++ b/include/linux/multipath.h
@@ -3,6 +3,7 @@
#define _LIBMULTIPATH_H
#include <linux/blkdev.h>
+#include <linux/blk-mq.h>
#include <linux/srcu.h>
extern const struct block_device_operations mpath_ops;
@@ -40,10 +41,12 @@ struct mpath_device {
};
struct mpath_head_template {
+ bool (*available_path)(struct mpath_device *, bool *);
bool (*is_disabled)(struct mpath_device *);
bool (*is_optimized)(struct mpath_device *);
enum mpath_access_state (*get_access_state)(struct mpath_device *);
enum mpath_iopolicy_e (*get_iopolicy)(struct mpath_head *);
+ struct bio *(*clone_bio)(struct bio *);
const struct attribute_group **device_groups;
};
@@ -56,12 +59,23 @@ struct mpath_head {
struct kref ref;
+ struct bio_list requeue_list; /* list for requeing bio */
+ spinlock_t requeue_lock;
+ struct work_struct requeue_work; /* work struct for requeue */
+
unsigned long flags;
struct mpath_device __rcu *current_path[MAX_NUMNODES];
const struct mpath_head_template *mpdt;
void *drvdata;
};
+#define REQ_MPATH REQ_DRV
+
+static inline bool is_mpath_request(struct request *req)
+{
+ return req->cmd_flags & REQ_MPATH;
+}
+
static inline struct mpath_disk *mpath_bd_device_to_disk(struct device *dev)
{
return dev_get_drvdata(dev);
@@ -82,6 +96,7 @@ int mpath_set_iopolicy(const char *val, int *iopolicy);
int mpath_get_iopolicy(char *buf, int iopolicy);
int mpath_get_head(struct mpath_head *mpath_head);
void mpath_put_head(struct mpath_head *mpath_head);
+void mpath_requeue_work(struct work_struct *work);
struct mpath_head *mpath_alloc_head(void);
void mpath_put_disk(struct mpath_disk *mpath_disk);
void mpath_remove_disk(struct mpath_disk *mpath_disk);
diff --git a/lib/multipath.c b/lib/multipath.c
index 65a0d2d2bf524..b494b35e8dccc 100644
--- a/lib/multipath.c
+++ b/lib/multipath.c
@@ -5,6 +5,7 @@
*/
#include <linux/module.h>
#include <linux/multipath.h>
+#include <trace/events/block.h>
static struct mpath_device *mpath_find_path(struct mpath_head *mpath_head);
@@ -227,7 +228,6 @@ static struct mpath_device *mpath_numa_path(struct mpath_head *mpath_head,
return mpath_device;
}
-__maybe_unused
static struct mpath_device *mpath_find_path(struct mpath_head *mpath_head)
{
enum mpath_iopolicy_e iopolicy =
@@ -243,6 +243,66 @@ static struct mpath_device *mpath_find_path(struct
mpath_head *mpath_head)
}
}
+static bool mpath_available_path(struct mpath_head *mpath_head)
+{
+ struct mpath_device *mpath_device;
+
+ if (!test_bit(MPATH_HEAD_DISK_LIVE, &mpath_head->flags))
+ return false;
+
+ list_for_each_entry_srcu(mpath_device, &mpath_head->dev_list, siblings,
+ srcu_read_lock_held(&mpath_head->srcu)) {
+ bool available = false;
+
+ if (!mpath_head->mpdt->available_path(mpath_device,
+ &available))
+ continue;
+ if (available)
+ return true;
+ }
+
+ return false;
+}
