dm-interposer.c/. h contains code for working with blk_interposer
and provides an API for interposer in device-mapper.
Signed-off-by: Sergei Shtepa <sergei.shtepa@xxxxxxxxx>
---
drivers/md/Makefile | 2 +-
drivers/md/dm-interposer.c | 258 +++++++++++++++++++++++++++++++++++++
drivers/md/dm-interposer.h | 40 ++++++
3 files changed, 299 insertions(+), 1 deletion(-)
create mode 100644 drivers/md/dm-interposer.c
create mode 100644 drivers/md/dm-interposer.h
diff --git a/drivers/md/Makefile b/drivers/md/Makefile
index ef7ddc27685c..bd5b38bee82e 100644
--- a/drivers/md/Makefile
+++ b/drivers/md/Makefile
@@ -5,7 +5,7 @@
dm-mod-y += dm.o dm-table.o dm-target.o dm-linear.o dm-stripe.o \
dm-ioctl.o dm-io.o dm-kcopyd.o dm-sysfs.o dm-stats.o \
- dm-rq.o
+ dm-rq.o dm-interposer.o
dm-multipath-y += dm-path-selector.o dm-mpath.o
dm-historical-service-time-y += dm-ps-historical-service-time.o
dm-io-affinity-y += dm-ps-io-affinity.o
diff --git a/drivers/md/dm-interposer.c b/drivers/md/dm-interposer.c
new file mode 100644
index 000000000000..e5346db81def
--- /dev/null
+++ b/drivers/md/dm-interposer.c
@@ -0,0 +1,258 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/bio.h>
+#include <linux/rwsem.h>
+#include <linux/refcount.h>
+#include <linux/device-mapper.h>
+#include <linux/interval_tree_generic.h>
+
+#include "dm-core.h"
+#include "dm-interposer.h"
+
+#define DM_MSG_PREFIX "interposer"
+
+struct dm_interposer {
+ struct bdev_interposer blk_ip;
+
+ struct kref kref;
+ struct rw_semaphore ip_devs_lock;
+ struct rb_root_cached ip_devs_root; /* dm_interposed_dev tree, since there can be multiple
+ * interceptors for different ranges for a single
+ * block device. */
+};
+
+/*
+ * Interval tree for device mapper
+ */
+#define START(node) ((node)->start)
+#define LAST(node) ((node)->last)
+INTERVAL_TREE_DEFINE(struct dm_rb_range, node, sector_t, _subtree_last,
+ START, LAST,, dm_rb);
+
+static DEFINE_MUTEX(dm_interposer_attach_lock);
+
+static void dm_submit_bio_interposer_fn(struct bio *bio)
+{
+ struct dm_interposer *ip;
+ unsigned int noio_flag = 0;
+ sector_t start;
+ sector_t last;
+ struct dm_rb_range *node;
+
+ ip = container_of(bio->bi_bdev->bd_interposer, struct dm_interposer, blk_ip);
+
+ start = bio->bi_iter.bi_sector;
+ if (bio_flagged(bio, BIO_REMAPPED))
+ start -= get_start_sect(bio->bi_bdev);
+ last = start + dm_sector_div_up(bio->bi_iter.bi_size, SECTOR_SIZE);
+
+ noio_flag = memalloc_noio_save();
+ down_read(&ip->ip_devs_lock);
+ node = dm_rb_iter_first(&ip->ip_devs_root, start, last);
+ while (node) {
+ struct dm_interposed_dev *ip_dev =
+ container_of(node, struct dm_interposed_dev, node);
+
+ atomic64_inc(&ip_dev->ip_cnt);
+ ip_dev->dm_interpose_bio(ip_dev, bio);
+
+ node = dm_rb_iter_next(node, start, last);
+ }
+ up_read(&ip->ip_devs_lock);
+ memalloc_noio_restore(noio_flag);
+}
+
+void dm_interposer_free(struct kref *kref)
+{
+ struct dm_interposer *ip = container_of(kref, struct dm_interposer, kref);
+
+ bdev_interposer_detach(&ip->blk_ip, dm_submit_bio_interposer_fn);
+
+ kfree(ip);
+}
+
+struct dm_interposer *dm_interposer_new(struct block_device *bdev)
+{
+ int ret = 0;
+ struct dm_interposer *ip;
+
+ ip = kzalloc(sizeof(struct dm_interposer), GFP_NOIO);
+ if (!ip)
+ return ERR_PTR(-ENOMEM);
+
+ kref_init(&ip->kref);
+ init_rwsem(&ip->ip_devs_lock);
+ ip->ip_devs_root = RB_ROOT_CACHED;
+
+ ret = bdev_interposer_attach(bdev, &ip->blk_ip, dm_submit_bio_interposer_fn);
+ if (ret) {
+ DMERR("Failed to attach bdev_interposer.");
+ kref_put(&ip->kref, dm_interposer_free);
+ return ERR_PTR(ret);
+ }
+
+ return ip;
+}
+
+static struct dm_interposer *dm_interposer_get(struct block_device *bdev)
+{
+ struct dm_interposer *ip;
+
+ if (!bdev_has_interposer(bdev))
+ return NULL;
+
+ if (bdev->bd_interposer->ip_submit_bio != dm_submit_bio_interposer_fn) {
+ DMERR("Block devices interposer slot already occupied.");
+ return ERR_PTR(-EBUSY);
+ }
+
+ ip = container_of(bdev->bd_interposer, struct dm_interposer, blk_ip);
+
+ kref_get(&ip->kref);
+ return ip;
+}
+
+static inline void dm_disk_freeze(struct gendisk *disk)
+{
+ blk_mq_freeze_queue(disk->queue);
+ blk_mq_quiesce_queue(disk->queue);
+}
+
+static inline void dm_disk_unfreeze(struct gendisk *disk)
+{
+ blk_mq_unquiesce_queue(disk->queue);
+ blk_mq_unfreeze_queue(disk->queue);
+}
+
+/**
+ * dm_interposer_dev_init - initialize interposed device
+ * @ip_dev: interposed device
+ * @ofs: offset from the beginning of the block device
+ * @len: the length of the part of the block device to which requests will be interposed
+ * @private: user purpose parameter
+ * @interpose_fn: interposing callback
+ *
+ * Initialize structure dm_interposed_dev.
+ * For interposing part of block device set ofs and len.
+ * For interposing whole device set ofs=0 and len=0.
+ */
+void dm_interposer_dev_init(struct dm_interposed_dev *ip_dev,
+ sector_t ofs, sector_t len,
+ void *private, dm_interpose_bio_t interpose_fn)
+{
+ ip_dev->node.start = ofs;
+ ip_dev->node.last = ofs + len - 1;
+ ip_dev->dm_interpose_bio = interpose_fn;
+ ip_dev->private = private;
+
+ atomic64_set(&ip_dev->ip_cnt, 0);
+}
+
+/**
+ * dm_interposer_dev_attach - attach interposed device to his block device
+ * @bdev: block device
+ * @ip_dev: interposed device
+ *
+ * Return error code.
+ */
+int dm_interposer_dev_attach(struct block_device *bdev, struct dm_interposed_dev *ip_dev)
+{
+ int ret = 0;
+ struct dm_interposer *ip = NULL;
+ unsigned int noio_flag = 0;
+
+ if (!ip_dev)
+ return -EINVAL;
+
+ dm_disk_freeze(bdev->bd_disk);
+ mutex_lock(&dm_interposer_attach_lock);
+ noio_flag = memalloc_noio_save();
+
+ ip = dm_interposer_get(bdev);
+ if (ip == NULL)
+ ip = dm_interposer_new(bdev);
+ if (IS_ERR(ip)) {
+ ret = PTR_ERR(ip);
+ goto out;
+ }
+
+ /* Attach dm_interposed_dev to dm_interposer */
+ down_write(&ip->ip_devs_lock);
+ do {
+ struct dm_rb_range *node;
+
+ /* checking that ip_dev already exists for this region */
+ node = dm_rb_iter_first(&ip->ip_devs_root, ip_dev->node.start, ip_dev->node.last);
+ if (node) {
+ DMERR("Block device in region [%llu,%llu] already have interposer.",
+ node->start, node->last);
+
+ ret = -EBUSY;
+ break;
+ }
+
+ /* insert ip_dev to ip tree */
+ dm_rb_insert(&ip_dev->node, &ip->ip_devs_root);
+ /* increment ip reference counter */
+ kref_get(&ip->kref);
+ } while (false);
+ up_write(&ip->ip_devs_lock);
+
+ kref_put(&ip->kref, dm_interposer_free);
+
+out:
+ memalloc_noio_restore(noio_flag);
+ mutex_unlock(&dm_interposer_attach_lock);
+ dm_disk_unfreeze(bdev->bd_disk);
+
+ return ret;
+}
+
+/**
+ * dm_interposer_detach_dev - detach interposed device from his block device
+ * @bdev: block device
+ * @ip_dev: interposed device
+ *
+ * Return error code.
+ */
+int dm_interposer_detach_dev(struct block_device *bdev, struct dm_interposed_dev *ip_dev)
+{
+ int ret = 0;
+ struct dm_interposer *ip = NULL;
+ unsigned int noio_flag = 0;
+
+ if (!ip_dev)
+ return -EINVAL;
+
+ dm_disk_freeze(bdev->bd_disk);
+ mutex_lock(&dm_interposer_attach_lock);
+ noio_flag = memalloc_noio_save();
+
+ ip = dm_interposer_get(bdev);
+ if (IS_ERR(ip)) {
+ ret = PTR_ERR(ip);
+ DMERR("Interposer not found.");
+ goto out;
+ }
+ if (unlikely(ip == NULL)) {
+ ret = -ENXIO;
+ DMERR("Interposer not found.");
+ goto out;
+ }
+
+ down_write(&ip->ip_devs_lock);
+ {
+ dm_rb_remove(&ip_dev->node, &ip->ip_devs_root);
+ /* the reference counter here cannot be zero */
+ kref_put(&ip->kref, dm_interposer_free);
+ }
+ up_write(&ip->ip_devs_lock);
+
+ /* detach and free interposer if it's not needed */
+ kref_put(&ip->kref, dm_interposer_free);
+out:
+ memalloc_noio_restore(noio_flag);
+ mutex_unlock(&dm_interposer_attach_lock);
+ dm_disk_unfreeze(bdev->bd_disk);
+
+ return ret;
+}
diff --git a/drivers/md/dm-interposer.h b/drivers/md/dm-interposer.h
new file mode 100644
index 000000000000..17a5411f6f00
--- /dev/null
+++ b/drivers/md/dm-interposer.h
@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Device mapper's interposer.
+ */
+
+#include <linux/rbtree.h>
+
+struct dm_rb_range {
+ struct rb_node node;
+ sector_t start; /* start sector of rb node */
+ sector_t last; /* end sector of rb node */
+ sector_t _subtree_last; /* highest sector in subtree of rb node */
+};
+
+typedef void (*dm_interpose_bio_t) (struct dm_interposed_dev *ip_dev, struct bio *bio);
+
+struct dm_interposed_dev {
+ struct dm_rb_range node;
+ void *private;
+ dm_interpose_bio_t dm_interpose_bio;
+
+ atomic64_t ip_cnt; /* for debug purpose only */
+};
+
+/*
+ * Initialize structure dm_interposed_dev.
+ * For interposing part of block device set ofs and len.
+ * For interposing whole device set ofs=0 and len=0.
+ */
+void dm_interposer_dev_init(struct dm_interposed_dev *ip_dev,
+ sector_t ofs, sector_t len,
+ void *private, dm_interpose_bio_t interpose_fn);
+/*
+ * Attach interposer to his block device.
+ */
+int dm_interposer_dev_attach(struct block_device *bdev, struct dm_interposed_dev *ip_dev);
+/*
+ * Detach interposer from his block device.
+ */
+int dm_interposer_detach_dev(struct block_device *bdev, struct dm_interposed_dev *ip_dev);
--
2.20.1
