[dm-devel] [PATCH 2/2] [dm] blk_interposer for dm-linear
Damien Le Moal
Damien.LeMoal at wdc.com
Fri Jan 29 01:46:11 UTC 2021
On 2021/01/29 2:23, Sergei Shtepa wrote:
> Implement a block interposer for device-mapper to attach
> to an existing block layer stack. Using the interposer,
> we can connect the dm-linear to a device with a mounted
> file system.
>
> changes:
> * the new dm_interposer structure contains blk_interposer
> to intercept bio from the interposed disk and interval tree
> of block devices on this disk.
> * the new interval tree for device mapper.
> * the dm_submit_bio_interposer_fn() function implements
> the bio interception logic.
> * the functions dm_interposer_attach_dev() &
> dm_interposer_detach_dev() allow to attach and detach devices
> to dm_interposer.
> * the new parameter 'noexcl' allows to create dm-linear to device
> with an already mounted file system.
> * the non_exclusive parameter in dm_target structure - it`s a sign
> that target device should be opened without FMODE_EXCL mode.
> * the new ioctl IOCTL_DEV_REMAP allow to attach dm device to
> a regular block device.
Same comment about changelog as in the previous patch.
> Signed-off-by: Sergei Shtepa <sergei.shtepa at veeam.com>
> ---
> drivers/md/dm-core.h | 46 +++-
> drivers/md/dm-ioctl.c | 39 ++++
> drivers/md/dm-linear.c | 17 +-
> drivers/md/dm-table.c | 12 +-
> drivers/md/dm.c | 383 ++++++++++++++++++++++++++++++++--
> drivers/md/dm.h | 2 +-
> include/linux/device-mapper.h | 7 +
> include/uapi/linux/dm-ioctl.h | 15 +-
> 8 files changed, 493 insertions(+), 28 deletions(-)
>
> diff --git a/drivers/md/dm-core.h b/drivers/md/dm-core.h
> index 086d293c2b03..0f870b1d4be4 100644
> --- a/drivers/md/dm-core.h
> +++ b/drivers/md/dm-core.h
> @@ -13,7 +13,7 @@
> #include <linux/ktime.h>
> #include <linux/genhd.h>
> #include <linux/blk-mq.h>
> -
whiteline change.
> +#include <linux/rbtree.h>
> #include <trace/events/block.h>
>
> #include "dm.h"
> @@ -109,6 +109,9 @@ struct mapped_device {
> bool init_tio_pdu:1;
>
> struct srcu_struct io_barrier;
> +
> + /* interposer device for remap */
> + struct dm_interposed_dev *ip_dev;
> };
>
> void disable_discard(struct mapped_device *md);
> @@ -164,6 +167,47 @@ struct dm_table {
> struct dm_md_mempools *mempools;
> };
>
> +/*
> + * Interval tree for device mapper
> + */
> +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 */
> +};
> +
> +void dm_rb_insert(struct dm_rb_range *node, struct rb_root_cached *root);
> +void dm_rb_remove(struct dm_rb_range *node, struct rb_root_cached *root);
> +
> +struct dm_rb_range *dm_rb_iter_first(struct rb_root_cached *root, sector_t start, sector_t last);
> +struct dm_rb_range *dm_rb_iter_next(struct dm_rb_range *node, sector_t start, sector_t last);
> +
> +/*
> + * For connecting blk_interposer and dm-targets devices.
Is this comment about the callback or the structure ? I think the latter, so it
is in the worng place. Please also add a comment for the callback definition
explaining what it should be doing.
> + */
> +typedef void (*dm_interpose_bio_t) (void *context, struct dm_rb_range *node, struct bio *bio);
> +
> +struct dm_interposed_dev {
> + struct gendisk *disk;
> + struct dm_rb_range node;
> + void *context;
> + dm_interpose_bio_t dm_interpose_bio;
> +
> + atomic64_t ip_cnt; /*for debug purpose*/
> +};
> +
> +struct dm_interposed_dev *dm_interposer_new_dev(struct gendisk *disk,
> + sector_t ofs, sector_t len,
> + void *context,
> + dm_interpose_bio_t dm_interpose_bio_t);
> +void dm_interposer_free_dev(struct dm_interposed_dev *ip_dev);
> +int dm_interposer_attach_dev(struct dm_interposed_dev *ip_dev);
> +int dm_interposer_detach_dev(struct dm_interposed_dev *ip_dev);
> +
> +int dm_remap_install(struct mapped_device *md, const char *donor_device_name);
> +int dm_remap_uninstall(struct mapped_device *md);
> +
> static inline struct completion *dm_get_completion_from_kobject(struct kobject *kobj)
> {
> return &container_of(kobj, struct dm_kobject_holder, kobj)->completion;
> diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
> index 5e306bba4375..2944d442c256 100644
> --- a/drivers/md/dm-ioctl.c
> +++ b/drivers/md/dm-ioctl.c
> @@ -1649,6 +1649,44 @@ static int target_message(struct file *filp, struct dm_ioctl *param, size_t para
> return r;
> }
>
> +static inline int dev_remap_start(struct mapped_device *md, uint8_t *params)
> +{
> + char *donor_device_name = (char *)params;
> +
> + return dm_remap_install(md, donor_device_name);
> +}
> +static int dev_remap_finish(struct mapped_device *md)
> +{
> + return dm_remap_uninstall(md);
> +}
> +
> +static int dev_remap(struct file *filp, struct dm_ioctl *param, size_t param_size)
> +{
> + int ret = 0;
> + struct mapped_device *md;
> + void *bin_data;
> + struct dm_remap_param *remap_param;
> +
> + md = find_device(param);
> + if (!md)
> + return -ENXIO;
> +
> + bin_data = (void *)(param) + param->data_start;
> + remap_param = bin_data;
> +
> + if (remap_param->cmd == REMAP_START_CMD)
> + ret = dev_remap_start(md, remap_param->params);
> + else if (remap_param->cmd == REMAP_FINISH_CMD)
> + ret = dev_remap_finish(md);
> + else {
> + DMWARN("Invalid remap command, %d", remap_param->cmd);
> + ret = -EINVAL;
> + }
> +
> + dm_put(md);
> + return ret;
> +}
> +
> /*
> * The ioctl parameter block consists of two parts, a dm_ioctl struct
> * followed by a data buffer. This flag is set if the second part,
> @@ -1691,6 +1729,7 @@ static ioctl_fn lookup_ioctl(unsigned int cmd, int *ioctl_flags)
> {DM_DEV_SET_GEOMETRY_CMD, 0, dev_set_geometry},
> {DM_DEV_ARM_POLL, IOCTL_FLAGS_NO_PARAMS, dev_arm_poll},
> {DM_GET_TARGET_VERSION, 0, get_target_version},
> + {DM_DEV_REMAP_CMD, 0, dev_remap},
> };
>
> if (unlikely(cmd >= ARRAY_SIZE(_ioctls)))
> diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
> index 00774b5d7668..ffb8b5ca4d10 100644
> --- a/drivers/md/dm-linear.c
> +++ b/drivers/md/dm-linear.c
> @@ -28,12 +28,13 @@ struct linear_c {
> */
> static int linear_ctr(struct dm_target *ti, unsigned int argc, char **argv)
> {
> + fmode_t mode;
> struct linear_c *lc;
> unsigned long long tmp;
> char dummy;
> int ret;
>
> - if (argc != 2) {
> + if ((argc < 2) || (argc > 3)) {
> ti->error = "Invalid argument count";
> return -EINVAL;
> }
> @@ -51,7 +52,19 @@ static int linear_ctr(struct dm_target *ti, unsigned int argc, char **argv)
> }
> lc->start = tmp;
>
> - ret = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &lc->dev);
> + ti->non_exclusive = false;
> + if (argc > 2) {
> + if (strcmp("noexcl", argv[2]) == 0)
> + ti->non_exclusive = true;
> + else if (strcmp("excl", argv[2]) == 0)
> + ti->non_exclusive = false;
It already is false.
> + else {
> + ti->error = "Invalid exclusive option";
> + return -EINVAL;
> + }
> + }
> +
> + ret = dm_get_device(ti, argv[0], mode, &lc->dev);
Where is mode initialized ? Why remove dm_table_get_mode(ti->table) ?
> if (ret) {
> ti->error = "Device lookup failed";
> goto bad;
I would prefer to see this change to dm-linear in its own patch, following this
one, with a clear explanation in the commit message how this change relates to
interposer since the explanation for this "exclusive" change is nowhere to be
seen. Also please check if there is a file describing dm-linear options under
Documentation/ (I can't remember if there is one). If there is one, it will need
to be updated too.
> diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
> index 4acf2342f7ad..f15bc2171f25 100644
> --- a/drivers/md/dm-table.c
> +++ b/drivers/md/dm-table.c
> @@ -322,7 +322,7 @@ static int device_area_is_invalid(struct dm_target *ti, struct dm_dev *dev,
> * device and not to touch the existing bdev field in case
> * it is accessed concurrently.
> */
> -static int upgrade_mode(struct dm_dev_internal *dd, fmode_t new_mode,
> +static int upgrade_mode(struct dm_dev_internal *dd, fmode_t new_mode, bool non_exclusive,
> struct mapped_device *md)
> {
> int r;
> @@ -330,7 +330,7 @@ static int upgrade_mode(struct dm_dev_internal *dd, fmode_t new_mode,
>
> old_dev = dd->dm_dev;
>
> - r = dm_get_table_device(md, dd->dm_dev->bdev->bd_dev,
> + r = dm_get_table_device(md, dd->dm_dev->bdev->bd_dev, non_exclusive,
> dd->dm_dev->mode | new_mode, &new_dev);
> if (r)
> return r;
> @@ -387,7 +387,8 @@ int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode,
> if (!dd)
> return -ENOMEM;
>
> - if ((r = dm_get_table_device(t->md, dev, mode, &dd->dm_dev))) {
> + r = dm_get_table_device(t->md, dev, mode, ti->non_exclusive, &dd->dm_dev);
> + if (r) {
> kfree(dd);
> return r;
> }
> @@ -396,8 +397,9 @@ int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode,
> list_add(&dd->list, &t->devices);
> goto out;
>
> - } else if (dd->dm_dev->mode != (mode | dd->dm_dev->mode)) {
> - r = upgrade_mode(dd, mode, t->md);
> + } else if ((dd->dm_dev->mode != (mode | dd->dm_dev->mode)) &&
> + (dd->dm_dev->non_exclusive != ti->non_exclusive)) {
> + r = upgrade_mode(dd, mode, ti->non_exclusive, t->md);
> if (r)
> return r;
> }
> diff --git a/drivers/md/dm.c b/drivers/md/dm.c
> index 7bac564f3faa..3b871d98b7b6 100644
> --- a/drivers/md/dm.c
> +++ b/drivers/md/dm.c
> @@ -28,6 +28,7 @@
> #include <linux/refcount.h>
> #include <linux/part_stat.h>
> #include <linux/blk-crypto.h>
> +#include <linux/interval_tree_generic.h>
>
> #define DM_MSG_PREFIX "core"
>
> @@ -56,6 +57,8 @@ static struct workqueue_struct *deferred_remove_workqueue;
> atomic_t dm_global_event_nr = ATOMIC_INIT(0);
> DECLARE_WAIT_QUEUE_HEAD(dm_global_eventq);
>
> +static DEFINE_MUTEX(interposer_mutex); /* synchronizing access to blk_interposer */
Why not dm_interposer_mutex as the name ? And the comment is not very useful: a
mutex is always for synchronizing :)
> +
> void dm_issue_global_event(void)
> {
> atomic_inc(&dm_global_event_nr);
> @@ -162,6 +165,26 @@ struct table_device {
> struct dm_dev dm_dev;
> };
>
> +/*
> + * Device mapper`s interposer.
> + */
> +struct dm_interposer {
> + struct blk_interposer blk_ip;
> + struct mapped_device *md;
> +
> + struct kref kref;
> + struct rw_semaphore ip_devs_lock;
> + struct rb_root_cached ip_devs_root; /* dm_interposed_dev tree */
> +};
> +
> +/*
> + * 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);
> +
> /*
> * Bio-based DM's mempools' reserved IOs set by the user.
> */
> @@ -733,28 +756,340 @@ static void dm_put_live_table_fast(struct mapped_device *md) __releases(RCU)
> rcu_read_unlock();
> }
>
> +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_disk->interposer, struct dm_interposer, blk_ip);
> + start = bio->bi_iter.bi_sector;
> + 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->context, node, bio);
> +
> + node = dm_rb_iter_next(node, start, last);
> + }
> + up_read(&ip->ip_devs_lock);
> + memalloc_noio_restore(noio_flag);
> +}
> +
> +static void free_interposer(struct kref *kref)
> +{
> + struct dm_interposer *ip = container_of(kref, struct dm_interposer, kref);
> +
> + blk_interposer_detach(&ip->blk_ip, dm_submit_bio_interposer_fn);
No queue freeze ?
> +
> + kfree(ip);
> +}
> +
> +static struct dm_interposer *new_interposer(struct gendisk *disk)
> +{
> + 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 = blk_interposer_attach(disk, &ip->blk_ip, dm_submit_bio_interposer_fn);
No queue freeze ?
> + if (ret) {
> + DMERR("Failed to attack blk_interposer");
> + kref_put(&ip->kref, free_interposer);
> + return ERR_PTR(ret);
> + }
> +
> + return ip;
> +}
> +
> +static struct dm_interposer *get_interposer(struct gendisk *disk)
> +{
> + struct dm_interposer *ip;
> +
> + if (!blk_has_interposer(disk))
> + return NULL;
> +
> + if (disk->interposer->ip_submit_bio != dm_submit_bio_interposer_fn) {
> + DMERR("Disks interposer slot already occupied.");
> + return ERR_PTR(-EBUSY);
This is weird... If there is an interposer, why not get a ref on that one. That
is what the function name suggests at least.
> + }
> +
> + ip = container_of(disk->interposer, struct dm_interposer, blk_ip);
> +
> + kref_get(&ip->kref);
> + return ip;
> +}
> +
> +struct dm_interposed_dev *dm_interposer_new_dev(struct gendisk *disk, sector_t ofs, sector_t len,
> + void *context, dm_interpose_bio_t dm_interpose_bio)
> +{
> + sector_t start = ofs;
> + sector_t last = ofs + len - 1;
> + struct dm_interposed_dev *ip_dev = NULL;
> +
> + /* Allocate new ip_dev */
> + ip_dev = kzalloc(sizeof(struct dm_interposed_dev), GFP_KERNEL);
> + if (!ip_dev)
> + return NULL;
> +
> + ip_dev->disk = disk;
> + ip_dev->node.start = start;
> + ip_dev->node.last = last;
> +
> + ip_dev->context = context;
> + ip_dev->dm_interpose_bio = dm_interpose_bio;
> +
> + atomic64_set(&ip_dev->ip_cnt, 0);
> +
> + return ip_dev;
> +}
> +
> +void dm_interposer_free_dev(struct dm_interposed_dev *ip_dev)
> +{
> + kfree(ip_dev);
> +}
Make this inline may be ?
> +
> +static inline void dm_disk_freeze(struct gendisk *disk)
> +{
> + blk_mq_freeze_queue(disk->queue);
> + blk_mq_quiesce_queue(disk->queue);
I think you can replace this with blk_mq_freeze_queue_wait().
> +}
> +
> +static inline void dm_disk_unfreeze(struct gendisk *disk)
> +{
> + blk_mq_unquiesce_queue(disk->queue);
> + blk_mq_unfreeze_queue(disk->queue);
> +}
> +
> +int dm_interposer_attach_dev(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(ip_dev->disk);
> + mutex_lock(&interposer_mutex);
> + noio_flag = memalloc_noio_save();
> +
> + ip = get_interposer(ip_dev->disk);
> + if (ip == NULL)
> + ip = new_interposer(ip_dev->disk);
> + 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("Disk part form [%llu] to [%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, free_interposer);
> +
> +out:
> + memalloc_noio_restore(noio_flag);
> + mutex_unlock(&interposer_mutex);
> + dm_disk_unfreeze(ip_dev->disk);
> +
> + return ret;
> +}
> +
> +int dm_interposer_detach_dev(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(ip_dev->disk);
> + mutex_lock(&interposer_mutex);
> + noio_flag = memalloc_noio_save();
> +
> + ip = get_interposer(ip_dev->disk);
> + 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);
> + do {
> + dm_rb_remove(&ip_dev->node, &ip->ip_devs_root);
> + /* the reference counter here cannot be zero */
> + kref_put(&ip->kref, free_interposer);
> +
> + } while (false);
> + up_write(&ip->ip_devs_lock);
> +
> + /* detach and free interposer if it`s not needed */
s/`/'/
> + kref_put(&ip->kref, free_interposer);
> +out:
> + memalloc_noio_restore(noio_flag);
> + mutex_unlock(&interposer_mutex);
> + dm_disk_unfreeze(ip_dev->disk);
> +
> + return ret;
> +}
> +
> +static void dm_remap_fn(void *context, struct dm_rb_range *node, struct bio *bio)
> +{
> + struct mapped_device *md = context;
> +
> + /* Set acceptor device. */
> + bio->bi_disk = md->disk;
> +
> + /* Remap disks offset */
> + bio->bi_iter.bi_sector -= node->start;
> +
> + /*
> + * bio should be resubmitted.
> + * We can just add bio to bio_list of the current process.
> + * current->bio_list must be initialized when this function is called.
> + * If call submit_bio_noacct(), the bio will be checked twice.
> + */
> + BUG_ON(!current->bio_list);
> + bio_list_add(¤t->bio_list[0], bio);
> +}
> +
> +int dm_remap_install(struct mapped_device *md, const char *donor_device_name)
> +{
> + int ret = 0;
> + struct block_device *donor_bdev;
> + fmode_t mode = FMODE_READ | FMODE_WRITE;
> +
> + DMDEBUG("Dm remap install for mapped device %s and donor device %s",
> + md->name, donor_device_name);
> +
> + donor_bdev = blkdev_get_by_path(donor_device_name, mode, "device-mapper remap");
> + if (IS_ERR(donor_bdev)) {
> + DMERR("Cannot open device [%s]", donor_device_name);
> + return PTR_ERR(donor_bdev);
> + }
> +
> + do {
> + sector_t ofs = get_start_sect(donor_bdev);
> + sector_t len = bdev_nr_sectors(donor_bdev);
> +
> + md->ip_dev = dm_interposer_new_dev(donor_bdev->bd_disk, ofs, len, md, dm_remap_fn);
> + if (!md->ip_dev) {
> + ret = -ENOMEM;
> + break;
> + }
> +
> + DMDEBUG("New interposed device 0x%p", md->ip_dev);
> + ret = dm_interposer_attach_dev(md->ip_dev);
> + if (ret) {
> + dm_interposer_free_dev(md->ip_dev);
> +
> + md->ip_dev = NULL;
> + DMERR("Failed to attach dm interposer");
> + break;
> + }
> +
> + DMDEBUG("Attached successfully.");
> + } while (false);
> +
> + blkdev_put(donor_bdev, mode);
> +
> + return ret;
> +}
> +
> +int dm_remap_uninstall(struct mapped_device *md)
> +{
> + int ret = 0;
> +
> + DMDEBUG("Dm remap uninstall for mapped device %s ip_dev=0x%p", md->name, md->ip_dev);
> +
> + if (!md->ip_dev) {
> + DMERR("Cannot detach dm interposer");
> + return -EINVAL;
> + }
> +
> + ret = dm_interposer_detach_dev(md->ip_dev);
> + if (ret) {
> + DMERR("Failed to detach dm interposer");
> + return ret;
> + }
> +
> + DMDEBUG("Detached successfully. %llu bios was interposed",
> + atomic64_read(&md->ip_dev->ip_cnt));
> + dm_interposer_free_dev(md->ip_dev);
> + md->ip_dev = NULL;
> +
> + return 0;
> +}
> +
> static char *_dm_claim_ptr = "I belong to device-mapper";
>
> /*
> * Open a table device so we can use it as a map destination.
> */
> static int open_table_device(struct table_device *td, dev_t dev,
> - struct mapped_device *md)
> + struct mapped_device *md, bool non_exclusive)
> {
> struct block_device *bdev;
> -
> - int r;
> + int ret;
>
> BUG_ON(td->dm_dev.bdev);
>
> - bdev = blkdev_get_by_dev(dev, td->dm_dev.mode | FMODE_EXCL, _dm_claim_ptr);
> - if (IS_ERR(bdev))
> - return PTR_ERR(bdev);
> + if (non_exclusive)
> + bdev = blkdev_get_by_dev(dev, td->dm_dev.mode, NULL);
> + else
> + bdev = blkdev_get_by_dev(dev, td->dm_dev.mode | FMODE_EXCL, _dm_claim_ptr);
>
> - r = bd_link_disk_holder(bdev, dm_disk(md));
> - if (r) {
> - blkdev_put(bdev, td->dm_dev.mode | FMODE_EXCL);
> - return r;
> + if (IS_ERR(bdev)) {
> + ret = PTR_ERR(bdev);
> + if (ret != -EBUSY)
> + return ret;
> + }
> +
> + if (!non_exclusive) {
> + ret = bd_link_disk_holder(bdev, dm_disk(md));
> + if (ret) {
> + blkdev_put(bdev, td->dm_dev.mode);
> + return ret;
> + }
> }
>
> td->dm_dev.bdev = bdev;
> @@ -770,33 +1105,38 @@ static void close_table_device(struct table_device *td, struct mapped_device *md
> if (!td->dm_dev.bdev)
> return;
>
> - bd_unlink_disk_holder(td->dm_dev.bdev, dm_disk(md));
> - blkdev_put(td->dm_dev.bdev, td->dm_dev.mode | FMODE_EXCL);
> + if (td->dm_dev.mode & FMODE_EXCL)
> + bd_unlink_disk_holder(td->dm_dev.bdev, dm_disk(md));
> +
> + blkdev_put(td->dm_dev.bdev, td->dm_dev.mode);
> +
> put_dax(td->dm_dev.dax_dev);
> td->dm_dev.bdev = NULL;
> td->dm_dev.dax_dev = NULL;
> }
>
> static struct table_device *find_table_device(struct list_head *l, dev_t dev,
> - fmode_t mode)
> + fmode_t mode, bool non_exclusive)
> {
> struct table_device *td;
>
> list_for_each_entry(td, l, list)
> - if (td->dm_dev.bdev->bd_dev == dev && td->dm_dev.mode == mode)
> + if (td->dm_dev.bdev->bd_dev == dev &&
> + td->dm_dev.mode == mode &&
> + td->dm_dev.non_exclusive == non_exclusive)
> return td;
>
> return NULL;
> }
>
> -int dm_get_table_device(struct mapped_device *md, dev_t dev, fmode_t mode,
> +int dm_get_table_device(struct mapped_device *md, dev_t dev, fmode_t mode, bool non_exclusive,
> struct dm_dev **result)
> {
> int r;
> struct table_device *td;
>
> mutex_lock(&md->table_devices_lock);
> - td = find_table_device(&md->table_devices, dev, mode);
> + td = find_table_device(&md->table_devices, dev, mode, non_exclusive);
> if (!td) {
> td = kmalloc_node(sizeof(*td), GFP_KERNEL, md->numa_node_id);
> if (!td) {
> @@ -807,7 +1147,8 @@ int dm_get_table_device(struct mapped_device *md, dev_t dev, fmode_t mode,
> td->dm_dev.mode = mode;
> td->dm_dev.bdev = NULL;
>
> - if ((r = open_table_device(td, dev, md))) {
> + r = open_table_device(td, dev, md, non_exclusive);
> + if (r) {
> mutex_unlock(&md->table_devices_lock);
> kfree(td);
> return r;
> @@ -2182,6 +2523,14 @@ static void __dm_destroy(struct mapped_device *md, bool wait)
>
> might_sleep();
>
> + if (md->ip_dev) {
> + if (dm_interposer_detach_dev(md->ip_dev))
> + DMERR("Failed to detach dm interposer");
> +
> + dm_interposer_free_dev(md->ip_dev);
> + md->ip_dev = NULL;
> + }
> +
> spin_lock(&_minor_lock);
> idr_replace(&_minor_idr, MINOR_ALLOCED, MINOR(disk_devt(dm_disk(md))));
> set_bit(DMF_FREEING, &md->flags);
> diff --git a/drivers/md/dm.h b/drivers/md/dm.h
> index fffe1e289c53..7bf20fb2de74 100644
> --- a/drivers/md/dm.h
> +++ b/drivers/md/dm.h
> @@ -179,7 +179,7 @@ int dm_open_count(struct mapped_device *md);
> int dm_lock_for_deletion(struct mapped_device *md, bool mark_deferred, bool only_deferred);
> int dm_cancel_deferred_remove(struct mapped_device *md);
> int dm_request_based(struct mapped_device *md);
> -int dm_get_table_device(struct mapped_device *md, dev_t dev, fmode_t mode,
> +int dm_get_table_device(struct mapped_device *md, dev_t dev, fmode_t mode, bool non_exclusive,
> struct dm_dev **result);
> void dm_put_table_device(struct mapped_device *md, struct dm_dev *d);
>
> diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
> index 61a66fb8ebb3..70002363bfc0 100644
> --- a/include/linux/device-mapper.h
> +++ b/include/linux/device-mapper.h
> @@ -150,6 +150,7 @@ struct dm_dev {
> struct block_device *bdev;
> struct dax_device *dax_dev;
> fmode_t mode;
> + bool non_exclusive;
> char name[16];
> };
>
> @@ -325,6 +326,12 @@ struct dm_target {
> * whether or not its underlying devices have support.
> */
> bool discards_supported:1;
> +
> + /*
> + * Set if this target needs to open device without FMODE_EXCL
> + * mode.
> + */
> + bool non_exclusive:1;
> };
>
> void *dm_per_bio_data(struct bio *bio, size_t data_size);
> diff --git a/include/uapi/linux/dm-ioctl.h b/include/uapi/linux/dm-ioctl.h
> index 4933b6b67b85..08d7dbff80f4 100644
> --- a/include/uapi/linux/dm-ioctl.h
> +++ b/include/uapi/linux/dm-ioctl.h
> @@ -214,6 +214,15 @@ struct dm_target_msg {
> char message[0];
> };
>
> +enum {
> + REMAP_START_CMD = 1,
> + REMAP_FINISH_CMD,
> +};
> +
> +struct dm_remap_param {
> + uint8_t cmd;
> + uint8_t params[0];
> +};
> /*
> * If you change this make sure you make the corresponding change
> * to dm-ioctl.c:lookup_ioctl()
> @@ -244,6 +253,7 @@ enum {
> DM_DEV_SET_GEOMETRY_CMD,
> DM_DEV_ARM_POLL_CMD,
> DM_GET_TARGET_VERSION_CMD,
> + DM_DEV_REMAP_CMD
> };
>
> #define DM_IOCTL 0xfd
> @@ -259,6 +269,7 @@ enum {
> #define DM_DEV_STATUS _IOWR(DM_IOCTL, DM_DEV_STATUS_CMD, struct dm_ioctl)
> #define DM_DEV_WAIT _IOWR(DM_IOCTL, DM_DEV_WAIT_CMD, struct dm_ioctl)
> #define DM_DEV_ARM_POLL _IOWR(DM_IOCTL, DM_DEV_ARM_POLL_CMD, struct dm_ioctl)
> +#define DM_DEV_REMAP _IOWR(DM_IOCTL, DM_DEV_REMAP_CMD, struct dm_ioctl)
>
> #define DM_TABLE_LOAD _IOWR(DM_IOCTL, DM_TABLE_LOAD_CMD, struct dm_ioctl)
> #define DM_TABLE_CLEAR _IOWR(DM_IOCTL, DM_TABLE_CLEAR_CMD, struct dm_ioctl)
> @@ -272,9 +283,9 @@ enum {
> #define DM_DEV_SET_GEOMETRY _IOWR(DM_IOCTL, DM_DEV_SET_GEOMETRY_CMD, struct dm_ioctl)
>
> #define DM_VERSION_MAJOR 4
> -#define DM_VERSION_MINOR 43
> +#define DM_VERSION_MINOR 44
> #define DM_VERSION_PATCHLEVEL 0
> -#define DM_VERSION_EXTRA "-ioctl (2020-10-01)"
> +#define DM_VERSION_EXTRA "-ioctl (2020-12-25)"
>
> /* Status bits */
> #define DM_READONLY_FLAG (1 << 0) /* In/Out */
>
--
Damien Le Moal
Western Digital Research
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