dm: allow remove to be deferred
This patch allows the removal of an open device to be deferred until it is closed. (Previously such a removal attempt would fail.) The deferred remove functionality is enabled by setting the flag DM_DEFERRED_REMOVE in the ioctl structure on DM_DEV_REMOVE or DM_REMOVE_ALL ioctl. On return from DM_DEV_REMOVE, the flag DM_DEFERRED_REMOVE indicates if the device was removed immediately or flagged to be removed on close - if the flag is clear, the device was removed. On return from DM_DEV_STATUS and other ioctls, the flag DM_DEFERRED_REMOVE is set if the device is scheduled to be removed on closure. A device that is scheduled to be deleted can be revived using the message "@cancel_deferred_remove". This message clears the DMF_DEFERRED_REMOVE flag so that the device won't be deleted on close. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Mikulas Patocka
Mike Snitzer
parent
7833b08e18
commit
2c140a246d
4 changed files with 99 additions and 12 deletions
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@ -57,7 +57,7 @@ struct vers_iter {
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static struct list_head _name_buckets[NUM_BUCKETS];
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static struct list_head _uuid_buckets[NUM_BUCKETS];
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static void dm_hash_remove_all(int keep_open_devices);
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static void dm_hash_remove_all(bool keep_open_devices, bool mark_deferred, bool only_deferred);
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/*
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* Guards access to both hash tables.
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@ -86,7 +86,7 @@ static int dm_hash_init(void)
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static void dm_hash_exit(void)
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{
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dm_hash_remove_all(0);
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dm_hash_remove_all(false, false, false);
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}
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/*-----------------------------------------------------------------
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@ -276,7 +276,7 @@ static struct dm_table *__hash_remove(struct hash_cell *hc)
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return table;
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}
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static void dm_hash_remove_all(int keep_open_devices)
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static void dm_hash_remove_all(bool keep_open_devices, bool mark_deferred, bool only_deferred)
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{
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int i, dev_skipped;
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struct hash_cell *hc;
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@ -293,7 +293,8 @@ static void dm_hash_remove_all(int keep_open_devices)
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md = hc->md;
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dm_get(md);
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if (keep_open_devices && dm_lock_for_deletion(md)) {
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if (keep_open_devices &&
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dm_lock_for_deletion(md, mark_deferred, only_deferred)) {
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dm_put(md);
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dev_skipped++;
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continue;
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@ -450,6 +451,11 @@ static struct mapped_device *dm_hash_rename(struct dm_ioctl *param,
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return md;
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}
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void dm_deferred_remove(void)
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{
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dm_hash_remove_all(true, false, true);
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}
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/*-----------------------------------------------------------------
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* Implementation of the ioctl commands
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*---------------------------------------------------------------*/
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@ -461,7 +467,7 @@ typedef int (*ioctl_fn)(struct dm_ioctl *param, size_t param_size);
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static int remove_all(struct dm_ioctl *param, size_t param_size)
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{
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dm_hash_remove_all(1);
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dm_hash_remove_all(true, !!(param->flags & DM_DEFERRED_REMOVE), false);
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param->data_size = 0;
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return 0;
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}
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@ -683,6 +689,9 @@ static void __dev_status(struct mapped_device *md, struct dm_ioctl *param)
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if (dm_suspended_md(md))
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param->flags |= DM_SUSPEND_FLAG;
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if (dm_test_deferred_remove_flag(md))
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param->flags |= DM_DEFERRED_REMOVE;
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param->dev = huge_encode_dev(disk_devt(disk));
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/*
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@ -832,8 +841,13 @@ static int dev_remove(struct dm_ioctl *param, size_t param_size)
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/*
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* Ensure the device is not open and nothing further can open it.
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*/
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r = dm_lock_for_deletion(md);
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r = dm_lock_for_deletion(md, !!(param->flags & DM_DEFERRED_REMOVE), false);
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if (r) {
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if (r == -EBUSY && param->flags & DM_DEFERRED_REMOVE) {
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up_write(&_hash_lock);
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dm_put(md);
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return 0;
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}
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DMDEBUG_LIMIT("unable to remove open device %s", hc->name);
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up_write(&_hash_lock);
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dm_put(md);
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@ -848,6 +862,8 @@ static int dev_remove(struct dm_ioctl *param, size_t param_size)
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dm_table_destroy(t);
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}
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param->flags &= ~DM_DEFERRED_REMOVE;
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if (!dm_kobject_uevent(md, KOBJ_REMOVE, param->event_nr))
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param->flags |= DM_UEVENT_GENERATED_FLAG;
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@ -1469,6 +1485,14 @@ static int message_for_md(struct mapped_device *md, unsigned argc, char **argv,
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if (**argv != '@')
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return 2; /* no '@' prefix, deliver to target */
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if (!strcasecmp(argv[0], "@cancel_deferred_remove")) {
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if (argc != 1) {
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DMERR("Invalid arguments for @cancel_deferred_remove");
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return -EINVAL;
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}
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return dm_cancel_deferred_remove(md);
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}
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r = dm_stats_message(md, argc, argv, result, maxlen);
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if (r < 2)
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return r;
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@ -49,6 +49,11 @@ static unsigned int _major = 0;
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static DEFINE_IDR(_minor_idr);
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static DEFINE_SPINLOCK(_minor_lock);
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static void do_deferred_remove(struct work_struct *w);
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static DECLARE_WORK(deferred_remove_work, do_deferred_remove);
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/*
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* For bio-based dm.
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* One of these is allocated per bio.
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@ -116,6 +121,7 @@ EXPORT_SYMBOL_GPL(dm_get_rq_mapinfo);
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#define DMF_DELETING 4
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#define DMF_NOFLUSH_SUSPENDING 5
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#define DMF_MERGE_IS_OPTIONAL 6
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#define DMF_DEFERRED_REMOVE 7
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/*
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* A dummy definition to make RCU happy.
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@ -299,6 +305,8 @@ static int __init local_init(void)
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static void local_exit(void)
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{
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flush_scheduled_work();
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kmem_cache_destroy(_rq_tio_cache);
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kmem_cache_destroy(_io_cache);
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unregister_blkdev(_major, _name);
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@ -404,7 +412,10 @@ static void dm_blk_close(struct gendisk *disk, fmode_t mode)
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spin_lock(&_minor_lock);
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atomic_dec(&md->open_count);
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if (atomic_dec_and_test(&md->open_count) &&
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(test_bit(DMF_DEFERRED_REMOVE, &md->flags)))
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schedule_work(&deferred_remove_work);
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dm_put(md);
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spin_unlock(&_minor_lock);
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@ -418,14 +429,18 @@ int dm_open_count(struct mapped_device *md)
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/*
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* Guarantees nothing is using the device before it's deleted.
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*/
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int dm_lock_for_deletion(struct mapped_device *md)
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int dm_lock_for_deletion(struct mapped_device *md, bool mark_deferred, bool only_deferred)
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{
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int r = 0;
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spin_lock(&_minor_lock);
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if (dm_open_count(md))
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if (dm_open_count(md)) {
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r = -EBUSY;
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if (mark_deferred)
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set_bit(DMF_DEFERRED_REMOVE, &md->flags);
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} else if (only_deferred && !test_bit(DMF_DEFERRED_REMOVE, &md->flags))
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r = -EEXIST;
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else
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set_bit(DMF_DELETING, &md->flags);
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@ -434,6 +449,27 @@ int dm_lock_for_deletion(struct mapped_device *md)
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return r;
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}
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int dm_cancel_deferred_remove(struct mapped_device *md)
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{
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int r = 0;
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spin_lock(&_minor_lock);
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if (test_bit(DMF_DELETING, &md->flags))
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r = -EBUSY;
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else
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clear_bit(DMF_DEFERRED_REMOVE, &md->flags);
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spin_unlock(&_minor_lock);
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return r;
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}
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static void do_deferred_remove(struct work_struct *w)
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{
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dm_deferred_remove();
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}
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sector_t dm_get_size(struct mapped_device *md)
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{
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return get_capacity(md->disk);
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@ -2894,6 +2930,11 @@ int dm_suspended_md(struct mapped_device *md)
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return test_bit(DMF_SUSPENDED, &md->flags);
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}
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int dm_test_deferred_remove_flag(struct mapped_device *md)
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{
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return test_bit(DMF_DEFERRED_REMOVE, &md->flags);
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}
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int dm_suspended(struct dm_target *ti)
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{
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return dm_suspended_md(dm_table_get_md(ti->table));
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@ -128,6 +128,16 @@ int dm_deleting_md(struct mapped_device *md);
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*/
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int dm_suspended_md(struct mapped_device *md);
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/*
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* Test if the device is scheduled for deferred remove.
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*/
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int dm_test_deferred_remove_flag(struct mapped_device *md);
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/*
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* Try to remove devices marked for deferred removal.
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*/
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void dm_deferred_remove(void);
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/*
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* The device-mapper can be driven through one of two interfaces;
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* ioctl or filesystem, depending which patch you have applied.
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@ -158,7 +168,8 @@ void dm_stripe_exit(void);
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void dm_destroy(struct mapped_device *md);
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void dm_destroy_immediate(struct mapped_device *md);
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int dm_open_count(struct mapped_device *md);
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int dm_lock_for_deletion(struct mapped_device *md);
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int dm_lock_for_deletion(struct mapped_device *md, bool mark_deferred, bool only_deferred);
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int dm_cancel_deferred_remove(struct mapped_device *md);
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int dm_request_based(struct mapped_device *md);
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sector_t dm_get_size(struct mapped_device *md);
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struct dm_stats *dm_get_stats(struct mapped_device *md);
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@ -267,9 +267,9 @@ enum {
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#define DM_DEV_SET_GEOMETRY _IOWR(DM_IOCTL, DM_DEV_SET_GEOMETRY_CMD, struct dm_ioctl)
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#define DM_VERSION_MAJOR 4
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#define DM_VERSION_MINOR 26
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#define DM_VERSION_MINOR 27
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#define DM_VERSION_PATCHLEVEL 0
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#define DM_VERSION_EXTRA "-ioctl (2013-08-15)"
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#define DM_VERSION_EXTRA "-ioctl (2013-10-30)"
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/* Status bits */
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#define DM_READONLY_FLAG (1 << 0) /* In/Out */
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@ -341,4 +341,15 @@ enum {
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*/
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#define DM_DATA_OUT_FLAG (1 << 16) /* Out */
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/*
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* If set with DM_DEV_REMOVE or DM_REMOVE_ALL this indicates that if
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* the device cannot be removed immediately because it is still in use
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* it should instead be scheduled for removal when it gets closed.
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*
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* On return from DM_DEV_REMOVE, DM_DEV_STATUS or other ioctls, this
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* flag indicates that the device is scheduled to be removed when it
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* gets closed.
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*/
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#define DM_DEFERRED_REMOVE (1 << 17) /* In/Out */
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#endif /* _LINUX_DM_IOCTL_H */
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