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authorMikulas Patocka <mpatocka@redhat.com>2013-11-02 02:27:41 +0400
committerMike Snitzer <snitzer@redhat.com>2013-11-10 03:20:22 +0400
commit2c140a246dc0bc085b98eddde978060fcec1080c (patch)
tree73d747f4422fe202868495d08ea5d189bc16bd79 /drivers/md/dm.c
parent7833b08e18241a1c35c09ef38be840cbf6c58acf (diff)
downloadlinux-2c140a246dc0bc085b98eddde978060fcec1080c.tar.xz
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>
Diffstat (limited to 'drivers/md/dm.c')
-rw-r--r--drivers/md/dm.c47
1 files changed, 44 insertions, 3 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index b3e26c7d1417..0704c523a76b 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -49,6 +49,11 @@ static unsigned int _major = 0;
static DEFINE_IDR(_minor_idr);
static DEFINE_SPINLOCK(_minor_lock);
+
+static void do_deferred_remove(struct work_struct *w);
+
+static DECLARE_WORK(deferred_remove_work, do_deferred_remove);
+
/*
* For bio-based dm.
* One of these is allocated per bio.
@@ -116,6 +121,7 @@ EXPORT_SYMBOL_GPL(dm_get_rq_mapinfo);
#define DMF_DELETING 4
#define DMF_NOFLUSH_SUSPENDING 5
#define DMF_MERGE_IS_OPTIONAL 6
+#define DMF_DEFERRED_REMOVE 7
/*
* A dummy definition to make RCU happy.
@@ -299,6 +305,8 @@ out_free_io_cache:
static void local_exit(void)
{
+ flush_scheduled_work();
+
kmem_cache_destroy(_rq_tio_cache);
kmem_cache_destroy(_io_cache);
unregister_blkdev(_major, _name);
@@ -404,7 +412,10 @@ static void dm_blk_close(struct gendisk *disk, fmode_t mode)
spin_lock(&_minor_lock);
- atomic_dec(&md->open_count);
+ if (atomic_dec_and_test(&md->open_count) &&
+ (test_bit(DMF_DEFERRED_REMOVE, &md->flags)))
+ schedule_work(&deferred_remove_work);
+
dm_put(md);
spin_unlock(&_minor_lock);
@@ -418,14 +429,18 @@ int dm_open_count(struct mapped_device *md)
/*
* Guarantees nothing is using the device before it's deleted.
*/
-int dm_lock_for_deletion(struct mapped_device *md)
+int dm_lock_for_deletion(struct mapped_device *md, bool mark_deferred, bool only_deferred)
{
int r = 0;
spin_lock(&_minor_lock);
- if (dm_open_count(md))
+ if (dm_open_count(md)) {
r = -EBUSY;
+ if (mark_deferred)
+ set_bit(DMF_DEFERRED_REMOVE, &md->flags);
+ } else if (only_deferred && !test_bit(DMF_DEFERRED_REMOVE, &md->flags))
+ r = -EEXIST;
else
set_bit(DMF_DELETING, &md->flags);
@@ -434,6 +449,27 @@ int dm_lock_for_deletion(struct mapped_device *md)
return r;
}
+int dm_cancel_deferred_remove(struct mapped_device *md)
+{
+ int r = 0;
+
+ spin_lock(&_minor_lock);
+
+ if (test_bit(DMF_DELETING, &md->flags))
+ r = -EBUSY;
+ else
+ clear_bit(DMF_DEFERRED_REMOVE, &md->flags);
+
+ spin_unlock(&_minor_lock);
+
+ return r;
+}
+
+static void do_deferred_remove(struct work_struct *w)
+{
+ dm_deferred_remove();
+}
+
sector_t dm_get_size(struct mapped_device *md)
{
return get_capacity(md->disk);
@@ -2894,6 +2930,11 @@ int dm_suspended_md(struct mapped_device *md)
return test_bit(DMF_SUSPENDED, &md->flags);
}
+int dm_test_deferred_remove_flag(struct mapped_device *md)
+{
+ return test_bit(DMF_DEFERRED_REMOVE, &md->flags);
+}
+
int dm_suspended(struct dm_target *ti)
{
return dm_suspended_md(dm_table_get_md(ti->table));