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authorMikulas Patocka <mpatocka@redhat.com>2013-11-01 18:27:41 -0400
committerMike Snitzer <snitzer@redhat.com>2013-11-09 18:20:22 -0500
commit2c140a246dc0bc085b98eddde978060fcec1080c (patch)
tree73d747f4422fe202868495d08ea5d189bc16bd79 /drivers/md/dm-ioctl.c
parent7833b08e18241a1c35c09ef38be840cbf6c58acf (diff)
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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-ioctl.c')
-rw-r--r--drivers/md/dm-ioctl.c36
1 files changed, 30 insertions, 6 deletions
diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index afe08146f73e..51521429fb59 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -57,7 +57,7 @@ struct vers_iter {
static struct list_head _name_buckets[NUM_BUCKETS];
static struct list_head _uuid_buckets[NUM_BUCKETS];
-static void dm_hash_remove_all(int keep_open_devices);
+static void dm_hash_remove_all(bool keep_open_devices, bool mark_deferred, bool only_deferred);
/*
* Guards access to both hash tables.
@@ -86,7 +86,7 @@ static int dm_hash_init(void)
static void dm_hash_exit(void)
{
- dm_hash_remove_all(0);
+ dm_hash_remove_all(false, false, false);
}
/*-----------------------------------------------------------------
@@ -276,7 +276,7 @@ static struct dm_table *__hash_remove(struct hash_cell *hc)
return table;
}
-static void dm_hash_remove_all(int keep_open_devices)
+static void dm_hash_remove_all(bool keep_open_devices, bool mark_deferred, bool only_deferred)
{
int i, dev_skipped;
struct hash_cell *hc;
@@ -293,7 +293,8 @@ retry:
md = hc->md;
dm_get(md);
- if (keep_open_devices && dm_lock_for_deletion(md)) {
+ if (keep_open_devices &&
+ dm_lock_for_deletion(md, mark_deferred, only_deferred)) {
dm_put(md);
dev_skipped++;
continue;
@@ -450,6 +451,11 @@ static struct mapped_device *dm_hash_rename(struct dm_ioctl *param,
return md;
}
+void dm_deferred_remove(void)
+{
+ dm_hash_remove_all(true, false, true);
+}
+
/*-----------------------------------------------------------------
* Implementation of the ioctl commands
*---------------------------------------------------------------*/
@@ -461,7 +467,7 @@ typedef int (*ioctl_fn)(struct dm_ioctl *param, size_t param_size);
static int remove_all(struct dm_ioctl *param, size_t param_size)
{
- dm_hash_remove_all(1);
+ dm_hash_remove_all(true, !!(param->flags & DM_DEFERRED_REMOVE), false);
param->data_size = 0;
return 0;
}
@@ -683,6 +689,9 @@ static void __dev_status(struct mapped_device *md, struct dm_ioctl *param)
if (dm_suspended_md(md))
param->flags |= DM_SUSPEND_FLAG;
+ if (dm_test_deferred_remove_flag(md))
+ param->flags |= DM_DEFERRED_REMOVE;
+
param->dev = huge_encode_dev(disk_devt(disk));
/*
@@ -832,8 +841,13 @@ static int dev_remove(struct dm_ioctl *param, size_t param_size)
/*
* Ensure the device is not open and nothing further can open it.
*/
- r = dm_lock_for_deletion(md);
+ r = dm_lock_for_deletion(md, !!(param->flags & DM_DEFERRED_REMOVE), false);
if (r) {
+ if (r == -EBUSY && param->flags & DM_DEFERRED_REMOVE) {
+ up_write(&_hash_lock);
+ dm_put(md);
+ return 0;
+ }
DMDEBUG_LIMIT("unable to remove open device %s", hc->name);
up_write(&_hash_lock);
dm_put(md);
@@ -848,6 +862,8 @@ static int dev_remove(struct dm_ioctl *param, size_t param_size)
dm_table_destroy(t);
}
+ param->flags &= ~DM_DEFERRED_REMOVE;
+
if (!dm_kobject_uevent(md, KOBJ_REMOVE, param->event_nr))
param->flags |= DM_UEVENT_GENERATED_FLAG;
@@ -1469,6 +1485,14 @@ static int message_for_md(struct mapped_device *md, unsigned argc, char **argv,
if (**argv != '@')
return 2; /* no '@' prefix, deliver to target */
+ if (!strcasecmp(argv[0], "@cancel_deferred_remove")) {
+ if (argc != 1) {
+ DMERR("Invalid arguments for @cancel_deferred_remove");
+ return -EINVAL;
+ }
+ return dm_cancel_deferred_remove(md);
+ }
+
r = dm_stats_message(md, argc, argv, result, maxlen);
if (r < 2)
return r;