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authorBenjamin Marzinski <bmarzins@redhat.com>2014-08-13 13:53:43 -0500
committerMike Snitzer <snitzer@redhat.com>2014-10-05 20:03:35 -0400
commit86f1152b117a404229fd6f08ec3faca779f37b92 (patch)
treedceee3703ab97065c3e425b55d42cb4edb9a079b /drivers/md/dm-table.c
parent1f271972478d84dd9e4d6dd82f414d70ed9e78ce (diff)
downloadop-kernel-dev-86f1152b117a404229fd6f08ec3faca779f37b92.zip
op-kernel-dev-86f1152b117a404229fd6f08ec3faca779f37b92.tar.gz
dm: allow active and inactive tables to share dm_devs
Until this change, when loading a new DM table, DM core would re-open all of the devices in the DM table. Now, DM core will avoid redundant device opens (and closes when destroying the old table) if the old table already has a device open using the same mode. This is achieved by managing reference counts on the table_devices that DM core now stores in the mapped_device structure (rather than in the dm_table structure). So a mapped_device's active and inactive dm_tables' dm_dev lists now just point to the dm_devs stored in the mapped_device's table_devices list. This improvement in DM core's device reference counting has the side-effect of fixing a long-standing limitation of the multipath target: a DM multipath table couldn't include any paths that were unusable (failed). For example: if all paths have failed and you add a new, working, path to the table; you can't use it since the table load would fail due to it still containing failed paths. Now a re-load of a multipath table can include failed devices and when those devices become active again they can be used instantly. The device list code in dm.c isn't a straight copy/paste from the code in dm-table.c, but it's very close (aside from some variable renames). One subtle difference is that find_table_device for the tables_devices list will only match devices with the same name and mode. This is because we don't want to upgrade a device's mode in the active table when an inactive table is loaded. Access to the mapped_device structure's tables_devices list requires a mutex (tables_devices_lock), so that tables cannot be created and destroyed concurrently. Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md/dm-table.c')
-rw-r--r--drivers/md/dm-table.c102
1 files changed, 34 insertions, 68 deletions
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index f9c6cb8..b2bd1eb 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -210,15 +210,16 @@ int dm_table_create(struct dm_table **result, fmode_t mode,
return 0;
}
-static void free_devices(struct list_head *devices)
+static void free_devices(struct list_head *devices, struct mapped_device *md)
{
struct list_head *tmp, *next;
list_for_each_safe(tmp, next, devices) {
struct dm_dev_internal *dd =
list_entry(tmp, struct dm_dev_internal, list);
- DMWARN("dm_table_destroy: dm_put_device call missing for %s",
- dd->dm_dev.name);
+ DMWARN("%s: dm_table_destroy: dm_put_device call missing for %s",
+ dm_device_name(md), dd->dm_dev->name);
+ dm_put_table_device(md, dd->dm_dev);
kfree(dd);
}
}
@@ -247,7 +248,7 @@ void dm_table_destroy(struct dm_table *t)
vfree(t->highs);
/* free the device list */
- free_devices(&t->devices);
+ free_devices(&t->devices, t->md);
dm_free_md_mempools(t->mempools);
@@ -262,53 +263,13 @@ static struct dm_dev_internal *find_device(struct list_head *l, dev_t dev)
struct dm_dev_internal *dd;
list_for_each_entry (dd, l, list)
- if (dd->dm_dev.bdev->bd_dev == dev)
+ if (dd->dm_dev->bdev->bd_dev == dev)
return dd;
return NULL;
}
/*
- * Open a device so we can use it as a map destination.
- */
-static int open_dev(struct dm_dev_internal *d, dev_t dev,
- struct mapped_device *md)
-{
- static char *_claim_ptr = "I belong to device-mapper";
- struct block_device *bdev;
-
- int r;
-
- BUG_ON(d->dm_dev.bdev);
-
- bdev = blkdev_get_by_dev(dev, d->dm_dev.mode | FMODE_EXCL, _claim_ptr);
- if (IS_ERR(bdev))
- return PTR_ERR(bdev);
-
- r = bd_link_disk_holder(bdev, dm_disk(md));
- if (r) {
- blkdev_put(bdev, d->dm_dev.mode | FMODE_EXCL);
- return r;
- }
-
- d->dm_dev.bdev = bdev;
- return 0;
-}
-
-/*
- * Close a device that we've been using.
- */
-static void close_dev(struct dm_dev_internal *d, struct mapped_device *md)
-{
- if (!d->dm_dev.bdev)
- return;
-
- bd_unlink_disk_holder(d->dm_dev.bdev, dm_disk(md));
- blkdev_put(d->dm_dev.bdev, d->dm_dev.mode | FMODE_EXCL);
- d->dm_dev.bdev = NULL;
-}
-
-/*
* If possible, this checks an area of a destination device is invalid.
*/
static int device_area_is_invalid(struct dm_target *ti, struct dm_dev *dev,
@@ -386,19 +347,17 @@ static int upgrade_mode(struct dm_dev_internal *dd, fmode_t new_mode,
struct mapped_device *md)
{
int r;
- struct dm_dev_internal dd_new, dd_old;
+ struct dm_dev *old_dev, *new_dev;
- dd_new = dd_old = *dd;
+ old_dev = dd->dm_dev;
- dd_new.dm_dev.mode |= new_mode;
- dd_new.dm_dev.bdev = NULL;
-
- r = open_dev(&dd_new, dd->dm_dev.bdev->bd_dev, md);
+ r = dm_get_table_device(md, dd->dm_dev->bdev->bd_dev,
+ dd->dm_dev->mode | new_mode, &new_dev);
if (r)
return r;
- dd->dm_dev.mode |= new_mode;
- close_dev(&dd_old, md);
+ dd->dm_dev = new_dev;
+ dm_put_table_device(md, old_dev);
return 0;
}
@@ -440,27 +399,22 @@ int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode,
if (!dd)
return -ENOMEM;
- dd->dm_dev.mode = mode;
- dd->dm_dev.bdev = NULL;
-
- if ((r = open_dev(dd, dev, t->md))) {
+ if ((r = dm_get_table_device(t->md, dev, mode, &dd->dm_dev))) {
kfree(dd);
return r;
}
- format_dev_t(dd->dm_dev.name, dev);
-
atomic_set(&dd->count, 0);
list_add(&dd->list, &t->devices);
- } else if (dd->dm_dev.mode != (mode | dd->dm_dev.mode)) {
+ } else if (dd->dm_dev->mode != (mode | dd->dm_dev->mode)) {
r = upgrade_mode(dd, mode, t->md);
if (r)
return r;
}
atomic_inc(&dd->count);
- *result = &dd->dm_dev;
+ *result = dd->dm_dev;
return 0;
}
EXPORT_SYMBOL(dm_get_device);
@@ -505,11 +459,23 @@ static int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev,
*/
void dm_put_device(struct dm_target *ti, struct dm_dev *d)
{
- struct dm_dev_internal *dd = container_of(d, struct dm_dev_internal,
- dm_dev);
+ int found = 0;
+ struct list_head *devices = &ti->table->devices;
+ struct dm_dev_internal *dd;
+ list_for_each_entry(dd, devices, list) {
+ if (dd->dm_dev == d) {
+ found = 1;
+ break;
+ }
+ }
+ if (!found) {
+ DMWARN("%s: device %s not in table devices list",
+ dm_device_name(ti->table->md), d->name);
+ return;
+ }
if (atomic_dec_and_test(&dd->count)) {
- close_dev(dd, ti->table->md);
+ dm_put_table_device(ti->table->md, d);
list_del(&dd->list);
kfree(dd);
}
@@ -906,7 +872,7 @@ static int dm_table_set_type(struct dm_table *t)
/* Non-request-stackable devices can't be used for request-based dm */
devices = dm_table_get_devices(t);
list_for_each_entry(dd, devices, list) {
- if (!blk_queue_stackable(bdev_get_queue(dd->dm_dev.bdev))) {
+ if (!blk_queue_stackable(bdev_get_queue(dd->dm_dev->bdev))) {
DMWARN("table load rejected: including"
" non-request-stackable devices");
return -EINVAL;
@@ -1043,7 +1009,7 @@ static struct gendisk * dm_table_get_integrity_disk(struct dm_table *t,
struct gendisk *prev_disk = NULL, *template_disk = NULL;
list_for_each_entry(dd, devices, list) {
- template_disk = dd->dm_dev.bdev->bd_disk;
+ template_disk = dd->dm_dev->bdev->bd_disk;
if (!blk_get_integrity(template_disk))
goto no_integrity;
if (!match_all && !blk_integrity_is_initialized(template_disk))
@@ -1629,7 +1595,7 @@ int dm_table_any_congested(struct dm_table *t, int bdi_bits)
int r = 0;
list_for_each_entry(dd, devices, list) {
- struct request_queue *q = bdev_get_queue(dd->dm_dev.bdev);
+ struct request_queue *q = bdev_get_queue(dd->dm_dev->bdev);
char b[BDEVNAME_SIZE];
if (likely(q))
@@ -1637,7 +1603,7 @@ int dm_table_any_congested(struct dm_table *t, int bdi_bits)
else
DMWARN_LIMIT("%s: any_congested: nonexistent device %s",
dm_device_name(t->md),
- bdevname(dd->dm_dev.bdev, b));
+ bdevname(dd->dm_dev->bdev, b));
}
list_for_each_entry(cb, &t->target_callbacks, list)
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