struct dm_table *new_map;
};
+/*
+ * A dummy definition to make RCU happy.
+ * struct dm_table should never be dereferenced in this file.
+ */
+struct dm_table {
+ int undefined__;
+};
+
struct vers_iter {
size_t param_size;
struct dm_target_versions *vers, *old_vers;
return -EBUSY;
}
-static void __hash_remove(struct hash_cell *hc)
+static struct dm_table *__hash_remove(struct hash_cell *hc)
{
struct dm_table *table;
+ int srcu_idx;
/* remove from the dev hash */
list_del(&hc->uuid_list);
dm_set_mdptr(hc->md, NULL);
mutex_unlock(&dm_hash_cells_mutex);
- table = dm_get_live_table(hc->md);
- if (table) {
+ table = dm_get_live_table(hc->md, &srcu_idx);
+ if (table)
dm_table_event(table);
- dm_table_put(table);
- }
+ dm_put_live_table(hc->md, srcu_idx);
+ table = NULL;
if (hc->new_map)
- dm_table_destroy(hc->new_map);
+ table = hc->new_map;
dm_put(hc->md);
free_cell(hc);
+
+ return table;
}
static void dm_hash_remove_all(int keep_open_devices)
int i, dev_skipped;
struct hash_cell *hc;
struct mapped_device *md;
+ struct dm_table *t;
retry:
dev_skipped = 0;
continue;
}
- __hash_remove(hc);
+ t = __hash_remove(hc);
up_write(&_hash_lock);
+ if (t) {
+ dm_sync_table(md);
+ dm_table_destroy(t);
+ }
dm_put(md);
if (likely(keep_open_devices))
dm_destroy(md);
struct dm_table *table;
struct mapped_device *md;
unsigned change_uuid = (param->flags & DM_UUID_FLAG) ? 1 : 0;
+ int srcu_idx;
/*
* duplicate new.
/*
* Wake up any dm event waiters.
*/
- table = dm_get_live_table(hc->md);
- if (table) {
+ table = dm_get_live_table(hc->md, &srcu_idx);
+ if (table)
dm_table_event(table);
- dm_table_put(table);
- }
+ dm_put_live_table(hc->md, srcu_idx);
if (!dm_kobject_uevent(hc->md, KOBJ_CHANGE, param->event_nr))
param->flags |= DM_UEVENT_GENERATED_FLAG;
* _hash_lock without first calling dm_table_put, because dm_table_destroy
* waits for this dm_table_put and could be called under this lock.
*/
-static struct dm_table *dm_get_inactive_table(struct mapped_device *md)
+static struct dm_table *dm_get_inactive_table(struct mapped_device *md, int *srcu_idx)
{
struct hash_cell *hc;
struct dm_table *table = NULL;
+ /* increment rcu count, we don't care about the table pointer */
+ dm_get_live_table(md, srcu_idx);
+
down_read(&_hash_lock);
hc = dm_get_mdptr(md);
if (!hc || hc->md != md) {
}
table = hc->new_map;
- if (table)
- dm_table_get(table);
out:
up_read(&_hash_lock);
}
static struct dm_table *dm_get_live_or_inactive_table(struct mapped_device *md,
- struct dm_ioctl *param)
+ struct dm_ioctl *param,
+ int *srcu_idx)
{
return (param->flags & DM_QUERY_INACTIVE_TABLE_FLAG) ?
- dm_get_inactive_table(md) : dm_get_live_table(md);
+ dm_get_inactive_table(md, srcu_idx) : dm_get_live_table(md, srcu_idx);
}
/*
{
struct gendisk *disk = dm_disk(md);
struct dm_table *table;
+ int srcu_idx;
param->flags &= ~(DM_SUSPEND_FLAG | DM_READONLY_FLAG |
DM_ACTIVE_PRESENT_FLAG);
param->event_nr = dm_get_event_nr(md);
param->target_count = 0;
- table = dm_get_live_table(md);
+ table = dm_get_live_table(md, &srcu_idx);
if (table) {
if (!(param->flags & DM_QUERY_INACTIVE_TABLE_FLAG)) {
if (get_disk_ro(disk))
param->flags |= DM_READONLY_FLAG;
param->target_count = dm_table_get_num_targets(table);
}
- dm_table_put(table);
param->flags |= DM_ACTIVE_PRESENT_FLAG;
}
+ dm_put_live_table(md, srcu_idx);
if (param->flags & DM_QUERY_INACTIVE_TABLE_FLAG) {
- table = dm_get_inactive_table(md);
+ int srcu_idx;
+ table = dm_get_inactive_table(md, &srcu_idx);
if (table) {
if (!(dm_table_get_mode(table) & FMODE_WRITE))
param->flags |= DM_READONLY_FLAG;
param->target_count = dm_table_get_num_targets(table);
- dm_table_put(table);
}
+ dm_put_live_table(md, srcu_idx);
}
}
struct hash_cell *hc;
struct mapped_device *md;
int r;
+ struct dm_table *t;
down_write(&_hash_lock);
hc = __find_device_hash_cell(param);
return r;
}
- __hash_remove(hc);
+ t = __hash_remove(hc);
up_write(&_hash_lock);
+ if (t) {
+ dm_sync_table(md);
+ dm_table_destroy(t);
+ }
+
if (!dm_kobject_uevent(md, KOBJ_REMOVE, param->event_nr))
param->flags |= DM_UEVENT_GENERATED_FLAG;
old_map = dm_swap_table(md, new_map);
if (IS_ERR(old_map)) {
+ dm_sync_table(md);
dm_table_destroy(new_map);
dm_put(md);
return PTR_ERR(old_map);
param->flags |= DM_UEVENT_GENERATED_FLAG;
}
+ /*
+ * Since dm_swap_table synchronizes RCU, nobody should be in
+ * read-side critical section already.
+ */
if (old_map)
dm_table_destroy(old_map);
int r = 0;
struct mapped_device *md;
struct dm_table *table;
+ int srcu_idx;
md = find_device(param);
if (!md)
*/
__dev_status(md, param);
- table = dm_get_live_or_inactive_table(md, param);
- if (table) {
+ table = dm_get_live_or_inactive_table(md, param, &srcu_idx);
+ if (table)
retrieve_status(table, param, param_size);
- dm_table_put(table);
- }
+ dm_put_live_table(md, srcu_idx);
out:
dm_put(md);
{
int r;
struct hash_cell *hc;
- struct dm_table *t;
+ struct dm_table *t, *old_map = NULL;
struct mapped_device *md;
struct target_type *immutable_target_type;
hc = dm_get_mdptr(md);
if (!hc || hc->md != md) {
DMWARN("device has been removed from the dev hash table.");
- dm_table_destroy(t);
up_write(&_hash_lock);
+ dm_table_destroy(t);
r = -ENXIO;
goto out;
}
if (hc->new_map)
- dm_table_destroy(hc->new_map);
+ old_map = hc->new_map;
hc->new_map = t;
up_write(&_hash_lock);
__dev_status(md, param);
out:
+ if (old_map) {
+ dm_sync_table(md);
+ dm_table_destroy(old_map);
+ }
+
dm_put(md);
return r;
{
struct hash_cell *hc;
struct mapped_device *md;
+ struct dm_table *old_map = NULL;
down_write(&_hash_lock);
}
if (hc->new_map) {
- dm_table_destroy(hc->new_map);
+ old_map = hc->new_map;
hc->new_map = NULL;
}
__dev_status(hc->md, param);
md = hc->md;
up_write(&_hash_lock);
+ if (old_map) {
+ dm_sync_table(md);
+ dm_table_destroy(old_map);
+ }
dm_put(md);
return 0;
{
struct mapped_device *md;
struct dm_table *table;
+ int srcu_idx;
md = find_device(param);
if (!md)
__dev_status(md, param);
- table = dm_get_live_or_inactive_table(md, param);
- if (table) {
+ table = dm_get_live_or_inactive_table(md, param, &srcu_idx);
+ if (table)
retrieve_deps(table, param, param_size);
- dm_table_put(table);
- }
+ dm_put_live_table(md, srcu_idx);
dm_put(md);
{
struct mapped_device *md;
struct dm_table *table;
+ int srcu_idx;
md = find_device(param);
if (!md)
__dev_status(md, param);
- table = dm_get_live_or_inactive_table(md, param);
- if (table) {
+ table = dm_get_live_or_inactive_table(md, param, &srcu_idx);
+ if (table)
retrieve_status(table, param, param_size);
- dm_table_put(table);
- }
+ dm_put_live_table(md, srcu_idx);
dm_put(md);
struct dm_target_msg *tmsg = (void *) param + param->data_start;
size_t maxlen;
char *result = get_result_buffer(param, param_size, &maxlen);
+ int srcu_idx;
md = find_device(param);
if (!md)
if (r <= 1)
goto out_argv;
- table = dm_get_live_table(md);
+ table = dm_get_live_table(md, &srcu_idx);
if (!table)
- goto out_argv;
+ goto out_table;
if (dm_deleting_md(md)) {
r = -ENXIO;
}
out_table:
- dm_table_put(table);
+ dm_put_live_table(md, srcu_idx);
out_argv:
kfree(argv);
out:
#define DMF_NOFLUSH_SUSPENDING 5
#define DMF_MERGE_IS_OPTIONAL 6
+/*
+ * A dummy definition to make RCU happy.
+ * struct dm_table should never be dereferenced in this file.
+ */
+struct dm_table {
+ int undefined__;
+};
+
/*
* Work processed by per-device workqueue.
*/
struct mapped_device {
- struct rw_semaphore io_lock;
+ struct srcu_struct io_barrier;
struct mutex suspend_lock;
- rwlock_t map_lock;
atomic_t holders;
atomic_t open_count;
/*
* The current mapping.
+ * Use dm_get_live_table{_fast} or take suspend_lock for
+ * dereference.
*/
struct dm_table *map;
unsigned int cmd, unsigned long arg)
{
struct mapped_device *md = bdev->bd_disk->private_data;
+ int srcu_idx;
struct dm_table *map;
struct dm_target *tgt;
int r = -ENOTTY;
retry:
- map = dm_get_live_table(md);
+ map = dm_get_live_table(md, &srcu_idx);
+
if (!map || !dm_table_get_size(map))
goto out;
r = tgt->type->ioctl(tgt, cmd, arg);
out:
- dm_table_put(map);
+ dm_put_live_table(md, srcu_idx);
if (r == -ENOTCONN) {
msleep(10);
/*
* Everyone (including functions in this file), should use this
* function to access the md->map field, and make sure they call
- * dm_table_put() when finished.
+ * dm_put_live_table() when finished.
*/
-struct dm_table *dm_get_live_table(struct mapped_device *md)
+struct dm_table *dm_get_live_table(struct mapped_device *md, int *srcu_idx) __acquires(md->io_barrier)
{
- struct dm_table *t;
- unsigned long flags;
+ *srcu_idx = srcu_read_lock(&md->io_barrier);
+
+ return srcu_dereference(md->map, &md->io_barrier);
+}
- read_lock_irqsave(&md->map_lock, flags);
- t = md->map;
- if (t)
- dm_table_get(t);
- read_unlock_irqrestore(&md->map_lock, flags);
+void dm_put_live_table(struct mapped_device *md, int srcu_idx) __releases(md->io_barrier)
+{
+ srcu_read_unlock(&md->io_barrier, srcu_idx);
+}
+
+void dm_sync_table(struct mapped_device *md)
+{
+ synchronize_srcu(&md->io_barrier);
+ synchronize_rcu_expedited();
+}
+
+/*
+ * A fast alternative to dm_get_live_table/dm_put_live_table.
+ * The caller must not block between these two functions.
+ */
+static struct dm_table *dm_get_live_table_fast(struct mapped_device *md) __acquires(RCU)
+{
+ rcu_read_lock();
+ return rcu_dereference(md->map);
+}
- return t;
+static void dm_put_live_table_fast(struct mapped_device *md) __releases(RCU)
+{
+ rcu_read_unlock();
}
/*
/*
* Entry point to split a bio into clones and submit them to the targets.
*/
-static void __split_and_process_bio(struct mapped_device *md, struct bio *bio)
+static void __split_and_process_bio(struct mapped_device *md,
+ struct dm_table *map, struct bio *bio)
{
struct clone_info ci;
int error = 0;
- ci.map = dm_get_live_table(md);
- if (unlikely(!ci.map)) {
+ if (unlikely(!map)) {
bio_io_error(bio);
return;
}
+ ci.map = map;
ci.md = md;
ci.io = alloc_io(md);
ci.io->error = 0;
/* drop the extra reference count */
dec_pending(ci.io, error);
- dm_table_put(ci.map);
}
/*-----------------------------------------------------------------
* CRUD END
struct bio_vec *biovec)
{
struct mapped_device *md = q->queuedata;
- struct dm_table *map = dm_get_live_table(md);
+ struct dm_table *map = dm_get_live_table_fast(md);
struct dm_target *ti;
sector_t max_sectors;
int max_size = 0;
ti = dm_table_find_target(map, bvm->bi_sector);
if (!dm_target_is_valid(ti))
- goto out_table;
+ goto out;
/*
* Find maximum amount of I/O that won't need splitting
max_size = 0;
-out_table:
- dm_table_put(map);
-
out:
+ dm_put_live_table_fast(md);
/*
* Always allow an entire first page
*/
int rw = bio_data_dir(bio);
struct mapped_device *md = q->queuedata;
int cpu;
+ int srcu_idx;
+ struct dm_table *map;
- down_read(&md->io_lock);
+ map = dm_get_live_table(md, &srcu_idx);
cpu = part_stat_lock();
part_stat_inc(cpu, &dm_disk(md)->part0, ios[rw]);
/* if we're suspended, we have to queue this io for later */
if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags))) {
- up_read(&md->io_lock);
+ dm_put_live_table(md, srcu_idx);
if (bio_rw(bio) != READA)
queue_io(md, bio);
return;
}
- __split_and_process_bio(md, bio);
- up_read(&md->io_lock);
+ __split_and_process_bio(md, map, bio);
+ dm_put_live_table(md, srcu_idx);
return;
}
static void dm_request_fn(struct request_queue *q)
{
struct mapped_device *md = q->queuedata;
- struct dm_table *map = dm_get_live_table(md);
+ int srcu_idx;
+ struct dm_table *map = dm_get_live_table(md, &srcu_idx);
struct dm_target *ti;
struct request *rq, *clone;
sector_t pos;
delay_and_out:
blk_delay_queue(q, HZ / 10);
out:
- dm_table_put(map);
+ dm_put_live_table(md, srcu_idx);
}
int dm_underlying_device_busy(struct request_queue *q)
{
int r;
struct mapped_device *md = q->queuedata;
- struct dm_table *map = dm_get_live_table(md);
+ struct dm_table *map = dm_get_live_table_fast(md);
if (!map || test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags))
r = 1;
else
r = dm_table_any_busy_target(map);
- dm_table_put(map);
+ dm_put_live_table_fast(md);
return r;
}
struct dm_table *map;
if (!test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) {
- map = dm_get_live_table(md);
+ map = dm_get_live_table_fast(md);
if (map) {
/*
* Request-based dm cares about only own queue for
bdi_bits;
else
r = dm_table_any_congested(map, bdi_bits);
-
- dm_table_put(map);
}
+ dm_put_live_table_fast(md);
}
return r;
if (r < 0)
goto bad_minor;
+ r = init_srcu_struct(&md->io_barrier);
+ if (r < 0)
+ goto bad_io_barrier;
+
md->type = DM_TYPE_NONE;
- init_rwsem(&md->io_lock);
mutex_init(&md->suspend_lock);
mutex_init(&md->type_lock);
spin_lock_init(&md->deferred_lock);
- rwlock_init(&md->map_lock);
atomic_set(&md->holders, 1);
atomic_set(&md->open_count, 0);
atomic_set(&md->event_nr, 0);
bad_disk:
blk_cleanup_queue(md->queue);
bad_queue:
+ cleanup_srcu_struct(&md->io_barrier);
+bad_io_barrier:
free_minor(minor);
bad_minor:
module_put(THIS_MODULE);
bioset_free(md->bs);
blk_integrity_unregister(md->disk);
del_gendisk(md->disk);
+ cleanup_srcu_struct(&md->io_barrier);
free_minor(minor);
spin_lock(&_minor_lock);
struct dm_table *old_map;
struct request_queue *q = md->queue;
sector_t size;
- unsigned long flags;
int merge_is_optional;
size = dm_table_get_size(t);
merge_is_optional = dm_table_merge_is_optional(t);
- write_lock_irqsave(&md->map_lock, flags);
old_map = md->map;
- md->map = t;
+ rcu_assign_pointer(md->map, t);
md->immutable_target_type = dm_table_get_immutable_target_type(t);
dm_table_set_restrictions(t, q, limits);
set_bit(DMF_MERGE_IS_OPTIONAL, &md->flags);
else
clear_bit(DMF_MERGE_IS_OPTIONAL, &md->flags);
- write_unlock_irqrestore(&md->map_lock, flags);
+ dm_sync_table(md);
return old_map;
}
static struct dm_table *__unbind(struct mapped_device *md)
{
struct dm_table *map = md->map;
- unsigned long flags;
if (!map)
return NULL;
dm_table_event_callback(map, NULL, NULL);
- write_lock_irqsave(&md->map_lock, flags);
- md->map = NULL;
- write_unlock_irqrestore(&md->map_lock, flags);
+ rcu_assign_pointer(md->map, NULL);
+ dm_sync_table(md);
return map;
}
static void __dm_destroy(struct mapped_device *md, bool wait)
{
struct dm_table *map;
+ int srcu_idx;
might_sleep();
spin_lock(&_minor_lock);
- map = dm_get_live_table(md);
+ map = dm_get_live_table(md, &srcu_idx);
idr_replace(&_minor_idr, MINOR_ALLOCED, MINOR(disk_devt(dm_disk(md))));
set_bit(DMF_FREEING, &md->flags);
spin_unlock(&_minor_lock);
dm_table_postsuspend_targets(map);
}
+ /* dm_put_live_table must be before msleep, otherwise deadlock is possible */
+ dm_put_live_table(md, srcu_idx);
+
/*
* Rare, but there may be I/O requests still going to complete,
* for example. Wait for all references to disappear.
dm_device_name(md), atomic_read(&md->holders));
dm_sysfs_exit(md);
- dm_table_put(map);
dm_table_destroy(__unbind(md));
free_dev(md);
}
struct mapped_device *md = container_of(work, struct mapped_device,
work);
struct bio *c;
+ int srcu_idx;
+ struct dm_table *map;
- down_read(&md->io_lock);
+ map = dm_get_live_table(md, &srcu_idx);
while (!test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) {
spin_lock_irq(&md->deferred_lock);
if (!c)
break;
- up_read(&md->io_lock);
-
if (dm_request_based(md))
generic_make_request(c);
else
- __split_and_process_bio(md, c);
-
- down_read(&md->io_lock);
+ __split_and_process_bio(md, map, c);
}
- up_read(&md->io_lock);
+ dm_put_live_table(md, srcu_idx);
}
static void dm_queue_flush(struct mapped_device *md)
* reappear.
*/
if (dm_table_has_no_data_devices(table)) {
- live_map = dm_get_live_table(md);
+ live_map = dm_get_live_table_fast(md);
if (live_map)
limits = md->queue->limits;
- dm_table_put(live_map);
+ dm_put_live_table_fast(md);
}
if (!live_map) {
goto out_unlock;
}
- map = dm_get_live_table(md);
+ map = md->map;
/*
* DMF_NOFLUSH_SUSPENDING must be set before presuspend.
if (!noflush && do_lockfs) {
r = lock_fs(md);
if (r)
- goto out;
+ goto out_unlock;
}
/*
* (dm_wq_work), we set BMF_BLOCK_IO_FOR_SUSPEND and call
* flush_workqueue(md->wq).
*/
- down_write(&md->io_lock);
set_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags);
- up_write(&md->io_lock);
+ synchronize_srcu(&md->io_barrier);
/*
* Stop md->queue before flushing md->wq in case request-based
*/
r = dm_wait_for_completion(md, TASK_INTERRUPTIBLE);
- down_write(&md->io_lock);
if (noflush)
clear_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
- up_write(&md->io_lock);
+ synchronize_srcu(&md->io_barrier);
/* were we interrupted ? */
if (r < 0) {
start_queue(md->queue);
unlock_fs(md);
- goto out; /* pushback list is already flushed, so skip flush */
+ goto out_unlock; /* pushback list is already flushed, so skip flush */
}
/*
dm_table_postsuspend_targets(map);
-out:
- dm_table_put(map);
-
out_unlock:
mutex_unlock(&md->suspend_lock);
return r;
if (!dm_suspended_md(md))
goto out;
- map = dm_get_live_table(md);
+ map = md->map;
if (!map || !dm_table_get_size(map))
goto out;
r = 0;
out:
- dm_table_put(map);
mutex_unlock(&md->suspend_lock);
return r;
projects / linux.git / commitdiff