This reverts commit f6007dce0cd35d634d9be91ef3515a6385dcee16.
Commit f6007dce0cd3 ("dm: fix a race condition in retrieve_deps") was
added to fix a race between retrieving the list of dm table devices and
multipath_message() modifying the list of table devices. But Commit
a48f6b82c5c4 ("dm mpath: don't call dm_get_device in multipath_message")
removed the call to dm_get_device() from multipath_message(). After that
commit, the only calls to dm_get_device() and dm_put_device() are in
target constructors and destructors, so the race with retrieve_deps() is
no longer possible.
Suggested-by: Martin Wilck <[email protected]>
Signed-off-by: Benjamin Marzinski <[email protected]>
---
drivers/md/dm-core.h | 1 -
drivers/md/dm-ioctl.c | 7 +------
drivers/md/dm-table.c | 32 ++++++++------------------------
3 files changed, 9 insertions(+), 31 deletions(-)
diff --git a/drivers/md/dm-core.h b/drivers/md/dm-core.h
index 1cda8618d74d..a3b8ad6e1c42 100644
--- a/drivers/md/dm-core.h
+++ b/drivers/md/dm-core.h
@@ -215,7 +215,6 @@ struct dm_table {
/* a list of devices used by this table */
struct list_head devices;
- struct rw_semaphore devices_lock;
/* events get handed up using this callback */
void (*event_fn)(void *data);
diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 4165fef4c170..fd4bf8e1d73e 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -1648,8 +1648,6 @@ static void retrieve_deps(struct dm_table *table,
struct dm_dev_internal *dd;
struct dm_target_deps *deps;
- down_read(&table->devices_lock);
-
deps = get_result_buffer(param, param_size, &len);
/*
@@ -1664,7 +1662,7 @@ static void retrieve_deps(struct dm_table *table,
needed = struct_size(deps, dev, count);
if (len < needed) {
param->flags |= DM_BUFFER_FULL_FLAG;
- goto out;
+ return;
}
/*
@@ -1676,9 +1674,6 @@ static void retrieve_deps(struct dm_table *table,
deps->dev[count++] = huge_encode_dev(dd->dm_dev->bdev->bd_dev);
param->data_size = param->data_start + needed;
-
-out:
- up_read(&table->devices_lock);
}
static int table_deps(struct file *filp, struct dm_ioctl *param, size_t
param_size)
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 4b70872725d0..7be1d8dc8bdd 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -139,7 +139,6 @@ int dm_table_create(struct dm_table **result, blk_mode_t
mode,
return -ENOMEM;
INIT_LIST_HEAD(&t->devices);
- init_rwsem(&t->devices_lock);
if (!num_targets)
num_targets = KEYS_PER_NODE;
@@ -380,20 +379,16 @@ int dm_get_device(struct dm_target *ti, const char *path,
blk_mode_t mode,
if (dev == disk_devt(t->md->disk))
return -EINVAL;
- down_write(&t->devices_lock);
-
dd = find_device(&t->devices, dev);
if (!dd) {
dd = kmalloc(sizeof(*dd), GFP_KERNEL);
- if (!dd) {
- r = -ENOMEM;
- goto unlock_ret_r;
- }
+ if (!dd)
+ return -ENOMEM;
r = dm_get_table_device(t->md, dev, mode, &dd->dm_dev);
if (r) {
kfree(dd);
- goto unlock_ret_r;
+ return r;
}
refcount_set(&dd->count, 1);
@@ -403,17 +398,12 @@ int dm_get_device(struct dm_target *ti, const char *path,
blk_mode_t mode,
} else if (dd->dm_dev->mode != (mode | dd->dm_dev->mode)) {
r = upgrade_mode(dd, mode, t->md);
if (r)
- goto unlock_ret_r;
+ return r;
}
refcount_inc(&dd->count);
out:
- up_write(&t->devices_lock);
*result = dd->dm_dev;
return 0;
-
-unlock_ret_r:
- up_write(&t->devices_lock);
- return r;
}
EXPORT_SYMBOL(dm_get_device);
@@ -464,12 +454,9 @@ 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)
{
int found = 0;
- struct dm_table *t = ti->table;
- struct list_head *devices = &t->devices;
+ struct list_head *devices = &ti->table->devices;
struct dm_dev_internal *dd;
- down_write(&t->devices_lock);
-
list_for_each_entry(dd, devices, list) {
if (dd->dm_dev == d) {
found = 1;
@@ -478,17 +465,14 @@ void dm_put_device(struct dm_target *ti, struct dm_dev *d)
}
if (!found) {
DMERR("%s: device %s not in table devices list",
- dm_device_name(t->md), d->name);
- goto unlock_ret;
+ dm_device_name(ti->table->md), d->name);
+ return;
}
if (refcount_dec_and_test(&dd->count)) {
- dm_put_table_device(t->md, d);
+ dm_put_table_device(ti->table->md, d);
list_del(&dd->list);
kfree(dd);
}
-
-unlock_ret:
- up_write(&t->devices_lock);
}
EXPORT_SYMBOL(dm_put_device);
--
2.50.1
