dm ioctl: remove unnecessary check when using dm_get_mdptr()

__hash_remove() removes hash_cell with _hash_lock locked, so acquiring
_hash_lock can guarantee no-NULL hc returned from dm_get_mdptr() must
have not been removed and hc->md must still be md.

__hash_remove() also acquires dm_hash_cells_mutex before setting mdptr
as NULL. So in dm_copy_name_and_uuid(), after acquiring
dm_hash_cells_mutex and ensuring returned hc is not NULL, the returned
hc must still be alive and hc->md must still be md.

Remove the unnecessary hc->md != md checks when using dm_get_mdptr()
with _hash_lock or dm_hash_cells_mutex acquired.

Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 067dfc0..50a1259 100644 (file)
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -789,7 +789,7 @@ static struct dm_table *dm_get_inactive_table(struct mapped_device *md, int *src
 
        down_read(&_hash_lock);
        hc = dm_get_mdptr(md);
-       if (!hc || hc->md != md) {
+       if (!hc) {
                DMERR("device has been removed from the dev hash table.");
                goto out;
        }
@@ -1500,7 +1500,7 @@ static int table_load(struct file *filp, struct dm_ioctl *param, size_t param_si
        /* stage inactive table */
        down_write(&_hash_lock);
        hc = dm_get_mdptr(md);
-       if (!hc || hc->md != md) {
+       if (!hc) {
                DMERR("device has been removed from the dev hash table.");
                up_write(&_hash_lock);
                r = -ENXIO;
@@ -2152,7 +2152,7 @@ int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid)
 
        mutex_lock(&dm_hash_cells_mutex);
        hc = dm_get_mdptr(md);
-       if (!hc || hc->md != md) {
+       if (!hc) {
                r = -ENXIO;
                goto out;
        }