[dm-devel] [PATCH 6/6] dm ioctl: remove unnecessary check when using dm_get_mdptr()

[Mike Snitzer <snitzer@kernel.org>]

From: Hou Tao <houtao1@huawei.com>

__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>
---
 drivers/md/dm-ioctl.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 067dfc08d4c3..50a1259294d1 100644
--- 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;
 	}
-- 
2.37.0 (Apple Git-136)

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