[PATCH] dm ioctl: allow change device target type to error

[Joe Jin]

commit a5664da "dm ioctl: make bio or request based device type immutable"
prevented "dmsetup wape_table" change the target type to "error".

Signed-off-by: Joe Jin <joe....@oracle.com>
---
 drivers/md/dm-ioctl.c |  6 +++++-
 drivers/md/dm-table.c | 12 ++++++++++++
 drivers/md/dm.h       |  1 +
 3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index f1b7586..1ee9e41 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -1250,7 +1250,7 @@ static int populate_table(struct dm_table *table,
 
 static int table_load(struct dm_ioctl *param, size_t param_size)
 {
-       int r;
+       int r = 0;
        struct hash_cell *hc;
        struct dm_table *t, *old_map = NULL;
        struct mapped_device *md;
@@ -1280,6 +1280,9 @@ static int table_load(struct dm_ioctl *param, size_t 
param_size)
                goto out;
        }
 
+       if (dm_is_error_target(t))
+               goto error_target;
+
        /* Protect md->type and md->queue against concurrent table loads. */
        dm_lock_md_type(md);
        if (dm_get_md_type(md) == DM_TYPE_NONE)
@@ -1303,6 +1306,7 @@ static int table_load(struct dm_ioctl *param, size_t 
param_size)
        }
        dm_unlock_md_type(md);
 
+error_target:
        /* stage inactive table */
        down_write(&_hash_lock);
        hc = dm_get_mdptr(md);
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index f221812..27be46a 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -184,6 +184,18 @@ static int alloc_targets(struct dm_table *t, unsigned int 
num)
        return 0;
 }
 
+bool dm_is_error_target(struct dm_table *t)
+{
+       unsigned i;
+
+       for (i = 0; i < t->num_targets; i++) {
+               struct dm_target *tgt = t->targets + i;
+               if (strcmp(tgt->type->name, "error") == 0)
+                       return true;
+       }
+       return false;
+}
+
 int dm_table_create(struct dm_table **result, fmode_t mode,
                    unsigned num_targets, struct mapped_device *md)
 {
diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index 45b97da..c7bceeb 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -69,6 +69,7 @@ unsigned dm_table_get_type(struct dm_table *t);
 struct target_type *dm_table_get_immutable_target_type(struct dm_table *t);
 bool dm_table_request_based(struct dm_table *t);
 bool dm_table_supports_discards(struct dm_table *t);
+bool dm_is_error_target(struct dm_table *t);
 int dm_table_alloc_md_mempools(struct dm_table *t);
 void dm_table_free_md_mempools(struct dm_table *t);
 struct dm_md_mempools *dm_table_get_md_mempools(struct dm_table *t);
-- 
1.8.3.1

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