From: Mike Snitzer Determine whether a mapped device is bio-based or request-based when loading its first (inactive) table and don't allow that to be changed later. This patch performs different device initialisation in each of the two cases. (We don't think it's necessary to add code to support changing between the two types.) Allowed md->type transitions: DM_TYPE_NONE to DM_TYPE_BIO_BASED DM_TYPE_NONE to DM_TYPE_REQUEST_BASED We now prevent table_load from replacing the inactive table with a conflicting type of table even after an explicit table_clear. Introduce 'type_lock' into the struct mapped_device to protect md->type and to prepare for the next patch that will change the queue initialization and allocate memory while md->type_lock is held. Signed-off-by: Mike Snitzer Acked-by: Kiyoshi Ueda Signed-off-by: Alasdair G Kergon drivers/md/dm-ioctl.c | 15 +++++++++++++++ drivers/md/dm.c | 37 ++++++++++++++++++++++++++++++------- drivers/md/dm.h | 5 +++++ include/linux/dm-ioctl.h | 4 ++-- 4 files changed, 52 insertions(+), 9 deletions(-) Index: linux-2.6.35/drivers/md/dm-ioctl.c =================================================================== --- linux-2.6.35.orig/drivers/md/dm-ioctl.c +++ linux-2.6.35/drivers/md/dm-ioctl.c @@ -1189,6 +1189,21 @@ static int table_load(struct dm_ioctl *p goto out; } + /* Protect md->type against concurrent table loads. */ + dm_lock_md_type(md); + if (dm_get_md_type(md) == DM_TYPE_NONE) + /* Initial table load: acquire type of table. */ + dm_set_md_type(md, dm_table_get_type(t)); + else if (dm_get_md_type(md) != dm_table_get_type(t)) { + DMWARN("can't change device type after initial table load."); + dm_table_destroy(t); + dm_unlock_md_type(md); + r = -EINVAL; + goto out; + } + dm_unlock_md_type(md); + + /* stage inactive table */ down_write(&_hash_lock); hc = dm_get_mdptr(md); if (!hc || hc->md != md) { Index: linux-2.6.35/drivers/md/dm.c =================================================================== --- linux-2.6.35.orig/drivers/md/dm.c +++ linux-2.6.35/drivers/md/dm.c @@ -125,6 +125,10 @@ struct mapped_device { unsigned long flags; struct request_queue *queue; + unsigned type; + /* Protect type against concurrent access. */ + struct mutex type_lock; + struct gendisk *disk; char name[16]; @@ -1877,8 +1881,10 @@ static struct mapped_device *alloc_dev(i if (r < 0) goto bad_minor; + 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); spin_lock_init(&md->barrier_error_lock); rwlock_init(&md->map_lock); @@ -2130,6 +2136,30 @@ int dm_create(int minor, struct mapped_d return 0; } +/* + * Functions to manage md->type. + * All are required to hold md->type_lock. + */ +void dm_lock_md_type(struct mapped_device *md) +{ + mutex_lock(&md->type_lock); +} + +void dm_unlock_md_type(struct mapped_device *md) +{ + mutex_unlock(&md->type_lock); +} + +void dm_set_md_type(struct mapped_device *md, unsigned type) +{ + md->type = type; +} + +unsigned dm_get_md_type(struct mapped_device *md) +{ + return md->type; +} + static struct mapped_device *dm_find_md(dev_t dev) { struct mapped_device *md; @@ -2440,13 +2470,6 @@ struct dm_table *dm_swap_table(struct ma goto out; } - /* cannot change the device type, once a table is bound */ - if (md->map && - (dm_table_get_type(md->map) != dm_table_get_type(table))) { - DMWARN("can't change the device type after a table is bound"); - goto out; - } - map = __bind(md, table, &limits); out: Index: linux-2.6.35/drivers/md/dm.h =================================================================== --- linux-2.6.35.orig/drivers/md/dm.h +++ linux-2.6.35/drivers/md/dm.h @@ -66,6 +66,11 @@ int dm_table_alloc_md_mempools(struct dm void dm_table_free_md_mempools(struct dm_table *t); struct dm_md_mempools *dm_table_get_md_mempools(struct dm_table *t); +void dm_lock_md_type(struct mapped_device *md); +void dm_unlock_md_type(struct mapped_device *md); +void dm_set_md_type(struct mapped_device *md, unsigned type); +unsigned dm_get_md_type(struct mapped_device *md); + /* * To check the return value from dm_table_find_target(). */ Index: linux-2.6.35/include/linux/dm-ioctl.h =================================================================== --- linux-2.6.35.orig/include/linux/dm-ioctl.h +++ linux-2.6.35/include/linux/dm-ioctl.h @@ -266,9 +266,9 @@ enum { #define DM_DEV_SET_GEOMETRY _IOWR(DM_IOCTL, DM_DEV_SET_GEOMETRY_CMD, struct dm_ioctl) #define DM_VERSION_MAJOR 4 -#define DM_VERSION_MINOR 17 +#define DM_VERSION_MINOR 18 #define DM_VERSION_PATCHLEVEL 0 -#define DM_VERSION_EXTRA "-ioctl (2010-03-05)" +#define DM_VERSION_EXTRA "-ioctl (2010-06-29)" /* Status bits */ #define DM_READONLY_FLAG (1 << 0) /* In/Out */