From 40bea431274c247425e7f5970d796ff7b37a2b22 Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Fri, 4 Sep 2009 20:40:25 +0100 Subject: dm stripe: expose correct io hints Set sensible I/O hints for striped DM devices in the topology infrastructure added for 2.6.31 for userspace tools to obtain via sysfs. Add .io_hints to 'struct target_type' to allow the I/O hints portion (io_min and io_opt) of the 'struct queue_limits' to be set by each target and implement this for dm-stripe. Signed-off-by: Mike Snitzer Signed-off-by: Alasdair G Kergon --- include/linux/device-mapper.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'include') diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h index 655e7721580..df7607e6dce 100644 --- a/include/linux/device-mapper.h +++ b/include/linux/device-mapper.h @@ -91,6 +91,9 @@ typedef int (*dm_iterate_devices_fn) (struct dm_target *ti, iterate_devices_callout_fn fn, void *data); +typedef void (*dm_io_hints_fn) (struct dm_target *ti, + struct queue_limits *limits); + /* * Returns: * 0: The target can handle the next I/O immediately. @@ -151,6 +154,7 @@ struct target_type { dm_merge_fn merge; dm_busy_fn busy; dm_iterate_devices_fn iterate_devices; + dm_io_hints_fn io_hints; /* For internal device-mapper use. */ struct list_head list; -- cgit v1.2.3 From 7ec23d50949d5062b5b749638dd9380ed75e58e5 Mon Sep 17 00:00:00 2001 From: Jonathan Brassow Date: Fri, 4 Sep 2009 20:40:34 +0100 Subject: dm log: userspace add luid to distinguish between concurrent log instances Device-mapper userspace logs (like the clustered log) are identified by a universally unique identifier (UUID). This identifier is used to associate requests from the kernel to a specific log in userspace. The UUID must be unique everywhere, since multiple machines may use this identifier when communicating about a particular log, as is the case for cluster logs. Sometimes, device-mapper/LVM may re-use a UUID. This is the case during pvmoves, when moving from one segment of an LV to another, or when resizing a mirror, etc. In these cases, a new log is created with the same UUID and loaded in the "inactive" slot. When a device-mapper "resume" is issued, the "live" table is deactivated and the new "inactive" table becomes "live". (The "inactive" table can also be removed via a device-mapper 'clear' command.) The above two issues were colliding. More than one log was being created with the same UUID, and there was no way to distinguish between them. So, sometimes the wrong log would be swapped out during the exchange. The solution is to create a locally unique identifier, 'luid', to go along with the UUID. This new identifier is used to determine exactly which log is being referenced by the kernel when the log exchange is made. The identifier is not universally safe, but it does not need to be, since create/destroy/suspend/resume operations are bound to a specific machine; and these are the operations that make up the exchange. Signed-off-by: Jonathan Brassow Signed-off-by: Alasdair G Kergon --- include/linux/dm-log-userspace.h | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/linux/dm-log-userspace.h b/include/linux/dm-log-userspace.h index 642e3017b51..8a1f972c0fe 100644 --- a/include/linux/dm-log-userspace.h +++ b/include/linux/dm-log-userspace.h @@ -371,7 +371,18 @@ (DM_ULOG_REQUEST_MASK & (request_type)) struct dm_ulog_request { - char uuid[DM_UUID_LEN]; /* Ties a request to a specific mirror log */ + /* + * The local unique identifier (luid) and the universally unique + * identifier (uuid) are used to tie a request to a specific + * mirror log. A single machine log could probably make due with + * just the 'luid', but a cluster-aware log must use the 'uuid' and + * the 'luid'. The uuid is what is required for node to node + * communication concerning a particular log, but the 'luid' helps + * differentiate between logs that are being swapped and have the + * same 'uuid'. (Think "live" and "inactive" device-mapper tables.) + */ + uint64_t luid; + char uuid[DM_UUID_LEN]; char padding[7]; /* Padding because DM_UUID_LEN = 129 */ int32_t error; /* Used to report back processing errors */ -- cgit v1.2.3