summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorJonathan Brassow <jbrassow@redhat.com>2009-09-04 20:40:34 +0100
committerAlasdair G Kergon <agk@redhat.com>2009-09-04 20:40:34 +0100
commit7ec23d50949d5062b5b749638dd9380ed75e58e5 (patch)
tree28183b6468683cf28abd63b9c322b9f31bcddc5e
parentd2b698644c97cb033261536a4f2010924a00eac9 (diff)
downloadkernel-uprobes-7ec23d50949d5062b5b749638dd9380ed75e58e5.tar.gz
kernel-uprobes-7ec23d50949d5062b5b749638dd9380ed75e58e5.tar.xz
kernel-uprobes-7ec23d50949d5062b5b749638dd9380ed75e58e5.zip
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 <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
-rw-r--r--drivers/md/dm-log-userspace-base.c23
-rw-r--r--drivers/md/dm-log-userspace-transfer.c6
-rw-r--r--drivers/md/dm-log-userspace-transfer.h2
-rw-r--r--include/linux/dm-log-userspace.h13
4 files changed, 31 insertions, 13 deletions
diff --git a/drivers/md/dm-log-userspace-base.c b/drivers/md/dm-log-userspace-base.c
index c49da0a41c8..6e186b1a062 100644
--- a/drivers/md/dm-log-userspace-base.c
+++ b/drivers/md/dm-log-userspace-base.c
@@ -21,6 +21,7 @@ struct log_c {
struct dm_target *ti;
uint32_t region_size;
region_t region_count;
+ uint64_t luid;
char uuid[DM_UUID_LEN];
char *usr_argv_str;
@@ -63,7 +64,7 @@ static int userspace_do_request(struct log_c *lc, const char *uuid,
* restored.
*/
retry:
- r = dm_consult_userspace(uuid, request_type, data,
+ r = dm_consult_userspace(uuid, lc->luid, request_type, data,
data_size, rdata, rdata_size);
if (r != -ESRCH)
@@ -74,14 +75,15 @@ retry:
set_current_state(TASK_INTERRUPTIBLE);
schedule_timeout(2*HZ);
DMWARN("Attempting to contact userspace log server...");
- r = dm_consult_userspace(uuid, DM_ULOG_CTR, lc->usr_argv_str,
+ r = dm_consult_userspace(uuid, lc->luid, DM_ULOG_CTR,
+ lc->usr_argv_str,
strlen(lc->usr_argv_str) + 1,
NULL, NULL);
if (!r)
break;
}
DMINFO("Reconnected to userspace log server... DM_ULOG_CTR complete");
- r = dm_consult_userspace(uuid, DM_ULOG_RESUME, NULL,
+ r = dm_consult_userspace(uuid, lc->luid, DM_ULOG_RESUME, NULL,
0, NULL, NULL);
if (!r)
goto retry;
@@ -153,6 +155,9 @@ static int userspace_ctr(struct dm_dirty_log *log, struct dm_target *ti,
return -ENOMEM;
}
+ /* The ptr value is sufficient for local unique id */
+ lc->luid = (uint64_t)lc;
+
lc->ti = ti;
if (strlen(argv[0]) > (DM_UUID_LEN - 1)) {
@@ -172,7 +177,7 @@ static int userspace_ctr(struct dm_dirty_log *log, struct dm_target *ti,
}
/* Send table string */
- r = dm_consult_userspace(lc->uuid, DM_ULOG_CTR,
+ r = dm_consult_userspace(lc->uuid, lc->luid, DM_ULOG_CTR,
ctr_str, str_size, NULL, NULL);
if (r == -ESRCH) {
@@ -182,7 +187,7 @@ static int userspace_ctr(struct dm_dirty_log *log, struct dm_target *ti,
/* Since the region size does not change, get it now */
rdata_size = sizeof(rdata);
- r = dm_consult_userspace(lc->uuid, DM_ULOG_GET_REGION_SIZE,
+ r = dm_consult_userspace(lc->uuid, lc->luid, DM_ULOG_GET_REGION_SIZE,
NULL, 0, (char *)&rdata, &rdata_size);
if (r) {
@@ -211,7 +216,7 @@ static void userspace_dtr(struct dm_dirty_log *log)
int r;
struct log_c *lc = log->context;
- r = dm_consult_userspace(lc->uuid, DM_ULOG_DTR,
+ r = dm_consult_userspace(lc->uuid, lc->luid, DM_ULOG_DTR,
NULL, 0,
NULL, NULL);
@@ -226,7 +231,7 @@ static int userspace_presuspend(struct dm_dirty_log *log)
int r;
struct log_c *lc = log->context;
- r = dm_consult_userspace(lc->uuid, DM_ULOG_PRESUSPEND,
+ r = dm_consult_userspace(lc->uuid, lc->luid, DM_ULOG_PRESUSPEND,
NULL, 0,
NULL, NULL);
@@ -238,7 +243,7 @@ static int userspace_postsuspend(struct dm_dirty_log *log)
int r;
struct log_c *lc = log->context;
- r = dm_consult_userspace(lc->uuid, DM_ULOG_POSTSUSPEND,
+ r = dm_consult_userspace(lc->uuid, lc->luid, DM_ULOG_POSTSUSPEND,
NULL, 0,
NULL, NULL);
@@ -251,7 +256,7 @@ static int userspace_resume(struct dm_dirty_log *log)
struct log_c *lc = log->context;
lc->in_sync_hint = 0;
- r = dm_consult_userspace(lc->uuid, DM_ULOG_RESUME,
+ r = dm_consult_userspace(lc->uuid, lc->luid, DM_ULOG_RESUME,
NULL, 0,
NULL, NULL);
diff --git a/drivers/md/dm-log-userspace-transfer.c b/drivers/md/dm-log-userspace-transfer.c
index 8ce74d95ae4..ba0edad2d04 100644
--- a/drivers/md/dm-log-userspace-transfer.c
+++ b/drivers/md/dm-log-userspace-transfer.c
@@ -147,7 +147,8 @@ static void cn_ulog_callback(void *data)
/**
* dm_consult_userspace
- * @uuid: log's uuid (must be DM_UUID_LEN in size)
+ * @uuid: log's universal unique identifier (must be DM_UUID_LEN in size)
+ * @luid: log's local unique identifier
* @request_type: found in include/linux/dm-log-userspace.h
* @data: data to tx to the server
* @data_size: size of data in bytes
@@ -163,7 +164,7 @@ static void cn_ulog_callback(void *data)
*
* Returns: 0 on success, -EXXX on failure
**/
-int dm_consult_userspace(const char *uuid, int request_type,
+int dm_consult_userspace(const char *uuid, uint64_t luid, int request_type,
char *data, size_t data_size,
char *rdata, size_t *rdata_size)
{
@@ -190,6 +191,7 @@ resend:
memset(tfr, 0, DM_ULOG_PREALLOCED_SIZE - overhead_size);
memcpy(tfr->uuid, uuid, DM_UUID_LEN);
+ tfr->luid = luid;
tfr->seq = dm_ulog_seq++;
/*
diff --git a/drivers/md/dm-log-userspace-transfer.h b/drivers/md/dm-log-userspace-transfer.h
index c26d8e4e271..04ee874f915 100644
--- a/drivers/md/dm-log-userspace-transfer.h
+++ b/drivers/md/dm-log-userspace-transfer.h
@@ -11,7 +11,7 @@
int dm_ulog_tfr_init(void);
void dm_ulog_tfr_exit(void);
-int dm_consult_userspace(const char *uuid, int request_type,
+int dm_consult_userspace(const char *uuid, uint64_t luid, int request_type,
char *data, size_t data_size,
char *rdata, size_t *rdata_size);
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 */