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| author | Jonathan Brassow <jbrassow@redhat.com> | 2011-01-13 19:59:52 +0000 |
|---|---|---|
| committer | Alasdair G Kergon <agk@redhat.com> | 2011-01-13 19:59:52 +0000 |
| commit | 86a54a4802df10d23ccd655e2083e812fe990243 (patch) | |
| tree | 168ccb5f1824e16fb55ac64e2d4754775aeaa958 | |
| parent | 085ae0651b2791f3a430ddb76da92925b9952e13 (diff) | |
| download | lwn-86a54a4802df10d23ccd655e2083e812fe990243.tar.gz lwn-86a54a4802df10d23ccd655e2083e812fe990243.zip | |
dm log userspace: add version number to comms
This patch adds a 'version' field to the 'dm_ulog_request'
structure.
The 'version' field is taken from a portion of the unused
'padding' field in the 'dm_ulog_request' structure. This
was done to avoid changing the size of the structure and
possibly disrupting backwards compatibility.
The version number will help notify user-space daemons
when a change has been made to the kernel/userspace
log API.
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
| -rw-r--r-- | drivers/md/dm-log-userspace-base.c | 6 | ||||
| -rw-r--r-- | drivers/md/dm-log-userspace-transfer.c | 1 | ||||
| -rw-r--r-- | include/linux/dm-log-userspace.h | 13 |
3 files changed, 17 insertions, 3 deletions
diff --git a/drivers/md/dm-log-userspace-base.c b/drivers/md/dm-log-userspace-base.c index 31e1687e7bf6..aa2e0c374ab3 100644 --- a/drivers/md/dm-log-userspace-base.c +++ b/drivers/md/dm-log-userspace-base.c @@ -12,6 +12,8 @@ #include "dm-log-userspace-transfer.h" +#define DM_LOG_USERSPACE_VSN "1.1.0" + struct flush_entry { int type; region_t region; @@ -765,7 +767,7 @@ static int __init userspace_dirty_log_init(void) return r; } - DMINFO("version 1.0.0 loaded"); + DMINFO("version " DM_LOG_USERSPACE_VSN " loaded"); return 0; } @@ -775,7 +777,7 @@ static void __exit userspace_dirty_log_exit(void) dm_ulog_tfr_exit(); mempool_destroy(flush_entry_pool); - DMINFO("version 1.0.0 unloaded"); + DMINFO("version " DM_LOG_USERSPACE_VSN " unloaded"); return; } diff --git a/drivers/md/dm-log-userspace-transfer.c b/drivers/md/dm-log-userspace-transfer.c index 075cbcf8a9f5..049eaf12aaab 100644 --- a/drivers/md/dm-log-userspace-transfer.c +++ b/drivers/md/dm-log-userspace-transfer.c @@ -198,6 +198,7 @@ resend: memset(tfr, 0, DM_ULOG_PREALLOCED_SIZE - sizeof(struct cn_msg)); memcpy(tfr->uuid, uuid, DM_UUID_LEN); + tfr->version = DM_ULOG_REQUEST_VERSION; tfr->luid = luid; tfr->seq = dm_ulog_seq++; diff --git a/include/linux/dm-log-userspace.h b/include/linux/dm-log-userspace.h index 0c3c3a2110c4..eeace7d3ff15 100644 --- a/include/linux/dm-log-userspace.h +++ b/include/linux/dm-log-userspace.h @@ -370,6 +370,16 @@ #define DM_ULOG_REQUEST_TYPE(request_type) \ (DM_ULOG_REQUEST_MASK & (request_type)) +/* + * DM_ULOG_REQUEST_VERSION is incremented when there is a + * change to the way information is passed between kernel + * and userspace. This could be a structure change of + * dm_ulog_request or a change in the way requests are + * issued/handled. Changes are outlined here: + * version 1: Initial implementation + */ +#define DM_ULOG_REQUEST_VERSION 1 + struct dm_ulog_request { /* * The local unique identifier (luid) and the universally unique @@ -383,8 +393,9 @@ struct dm_ulog_request { */ uint64_t luid; char uuid[DM_UUID_LEN]; - char padding[7]; /* Padding because DM_UUID_LEN = 129 */ + char padding[3]; /* Padding because DM_UUID_LEN = 129 */ + uint32_t version; /* See DM_ULOG_REQUEST_VERSION */ int32_t error; /* Used to report back processing errors */ uint32_t seq; /* Sequence number for request */ |