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| author | Mikulas Patocka <mpatocka@redhat.com> | 2009-06-22 10:12:20 +0100 |
|---|---|---|
| committer | Alasdair G Kergon <agk@redhat.com> | 2009-06-22 10:12:20 +0100 |
| commit | f9ab94cee313746573b2d693bc2afb807ebb0998 (patch) | |
| tree | 150155f364db0f26c7217e1f92d31344aa67a3f0 /include/linux/device-mapper.h | |
| parent | 27eaa14975d8b53f0bad422e53cdf8e5f6dd44ec (diff) | |
| download | lwn-f9ab94cee313746573b2d693bc2afb807ebb0998.tar.gz lwn-f9ab94cee313746573b2d693bc2afb807ebb0998.zip | |
dm: introduce num_flush_requests
Introduce num_flush_requests for a target to set to say how many flush
instructions (empty barriers) it wants to receive. These are sent by
__clone_and_map_empty_barrier with map_info->flush_request going from 0
to (num_flush_requests - 1).
Old targets without flush support won't receive any flush requests.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'include/linux/device-mapper.h')
| -rw-r--r-- | include/linux/device-mapper.h | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h index 49c2362977fd..fc36a4d07723 100644 --- a/include/linux/device-mapper.h +++ b/include/linux/device-mapper.h @@ -21,6 +21,7 @@ typedef enum { STATUSTYPE_INFO, STATUSTYPE_TABLE } status_type_t; union map_info { void *ptr; unsigned long long ll; + unsigned flush_request; }; /* @@ -168,6 +169,16 @@ struct dm_target { sector_t split_io; /* + * A number of zero-length barrier requests that will be submitted + * to the target for the purpose of flushing cache. + * + * The request number will be placed in union map_info->flush_request. + * It is a responsibility of the target driver to remap these requests + * to the real underlying devices. + */ + unsigned num_flush_requests; + + /* * These are automatically filled in by * dm_table_get_device. */ |