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2014-08-01dm switch: efficiently support repetitive patternsMikulas Patocka1-0/+12
Add support for quickly loading a repetitive pattern into the dm-switch target. In the "set_regions_mappings" message, the user may now use "Rn,m" as one of the arguments. "n" and "m" are hexadecimal numbers. The "Rn,m" argument repeats the last "n" arguments in the following "m" slots. For example: dmsetup message switch 0 set_region_mappings 1000:1 :2 R2,10 is equivalent to dmsetup message switch 0 set_region_mappings 1000:1 :2 :1 :2 :1 :2 :1 :2 \ :1 :2 :1 :2 :1 :2 :1 :2 :1 :2 Requested-by: Jay Wang <jwang@nimblestorage.com> Tested-by: Jay Wang <jwang@nimblestorage.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2013-07-11dm: add switch targetJim Ramsay1-0/+126
dm-switch is a new target that maps IO to underlying block devices efficiently when there is a large number of fixed-sized address regions but there is no simple pattern to allow for a compact mapping representation such as dm-stripe. Though we have developed this target for a specific storage device, Dell EqualLogic, we have made an effort to keep it as general purpose as possible in the hope that others may benefit. Originally developed by Jim Ramsay. Simplified by Mikulas Patocka. Signed-off-by: Jim Ramsay <jim_ramsay@dell.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>