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| author | Mike Snitzer <snitzer@redhat.com> | 2019-02-25 19:07:10 +0300 |
|---|---|---|
| committer | Mike Snitzer <snitzer@redhat.com> | 2019-03-05 22:53:52 +0300 |
| commit | de7180ff908b2bc0342e832dbdaa9a5f1ecaa33a (patch) | |
| tree | db7c3b6e894a7d5f96ab155500ff5a8275cfad66 /Documentation/device-mapper/cache.txt | |
| parent | f87e033b3b923d91194348c11221e1bbc92e51b2 (diff) | |
| download | linux-de7180ff908b2bc0342e832dbdaa9a5f1ecaa33a.tar.xz | |
dm cache: add support for discard passdown to the origin device
DM cache now defaults to passing discards down to the origin device.
User may disable this using the "no_discard_passdown" feature when
creating the cache device.
If the cache's underlying origin device doesn't support discards then
passdown is disabled (with warning). Similarly, if the underlying
origin device's max_discard_sectors is less than a cache block discard
passdown will be disabled (this is required because sizing of the cache
internal discard bitset depends on it).
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'Documentation/device-mapper/cache.txt')
| -rw-r--r-- | Documentation/device-mapper/cache.txt | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/Documentation/device-mapper/cache.txt b/Documentation/device-mapper/cache.txt index ff0841711fd5..8ae1cf8e94da 100644 --- a/Documentation/device-mapper/cache.txt +++ b/Documentation/device-mapper/cache.txt @@ -206,6 +206,9 @@ Optional feature arguments are: in a separate btree, which improves speed of shutting down the cache. + no_discard_passdown : disable passing down discards from the cache + to the origin's data device. + A policy called 'default' is always registered. This is an alias for the policy we currently think is giving best all round performance. |