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    Subject[PATCH AUTOSEL for 4.4 116/162] dm thin: fix documentation relative to low water mark threshold
    Date
    From: mulhern <amulhern@redhat.com>

    [ Upstream commit 9b28a1102efc75d81298198166ead87d643a29ce ]

    Fixes:
    1. The use of "exceeds" when the opposite of exceeds, falls below,
    was meant.
    2. Properly speaking, a table can not exceed a threshold.

    It emphasizes the important point, which is that it is the userspace
    daemon's responsibility to check for low free space when a device
    is resumed, since it won't get a special event indicating low free
    space in that situation.

    Signed-off-by: mulhern <amulhern@redhat.com>
    Signed-off-by: Mike Snitzer <snitzer@redhat.com>
    Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
    ---
    Documentation/device-mapper/thin-provisioning.txt | 8 +++++---
    1 file changed, 5 insertions(+), 3 deletions(-)

    diff --git a/Documentation/device-mapper/thin-provisioning.txt b/Documentation/device-mapper/thin-provisioning.txt
    index 1699a55b7b70..ef639960b272 100644
    --- a/Documentation/device-mapper/thin-provisioning.txt
    +++ b/Documentation/device-mapper/thin-provisioning.txt
    @@ -112,9 +112,11 @@ $low_water_mark is expressed in blocks of size $data_block_size. If
    free space on the data device drops below this level then a dm event
    will be triggered which a userspace daemon should catch allowing it to
    extend the pool device. Only one such event will be sent.
    -Resuming a device with a new table itself triggers an event so the
    -userspace daemon can use this to detect a situation where a new table
    -already exceeds the threshold.
    +
    +No special event is triggered if a just resumed device's free space is below
    +the low water mark. However, resuming a device always triggers an
    +event; a userspace daemon should verify that free space exceeds the low
    +water mark when handling this event.

    A low water mark for the metadata device is maintained in the kernel and
    will trigger a dm event if free space on the metadata device drops below
    --
    2.15.1
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