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    dm: optimize use SRCU and RCU · 83d5e5b0
    Mikulas Patocka 提交于
    This patch removes "io_lock" and "map_lock" in struct mapped_device and
    "holders" in struct dm_table and replaces these mechanisms with
    sleepable-rcu.
    
    Previously, the code would call "dm_get_live_table" and "dm_table_put" to
    get and release table. Now, the code is changed to call "dm_get_live_table"
    and "dm_put_live_table". dm_get_live_table locks sleepable-rcu and
    dm_put_live_table unlocks it.
    
    dm_get_live_table_fast/dm_put_live_table_fast can be used instead of
    dm_get_live_table/dm_put_live_table. These *_fast functions use
    non-sleepable RCU, so the caller must not block between them.
    
    If the code changes active or inactive dm table, it must call
    dm_sync_table before destroying the old table.
    Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
    Signed-off-by: NJun'ichi Nomura <j-nomura@ce.jp.nec.com>
    Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
    83d5e5b0
dm-ioctl.h 9.9 KB