dm: optimize use SRCU and RCU
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: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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Alasdair G Kergon

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2480945cd4
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83d5e5b0af
@@ -267,9 +267,9 @@ enum {
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#define DM_DEV_SET_GEOMETRY _IOWR(DM_IOCTL, DM_DEV_SET_GEOMETRY_CMD, struct dm_ioctl)
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#define DM_VERSION_MAJOR 4
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#define DM_VERSION_MINOR 24
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#define DM_VERSION_MINOR 25
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#define DM_VERSION_PATCHLEVEL 0
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#define DM_VERSION_EXTRA "-ioctl (2013-01-15)"
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#define DM_VERSION_EXTRA "-ioctl (2013-06-26)"
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/* Status bits */
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#define DM_READONLY_FLAG (1 << 0) /* In/Out */
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