[PATCH v6 0/2] tcmu: Dynamic growing data area support

[lixiubo@cmss.chinamobile.com]

From: Xiubo Li <lixiubo@cmss.chinamobile.com>

Changed for V6:
- Remove the tcmu_vma_close(). Since the unmap thread will do the same for it 
- The unmap thread will skip the busy devices.
- Using and testing the V5 version 3 weeks and the V6 for about 1 week, all in a higher IOPS environment:
  * using fio and dd commands
  * using about 4 targets based user:rbd/user:file backend
  * set the global pool size to 512 * 1024 blocks * block_size, for 4K page size, the size is 2G.
  * each target here needs more than 1100 blocks.
  * fio: -iodepth 16 -thread -rw=[read write] -bs=[1M] -size=20G -numjobs=10 -runtime=1000  ...
  * restart the tcmu-runner at any time.

Changed for V5:
- Rebase to the newest target-pending repository.
- Add as many comments as possbile to make the patch more readable.
- Move tcmu_handle_completions() in timeout handler to unmap thread
  and then replace the spin lock with mutex lock(because the unmap_*
  or zap_* may goto sleep) to simplify the patch and the code.
- Thanks very much for Mike's tips and suggestions.
- Tested this for more than 3 days by:
  * using fio and dd commands
  * using about 1~5 targets
  * set the global pool size to [512 1024 2048 512 * 1024] blocks * block_size
  * each target here needs more than 450 blocks when running in my environments.
  * fio: -iodepth [1 2 4 8 16] -thread -rw=[read write] -bs=[1K 2K 3K 5K 7K 16K 64K 1M] -size=20G -numjobs=10 -runtime=1000  ...
  * in the tcmu-runner, try to touch blocks out of tcmu_cmds' iov[] manually
  * restart the tcmu-runner at any time.
  * in my environment for the low IOPS case: the read throughput goes from about 5200KB/s to 6700KB/s; the write throughput goes from about 3000KB/s to 3700KB/s.

Xiubo Li (2):
  tcmu: Add dynamic growing data area feature support
  tcmu: Add global data block pool support

 drivers/target/target_core_user.c | 598 ++++++++++++++++++++++++++++++--------
 1 file changed, 469 insertions(+), 129 deletions(-)

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1.8.3.1