[PATCH 0/8] Misc improvements to dev-replace code

[Nikolay Borisov <nborisov@suse.com>]

While fixing the failing ASSERT in device replace finishing procedure I also 
found several oddities/bugs. Here is the resultant pile.

First 3 patches are a couple simple cleanups.

Patch 4 fixes a real bug since btrfs_init_dev_replace_tgtdev accesses values
which might be updated by transaction commit, so naturally it should be called
after the transaction is actually committed. I think this should go to stable. 

Patch 5 cleanups unlocking code in btrfs_dev_replace_start removing a goto label 
and a local variable. 

Patch 6 also fixes a bug, since persisting the dev-replace item relied on global 
reserve being able to satisfy the condition. While this is not wrong per-se I 
find it somewhat subtle, so just be explicit and start a transaction with 
reservation for at least 1 item.

Patch 7 fixes the race condition which caused the newly added ASSERT to trigger. 
I've added the Fixes: tag to point to the first commit which introduced taking 
chunk_mutex. This is also stable material. 

Patch 8 is also a minor cleanup, just removing what I believe to be a redundant 
assignment. 

This series went under multiple xfstest runs and no regressions were observed. 

Nikolay Borisov (8):
  btrfs: Don't opencode sync_blockdev in btrfs_init_dev_replace_tgtdev
  btrfs: Reduce critical section in btrfs_init_dev_replace_tgtdev
  btrfs: Remove impossible WARN_ON
  btrfs: Ensure btrfs_init_dev_replace_tgtdev sees up to date values
  btrfs: Streamline replace sem unlock in btrfs_dev_replace_start
  btrfs: Explicitly reserve space for devreplace item
  btrfs: Ensure replaced device doesn't have pending chunk allocation
  btrfs: Remove redundant assignment of tgt_device->commit_total_bytes

 fs/btrfs/dev-replace.c | 59 +++++++++++++++++++++++-------------------
 1 file changed, 32 insertions(+), 27 deletions(-)

-- 
2.17.1