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btrfs: dev-replace: swich locking to rw semaphore

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This is the first part of removing the custom locking and waiting scheme
used for device replace. It was probably copied from extent buffer
locking, but there's nothing that would require more than is provided by
the common locking primitives.

The rw spinlock protects waiting tasks counter in case of incompatible
locks and the waitqueue. Same as rw semaphore.

This patch only switches the locking primitive, for better
bisectability.  There should be no functional change other than the
overhead of the locking and potential sleeping instead of spinning when
the lock is contended.

Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
David Sterba 2018-04-05 01:29:24 +02:00
parent ceb21a8db4
commit 129827e300
3 changed files with 8 additions and 8 deletions
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2
fs/btrfs/disk-io.c
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@ -2141,7 +2141,7 @@ static void btrfs_init_btree_inode(struct btrfs_fs_info *fs_info)
static void btrfs_init_dev_replace_locks(struct btrfs_fs_info *fs_info)
{
mutex_init(&fs_info->dev_replace.lock_finishing_cancel_unmount);
rwlock_init(&fs_info->dev_replace.lock);
init_rwsem(&fs_info->dev_replace.rwsem);
atomic_set(&fs_info->dev_replace.blocking_readers, 0);
init_waitqueue_head(&fs_info->dev_replace.replace_wait);
init_waitqueue_head(&fs_info->dev_replace.read_lock_wq);