From: David Sterba <dsterba@suse.com>
To: linux-btrfs@vger.kernel.org
Cc: David Sterba <dsterba@suse.com>
Subject: [PATCH 01/11] btrfs: remove btrfs_dev_replace::read_locks
Date: Fri, 7 Sep 2018 16:55:02 +0200 [thread overview]
Message-ID: <8787a706839a04a736f389d9d24ab215f15467d5.1536331604.git.dsterba@suse.com> (raw)
In-Reply-To: <cover.1536331604.git.dsterba@suse.com>
This member seems to be copied from the extent_buffer locking scheme and
is at least used to assert that the read lock/unlock is properly nested.
In some way. While the _inc/_dec are called inside the read lock
section, the asserts are both inside and outside, so the ordering is not
guaranteed and we can see read/inc/dec ordered in any way
(theoretically).
A missing call of btrfs_dev_replace_clear_lock_blocking could cause
unexpected read_locks count, so this at least looks like a valid
assertion, but this will become unnecessary with later updates.
Signed-off-by: David Sterba <dsterba@suse.com>
---
fs/btrfs/ctree.h | 1 -
fs/btrfs/dev-replace.c | 5 -----
fs/btrfs/disk-io.c | 1 -
3 files changed, 7 deletions(-)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 441610de9908..31f7a58add7e 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -367,7 +367,6 @@ struct btrfs_dev_replace {
struct mutex lock_finishing_cancel_unmount;
rwlock_t lock;
- atomic_t read_locks;
atomic_t blocking_readers;
wait_queue_head_t read_lock_wq;
diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index dec01970d8c5..24529d2c723a 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -961,13 +961,10 @@ int btrfs_dev_replace_is_ongoing(struct btrfs_dev_replace *dev_replace)
void btrfs_dev_replace_read_lock(struct btrfs_dev_replace *dev_replace)
{
read_lock(&dev_replace->lock);
- atomic_inc(&dev_replace->read_locks);
}
void btrfs_dev_replace_read_unlock(struct btrfs_dev_replace *dev_replace)
{
- ASSERT(atomic_read(&dev_replace->read_locks) > 0);
- atomic_dec(&dev_replace->read_locks);
read_unlock(&dev_replace->lock);
}
@@ -994,7 +991,6 @@ void btrfs_dev_replace_set_lock_blocking(
struct btrfs_dev_replace *dev_replace)
{
/* only set blocking for read lock */
- ASSERT(atomic_read(&dev_replace->read_locks) > 0);
atomic_inc(&dev_replace->blocking_readers);
read_unlock(&dev_replace->lock);
}
@@ -1004,7 +1000,6 @@ void btrfs_dev_replace_clear_lock_blocking(
struct btrfs_dev_replace *dev_replace)
{
/* only set blocking for read lock */
- ASSERT(atomic_read(&dev_replace->read_locks) > 0);
ASSERT(atomic_read(&dev_replace->blocking_readers) > 0);
read_lock(&dev_replace->lock);
/* Barrier implied by atomic_dec_and_test */
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 3611df2ce5c1..acd0cbc5a6b9 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2155,7 +2155,6 @@ 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);
- atomic_set(&fs_info->dev_replace.read_locks, 0);
atomic_set(&fs_info->dev_replace.blocking_readers, 0);
init_waitqueue_head(&fs_info->replace_wait);
init_waitqueue_head(&fs_info->dev_replace.read_lock_wq);
--
2.18.0
next prev parent reply other threads:[~2018-09-07 19:36 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-07 14:54 [PATCH 00/11] Cleanup dev-replace locking David Sterba
2018-09-07 14:55 ` David Sterba [this message]
2018-09-07 14:55 ` [PATCH 02/11] btrfs: open code btrfs_dev_replace_clear_lock_blocking David Sterba
2018-09-07 14:55 ` [PATCH 03/11] btrfs: open code btrfs_dev_replace_stats_inc David Sterba
2018-09-07 21:02 ` Omar Sandoval
2018-09-07 14:55 ` [PATCH 04/11] btrfs: open code btrfs_after_dev_replace_commit David Sterba
2018-09-07 21:03 ` Omar Sandoval
2018-09-07 14:55 ` [PATCH 05/11] btrfs: dev-replace: avoid useless lock on error handling path David Sterba
2018-09-07 21:06 ` Omar Sandoval
2018-09-14 16:53 ` David Sterba
2018-09-07 14:55 ` [PATCH 06/11] btrfs: dev-replace: move replace members out of fs_info David Sterba
2018-09-07 21:09 ` Omar Sandoval
2018-09-07 14:55 ` [PATCH 07/11] btrfs: dev-replace: remove pointless assert in write unlock David Sterba
2018-09-07 14:55 ` [PATCH 08/11] btrfs: reada: reorder dev-replace locks before radix tree preload David Sterba
2018-09-07 14:55 ` [PATCH 09/11] btrfs: dev-replace: swich locking to rw semaphore David Sterba
2018-09-07 14:55 ` [PATCH 10/11] btrfs: dev-replace: remove custom read/write blocking scheme David Sterba
2018-09-07 14:55 ` [PATCH 11/11] btrfs: dev-replace: open code trivial locking helpers David Sterba
2018-09-27 11:06 ` [PATCH 00/11] Cleanup dev-replace locking David Sterba
2018-10-04 1:06 ` Anand Jain
2018-10-04 10:13 ` David Sterba
2018-10-05 8:58 ` Anand Jain
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