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authorJosef Bacik <jbacik@fb.com>2015-09-24 16:17:39 -0400
committerChris Mason <clm@fb.com>2015-10-21 18:51:40 -0700
commit161c3549b45aeef05451b6822d8aaaf39c7bedce (patch)
treef14c534323f7b8d6bf181c9610df66313358360b /fs/btrfs/transaction.c
parenta408365c62762c30419018587cffd2b89836434e (diff)
Btrfs: change how we wait for pending ordered extents
We have a mechanism to make sure we don't lose updates for ordered extents that were logged in the transaction that is currently running. We add the ordered extent to a transaction list and then the transaction waits on all the ordered extents in that list. However are substantially large file systems this list can be extremely large, and can give us soft lockups, since the ordered extents don't remove themselves from the list when they do complete. To fix this we simply add a counter to the transaction that is incremented any time we have a logged extent that needs to be completed in the current transaction. Then when the ordered extent finally completes it decrements the per transaction counter and wakes up the transaction if we are the last ones. This will eliminate the softlockup. Thanks, Signed-off-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Chris Mason <clm@fb.com>
Diffstat (limited to 'fs/btrfs/transaction.c')
-rw-r--r--fs/btrfs/transaction.c34
1 files changed, 6 insertions, 28 deletions
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 9354e7a1247f..68a56c3cc555 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -232,6 +232,7 @@ loop:
extwriter_counter_init(cur_trans, type);
init_waitqueue_head(&cur_trans->writer_wait);
init_waitqueue_head(&cur_trans->commit_wait);
+ init_waitqueue_head(&cur_trans->pending_wait);
cur_trans->state = TRANS_STATE_RUNNING;
/*
* One for this trans handle, one so it will live on until we
@@ -239,6 +240,7 @@ loop:
*/
atomic_set(&cur_trans->use_count, 2);
cur_trans->have_free_bgs = 0;
+ atomic_set(&cur_trans->pending_ordered, 0);
cur_trans->start_time = get_seconds();
cur_trans->dirty_bg_run = 0;
@@ -266,7 +268,6 @@ loop:
INIT_LIST_HEAD(&cur_trans->pending_snapshots);
INIT_LIST_HEAD(&cur_trans->pending_chunks);
INIT_LIST_HEAD(&cur_trans->switch_commits);
- INIT_LIST_HEAD(&cur_trans->pending_ordered);
INIT_LIST_HEAD(&cur_trans->dirty_bgs);
INIT_LIST_HEAD(&cur_trans->io_bgs);
INIT_LIST_HEAD(&cur_trans->dropped_roots);
@@ -551,7 +552,6 @@ again:
h->can_flush_pending_bgs = true;
INIT_LIST_HEAD(&h->qgroup_ref_list);
INIT_LIST_HEAD(&h->new_bgs);
- INIT_LIST_HEAD(&h->ordered);
smp_mb();
if (cur_trans->state >= TRANS_STATE_BLOCKED &&
@@ -784,12 +784,6 @@ static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
if (!list_empty(&trans->new_bgs))
btrfs_create_pending_block_groups(trans, root);
- if (!list_empty(&trans->ordered)) {
- spin_lock(&info->trans_lock);
- list_splice_init(&trans->ordered, &cur_trans->pending_ordered);
- spin_unlock(&info->trans_lock);
- }
-
trans->delayed_ref_updates = 0;
if (!trans->sync) {
must_run_delayed_refs =
@@ -1788,25 +1782,10 @@ static inline void btrfs_wait_delalloc_flush(struct btrfs_fs_info *fs_info)
}
static inline void
-btrfs_wait_pending_ordered(struct btrfs_transaction *cur_trans,
- struct btrfs_fs_info *fs_info)
+btrfs_wait_pending_ordered(struct btrfs_transaction *cur_trans)
{
- struct btrfs_ordered_extent *ordered;
-
- spin_lock(&fs_info->trans_lock);
- while (!list_empty(&cur_trans->pending_ordered)) {
- ordered = list_first_entry(&cur_trans->pending_ordered,
- struct btrfs_ordered_extent,
- trans_list);
- list_del_init(&ordered->trans_list);
- spin_unlock(&fs_info->trans_lock);
-
- wait_event(ordered->wait, test_bit(BTRFS_ORDERED_COMPLETE,
- &ordered->flags));
- btrfs_put_ordered_extent(ordered);
- spin_lock(&fs_info->trans_lock);
- }
- spin_unlock(&fs_info->trans_lock);
+ wait_event(cur_trans->pending_wait,
+ atomic_read(&cur_trans->pending_ordered) == 0);
}
int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
@@ -1890,7 +1869,6 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
}
spin_lock(&root->fs_info->trans_lock);
- list_splice_init(&trans->ordered, &cur_trans->pending_ordered);
if (cur_trans->state >= TRANS_STATE_COMMIT_START) {
spin_unlock(&root->fs_info->trans_lock);
atomic_inc(&cur_trans->use_count);
@@ -1949,7 +1927,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
btrfs_wait_delalloc_flush(root->fs_info);
- btrfs_wait_pending_ordered(cur_trans, root->fs_info);
+ btrfs_wait_pending_ordered(cur_trans);
btrfs_scrub_pause(root);
/*