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btrfs: fix deadlock in delayed_ref_async_start

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"Btrfs: track transid for delayed ref flushing" was deadlocking on
btrfs_attach_transaction because its not safe to call from the async
delayed ref start code.  This commit brings back btrfs_join_transaction
instead and checks for a blocked commit.

Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>
This commit is contained in:
Chris Mason 2016-04-27 09:59:38 -04:00
parent 31b9655f43
commit 0f873eca82
1 changed files with 11 additions and 9 deletions
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20
fs/btrfs/extent-tree.c
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@ -2851,16 +2851,13 @@ static void delayed_ref_async_start(struct btrfs_work *work)
async = container_of(work, struct async_delayed_refs, work);
trans = btrfs_attach_transaction(async->root);
if (IS_ERR(trans)) {
if (PTR_ERR(trans) != -ENOENT)
async->error = PTR_ERR(trans);
/* if the commit is already started, we don't need to wait here */
if (btrfs_transaction_blocked(async->root->fs_info))
goto done;
}
/* Don't bother flushing if we got into a different transaction */
if (trans->transid != async->transid) {
btrfs_end_transaction(trans, async->root);
trans = btrfs_join_transaction(async->root);
if (IS_ERR(trans)) {
async->error = PTR_ERR(trans);
goto done;
}
@ -2869,10 +2866,15 @@ static void delayed_ref_async_start(struct btrfs_work *work)
* wait on delayed refs
*/
trans->sync = true;
/* Don't bother flushing if we got into a different transaction */
if (trans->transid > async->transid)
goto end;
ret = btrfs_run_delayed_refs(trans, async->root, async->count);
if (ret)
async->error = ret;
end:
ret = btrfs_end_transaction(trans, async->root);
if (ret && !async->error)
async->error = ret;