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SubjectRe: [PATCH v3 2/2] ceph: wait the first reply of inflight async unlink
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On 5/17/22 10:36 PM, Matthew Wilcox wrote:
> On Tue, May 17, 2022 at 08:55:49PM +0800, Xiubo Li wrote:
>> +int ceph_wait_on_conflict_unlink(struct dentry *dentry)
>> +{
>> + struct ceph_fs_client *fsc = ceph_sb_to_client(dentry->d_sb);
>> + struct dentry *pdentry = dentry->d_parent;
>> + struct dentry *udentry, *found = NULL;
>> + struct ceph_dentry_info *di;
>> + struct qstr dname;
>> + u32 hash = dentry->d_name.hash;
>> + int err;
>> +
>> + dname.name = dentry->d_name.name;
>> + dname.len = dentry->d_name.len;
>> +
>> + rcu_read_lock();
>> + hash_for_each_possible_rcu(fsc->async_unlink_conflict, di,
>> + hnode, hash) {
>> + udentry = di->dentry;
>> +
>> + spin_lock(&udentry->d_lock);
>> + if (udentry->d_name.hash != hash)
>> + goto next;
>> + if (unlikely(udentry->d_parent != pdentry))
>> + goto next;
>> + if (!hash_hashed(&di->hnode))
>> + goto next;
>> +
>> + if (!test_bit(CEPH_DENTRY_ASYNC_UNLINK_BIT, &di->flags))
>> + pr_warn("%s dentry %p:%pd async unlink bit is not set\n",
>> + __func__, dentry, dentry);
>> +
>> + if (d_compare(pdentry, udentry, &dname))
>> + goto next;
>> +
>> + spin_unlock(&udentry->d_lock);
>> + found = dget(udentry);
>> + break;
>> +next:
>> + spin_unlock(&udentry->d_lock);
>> + }
>> + rcu_read_unlock();
>> +
>> + if (likely(!found))
>> + return 0;
>> +
>> + dout("%s dentry %p:%pd conflict with old %p:%pd\n", __func__,
>> + dentry, dentry, found, found);
>> +
>> + err = wait_on_bit(&di->flags, CEPH_DENTRY_ASYNC_UNLINK_BIT,
>> + TASK_INTERRUPTIBLE);
> Do you really want to use TASK_INTERRUPTIBLE here? If the window is
> resized and you get a SIGWINCH, or a timer goes off and you get a
> SIGALRM, you want to return -EINTR? I would suggest that TASK_KILLABLE
> is probably the semantics that you want.
>
Sounds reasonable.  I will switch to use the TASK_KILLABLE.

@Jeff

I just copied this code from ceph_wait_on_async_create(). BTW, do we
have any other consideration that we must use the TASK_INTERRUPTIBLE there ?

Thanks.

-- Xiubo

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