nbd: fix possible sysfs duplicate warning
1. nbd_put takes the mutex and drops nbd->ref to 0. It then does idr_remove and drops the mutex. 2. nbd_genl_connect takes the mutex. idr_find/idr_for_each fails to find an existing device, so it does nbd_dev_add. 3. just before the nbd_put could call nbd_dev_remove or not finished totally, but if nbd_dev_add try to add_disk, we can hit: debugfs: Directory 'nbd1' with parent 'block' already present! This patch will make sure all the disk add/remove stuff are done by holding the nbd_index_mutex lock. Reported-by: Mike Christie <mchristi@redhat.com> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Xiubo Li <xiubli@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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@ -248,8 +248,8 @@ static void nbd_put(struct nbd_device *nbd)
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if (refcount_dec_and_mutex_lock(&nbd->refs,
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if (refcount_dec_and_mutex_lock(&nbd->refs,
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&nbd_index_mutex)) {
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&nbd_index_mutex)) {
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idr_remove(&nbd_index_idr, nbd->index);
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idr_remove(&nbd_index_idr, nbd->index);
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mutex_unlock(&nbd_index_mutex);
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nbd_dev_remove(nbd);
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nbd_dev_remove(nbd);
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mutex_unlock(&nbd_index_mutex);
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}
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}
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}
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}
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