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nfs/blocklayout: Limit repeat device registration on failure

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Every pNFS SCSI IO wants to do LAYOUTGET, then within the layout find the
device which can drive GETDEVINFO, then finally may need to prep the device
with a reservation.  This slow work makes a mess of IO latencies if one of
the later steps is going to fail for awhile.

If we're unable to register a SCSI device, ensure we mark the device as
unavailable so that it will timeout and be re-added via GETDEVINFO.  This
avoids repeated doomed attempts to register a device in the IO path.

Add some clarifying comments as well.

Fixes: d869da91cc ("nfs/blocklayout: Fix premature PR key unregistration")
Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
This commit is contained in:
Benjamin Coddington 2024-11-22 10:11:12 -05:00 committed by Trond Myklebust
parent 3a4ce14d9a
commit 614733f944
1 changed files with 14 additions and 1 deletions
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15
fs/nfs/blocklayout/blocklayout.c
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@ -571,19 +571,32 @@ bl_find_get_deviceid(struct nfs_server *server,
if (!node)
return ERR_PTR(-ENODEV);
/*
* Devices that are marked unavailable are left in the cache with a
* timeout to avoid sending GETDEVINFO after every LAYOUTGET, or
* constantly attempting to register the device. Once marked as
* unavailable they must be deleted and never reused.
*/
if (test_bit(NFS_DEVICEID_UNAVAILABLE, &node->flags)) {
unsigned long end = jiffies;
unsigned long start = end - PNFS_DEVICE_RETRY_TIMEOUT;
if (!time_in_range(node->timestamp_unavailable, start, end)) {
/* Uncork subsequent GETDEVINFO operations for this device */
nfs4_delete_deviceid(node->ld, node->nfs_client, id);
goto retry;
}
goto out_put;
}
if (!bl_register_dev(container_of(node, struct pnfs_block_dev, node)))
if (!bl_register_dev(container_of(node, struct pnfs_block_dev, node))) {
/*
* If we cannot register, treat this device as transient:
* Make a negative cache entry for the device
*/
nfs4_mark_deviceid_unavailable(node);
goto out_put;
}
return node;