From 614733f9441ed53bb442d4734112ec1e24bd6da7 Mon Sep 17 00:00:00 2001 From: Benjamin Coddington Date: Fri, 22 Nov 2024 10:11:12 -0500 Subject: [PATCH] nfs/blocklayout: Limit repeat device registration on failure 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: d869da91cccb ("nfs/blocklayout: Fix premature PR key unregistration") Signed-off-by: Benjamin Coddington Reviewed-by: Christoph Hellwig Reviewed-by: Chuck Lever Signed-off-by: Trond Myklebust --- fs/nfs/blocklayout/blocklayout.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/fs/nfs/blocklayout/blocklayout.c b/fs/nfs/blocklayout/blocklayout.c index 0becdec129704..47189476b5538 100644 --- a/fs/nfs/blocklayout/blocklayout.c +++ b/fs/nfs/blocklayout/blocklayout.c @@ -571,19 +571,32 @@ retry: 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; -- 2.49.0