Patch "nfs/blocklayout: Limit repeat device registration on failure" has been added to the 6.11-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    nfs/blocklayout: Limit repeat device registration on failure

to the 6.11-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     nfs-blocklayout-limit-repeat-device-registration-on-.patch
and it can be found in the queue-6.11 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 89f1fdac02766523cd94bc92800aeb3356cddf5c
Author: Benjamin Coddington <bcodding@xxxxxxxxxx>
Date:   Fri Nov 22 10:11:12 2024 -0500

    nfs/blocklayout: Limit repeat device registration on failure
    
    [ Upstream commit 614733f9441ed53bb442d4734112ec1e24bd6da7 ]
    
    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 <bcodding@xxxxxxxxxx>
    Reviewed-by: Christoph Hellwig <hch@xxxxxx>
    Reviewed-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
    Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

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 @@ 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;