On 25 Jun 2024, at 16:02, cel@xxxxxxxxxx wrote:
> From: Chuck Lever <chuck.lever@xxxxxxxxxx>
>
> During generic/069 runs with pNFS SCSI layouts, the NFS client emits
> the following in the system journal:
>
> kernel: pNFS: failed to open device /dev/disk/by-id/dm-uuid-mpath-0x6001405e3366f045b7949eb8e4540b51 (-2)
> kernel: pNFS: using block device sdb (reservation key 0x666b60901e7b26b3)
> kernel: pNFS: failed to open device /dev/disk/by-id/dm-uuid-mpath-0x6001405e3366f045b7949eb8e4540b51 (-2)
> kernel: pNFS: using block device sdb (reservation key 0x666b60901e7b26b3)
> kernel: sd 6:0:0:1: reservation conflict
> kernel: sd 6:0:0:1: [sdb] tag#16 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_OK cmd_age=0s
> kernel: sd 6:0:0:1: [sdb] tag#16 CDB: Write(10) 2a 00 00 00 00 50 00 00 08 00
> kernel: reservation conflict error, dev sdb, sector 80 op 0x1:(WRITE) flags 0x0 phys_seg 1 prio class 2
> kernel: sd 6:0:0:1: reservation conflict
> kernel: sd 6:0:0:1: reservation conflict
> kernel: sd 6:0:0:1: [sdb] tag#18 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_OK cmd_age=0s
> kernel: sd 6:0:0:1: [sdb] tag#17 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_OK cmd_age=0s
> kernel: sd 6:0:0:1: [sdb] tag#18 CDB: Write(10) 2a 00 00 00 00 60 00 00 08 00
> kernel: sd 6:0:0:1: [sdb] tag#17 CDB: Write(10) 2a 00 00 00 00 58 00 00 08 00
> kernel: reservation conflict error, dev sdb, sector 96 op 0x1:(WRITE) flags 0x0 phys_seg 1 prio class 0
> kernel: reservation conflict error, dev sdb, sector 88 op 0x1:(WRITE) flags 0x0 phys_seg 1 prio class 0
> systemd[1]: fstests-generic-069.scope: Deactivated successfully.
> systemd[1]: fstests-generic-069.scope: Consumed 5.092s CPU time.
> systemd[1]: media-test.mount: Deactivated successfully.
> systemd[1]: media-scratch.mount: Deactivated successfully.
> kernel: sd 6:0:0:1: reservation conflict
> kernel: failed to unregister PR key.
>
> This appears to be due to a race. bl_alloc_lseg() calls this:
>
> 561 static struct nfs4_deviceid_node *
> 562 bl_find_get_deviceid(struct nfs_server *server,
> 563 const struct nfs4_deviceid *id, const struct cred *cred,
> 564 gfp_t gfp_mask)
> 565 {
> 566 struct nfs4_deviceid_node *node;
> 567 unsigned long start, end;
> 568
> 569 retry:
> 570 node = nfs4_find_get_deviceid(server, id, cred, gfp_mask);
> 571 if (!node)
> 572 return ERR_PTR(-ENODEV);
>
> nfs4_find_get_deviceid() does a lookup without the spin lock first.
> If it can't find a matching deviceid, it creates a new device_info
> (which calls bl_alloc_deviceid_node, and that registers the device's
> PR key).
>
> Then it takes the nfs4_deviceid_lock and looks up the deviceid again.
> If it finds it this time, bl_find_get_deviceid() frees the spare
> (new) device_info, which unregisters the PR key for the same device.
>
> Any subsequent I/O from this client on that device gets EBADE.
>
> The umount later unregisters the device's PR key again.
>
> To prevent this problem, register the PR key after the deviceid_node
> lookup.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
> ---
> fs/nfs/blocklayout/blocklayout.c | 25 +++++----
> fs/nfs/blocklayout/blocklayout.h | 9 +++-
> fs/nfs/blocklayout/dev.c | 91 ++++++++++++++++++++++++--------
> 3 files changed, 94 insertions(+), 31 deletions(-)
>
> diff --git a/fs/nfs/blocklayout/blocklayout.c b/fs/nfs/blocklayout/blocklayout.c
> index 6be13e0ec170..0becdec12970 100644
> --- a/fs/nfs/blocklayout/blocklayout.c
> +++ b/fs/nfs/blocklayout/blocklayout.c
> @@ -564,25 +564,32 @@ bl_find_get_deviceid(struct nfs_server *server,
> gfp_t gfp_mask)
> {
> struct nfs4_deviceid_node *node;
> - unsigned long start, end;
> + int err = -ENODEV;
Just a nit - this err var seems unnecessary.. especially as still we do..
> retry:
> node = nfs4_find_get_deviceid(server, id, cred, gfp_mask);
> if (!node)
> return ERR_PTR(-ENODEV);
.. this, which seems clearer. Looking at the return at the bottom makes me
think 'err' could be something else, but it can't. Looks good to me
otherwise.
Reviewed-by: Benjamin Coddington <bcodding@xxxxxxxxxx>
Ben
