[PATCH v2 00/40] afs: Fix probe handling, server rotation and RO volume callback handling

David Howells
2023-12-13T13:50:11Z

Hi Marc,

Here are a set of patches to make some substantial fixes to the afs
filesystem including:

(1) Fix fileserver probe handling so that the next round of probes doesn't
break ongoing server/address rotation by clearing all the probe result
tracking. This could occasionally cause the rotation algorithm to
drop straight through, give a 'successful' result without actually
emitting any RPC calls, leaving the reply buffer in an undefined
state.

Instead, detach the probe results into a separate struct
and allocate a new one each time we start probing and update the
pointer to it. Probes are also sent in order of address preference to
try and improve the chance that the preferred one will complete first.

(2) Fix server rotation so that it uses configurable address preferences
across on the probes that have completed so far than ranking them by
RTT as the latter doesn't necessarily give the best route. The
preference list can be altered by echoing commands into
/proc/net/afs/addr_prefs.

(3) Fix the handling of Read-Only (and Backup) volume callbacks as there
is one per volume, not one per file, so if someone performs a command
that, say, offlines the volume but doesn't change it, when it comes
back online we don't spam the server with a status fetch for every
vnode we're using. Instead, check the Creation timestamp in the
VolSync record when prompted by a callback break.

(4) Handle volume regression (ie. a RW volume being restored from a
backup) by scrubbing all cache data for that volume. This is detected
from the VolSync creation timestamp.

(5) Adjust abort handling and abort -> error mapping to match better with
what other AFS clients do.

(6) Fix offline and busy volume state handling as they only apply to
individual server instances and not entire volumes and the rotation
algorithm should go and look at other servers if available. Also make
it sleep briefly before each retry if all the volume instances are
unavailable.

In addition there are a number of small fixes in rxrpc and afs included
here so that those problems don't affect testing.

The patches can be found here:

https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/log/?h=afs-fixes

Thanks,
David

Changes
=======
ver #2)
- Drop the first two rxrpc fix patches - one has gone through the net tree
and the other needs a bit more work, but neither is necessary for this
series.
- Add a couple of missing symbol exports.
- Treat UAEIO as VIO too.
- Switch to using atomic64_t for creation & update times because 64-bit
cmpxchg isn't available on some 32-bit arches.
- Some patches went upstream separately as fixes (commit
5b7ad877e4d81f8904ce83982b1ba5c6e83deccb).
- Use atomic64_t for vnode->cb_expires_at() as 64-bit xchg() is not
univerally available.
- Use rcu_access_pointer() rather than passing an __rcu pointer directly to
kfree_rcu().

Link: https://lore.kernel.org/r/20231109154004.3317227-1-dhowells@redhat.com/ # v1
---
%(shortlog)s
%(diffstat)s

David Howells (36):
afs: Remove whitespace before most ')' from the trace header
afs: Automatically generate trace tag enums
afs: Add comments on abort handling
afs: Turn the afs_addr_list address array into an array of structs
rxrpc, afs: Allow afs to pin rxrpc_peer objects
afs: Don't skip server addresses for which we didn't get an RTT
reading
afs: Rename addr_list::failed to probe_failed
afs: Handle the VIO and UAEIO aborts explicitly
afs: Use op->nr_iterations=-1 to indicate to begin fileserver
iteration
afs: Wrap most op->error accesses with inline funcs
afs: Don't put afs_call in afs_wait_for_call_to_complete()
afs: Simplify error handling
afs: Add a tracepoint for struct afs_addr_list
afs: Rename some fields
afs: Use peer + service_id as call address
afs: Fold the afs_addr_cursor struct in
rxrpc: Create a procfile to display outstanding client conn bundles
afs: Add some more info to /proc/net/afs/servers
afs: Remove the unimplemented afs_cmp_addr_list()
afs: Provide a way to configure address priorities
afs: Mark address lists with configured priorities
afs: Dispatch fileserver probes in priority order
afs: Dispatch vlserver probes in priority order
afs: Keep a record of the current fileserver endpoint state
afs: Combine the endpoint state bools into a bitmask
afs: Make it possible to find the volumes that are using a server
afs: Defer volume record destruction to a workqueue
afs: Move the vnode/volume validity checking code into its own file
afs: Apply server breaks to mmap'd files in the call processor
afs: Fix comment in afs_do_lookup()
afs: Don't leave DONTUSE/NEWREPSITE servers out of server list
afs: Parse the VolSync record in the reply of a number of RPC ops
afs: Overhaul invalidation handling to better support RO volumes
afs: Fix fileserver rotation
afs: Fix offline and busy message emission
afs: trace: Log afs_make_call(), including server address

Oleg Nesterov (4):
afs: fix the usage of read_seqbegin_or_lock() in
afs_lookup_volume_rcu()
afs: fix the usage of read_seqbegin_or_lock() in afs_find_server*()
afs: use read_seqbegin() in afs_check_validity() and afs_getattr()
rxrpc_find_service_conn_rcu: fix the usage of read_seqbegin_or_lock()

fs/afs/Makefile | 2 +
fs/afs/addr_list.c | 224 +++++-----
fs/afs/addr_prefs.c | 531 ++++++++++++++++++++++++
fs/afs/afs.h | 3 +-
fs/afs/callback.c | 141 ++++---
fs/afs/cell.c | 5 +-
fs/afs/cmservice.c | 5 +-
fs/afs/dir.c | 59 +--
fs/afs/dir_silly.c | 2 +-
fs/afs/file.c | 20 +-
fs/afs/fs_operation.c | 85 ++--
fs/afs/fs_probe.c | 323 +++++++++------
fs/afs/fsclient.c | 74 +++-
fs/afs/inode.c | 204 +--------
fs/afs/internal.h | 370 +++++++++++------
fs/afs/main.c | 1 +
fs/afs/misc.c | 10 +-
fs/afs/proc.c | 102 ++++-
fs/afs/rotate.c | 520 ++++++++++++++++-------
fs/afs/rxrpc.c | 107 ++---
fs/afs/server.c | 135 +++---
fs/afs/server_list.c | 174 ++++++--
fs/afs/super.c | 7 +-
fs/afs/validation.c | 467 +++++++++++++++++++++
fs/afs/vl_alias.c | 69 +---
fs/afs/vl_list.c | 29 +-
fs/afs/vl_probe.c | 60 ++-
fs/afs/vl_rotate.c | 215 ++++++----
fs/afs/vlclient.c | 143 ++++---
fs/afs/volume.c | 61 ++-
fs/afs/write.c | 6 +-
fs/afs/yfsclient.c | 25 +-
include/net/af_rxrpc.h | 15 +-
include/trace/events/afs.h | 779 ++++++++++++++++++++---------------
include/trace/events/rxrpc.h | 3 +
net/rxrpc/af_rxrpc.c | 62 ++-
net/rxrpc/ar-internal.h | 6 +-
net/rxrpc/call_object.c | 17 +-
net/rxrpc/conn_client.c | 10 +
net/rxrpc/conn_service.c | 3 +-
net/rxrpc/net_ns.c | 4 +
net/rxrpc/peer_object.c | 58 ++-
net/rxrpc/proc.c | 76 ++++
net/rxrpc/sendmsg.c | 11 +-
44 files changed, 3532 insertions(+), 1691 deletions(-)
create mode 100644 fs/afs/addr_prefs.c
create mode 100644 fs/afs/validation.c