When applying the status and callback in the response of an operation,
apply them in the same critical section so that there's no race between
checking the callback state and checking status-dependent state (such as
the data version).
Fix this by:
(1) Allocating a joint {status,callback} record (afs_status_cb) before
calling the RPC function for each vnode for which the RPC reply
contains a status or a status plus a callback. A flag is set in the
record to indicate if a callback was actually received.
(2) These records are passed into the RPC functions to be filled in. The
afs_decode_status() and yfs_decode_status() functions are removed and
the cb_lock is no longer taken.
(3) xdr_decode_AFSFetchStatus() and xdr_decode_YFSFetchStatus() no longer
update the vnode.
(4) xdr_decode_AFSCallBack() and xdr_decode_YFSCallBack() no longer update
the vnode.
(5) vnodes, expected data-version numbers and callback break counters
(cb_break) no longer need to be passed to the reply delivery
functions.
Note that, for the moment, the file locking functions still need
access to both the call and the vnode at the same time.
(6) afs_vnode_commit_status() is now given the cb_break value and the
expected data_version and the task of applying the status and the
callback to the vnode are now done here.
This is done under a single taking of vnode->cb_lock.
(7) afs_pages_written_back() is now called by afs_store_data() rather than
by the reply delivery function.
afs_pages_written_back() has been moved to before the call point and
is now given the first and last page numbers rather than a pointer to
the call.
(8) The indicator from YFS.RemoveFile2 as to whether the target file
actually got removed (status.abort_code == VNOVNODE) rather than
merely dropping a link is now checked in afs_unlink rather than in
xdr_decode_YFSFetchStatus().
Supplementary fixes:
(*) afs_cache_permit() now gets the caller_access mask from the
afs_status_cb object rather than picking it out of the vnode's status
record. afs_fetch_status() returns caller_access through its argument
list for this purpose also.
(*) afs_inode_init_from_status() now uses a write lock on cb_lock rather
than a read lock and now sets the callback inside the same critical
section.
Fixes: c435ee3455 ("afs: Overhaul the callback handling")
Signed-off-by: David Howells <dhowells@redhat.com>
Make certain RPC operations non-interruptible, including:
(*) Set attributes
(*) Store data
We don't want to get interrupted during a flush on close, flush on
unlock, writeback or an inode update, leaving us in a state where we
still need to do the writeback or update.
(*) Extend lock
(*) Release lock
We don't want to get lock extension interrupted as the file locks on
the server are time-limited. Interruption during lock release is less
of an issue since the lock is time-limited, but it's better to
complete the release to avoid a several-minute wait to recover it.
*Setting* the lock isn't a problem if it's interrupted since we can
just return to the user and tell them they were interrupted - at
which point they can elect to retry.
(*) Silly unlink
We want to remove silly unlink files if we can, rather than leaving
them for the salvager to clear up.
Note that whilst these calls are no longer interruptible, they do have
timeouts on them, so if the server stops responding the call will fail with
something like ETIME or ECONNRESET.
Without this, the following:
kAFS: Unexpected error from FS.StoreData -512
appears in dmesg when a pending store data gets interrupted and some
processes may just hang.
Additionally, make the code that checks/updates the server record ignore
failure due to interruption if the main call is uninterruptible and if the
server has an address list. The next op will check it again since the
expiration time on the old list has past.
Fixes: d2ddc776a4 ("afs: Overhaul volume and server record caching and fileserver rotation")
Reported-by: Jonathan Billings <jsbillings@jsbillings.org>
Reported-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Implement sillyrename for AFS unlink and rename, using the NFS variant
implementation as a basis.
Note that the asynchronous file locking extender/releaser has to be
notified with a state change to stop it complaining if there's a race
between that and the actual file deletion.
A tracepoint, afs_silly_rename, is also added to note the silly rename and
the cleanup. The afs_edit_dir tracepoint is given some extra reason
indicators and the afs_flock_ev tracepoint is given a silly-delete file
lock cancellation indicator.
Signed-off-by: David Howells <dhowells@redhat.com>
