kernel/linux.git/fs/afs/proc.c, branch v6.12.80

afs: Fix missing/incorrect unlocking of RCU read lock

2024-01-22T22:30:38+00:00

In afs_proc_addr_prefs_show(), we need to unlock the RCU read lock in both places before returning (and not lock it again). Fixes: f94f70d39cc2 ("afs: Provide a way to configure address priorities") Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-lkp/202401172243.cd53d5f6-oliver.sang@intel.com Signed-off-by: David Howells cc: linux-afs@lists.infradead.org cc: linux-fsdevel@vger.kernel.org

afs: Overhaul invalidation handling to better support RO volumes

2024-01-01T16:37:27+00:00

Overhaul the third party-induced invalidation handling, making use of the previously added volume-level event counters (cb_scrub and cb_ro_snapshot) that are now being parsed out of the VolSync record returned by the fileserver in many of its replies. This allows better handling of RO (and Backup) volumes. Since these are snapshot of a RW volume that are updated atomically simultantanously across all servers that host them, they only require a single callback promise for the entire volume. The currently upstream code assumes that RO volumes operate in the same manner as RW volumes, and that each file has its own individual callback - which means that it does a status fetch for *every* file in a RO volume, whether or not the volume got "released" (volume callback breaks can occur for other reasons too, such as the volumeserver taking ownership of a volume from a fileserver). To this end, make the following changes: (1) Change the meaning of the volume's cb_v_break counter so that it is now a hint that we need to issue a status fetch to work out the state of a volume. cb_v_break is incremented by volume break callbacks and by server initialisation callbacks. (2) Add a second counter, cb_v_check, to the afs_volume struct such that if this differs from cb_v_break, we need to do a check. When the check is complete, cb_v_check is advanced to what cb_v_break was at the start of the status fetch. (3) Move the list of mmap'd vnodes to the volume and trigger removal of PTEs that map to files on a volume break rather than on a server break. (4) When a server reinitialisation callback comes in, use the server-to-volume reverse mapping added in a preceding patch to iterate over all the volumes using that server and clear the volume callback promises for that server and the general volume promise as a whole to trigger reanalysis. (5) Replace the AFS_VNODE_CB_PROMISED flag with an AFS_NO_CB_PROMISE (TIME64_MIN) value in the cb_expires_at field, reducing the number of checks we need to make. (6) Change afs_check_validity() to quickly see if various event counters have been incremented or if the vnode or volume callback promise is due to expire/has expired without making any changes to the state. That is now left to afs_validate() as this may get more complicated in future as we may have to examine server records too. (7) Overhaul afs_validate() so that it does a single status fetch if we need to check the state of either the vnode or the volume - and do so under appropriate locking. The function does the following steps: (A) If the vnode/volume is no longer seen as valid, then we take the vnode validation lock and, if the volume promise has expired, the volume check lock also. The latter prevents redundant checks being made to find out if a new version of the volume got released. (B) If a previous RPC call found that the volsync changed unexpectedly or that a RO volume was updated, then we unmap all PTEs pointing to the file to stop mmap being used for access. (C) If the vnode is still seen to be of uncertain validity, then we perform an FS.FetchStatus RPC op to jointly update the volume status and the vnode status. This assessment is done as part of parsing the reply: If the RO volume creation timestamp advances, cb_ro_snapshot is incremented; if either the creation or update timestamps changes in an unexpected way, the cb_scrub counter is incremented If the Data Version returned doesn't match the copy we have locally, then we ask for the pagecache to be zapped. This takes care of handling RO update. (D) If cb_scrub differs between volume and vnode, the vnode's pagecache is zapped and the vnode's cb_scrub is updated unless the file is marked as having been deleted. Signed-off-by: David Howells cc: Marc Dionne cc: linux-afs@lists.infradead.org

afs: Keep a record of the current fileserver endpoint state

2024-01-01T16:37:27+00:00

Keep a record of the current fileserver endpoint state, including the probe state, and replace it when a new probe is started rather than just squelching the old state and overwriting it. Clearance of the old state can cause a race if there's another thread also currently trying to communicate with that server. It appears that this race might be the culprit for some occasions where kafs complains about invalid data in the RPC reply because the rotation algorithm fell all the way through without actually issuing an RPC call and the error return got filled in from the probe state (which has a zero error recorded). Whatever happens to be in the caller's reply buffer is then taken as the response. Signed-off-by: David Howells cc: Marc Dionne cc: linux-afs@lists.infradead.org

afs: Mark address lists with configured priorities

2024-01-01T16:37:27+00:00

Add a field to each address in an address list (afs_addr_list struct) that records the current priority for that address according to the address preference table. We don't want to do this every time we use an address list, so the version number of the address preference table is recorded in the address list too and we only re-mark the list when we see the version change. These numbers are then displayed through /proc/net/afs/servers. Signed-off-by: David Howells cc: Marc Dionne cc: linux-afs@lists.infradead.org

afs: Provide a way to configure address priorities

2024-01-01T16:37:26+00:00

AFS servers may have multiple addresses, but the client can't easily judge between them as to which one is best. For instance, an address that has a larger RTT might actually have a better bandwidth because it goes through a switch rather than being directly connected - but we can't work this out dynamically unless we push through sufficient data that we can measure it. To allow the administrator to configure this, add a list of preference weightings for server addresses by IPv4/IPv6 address or subnet and allow this to be viewed through a procfile and altered by writing text commands to that same file. Preference rules can be added/updated by: echo "add [/] " >/proc/fs/afs/addr_prefs echo "add udp 1.2.3.4 1000" >/proc/fs/afs/addr_prefs echo "add udp 192.168.0.0/16 3000" >/proc/fs/afs/addr_prefs echo "add udp 1001:2002:0:6::/64 4000" >/proc/fs/afs/addr_prefs and removed by: echo "del [/]" >/proc/fs/afs/addr_prefs echo "del udp 1.2.3.4" >/proc/fs/afs/addr_prefs where the priority is a number between 0 and 65535. The list is split between IPv4 and IPv6 addresses and each sublist is kept in numerical order, with rules that would otherwise match but have different subnet masking being ordered with the most specific submatch first. A subsequent patch will apply these rules. Signed-off-by: David Howells cc: Marc Dionne cc: linux-afs@lists.infradead.org

afs: Add some more info to /proc/net/afs/servers

2024-01-01T16:36:58+00:00

In /proc/net/afs/servers, show the cell name and the last error for each address in the server's list. Signed-off-by: David Howells cc: Marc Dionne cc: linux-afs@lists.infradead.org

afs: Rename addr_list::failed to probe_failed

2023-12-24T15:22:51+00:00

Rename the failed member of struct addr_list to probe_failed as it's specifically related to probe failures. Signed-off-by: David Howells cc: Marc Dionne cc: linux-afs@lists.infradead.org

rxrpc, afs: Allow afs to pin rxrpc_peer objects

2023-12-24T15:22:50+00:00

Change rxrpc's API such that: (1) A new function, rxrpc_kernel_lookup_peer(), is provided to look up an rxrpc_peer record for a remote address and a corresponding function, rxrpc_kernel_put_peer(), is provided to dispose of it again. (2) When setting up a call, the rxrpc_peer object used during a call is now passed in rather than being set up by rxrpc_connect_call(). For afs, this meenat passing it to rxrpc_kernel_begin_call() rather than the full address (the service ID then has to be passed in as a separate parameter). (3) A new function, rxrpc_kernel_remote_addr(), is added so that afs can get a pointer to the transport address for display purposed, and another, rxrpc_kernel_remote_srx(), to gain a pointer to the full rxrpc address. (4) The function to retrieve the RTT from a call, rxrpc_kernel_get_srtt(), is then altered to take a peer. This now returns the RTT or -1 if there are insufficient samples. (5) Rename rxrpc_kernel_get_peer() to rxrpc_kernel_call_get_peer(). (6) Provide a new function, rxrpc_kernel_get_peer(), to get a ref on a peer the caller already has. This allows the afs filesystem to pin the rxrpc_peer records that it is using, allowing faster lookups and pointer comparisons rather than comparing sockaddr_rxrpc contents. It also makes it easier to get hold of the RTT. The following changes are made to afs: (1) The addr_list struct's addrs[] elements now hold a peer struct pointer and a service ID rather than a sockaddr_rxrpc. (2) When displaying the transport address, rxrpc_kernel_remote_addr() is used. (3) The port arg is removed from afs_alloc_addrlist() since it's always overridden. (4) afs_merge_fs_addr4() and afs_merge_fs_addr6() do peer lookup and may now return an error that must be handled. (5) afs_find_server() now takes a peer pointer to specify the address. (6) afs_find_server(), afs_compare_fs_alists() and afs_merge_fs_addr[46]{} now do peer pointer comparison rather than address comparison. Signed-off-by: David Howells cc: Marc Dionne cc: linux-afs@lists.infradead.org

afs: Turn the afs_addr_list address array into an array of structs

2023-12-24T15:22:50+00:00

Turn the afs_addr_list address array into an array of structs, thereby allowing per-address (such as RTT) info to be added. Signed-off-by: David Howells cc: Marc Dionne cc: linux-afs@lists.infradead.org

afs: Use refcount_t rather than atomic_t

2022-08-02T17:10:11+00:00

Use refcount_t rather than atomic_t in afs to make use of the count checking facilities provided. Signed-off-by: David Howells Reviewed-by: Marc Dionne cc: linux-afs@lists.infradead.org Link: https://lore.kernel.org/r/165911277768.3745403.423349776836296452.stgit@warthog.procyon.org.uk/ # v1