summaryrefslogtreecommitdiff
path: root/fs/afs/rotate.c
diff options
context:
space:
mode:
authorDavid Howells <dhowells@redhat.com>2023-11-08 13:57:42 +0000
committerDavid Howells <dhowells@redhat.com>2024-01-01 16:37:27 +0000
commit453924de6212ac159f946b75c6b59918e2e30944 (patch)
tree5ce08d7d0216e4473ffc19733be849a3d5778eaf /fs/afs/rotate.c
parent16069e1349a0c5535e189f9dc5d937bfd7631a06 (diff)
afs: Overhaul invalidation handling to better support RO volumes
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 <dhowells@redhat.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: linux-afs@lists.infradead.org
Diffstat (limited to 'fs/afs/rotate.c')
-rw-r--r--fs/afs/rotate.c24
1 files changed, 19 insertions, 5 deletions
diff --git a/fs/afs/rotate.c b/fs/afs/rotate.c
index 5c50c9aa1f87..a8554b4d91b8 100644
--- a/fs/afs/rotate.c
+++ b/fs/afs/rotate.c
@@ -59,7 +59,7 @@ static bool afs_start_fs_iteration(struct afs_operation *op,
write_seqlock(&vnode->cb_lock);
ASSERTCMP(cb_server, ==, vnode->cb_server);
vnode->cb_server = NULL;
- if (test_and_clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags))
+ if (atomic64_xchg(&vnode->cb_expires_at, AFS_NO_CB_PROMISE) != AFS_NO_CB_PROMISE)
vnode->cb_break++;
write_sequnlock(&vnode->cb_lock);
}
@@ -140,6 +140,22 @@ bool afs_select_fileserver(struct afs_operation *op)
switch (op->call_error) {
case 0:
op->cumul_error.responded = true;
+
+ /* We succeeded, but we may need to redo the op from another
+ * server if we're looking at a set of RO volumes where some of
+ * the servers have not yet been brought up to date lest we
+ * regress the data. We only switch to the new version once
+ * >=50% of the servers are updated.
+ */
+ error = afs_update_volume_state(op);
+ if (error != 0) {
+ if (error == 1) {
+ afs_sleep_and_retry(op);
+ goto restart_from_beginning;
+ }
+ afs_op_set_error(op, error);
+ goto failed;
+ }
fallthrough;
default:
/* Success or local failure. Stop. */
@@ -484,10 +500,8 @@ selected_server:
op->server = server;
if (vnode->cb_server != server) {
vnode->cb_server = server;
- vnode->cb_s_break = server->cb_s_break;
- vnode->cb_fs_s_break = atomic_read(&server->cell->fs_s_break);
- vnode->cb_v_break = atomic_read(&vnode->volume->cb_v_break);
- clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags);
+ vnode->cb_v_check = atomic_read(&vnode->volume->cb_v_break);
+ atomic64_set(&vnode->cb_expires_at, AFS_NO_CB_PROMISE);
}
read_lock(&server->fs_lock);