[...]
@@ -2473,7 +2621,23 @@ int __ceph_setattr(struct inode *inode, struct iattr *attr, struct ceph_iattr *c
req->r_args.setattr.mask = cpu_to_le32(mask);
req->r_num_caps = 1;
req->r_stamp = attr->ia_ctime;
+ if (fill_fscrypt) {
+ err = fill_fscrypt_truncate(inode, req, attr);
+ if (err)
+ goto out;
+ }
+
+ /*
+ * The truncate will return -EAGAIN when some one
+ * has updated the last block before the MDS hold
+ * the xlock for the FILE lock. Need to retry it.
+ */
err = ceph_mdsc_do_request(mdsc, NULL, req);
+ if (err == -EAGAIN) {
+ dout("setattr %p result=%d (%s locally, %d remote), retry it!\n",
+ inode, err, ceph_cap_string(dirtied), mask);
+ goto retry;
+ }
The rest looks reasonable. We may want to cap the number of retries in
case something goes really wrong or in the case of a livelock with a
competing client. I'm not sure what a reasonable number of tries would
be though -- 5? 10? 100? We may want to benchmark out how long this rmw
operation takes and then we can use that to determine a reasonable
number of tries.
<7>[ 330.648749] ceph: setattr 00000000197f0d87 issued pAsxLsXsxFsxcrwb
<7>[ 330.648752] ceph: setattr 00000000197f0d87 size 11 -> 2
<7>[ 330.648756] ceph: setattr 00000000197f0d87 mtime
1635574177.43176541 -> 1635574210.35946684
<7>[ 330.648760] ceph: setattr 00000000197f0d87 ctime
1635574177.43176541 -> 1635574210.35946684 (ignored)
<7>[ 330.648765] ceph: setattr 00000000197f0d87 ATTR_FILE ... hrm!
...
<7>[ 330.653696] ceph: fill_fscrypt_truncate 00000000197f0d87 size
dropping cap refs on Fr
...
<7>[ 330.697464] ceph: setattr 00000000197f0d87 result=0 (Fx locally,
4128 remote)
It takes around 50ms.
Shall we retry 20 times ?
If you run out of tries, you could probably just return -EAGAIN in that
case. That's not listed in the truncate(2) manpage, but it seems like a
reasonable way to handle that sort of problem.
[...]
