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ceph: don't skip updating wanted caps when cap is stale 

1. try_get_cap_refs() fails to get caps and finds that mds_wanted
   does not include what it wants. It returns -ESTALE.
2. ceph_get_caps() calls ceph_renew_caps(). ceph_renew_caps() finds
   that inode has cap, so it calls ceph_check_caps().
3. ceph_check_caps() finds that issued caps (without checking if it's
   stale) already includes caps wanted by open file, so it skips
   updating wanted caps.

Above events can cause an infinite loop inside ceph_get_caps().

Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
This commit is contained in:
Yan, Zheng 2020-03-10 19:34:20 +08:00 committed by Ilya Dryomov
parent 42d70f8e31
commit 0aa971b6fd
1 changed files with 6 additions and 2 deletions
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8
fs/ceph/caps.c
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@ -2008,8 +2008,12 @@ retry_locked:
}
/* want more caps from mds? */
if (want & ~(cap->mds_wanted | cap->issued))
goto ack;
if (want & ~cap->mds_wanted) {
if (want & ~(cap->mds_wanted | cap->issued))
goto ack;
if (!__cap_is_valid(cap))
goto ack;
}
/* things we might delay */
if ((cap->issued & ~retain) == 0)