If the pagecaches writeback just finished and the i_wrbuffer_ref reaches zero it will try to trigger ceph_check_caps(). But if just before ceph_check_caps() the i_wrbuffer_ref could be increased again by mmap/cache write, then the Fwb revoke will fail. We need to try to queue a writeback in this case instead of triggering the writeback by BDI's delayed work per 5 seconds. URL: https://tracker.ceph.com/issues/55377 URL: https://tracker.ceph.com/issues/46904 Signed-off-by: Xiubo Li <xiubli@xxxxxxxxxx> --- fs/ceph/caps.c | 28 ++++++++++++++++++++++++---- 1 file changed, 24 insertions(+), 4 deletions(-) diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c index 906c95d2a4ed..22dae29be64d 100644 --- a/fs/ceph/caps.c +++ b/fs/ceph/caps.c @@ -1912,6 +1912,7 @@ void ceph_check_caps(struct ceph_inode_info *ci, int flags, struct rb_node *p; bool queue_invalidate = false; bool tried_invalidate = false; + bool queue_writeback = false; if (session) ceph_get_mds_session(session); @@ -2064,10 +2065,27 @@ void ceph_check_caps(struct ceph_inode_info *ci, int flags, } /* completed revocation? going down and there are no caps? */ - if (revoking && (revoking & cap_used) == 0) { - dout("completed revocation of %s\n", - ceph_cap_string(cap->implemented & ~cap->issued)); - goto ack; + if (revoking) { + if ((revoking & cap_used) == 0) { + dout("completed revocation of %s\n", + ceph_cap_string(cap->implemented & ~cap->issued)); + goto ack; + } + + /* + * If the "i_wrbuffer_ref" was increased by mmap or generic + * cache write just before the ceph_check_caps() is called, + * the Fb capability revoking will fail this time. Then we + * must wait for the BDI's delayed work to flush the dirty + * pages and to release the "i_wrbuffer_ref", which will cost + * at most 5 seconds. That means the MDS needs to wait at + * most 5 seconds to finished the Fb capability's revocation. + * + * Let's queue a writeback for it. + */ + if (S_ISREG(inode->i_mode) && ci->i_wrbuffer_ref && + (revoking & CEPH_CAP_FILE_BUFFER)) + queue_writeback = true; } /* want more caps from mds? */ @@ -2137,6 +2155,8 @@ void ceph_check_caps(struct ceph_inode_info *ci, int flags, spin_unlock(&ci->i_ceph_lock); ceph_put_mds_session(session); + if (queue_writeback) + ceph_queue_writeback(inode); if (queue_invalidate) ceph_queue_invalidate(inode); } -- 2.36.0.rc1
