Please ignore this, just forgot to add the v2 tag.
-- Xiubo
On 4/28/22 8:48 PM, Xiubo Li wrote:
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);
}
