Re: [PATCH] ceph: try to queue a writeback if revoking fails

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



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);
  }




[Index of Archives]     [CEPH Users]     [Ceph Large]     [Ceph Dev]     [Information on CEPH]     [Linux BTRFS]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux