ceph: fix cap ref leak via netfs init_request

From: Patrick Donnelly <[email protected]>

Log recovered from a user's cluster:

    <7>[ 5413.970692] ceph:  get_cap_refs 00000000958c114b ret 1 got Fr
    <7>[ 5413.970695] ceph:  start_read 00000000958c114b, no cache cap
    ...
    <7>[ 5473.934609] ceph:   my wanted = Fr, used = Fr, dirty -
    <7>[ 5473.934616] ceph:  revocation: pAsLsXsFr -> pAsLsXs (revoking Fr)
    <7>[ 5473.934632] ceph:  __ceph_caps_issued 00000000958c114b cap 00000000f7784259 issued pAsLsXs
    <7>[ 5473.934638] ceph:  check_caps 10000000e68.fffffffffffffffe file_want - used Fr dirty - flushing - issued pAsLsXs revoking Fr retain pAsLsXsFsr  AUTHONLY NOINVAL FLUSH_FORCE

The MDS subsequently complains that the kernel client is late releasing caps.

Approximately, a series of changes to this code by the three commits cited below resulted in subtle resource cleanup to be missed. The main culprit is the change in error handling in 2d31604 which meant that a failure in init_request would no longer cause cleanup to be called. That would prevent the ceph_put_cap_refs which would cleanup the leaked cap ref.

Closes https://tracker.ceph.com/issues/67008

Fixes 49870056005ca9387e5ee31451991491f99cc45f ("ceph: convert ceph_readpages to ceph_readahead")

Fixes 2de160417315b8d64455fe03e9bb7d3308ac3281 ("netfs: Change ->init_request() to return an error code")

Fixes a5c9dc4451394b2854493944dcc0ff71af9705a3 ("ceph: Make ceph_init_request() check caps on readahead")

Signed-off-by Patrick Donnelly <[email protected]>

Cc [email protected]

---
 fs/ceph/addr.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

fs/ceph/addr.c +4 -1

index 53fef258c2bc..702c6a730b70 100644
@@ -489,8 +489,11 @@ static int ceph_init_request(struct netfs_io_request *rreq, struct file *file)
        rreq->io_streams[0].sreq_max_len = fsc->mount_options->rsize;
 
 out:
-       if (ret < 0)
+       if (ret < 0) {
+               if (got)
+                       ceph_put_cap_refs(ceph_inode(inode), got);
                kfree(priv);
+       }
 
        return ret;
 }

base-commit: e32cde8d2bd7d251a8f9b434143977ddf13dcec6 --
Patrick Donnelly, Ph.D.
He / Him / His
Red Hat Partner Engineer
IBM, Inc.
GPG: 19F28A586F808C2402351B93C3301A3E258DD79D

Log recovered from a user's cluster:

    <7>[ 5413.970692] ceph:  get_cap_refs 00000000958c114b ret 1 got Fr
    <7>[ 5413.970695] ceph:  start_read 00000000958c114b, no cache cap
    ...
    <7>[ 5473.934609] ceph:   my wanted = Fr, used = Fr, dirty -
    <7>[ 5473.934616] ceph:  revocation: pAsLsXsFr -> pAsLsXs (revoking Fr)
    <7>[ 5473.934632] ceph:  __ceph_caps_issued 00000000958c114b cap 00000000f7784259 issued pAsLsXs
    <7>[ 5473.934638] ceph:  check_caps 10000000e68.fffffffffffffffe file_want - used Fr dirty - flushing - issued pAsLsXs revoking Fr retain pAsLsXsFsr  AUTHONLY NOINVAL FLUSH_FORCE

The MDS subsequently complains that the kernel client is late releasing caps.

Approximately, a series of changes to this code by the three commits cited below resulted in subtle resource cleanup to be missed. The main culprit is the change in error handling in 2d31604 which meant that a failure in init_request would no longer cause cleanup to be called. That would prevent the ceph_put_cap_refs which would cleanup the leaked cap ref.

Closes https://tracker.ceph.com/issues/67008

Fixes 49870056005ca9387e5ee31451991491f99cc45f ("ceph: convert ceph_readpages to ceph_readahead")

Fixes 2de160417315b8d64455fe03e9bb7d3308ac3281 ("netfs: Change ->init_request() to return an error code")

Fixes a5c9dc4451394b2854493944dcc0ff71af9705a3 ("ceph: Make ceph_init_request() check caps on readahead")

Signed-off-by Patrick Donnelly <[email protected]>

Cc [email protected]

Hi Ilya,

Are you going to pick this up, or should I ask Christian to take it through the vfs tree?

From: Patrick Donnelly <[email protected]>

Log recovered from a user's cluster:

     <7>[ 5413.970692] ceph:  get_cap_refs 00000000958c114b ret 1 got Fr
     <7>[ 5413.970695] ceph:  start_read 00000000958c114b, no cache cap
     ...
     <7>[ 5473.934609] ceph:   my wanted = Fr, used = Fr, dirty -
     <7>[ 5473.934616] ceph:  revocation: pAsLsXsFr -> pAsLsXs (revoking Fr)
     <7>[ 5473.934632] ceph:  __ceph_caps_issued 00000000958c114b cap 00000000f7784259 issued pAsLsXs
     <7>[ 5473.934638] ceph:  check_caps 10000000e68.fffffffffffffffe file_want - used Fr dirty - flushing - issued pAsLsXs revoking Fr retain pAsLsXsFsr  AUTHONLY NOINVAL FLUSH_FORCE

The MDS subsequently complains that the kernel client is late releasing caps.

Approximately, a series of changes to this code by the three commits cited below resulted in subtle resource cleanup to be missed. The main culprit is the change in error handling in 2d31604 which meant that a failure in init_request would no longer cause cleanup to be called. That would prevent the ceph_put_cap_refs which would cleanup the leaked cap ref.

Closes https://tracker.ceph.com/issues/67008

Fixes 49870056005ca9387e5ee31451991491f99cc45f ("ceph: convert ceph_readpages to ceph_readahead")

Fixes 2de160417315b8d64455fe03e9bb7d3308ac3281 ("netfs: Change ->init_request() to return an error code")

Fixes a5c9dc4451394b2854493944dcc0ff71af9705a3 ("ceph: Make ceph_init_request() check caps on readahead")

Signed-off-by Patrick Donnelly <[email protected]>

Cc [email protected]

---
  fs/ceph/addr.c | 5 ++++-
  1 file changed, 4 insertions(+), 1 deletion(-)

fs/ceph/addr.c +4 -1

index 53fef258c2bc..702c6a730b70 100644
@@ -489,8 +489,11 @@ static int ceph_init_request(struct netfs_io_request *rreq, struct file *file)
  	rreq->io_streams[0].sreq_max_len = fsc->mount_options->rsize;
 
  out:
-	if (ret < 0)
+	if (ret < 0) {
+		if (got)
+			ceph_put_cap_refs(ceph_inode(inode), got);
  		kfree(priv);
+	}
 
  	return ret;
  }

base-commit: e32cde8d2bd7d251a8f9b434143977ddf13dcec6