[PATCH v3] ceph: skip existing superblocks that are blocklisted or shut down when mounting

[Jeff Layton <jlayton@kernel.org>]

Currently when mounting, we may end up finding an existing superblock
that corresponds to a blocklisted MDS client. This means that the new
mount ends up being unusable.

If we've found an existing superblock with a client that is already
blocklisted, and the client is not configured to recover on its own,
fail the match. Ditto if the superblock has been forcibly unmounted.

While we're in here, also rename "other" to the more conventional "fsc".

Cc: Patrick Donnelly <pdonnell@redhat.com>
Cc: Niels de Vos <ndevos@redhat.com>
Cc: "Yan, Zheng" <ukernel@gmail.com>
Cc: stable@vger.kernel.org
URL: https://bugzilla.redhat.com/show_bug.cgi?id=1901499
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>

ceph: when comparing superblocks, skip ones that have been forcibly unmounted

Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
 fs/ceph/super.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

v3: also handle the case where we have a forcibly unmounted superblock
    that is detached but still extant

diff --git a/fs/ceph/super.c b/fs/ceph/super.c
index f517ad9eeb26..b9ba50c9dc95 100644
--- a/fs/ceph/super.c
+++ b/fs/ceph/super.c
@@ -1123,16 +1123,16 @@ static int ceph_compare_super(struct super_block *sb, struct fs_context *fc)
 	struct ceph_fs_client *new = fc->s_fs_info;
 	struct ceph_mount_options *fsopt = new->mount_options;
 	struct ceph_options *opt = new->client->options;
-	struct ceph_fs_client *other = ceph_sb_to_client(sb);
+	struct ceph_fs_client *fsc = ceph_sb_to_client(sb);
 
 	dout("ceph_compare_super %p\n", sb);
 
-	if (compare_mount_options(fsopt, opt, other)) {
+	if (compare_mount_options(fsopt, opt, fsc)) {
 		dout("monitor(s)/mount options don't match\n");
 		return 0;
 	}
 	if ((opt->flags & CEPH_OPT_FSID) &&
-	    ceph_fsid_compare(&opt->fsid, &other->client->fsid)) {
+	    ceph_fsid_compare(&opt->fsid, &fsc->client->fsid)) {
 		dout("fsid doesn't match\n");
 		return 0;
 	}
@@ -1140,6 +1140,17 @@ static int ceph_compare_super(struct super_block *sb, struct fs_context *fc)
 		dout("flags differ\n");
 		return 0;
 	}
+	/* Exclude any blocklisted superblocks */
+	if (fsc->blocklisted && !ceph_test_mount_opt(fsc, CLEANRECOVER)) {
+		dout("client is blocklisted (and CLEANRECOVER is not set)\n");
+		return 0;
+	}
+
+	if (fsc->mount_state == CEPH_MOUNT_SHUTDOWN) {
+		dout("client has been forcibly unmounted\n");
+		return 0;
+	}
+
 	return 1;
 }
 
-- 
2.31.1