From: Jeff Layton <jlayton@xxxxxxxxxx> [ Upstream commit 8cfc0c7ed34f7929ce7e5d7c6eecf4d01ba89a84 ] ceph_statfs currently stuffs the cluster fsid into the f_fsid field. This was fine when we only had a single filesystem per cluster, but now that we have multiples we need to use something that will vary between them. Change ceph_statfs to xor each 32-bit chunk of the fsid (aka cluster id) into the lower bits of the statfs->f_fsid. Change the lower bits to hold the fscid (filesystem ID within the cluster). That should give us a value that is guaranteed to be unique between filesystems within a cluster, and should minimize the chance of collisions between mounts of different clusters. URL: https://tracker.ceph.com/issues/52812 Reported-by: Sachin Prabhu <sprabhu@xxxxxxxxxx> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx> Reviewed-by: Xiubo Li <xiubli@xxxxxxxxxx> Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- fs/ceph/super.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/fs/ceph/super.c b/fs/ceph/super.c index fd8742bae8471..202ddde3d62ad 100644 --- a/fs/ceph/super.c +++ b/fs/ceph/super.c @@ -52,8 +52,7 @@ static int ceph_statfs(struct dentry *dentry, struct kstatfs *buf) struct ceph_fs_client *fsc = ceph_inode_to_client(d_inode(dentry)); struct ceph_mon_client *monc = &fsc->client->monc; struct ceph_statfs st; - u64 fsid; - int err; + int i, err; u64 data_pool; if (fsc->mdsc->mdsmap->m_num_data_pg_pools == 1) { @@ -99,12 +98,14 @@ static int ceph_statfs(struct dentry *dentry, struct kstatfs *buf) buf->f_namelen = NAME_MAX; /* Must convert the fsid, for consistent values across arches */ + buf->f_fsid.val[0] = 0; mutex_lock(&monc->mutex); - fsid = le64_to_cpu(*(__le64 *)(&monc->monmap->fsid)) ^ - le64_to_cpu(*((__le64 *)&monc->monmap->fsid + 1)); + for (i = 0 ; i < sizeof(monc->monmap->fsid) / sizeof(__le32) ; ++i) + buf->f_fsid.val[0] ^= le32_to_cpu(((__le32 *)&monc->monmap->fsid)[i]); mutex_unlock(&monc->mutex); - buf->f_fsid = u64_to_fsid(fsid); + /* fold the fs_cluster_id into the upper bits */ + buf->f_fsid.val[1] = monc->fs_cluster_id; return 0; } -- 2.33.0
