ceph: quota: don't allow cross-quota renames

This patch changes ceph_rename so that -EXDEV is returned if an attempt is
made to mv a file between two different dir trees with different quotas
setup.

Signed-off-by: Luis Henriques <lhenriques@suse.com>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

3 files changed, 75 insertions, 0 deletions

diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index 7d9851cd51bb..1f60498c4631 100644
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -1080,6 +1080,11 @@ static int ceph_rename(struct inode *old_dir, struct dentry *old_dentry,
                 else
                         return -EROFS;
         }
+        /* don't allow cross-quota renames */
+        if ((old_dir != new_dir) &&
+            (!ceph_quota_is_same_realm(old_dir, new_dir)))
+                return -EXDEV;
+
         dout("rename dir %p dentry %p to dir %p dentry %p\n",
              old_dir, old_dentry, new_dir, new_dentry);
         req = ceph_mdsc_create_request(mdsc, op, USE_AUTH_MDS);
diff --git a/fs/ceph/quota.c b/fs/ceph/quota.c
index cf1c78c4a4d2..5d7dada91a57 100644
--- a/fs/ceph/quota.c
+++ b/fs/ceph/quota.c
@@ -21,6 +21,11 @@
 #include "super.h"
 #include "mds_client.h"
 
+static inline bool ceph_has_quota(struct ceph_inode_info *ci)
+{
+        return (ci && (ci->i_max_files || ci->i_max_bytes));
+}
+
 void ceph_handle_quota(struct ceph_mds_client *mdsc,
                        struct ceph_mds_session *session,
                        struct ceph_msg *msg)
@@ -64,6 +69,70 @@ void ceph_handle_quota(struct ceph_mds_client *mdsc,
         iput(inode);
 }
 
+/*
+ * This function walks through the snaprealm for an inode and returns the
+ * ceph_snap_realm for the first snaprealm that has quotas set (either max_files
+ * or max_bytes).  If the root is reached, return the root ceph_snap_realm
+ * instead.
+ *
+ * Note that the caller is responsible for calling ceph_put_snap_realm() on the
+ * returned realm.
+ */
+static struct ceph_snap_realm *get_quota_realm(struct ceph_mds_client *mdsc,
+                                               struct inode *inode)
+{
+        struct ceph_inode_info *ci = NULL;
+        struct ceph_snap_realm *realm, *next;
+        struct ceph_vino vino;
+        struct inode *in;
+
+        realm = ceph_inode(inode)->i_snap_realm;
+        ceph_get_snap_realm(mdsc, realm);
+        while (realm) {
+                vino.ino = realm->ino;
+                vino.snap = CEPH_NOSNAP;
+                in = ceph_find_inode(inode->i_sb, vino);
+                if (!in) {
+                        pr_warn("Failed to find inode for %llu\n", vino.ino);
+                        break;
+                }
+                ci = ceph_inode(in);
+                if (ceph_has_quota(ci) || (ci->i_vino.ino == CEPH_INO_ROOT)) {
+                        iput(in);
+                        return realm;
+                }
+                iput(in);
+                next = realm->parent;
+                ceph_get_snap_realm(mdsc, next);
+                ceph_put_snap_realm(mdsc, realm);
+                realm = next;
+        }
+        if (realm)
+                ceph_put_snap_realm(mdsc, realm);
+
+        return NULL;
+}
+
+bool ceph_quota_is_same_realm(struct inode *old, struct inode *new)
+{
+        struct ceph_mds_client *mdsc = ceph_inode_to_client(old)->mdsc;
+        struct ceph_snap_realm *old_realm, *new_realm;
+        bool is_same;
+
+        down_read(&mdsc->snap_rwsem);
+        old_realm = get_quota_realm(mdsc, old);
+        new_realm = get_quota_realm(mdsc, new);
+        is_same = (old_realm == new_realm);
+        up_read(&mdsc->snap_rwsem);
+
+        if (old_realm)
+                ceph_put_snap_realm(mdsc, old_realm);
+        if (new_realm)
+                ceph_put_snap_realm(mdsc, new_realm);
+
+        return is_same;
+}
+
 enum quota_check_op {
         QUOTA_CHECK_MAX_FILES_OP        /* check quota max_files limit */
 };
diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index 4afc6cca8786..eea6f70f3bf9 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -1078,5 +1078,6 @@ extern void ceph_handle_quota(struct ceph_mds_client *mdsc,
                               struct ceph_mds_session *session,
                               struct ceph_msg *msg);
 extern bool ceph_quota_is_max_files_exceeded(struct inode *inode);
+extern bool ceph_quota_is_same_realm(struct inode *old, struct inode *new);
 
 #endif /* _FS_CEPH_SUPER_H */