UBI: implement multiple volumes rename

Quite useful ioctl which allows to make atomic system upgrades.
The idea belongs to Richard Titmuss <richard_titmuss@logitech.com>

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

1 files changed, 187 insertions, 1 deletions

diff --git a/drivers/mtd/ubi/cdev.c b/drivers/mtd/ubi/cdev.c
index 7c19918cc914..bc8199c6a9f5 100644
--- a/drivers/mtd/ubi/cdev.c
+++ b/drivers/mtd/ubi/cdev.c
@@ -605,6 +605,166 @@ static int verify_rsvol_req(const struct ubi_device *ubi,
         return 0;
 }
 
+/**
+ * rename_volumes - rename UBI volumes.
+ * @ubi: UBI device description object
+ * @req: volumes re-name request
+ *
+ * This is a helper function for the volume re-name IOCTL which validates the
+ * the request, opens the volume and calls corresponding volumes management
+ * function. Returns zero in case of success and a negative error code in case
+ * of failure.
+ */
+static int rename_volumes(struct ubi_device *ubi,
+                          struct ubi_rnvol_req *req)
+{
+        int i, n, err;
+        struct list_head rename_list;
+        struct ubi_rename_entry *re, *re1;
+
+        if (req->count < 0 || req->count > UBI_MAX_RNVOL)
+                return -EINVAL;
+
+        if (req->count == 0)
+                return 0;
+
+        /* Validate volume IDs and names in the request */
+        for (i = 0; i < req->count; i++) {
+                if (req->ents[i].vol_id < 0 ||
+                    req->ents[i].vol_id >= ubi->vtbl_slots)
+                        return -EINVAL;
+                if (req->ents[i].name_len < 0)
+                        return -EINVAL;
+                if (req->ents[i].name_len > UBI_VOL_NAME_MAX)
+                        return -ENAMETOOLONG;
+                req->ents[i].name[req->ents[i].name_len] = '\0';
+                n = strlen(req->ents[i].name);
+                if (n != req->ents[i].name_len)
+                        err = -EINVAL;
+        }
+
+        /* Make sure volume IDs and names are unique */
+        for (i = 0; i < req->count - 1; i++) {
+                for (n = i + 1; n < req->count; n++) {
+                        if (req->ents[i].vol_id == req->ents[n].vol_id) {
+                                dbg_err("duplicated volume id %d",
+                                        req->ents[i].vol_id);
+                                return -EINVAL;
+                        }
+                        if (!strcmp(req->ents[i].name, req->ents[n].name)) {
+                                dbg_err("duplicated volume name \"%s\"",
+                                        req->ents[i].name);
+                                return -EINVAL;
+                        }
+                }
+        }
+
+        /* Create the re-name list */
+        INIT_LIST_HEAD(&rename_list);
+        for (i = 0; i < req->count; i++) {
+                int vol_id = req->ents[i].vol_id;
+                int name_len = req->ents[i].name_len;
+                const char *name = req->ents[i].name;
+
+                re = kzalloc(sizeof(struct ubi_rename_entry), GFP_KERNEL);
+                if (!re) {
+                        err = -ENOMEM;
+                        goto out_free;
+                }
+
+                re->desc = ubi_open_volume(ubi->ubi_num, vol_id, UBI_EXCLUSIVE);
+                if (IS_ERR(re->desc)) {
+                        err = PTR_ERR(re->desc);
+                        dbg_err("cannot open volume %d, error %d", vol_id, err);
+                        kfree(re);
+                        goto out_free;
+                }
+
+                /* Skip this re-naming if the name does not really change */
+                if (re->desc->vol->name_len == name_len &&
+                    !memcmp(re->desc->vol->name, name, name_len)) {
+                        ubi_close_volume(re->desc);
+                        kfree(re);
+                        continue;
+                }
+
+                re->new_name_len = name_len;
+                memcpy(re->new_name, name, name_len);
+                list_add_tail(&re->list, &rename_list);
+                dbg_msg("will rename volume %d from \"%s\" to \"%s\"",
+                        vol_id, re->desc->vol->name, name);
+        }
+
+        if (list_empty(&rename_list))
+                return 0;
+
+        /* Find out the volumes which have to be removed */
+        list_for_each_entry(re, &rename_list, list) {
+                struct ubi_volume_desc *desc;
+                int no_remove_needed = 0;
+
+                /*
+                 * Volume @re->vol_id is going to be re-named to
+                 * @re->new_name, while its current name is @name. If a volume
+                 * with name @re->new_name currently exists, it has to be
+                 * removed, unless it is also re-named in the request (@req).
+                 */
+                list_for_each_entry(re1, &rename_list, list) {
+                        if (re->new_name_len == re1->desc->vol->name_len &&
+                            !memcmp(re->new_name, re1->desc->vol->name,
+                                    re1->desc->vol->name_len)) {
+                                no_remove_needed = 1;
+                                break;
+                        }
+                }
+
+                if (no_remove_needed)
+                        continue;
+
+                /*
+                 * It seems we need to remove volume with name @re->new_name,
+                 * if it exists.
+                 */
+                desc = ubi_open_volume_nm(ubi->ubi_num, re->new_name, UBI_EXCLUSIVE);
+                if (IS_ERR(desc)) {
+                        err = PTR_ERR(desc);
+                        if (err == -ENODEV)
+                                /* Re-naming into a non-existing volume name */
+                                continue;
+
+                        /* The volume exists but busy, or an error occurred */
+                        dbg_err("cannot open volume \"%s\", error %d",
+                                re->new_name, err);
+                        goto out_free;
+                }
+
+                re = kzalloc(sizeof(struct ubi_rename_entry), GFP_KERNEL);
+                if (!re) {
+                        err = -ENOMEM;
+                        ubi_close_volume(desc);
+                        goto out_free;
+                }
+
+                re->remove = 1;
+                re->desc = desc;
+                list_add(&re->list, &rename_list);
+                dbg_msg("will remove volume %d, name \"%s\"",
+                        re->desc->vol->vol_id, re->desc->vol->name);
+        }
+
+        mutex_lock(&ubi->volumes_mutex);
+        err = ubi_rename_volumes(ubi, &rename_list);
+        mutex_unlock(&ubi->volumes_mutex);
+
+out_free:
+        list_for_each_entry_safe(re, re1, &rename_list, list) {
+                ubi_close_volume(re->desc);
+                list_del(&re->list);
+                kfree(re);
+        }
+        return err;
+}
+
 static int ubi_cdev_ioctl(struct inode *inode, struct file *file,
                           unsigned int cmd, unsigned long arg)
 {
@@ -670,7 +830,7 @@ static int ubi_cdev_ioctl(struct inode *inode, struct file *file,
                 }
 
                 mutex_lock(&ubi->volumes_mutex);
-                err = ubi_remove_volume(desc);
+                err = ubi_remove_volume(desc, 0);
                 mutex_unlock(&ubi->volumes_mutex);
 
                 /*
@@ -717,6 +877,32 @@ static int ubi_cdev_ioctl(struct inode *inode, struct file *file,
                 break;
         }
 
+        /* Re-name volumes command */
+        case UBI_IOCRNVOL:
+        {
+                struct ubi_rnvol_req *req;
+
+                dbg_msg("re-name volumes");
+                req = kmalloc(sizeof(struct ubi_rnvol_req), GFP_KERNEL);
+                if (!req) {
+                        err = -ENOMEM;
+                        break;
+                };
+
+                err = copy_from_user(req, argp, sizeof(struct ubi_rnvol_req));
+                if (err) {
+                        err = -EFAULT;
+                        kfree(req);
+                        break;
+                }
+
+                mutex_lock(&ubi->mult_mutex);
+                err = rename_volumes(ubi, req);
+                mutex_unlock(&ubi->mult_mutex);
+                kfree(req);
+                break;
+        }
+
         default:
                 err = -ENOTTY;
                 break;