Jeff Liu
2012-Dec-17 11:35 UTC
[PATCH V5 2/4] Btrfs-progs: Change the label of a mounted file system
With this new ioctl(2), we can set/change the label for a mounted file system.
It still does normal process for an umounted file system.
Signed-off-by: Jie Liu <jeff.liu@oracle.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
btrfslabel.c | 90 +++++++++++++++++++++++++++++++++++-----------------------
ioctl.h | 2 ++
2 files changed, 57 insertions(+), 35 deletions(-)
diff --git a/btrfslabel.c b/btrfslabel.c
index 443eff6..938e8b4 100644
--- a/btrfslabel.c
+++ b/btrfslabel.c
@@ -46,25 +46,58 @@
#define GET_LABEL 3
#define SET_LABEL 4
-static void change_label_unmounted(char *dev, char *nLabel)
+static int set_label_unmounted(const char *dev, const char *label)
{
- struct btrfs_root *root;
- struct btrfs_trans_handle *trans;
-
- /* Open the super_block at the default location
- * and as read-write.
- */
- root = open_ctree(dev, 0, 1);
- if (!root) /* errors are printed by open_ctree() */
- return;
-
- trans = btrfs_start_transaction(root, 1);
- strncpy(root->fs_info->super_copy.label, nLabel,
BTRFS_LABEL_SIZE);
- root->fs_info->super_copy.label[BTRFS_LABEL_SIZE-1] = 0;
- btrfs_commit_transaction(trans, root);
-
- /* Now we close it since we are done. */
- close_ctree(root);
+ struct btrfs_trans_handle *trans;
+ struct btrfs_root *root;
+ int ret;
+
+ ret = check_mounted(dev);
+ if (ret < 0) {
+ fprintf(stderr, "FATAL: error checking %s mount status\n",
dev);
+ return -1;
+ }
+ if (ret > 0) {
+ fprintf(stderr, "ERROR: dev %s is mounted, use mount point\n",
+ dev);
+ return -1;
+ }
+
+ /* Open the super_block at the default location
+ * and as read-write.
+ */
+ root = open_ctree(dev, 0, 1);
+ if (!root) /* errors are printed by open_ctree() */
+ return -1;
+
+ trans = btrfs_start_transaction(root, 1);
+ strncpy(root->fs_info->super_copy.label, label, BTRFS_LABEL_SIZE);
+ root->fs_info->super_copy.label[BTRFS_LABEL_SIZE-1] = 0;
+ btrfs_commit_transaction(trans, root);
+
+ /* Now we close it since we are done. */
+ close_ctree(root);
+ return 0;
+}
+
+static int set_label_mounted(const char *mount_path, const char *label)
+{
+ int fd;
+
+ fd = open(mount_path, O_RDONLY | O_NOATIME);
+ if (fd < 0) {
+ fprintf(stderr, "ERROR: unable access to ''%s''\n",
mount_path);
+ return -1;
+ }
+
+ if (ioctl(fd, BTRFS_IOC_SET_FSLABEL, label) < 0) {
+ fprintf(stderr, "ERROR: unable to set label %s\n",
+ strerror(errno));
+ close(fd);
+ return -1;
+ }
+
+ return 0;
}
static int get_label_unmounted(const char *dev)
@@ -131,22 +164,9 @@ int get_label(const char *btrfs_dev)
get_label_mounted(btrfs_dev);
}
-int set_label(char *btrfs_dev, char *nLabel)
+int set_label(char *btrfs_dev, char *label)
{
-
- int ret;
- ret = check_mounted(btrfs_dev);
- if (ret < 0)
- {
- fprintf(stderr, "FATAL: error checking %s mount status\n",
btrfs_dev);
- return -1;
- }
-
- if(ret != 0)
- {
- fprintf(stderr, "FATAL: the filesystem has to be
unmounted\n");
- return -2;
- }
- change_label_unmounted(btrfs_dev, nLabel);
- return 0;
+ return is_existing_blk_or_reg_file(btrfs_dev) ?
+ set_label_unmounted(btrfs_dev, label) :
+ set_label_mounted(btrfs_dev, label);
}
diff --git a/ioctl.h b/ioctl.h
index 0807b05..0882d6c 100644
--- a/ioctl.h
+++ b/ioctl.h
@@ -434,4 +434,6 @@ struct btrfs_ioctl_clone_range_args {
struct btrfs_ioctl_qgroup_limit_args)
#define BTRFS_IOC_GET_FSLABEL _IOR(BTRFS_IOCTL_MAGIC, 49, \
char[BTRFS_LABEL_SIZE])
+#define BTRFS_IOC_SET_FSLABEL _IOW(BTRFS_IOCTL_MAGIC, 50, \
+ char[BTRFS_LABEL_SIZE])
#endif
--
1.7.9.5
--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs"
in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html