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Btrfs-progs: Change the label of a mounted file system

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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>
This commit is contained in:
Jeff Liu 2012-12-17 11:35:23 +00:00 committed by David Sterba
parent 704a08cb8a
commit 619dc61cae
2 changed files with 55 additions and 31 deletions
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82
btrfslabel.c
View File

@ -46,26 +46,58 @@
#define GET_LABEL 3
#define SET_LABEL 4
static int 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;
struct btrfs_trans_handle *trans;
struct btrfs_root *root;
int ret;
/* 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() */
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;
}
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);
/* 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;
/* Now we close it since we are done. */
close_ctree(root);
return 0;
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;
}
int get_label_unmounted(char *dev)
@ -108,21 +140,9 @@ int get_label(char *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;
}
return change_label_unmounted(btrfs_dev, nLabel);
return is_existing_blk_or_reg_file(btrfs_dev) ?
set_label_unmounted(btrfs_dev, label) :
set_label_mounted(btrfs_dev, label);
}

4
ioctl.h
View File

@ -520,6 +520,10 @@ struct btrfs_ioctl_clone_range_args {
struct btrfs_ioctl_qgroup_create_args)
#define BTRFS_IOC_QGROUP_LIMIT _IOR(BTRFS_IOCTL_MAGIC, 43, \
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])
#define BTRFS_IOC_GET_DEV_STATS _IOWR(BTRFS_IOCTL_MAGIC, 52, \
struct btrfs_ioctl_get_dev_stats)
#define BTRFS_IOC_DEV_REPLACE _IOWR(BTRFS_IOCTL_MAGIC, 53, \