Add a new ioctl(2) BTRFS_IOC_GET_FSLABLE, so that we can get the label upon a mounted filesystem.
Signed-off-by: Jie Liu <jeff.liu@xxxxxxxxxx>
Signed-off-by: Anand Jain <anand.jain@xxxxxxxxxx>
Cc: Miao Xie <miaox@xxxxxxxxxxxxxx>
Cc: Goffredo Baroncelli <kreijack@xxxxxxxxx>
Cc: David Sterba <dsterba@xxxxxxx>
---
fs/btrfs/ioctl.c | 21 +++++++++++++++++++++
fs/btrfs/ioctl.h | 2 ++
2 files changed, 23 insertions(+)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 8fcf9a5..ef2f55a 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3699,6 +3699,25 @@ out:
return ret;
}
+static int btrfs_ioctl_get_fslabel(struct file *file, void __user *arg)
+{
+ struct btrfs_root *root = BTRFS_I(fdentry(file)->d_inode)->root;
+ const char *label = root->fs_info->super_copy->label;
+ size_t len = strnlen(label, BTRFS_LABEL_SIZE);
+ int ret;
+
+ if (len == BTRFS_LABEL_SIZE) {
+ pr_warn("btrfs: label is too long, return the first %zu bytes\n",
+ --len);
+ }
+
+ mutex_lock(&root->fs_info->volume_mutex);
+ ret = copy_to_user(arg, label, len);
+ mutex_unlock(&root->fs_info->volume_mutex);
+
+ return ret ? -EFAULT : 0;
+}
+
long btrfs_ioctl(struct file *file, unsigned int
cmd, unsigned long arg)
{
@@ -3797,6 +3816,8 @@ long btrfs_ioctl(struct file *file, unsigned int
return btrfs_ioctl_qgroup_create(root, argp);
case BTRFS_IOC_QGROUP_LIMIT:
return btrfs_ioctl_qgroup_limit(root, argp);
+ case BTRFS_IOC_GET_FSLABEL:
+ return btrfs_ioctl_get_fslabel(file, argp);
}
return -ENOTTY;
diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h
index 731e287..5b2cbef 100644
--- a/fs/btrfs/ioctl.h
+++ b/fs/btrfs/ioctl.h
@@ -451,6 +451,8 @@ struct btrfs_ioctl_send_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_GET_DEV_STATS _IOWR(BTRFS_IOCTL_MAGIC, 52, \
struct btrfs_ioctl_get_dev_stats)
#endif
--
1.7.9.5
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