Re: [RFC PATCH V6 2/2] Btrfs: Add a new ioctl to change the label of a mounted file system
From: Miao Xie <hidden>
Date: 2012-12-18 03:31:27
On Tue, 18 Dec 2012 11:06:07 +0800, Jeff Liu wrote:
Introduce a new ioctl BTRFS_IOC_SET_FSLABEL to change the label of a mounted file system. Signed-off-by: Jie Liu <redacted> Signed-off-by: Anand Jain <redacted> Cc: Miao Xie <redacted> Cc: Goffredo Baroncelli <redacted>
Reviewed-by: Miao Xie <redacted>
quoted hunk ↗ jump to hunk
--- fs/btrfs/ioctl.c | 39 +++++++++++++++++++++++++++++++++++++++ fs/btrfs/ioctl.h | 2 ++ 2 files changed, 41 insertions(+)diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 6a2488a..2bb037e 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c@@ -3712,6 +3712,43 @@ static int btrfs_ioctl_get_fslabel(struct file *file, void __user *arg) return ret ? -EFAULT : 0; } +static int btrfs_ioctl_set_fslabel(struct file *file, void __user *arg) +{ + struct btrfs_root *root = BTRFS_I(fdentry(file)->d_inode)->root; + struct btrfs_super_block *super_block = root->fs_info->super_copy; + struct btrfs_trans_handle *trans; + char label[BTRFS_LABEL_SIZE]; + int ret; + + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + if (copy_from_user(label, arg, sizeof(label))) + return -EFAULT; + + if (strnlen(label, BTRFS_LABEL_SIZE) == BTRFS_LABEL_SIZE) + return -EINVAL; + + ret = mnt_want_write_file(file); + if (ret) + return ret; + + mutex_lock(&root->fs_info->volume_mutex); + trans = btrfs_start_transaction(root, 1); + if (IS_ERR(trans)) { + ret = PTR_ERR(trans); + goto out_unlock; + } + + strcpy(super_block->label, label); + btrfs_end_transaction(trans, root); + +out_unlock: + mutex_unlock(&root->fs_info->volume_mutex); + mnt_drop_write_file(file); + return ret; +} + long btrfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg) {@@ -3812,6 +3849,8 @@ long btrfs_ioctl(struct file *file, unsigned int return btrfs_ioctl_qgroup_limit(root, argp); case BTRFS_IOC_GET_FSLABEL: return btrfs_ioctl_get_fslabel(file, argp); + case BTRFS_IOC_SET_FSLABEL: + return btrfs_ioctl_set_fslabel(file, argp); } return -ENOTTY;diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h index 5b2cbef..2abe239 100644 --- a/fs/btrfs/ioctl.h +++ b/fs/btrfs/ioctl.h@@ -453,6 +453,8 @@ struct btrfs_ioctl_send_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]) #define BTRFS_IOC_GET_DEV_STATS _IOWR(BTRFS_IOCTL_MAGIC, 52, \ struct btrfs_ioctl_get_dev_stats) #endif