[RFC PATCH v7 2/2] Btrfs: Add a new ioctl to set/change the label of a mounted file system
From: Jeff Liu <hidden>
Date: 2012-12-20 08:44:11
Subsystem:
btrfs file system, filesystems (vfs and infrastructure), the rest · Maintainers:
Chris Mason, David Sterba, Alexander Viro, Christian Brauner, Linus Torvalds
With the new ioctl(2) BTRFS_IOC_SET_FSLABEL, we can set/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> Cc: David Sterba <redacted> --- 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..99aa812 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); + ret = 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
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1.7.9.5