| Message ID | 50C7F894.9000709@oracle.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On wed, 12 Dec 2012 11:23:00 +0800, Jeff Liu wrote: > Add a new ioctl BTRFS_FS_SETLABEL to change the label of a mounted filesystem. > > > Signed-off-by: Jie Liu <jeff.liu@oracle.com> > Signed-off-by: Anand Jain <anand.jain@oracle.com> > > --- > fs/btrfs/ioctl.c | 34 ++++++++++++++++++++++++++++++++++ > fs/btrfs/ioctl.h | 2 ++ > 2 files changed, 36 insertions(+) > > diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c > index b0a5e17..ebbf634 100644 > --- a/fs/btrfs/ioctl.c > +++ b/fs/btrfs/ioctl.c > @@ -3711,6 +3711,38 @@ static int btrfs_ioctl_get_fslabel(struct btrfs_root *root, void __user *arg) > return ret ? -EFAULT : 0; > } > > +static int btrfs_ioctl_set_fslabel(struct btrfs_root *root, void __user *arg) > +{ > + struct btrfs_super_block *super_block = root->fs_info->super_copy; > + struct btrfs_trans_handle *trans; > + char label[BTRFS_LABEL_SIZE]; > + int ret = 0; > + > + if (!capable(CAP_SYS_ADMIN)) > + return -EPERM; > + > + if (btrfs_root_readonly(root)) > + return -EROFS; Since this label is a global parameter, we needn't check the root is R/O or not. The check we need is the write access of the fs, so we need call mnt_want_write_file() > + > + if (copy_from_user(label, arg, sizeof(label))) > + return -EFAULT; > + > + label[BTRFS_LABEL_SIZE - 1] = '\0'; I don't think setting the last byte to '\0' is a good way, because the user would be very strange that the new label is truncated, but the program told him that it was done successfully. > + > + 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); > + return ret; > +} > + > long btrfs_ioctl(struct file *file, unsigned int > cmd, unsigned long arg) > { > @@ -3811,6 +3843,8 @@ 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(root, argp); > + case BTRFS_IOC_SET_FSLABEL: > + return btrfs_ioctl_set_fslabel(root, argp); > } > > return -ENOTTY; > diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h > index 98f896f..cc4e657 100644 > --- a/fs/btrfs/ioctl.h > +++ b/fs/btrfs/ioctl.h > @@ -455,4 +455,6 @@ struct btrfs_ioctl_send_args { > struct btrfs_ioctl_get_dev_stats) > #define BTRFS_IOC_GET_FSLABEL _IOR(BTRFS_IOCTL_MAGIC, 53, \ > char[BTRFS_LABEL_SIZE]) > +#define BTRFS_IOC_SET_FSLABEL _IOW(BTRFS_IOCTL_MAGIC, 54, \ > + char[BTRFS_LABEL_SIZE]) > #endif number 50 has been reserved for this feature. Thanks Miao -- 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
Sorry for my late response, I missed your feedback somehow. On 12/12/2012 12:15 PM, Miao Xie wrote: > On wed, 12 Dec 2012 11:23:00 +0800, Jeff Liu wrote: >> Add a new ioctl BTRFS_FS_SETLABEL to change the label of a mounted filesystem. >> >> >> Signed-off-by: Jie Liu <jeff.liu@oracle.com> >> Signed-off-by: Anand Jain <anand.jain@oracle.com> >> >> --- >> fs/btrfs/ioctl.c | 34 ++++++++++++++++++++++++++++++++++ >> fs/btrfs/ioctl.h | 2 ++ >> 2 files changed, 36 insertions(+) >> >> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c >> index b0a5e17..ebbf634 100644 >> --- a/fs/btrfs/ioctl.c >> +++ b/fs/btrfs/ioctl.c >> @@ -3711,6 +3711,38 @@ static int btrfs_ioctl_get_fslabel(struct btrfs_root *root, void __user *arg) >> return ret ? -EFAULT : 0; >> } >> >> +static int btrfs_ioctl_set_fslabel(struct btrfs_root *root, void __user *arg) >> +{ >> + struct btrfs_super_block *super_block = root->fs_info->super_copy; >> + struct btrfs_trans_handle *trans; >> + char label[BTRFS_LABEL_SIZE]; >> + int ret = 0; >> + >> + if (!capable(CAP_SYS_ADMIN)) >> + return -EPERM; >> + >> + if (btrfs_root_readonly(root)) >> + return -EROFS; > > Since this label is a global parameter, we needn't check the root > is R/O or not. > > The check we need is the write access of the fs, so we need call > mnt_want_write_file() Yes, you are right. > >> + >> + if (copy_from_user(label, arg, sizeof(label))) >> + return -EFAULT; >> + >> + label[BTRFS_LABEL_SIZE - 1] = '\0'; > > I don't think setting the last byte to '\0' is a good way, because the user would be > very strange that the new label is truncated, but the program told him that it was done > successfully. Good point, will revise it later. Thanks, -Jeff > >> + >> + 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); >> + return ret; >> +} >> + >> long btrfs_ioctl(struct file *file, unsigned int >> cmd, unsigned long arg) >> { >> @@ -3811,6 +3843,8 @@ 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(root, argp); >> + case BTRFS_IOC_SET_FSLABEL: >> + return btrfs_ioctl_set_fslabel(root, argp); >> } >> >> return -ENOTTY; >> diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h >> index 98f896f..cc4e657 100644 >> --- a/fs/btrfs/ioctl.h >> +++ b/fs/btrfs/ioctl.h >> @@ -455,4 +455,6 @@ struct btrfs_ioctl_send_args { >> struct btrfs_ioctl_get_dev_stats) >> #define BTRFS_IOC_GET_FSLABEL _IOR(BTRFS_IOCTL_MAGIC, 53, \ >> char[BTRFS_LABEL_SIZE]) >> +#define BTRFS_IOC_SET_FSLABEL _IOW(BTRFS_IOCTL_MAGIC, 54, \ >> + char[BTRFS_LABEL_SIZE]) >> #endif > > number 50 has been reserved for this feature. > > Thanks > Miao > -- 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
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index b0a5e17..ebbf634 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -3711,6 +3711,38 @@ static int btrfs_ioctl_get_fslabel(struct btrfs_root *root, void __user *arg) return ret ? -EFAULT : 0; } +static int btrfs_ioctl_set_fslabel(struct btrfs_root *root, void __user *arg) +{ + struct btrfs_super_block *super_block = root->fs_info->super_copy; + struct btrfs_trans_handle *trans; + char label[BTRFS_LABEL_SIZE]; + int ret = 0; + + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + if (btrfs_root_readonly(root)) + return -EROFS; + + if (copy_from_user(label, arg, sizeof(label))) + return -EFAULT; + + label[BTRFS_LABEL_SIZE - 1] = '\0'; + + 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); + return ret; +} + long btrfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { @@ -3811,6 +3843,8 @@ 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(root, argp); + case BTRFS_IOC_SET_FSLABEL: + return btrfs_ioctl_set_fslabel(root, argp); } return -ENOTTY; diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h index 98f896f..cc4e657 100644 --- a/fs/btrfs/ioctl.h +++ b/fs/btrfs/ioctl.h @@ -455,4 +455,6 @@ struct btrfs_ioctl_send_args { struct btrfs_ioctl_get_dev_stats) #define BTRFS_IOC_GET_FSLABEL _IOR(BTRFS_IOCTL_MAGIC, 53, \ char[BTRFS_LABEL_SIZE]) +#define BTRFS_IOC_SET_FSLABEL _IOW(BTRFS_IOCTL_MAGIC, 54, \ + char[BTRFS_LABEL_SIZE]) #endif