Jeff Liu
2012-Dec-28 03:42 UTC
[RFC PATCH v8 2/2] Btrfs: Add a new ioctl to set/change the label of a mounted file system
With this new ioctl(2) BTRFS_IOC_SET_FSLABEL, we can set/change the label of a
mounted file system.
Signed-off-by: Jie Liu <jeff.liu@oracle.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>
Reviewed-by: Goffredo Baroncelli <kreijack@inwind.it>
Reviewed-by: David Sterba <dsterba@suse.cz>
---
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 4be5d15..7383f49 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3719,6 +3719,43 @@ 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)
{
@@ -3819,6 +3856,8 @@ 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
--
1.7.9.5
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David Sterba
2012-Dec-28 12:03 UTC
Re: [RFC PATCH v8 2/2] Btrfs: Add a new ioctl to set/change the label of a mounted file system
On Fri, Dec 28, 2012 at 11:42:40AM +0800, Jeff Liu wrote:> +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)I would expect a message if this happens, similar to the ''get_fslabel'' one, otherwise it''s difficult to find out the reason.> + 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);Do we need to reserve 1 unit here? This does not touch any non-superblock metadata, modifies superblock in place. This could lead to an ENOSPC (changing label on a full fs), altghouh it need not happen.> + 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; > +}-- 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
Jeff Liu
2012-Dec-31 10:23 UTC
Re: [RFC PATCH v8 2/2] Btrfs: Add a new ioctl to set/change the label of a mounted file system
On 12/28/2012 08:03 PM, David Sterba wrote:> On Fri, Dec 28, 2012 at 11:42:40AM +0800, Jeff Liu wrote: >> +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) > > I would expect a message if this happens, similar to the ''get_fslabel'' > one, otherwise it''s difficult to find out the reason.That''s sounds make sense.> >> + 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); > > Do we need to reserve 1 unit here? This does not touch any > non-superblock metadata, modifies superblock in place. This could lead > to an ENOSPC (changing label on a full fs), altghouh it need not happen.Don''t need, I can not recalled why I did that before, will fix it. Thanks, -Jeff> >> + 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; >> +}-- 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