Re: [PATCH 4/4] Adds ioctl interface support for ext4 project

Jan Kara
2014-09-24T16:25:12Z

On Wed 24-09-14 22:04:30, Li Xi wrote:
> This patch adds ioctl interface for setting/getting project of ext4.
The patch looks good to me. I was just wondering whether it won't be
useful to add an ioctl() which isn't ext4 specific. We could just extend
->setattr() to allow setting of project ID (most filesystems would just
return -EOPNOTSUPP but ext4 and xfs could do the right thing) and then call
->setattr from the generic ioctl. That way userspace won't have to care
about filesystem type when setting project ID... What do others think?

Honza

> Signed-off-by: Li Xi <lixi@ddn.com>
> ---
> Documentation/filesystems/ext4.txt | 4 ++
> fs/ext4/ext4.h | 2 +
> fs/ext4/ioctl.c | 85 ++++++++++++++++++++++++++++++++++++
> 3 files changed, 91 insertions(+), 0 deletions(-)
>
> diff --git a/Documentation/filesystems/ext4.txt b/Documentation/filesystems/ext4.txt
> index 919a329..9c98e62 100644
> --- a/Documentation/filesystems/ext4.txt
> +++ b/Documentation/filesystems/ext4.txt
> @@ -609,6 +609,10 @@ EXT4_IOC_SWAP_BOOT Swap i_blocks and associated attributes
> The data blocks of the previous boot loader
> will be associated with the given inode.
>
> + EXT4_IOC_GETPROJECT Get project ID associated with inode.
> +
> + EXT4_IOC_SETPROJECT Set Project ID associated with inode.
> +
> ..............................................................................
>
> References
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index f8be9bf..51946fd 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -617,6 +617,8 @@ enum {
> #define EXT4_IOC_RESIZE_FS _IOW('f', 16, __u64)
> #define EXT4_IOC_SWAP_BOOT _IO('f', 17)
> #define EXT4_IOC_PRECACHE_EXTENTS _IO('f', 18)
> +#define EXT4_IOC_GETPROJECT _IOR('f', 19, long)
> +#define EXT4_IOC_SETPROJECT _IOW('f', 20, long)
>
> #if defined(__KERNEL__) && defined(CONFIG_COMPAT)
> /*
> diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
> index 0f2252e..93b7ff4 100644
> --- a/fs/ext4/ioctl.c
> +++ b/fs/ext4/ioctl.c
> @@ -14,6 +14,8 @@
> #include <linux/compat.h>
> #include <linux/mount.h>
> #include <linux/file.h>
> +#include <linux/quotaops.h>
> +#include <linux/quota.h>
> #include <asm/uaccess.h>
> #include "ext4_jbd2.h"
> #include "ext4.h"
> @@ -611,6 +613,89 @@ resizefs_out:
> case EXT4_IOC_PRECACHE_EXTENTS:
> return ext4_ext_precache(inode);
>
> + case EXT4_IOC_GETPROJECT:
> + {
> + __u32 projid;
> +
> + projid = (__u32)from_kprojid(&init_user_ns,
> + EXT4_I(inode)->i_projid);
> + return put_user(projid, (__u32 __user *) arg);
> + }
> + case EXT4_IOC_SETPROJECT:
> + {
> + __u32 projid;
> + int err;
> + handle_t *handle;
> + kprojid_t kprojid;
> + struct ext4_iloc iloc;
> + struct ext4_inode *raw_inode;
> +
> + struct dquot *transfer_to[EXT4_MAXQUOTAS] = { };
> +
> + /* Make sure caller can change project. */
> + if (!capable(CAP_SYS_ADMIN))
> + return -EACCES;
> +
> + if (get_user(projid, (__u32 __user *) arg))
> + return -EFAULT;
> +
> + kprojid = make_kprojid(&init_user_ns, (projid_t)projid);
> +
> + if (projid_eq(kprojid, EXT4_I(inode)->i_projid))
> + return 0;
> +
> + err = mnt_want_write_file(filp);
> + if (err)
> + return err;
> +
> + err = -EPERM;
> + mutex_lock(&inode->i_mutex);
> + /* Is it quota file? Do not allow user to mess with it */
> + if (IS_NOQUOTA(inode))
> + goto project_out;
> +
> + dquot_initialize(inode);
> +
> + handle = ext4_journal_start(inode, EXT4_HT_QUOTA,
> + EXT4_QUOTA_INIT_BLOCKS(sb) +
> + EXT4_QUOTA_DEL_BLOCKS(sb) + 3);
> + if (IS_ERR(handle)) {
> + err = PTR_ERR(handle);
> + goto project_out;
> + }
> +
> + err = ext4_reserve_inode_write(handle, inode, &iloc);
> + if (err)
> + goto project_stop;
> +
> + raw_inode = ext4_raw_inode(&iloc);
> + if ((EXT4_INODE_SIZE(inode->i_sb) <=
> + EXT4_GOOD_OLD_INODE_SIZE) ||
> + (!EXT4_FITS_IN_INODE(raw_inode, ei, i_projid))) {
> + err = -EFBIG;
> + goto project_stop;
> + }
> +
> + transfer_to[PRJQUOTA] = dqget(sb, make_kqid_projid(kprojid));
> + if (!transfer_to[PRJQUOTA])
> + goto project_set;
> +
> + err = __dquot_transfer(inode, transfer_to);
> + dqput(transfer_to[PRJQUOTA]);
> + if (err)
> + goto project_stop;
> +
> +project_set:
> + EXT4_I(inode)->i_projid = kprojid;
> + inode->i_ctime = ext4_current_time(inode);
> + err = ext4_mark_iloc_dirty(handle, inode, &iloc);
> +project_stop:
> + ext4_journal_stop(handle);
> +project_out:
> + mutex_unlock(&inode->i_mutex);
> + mnt_drop_write_file(filp);
> + return err;
> + }
> default:
> return -ENOTTY;
> }
> --
> 1.7.1
>
--
Jan Kara <jack@suse.cz>
SUSE Labs, CR