[Btrfs-devel] [PATCH] Add btrfs acl checking

[Yan Zheng]

2008/1/19, only flyer <onlyflyer at gmail.com>:
> Hi:
> This patch add btrfs acl checking. It makes btrfs's acl checking
> really work if you mount btrfs by using "acl" option, e.g. mount -t
> btrfs -o acl /dev/hda1 /mnt/
>
> Thanks
> LiuHui
>
> diff -r 6c243ad8dddf acl.c
> --- a/acl.c     Fri Jan 18 10:54:22 2008 -0500
> +++ b/acl.c     Sat Jan 19 21:38:02 2008 +0800
> @@ -26,6 +26,35 @@
>  #define is_owner_or_cap(inode) \
>         ((current->fsuid == (inode)->i_uid) || capable(CAP_FOWNER))
>  #endif
> +
> +struct posix_acl *btrfs_get_posix_acl(struct inode *inode, int type)
> +{
> +        int ret, len;
> +        char *value = NULL;
> +        struct posix_acl *acl;
> +
> +        len = btrfs_xattr_get(inode, type, "", NULL, 0);
> +        if (len > 0) {
> +                value = kmalloc(len, GFP_KERNEL);
> +                if (!value) {
> +                        return ERR_PTR(-ENOMEM);
> +                }
> +
> +        } else {
> +                return NULL;
> +        }
> +        ret = btrfs_xattr_get(inode, type, "", value, len);
> +        if (ret > 0) {
> +                acl = posix_acl_from_xattr(value, len);
> +        } else if (-ENODATA == ret) {
> +                acl = NULL;
> +        } else {
> +                acl = ERR_PTR(ret);
> +        }
> +
> +        kfree(value);
> +        return acl;
> +}
>
>  static int btrfs_xattr_set_acl(struct inode *inode, int type,
>                                const void *value, size_t size)
> diff -r 6c243ad8dddf ctree.h
> --- a/ctree.h   Fri Jan 18 10:54:22 2008 -0500
> +++ b/ctree.h   Sat Jan 19 21:38:02 2008 +0800
> @@ -446,6 +446,7 @@ struct btrfs_root {
>  #define BTRFS_MOUNT_NODATACOW          (1 << 1)
>  #define BTRFS_MOUNT_NOBARRIER          (1 << 2)
>  #define BTRFS_MOUNT_SSD                        (1 << 3)
> +#define BTRFS_MOUNT_POSIX_ACL          (1 << 4)
>
>  #define btrfs_clear_opt(o, opt)                ((o) &= ~BTRFS_MOUNT_##opt)
>  #define btrfs_set_opt(o, opt)          ((o) |= BTRFS_MOUNT_##opt)
> diff -r 6c243ad8dddf inode.c
> --- a/inode.c   Fri Jan 18 10:54:22 2008 -0500
> +++ b/inode.c   Sat Jan 19 21:38:02 2008 +0800
> @@ -33,12 +33,16 @@
>  #include <linux/bit_spinlock.h>
>  #include <linux/version.h>
>  #include <linux/xattr.h>
> +#include <linux/posix_acl.h>
>  #include "ctree.h"
>  #include "disk-io.h"
>  #include "transaction.h"
>  #include "btrfs_inode.h"
>  #include "ioctl.h"
>  #include "print-tree.h"
> +#include "xattr.h"
> +
> +extern struct posix_acl *btrfs_get_posix_acl(struct inode *inode, int type);
>
>  struct btrfs_iget_args {
>         u64 ino;
> @@ -2886,12 +2890,29 @@ out_fail:
>         btrfs_throttle(root);
>         return err;
>  }
> +
> +static int btrfs_check_acl(struct inode *inode, int mask)
> +{
> +        struct posix_acl *acl;
> +        acl = btrfs_get_posix_acl(inode, BTRFS_XATTR_INDEX_POSIX_ACL_ACCESS);
> +
> +       if (IS_ERR(acl))
> +               return PTR_ERR(acl);
> +       if (acl) {
> +               int error = posix_acl_permission(inode, acl, mask);
> +               posix_acl_release(acl);
> +               return error;
> +       }
> +
> +       return -EAGAIN;
> +}
> +
I feel this function should be moved into acl.c, so that btrfs can be
compiled on kernel without acl support.

>  static int btrfs_permission(struct inode *inode, int mask,
>                             struct nameidata *nd)
>  {
>         if (btrfs_test_flag(inode, READONLY) && (mask & MAY_WRITE))
>                 return -EACCES;
> -       return generic_permission(inode, mask, NULL);
> +       return generic_permission(inode, mask, btrfs_check_acl);
>  }
>
>  static struct inode_operations btrfs_dir_inode_operations = {
> diff -r 6c243ad8dddf super.c
> --- a/super.c   Fri Jan 18 10:54:22 2008 -0500
> +++ b/super.c   Sat Jan 19 21:38:02 2008 +0800
> @@ -64,7 +64,7 @@ static void btrfs_put_super (struct supe
>
>  enum {
>         Opt_subvol, Opt_nodatasum, Opt_nodatacow, Opt_max_extent,
> -       Opt_alloc_start, Opt_nobarrier, Opt_ssd, Opt_err,
> +       Opt_alloc_start, Opt_nobarrier, Opt_ssd, Opt_posix_acl, Opt_err,
>  };
>
>  static match_table_t tokens = {
> @@ -75,6 +75,7 @@ static match_table_t tokens = {
>         {Opt_max_extent, "max_extent=%s"},
>         {Opt_alloc_start, "alloc_start=%s"},
>         {Opt_ssd, "ssd"},
> +        {Opt_posix_acl, "acl"},
>         {Opt_err, NULL}
>  };
>
> @@ -162,6 +163,14 @@ static int parse_options (char * options
>                                 btrfs_set_opt(info->mount_opt, NOBARRIER);
>                         }
>                         break;
> +
> +                case Opt_posix_acl:
> +                        if (info) {
> +                                printk("btrfs: enabling posix acl\n");
> +                                btrfs_set_opt(info->mount_opt, POSIX_ACL);
> +                        }
> +                        break;
> +
>                 case Opt_max_extent:
>                         if (info) {
>                                 char *num = match_strdup(&args[0]);
> @@ -247,6 +256,12 @@ static int btrfs_fill_super(struct super
>         }
>
>         parse_options((char *)data, tree_root, NULL);
> +
> +        if (tree_root->fs_info->mount_opt & BTRFS_MOUNT_POSIX_ACL) {
You can use 'btrfs_test_opt' to do this test.

> +                sb->s_flags |= MS_POSIXACL;
> +        } else {
> +                sb->s_flags = sb->s_flags & ~MS_POSIXACL;
> +        }
>
>         /* this does the super kobj at the same time */
>         err = btrfs_sysfs_add_super(tree_root->fs_info);
>

Regards
YZ