On 2018/04/21 2:02, David Sterba wrote:
> The new ioctl is an extension to the FS_IOC_SETFLAGS and adds new
> flags and is extensible. Don't get fooled by the XATTR in the name, it
> does not have anything in common with the extended attributes,
> incidentally also abbreviated as XATTRs.
>
> This patch allows to set the xflags portion of the fsxattr structure,
> other items have no meaning and non-zero values will result in
> EOPNOTSUPP.
>
> Currently supported xflags:
>
> - APPEND
> - IMMUTABLE
> - NOATIME
> - NODUMP
> - SYNC
>
> The structure of btrfs_ioctl_fssetxattr copies btrfs_ioctl_setflags but
> is simpler on the flag setting side.
>
> The original patch was written by Chandan Jay Sharma but was incomplete
> and no further revision has been sent.
>
> Based-on-patches-by: Chandan Jay Sharma <chandansbg@xxxxxxxxx>
> Signed-off-by: David Sterba <dsterba@xxxxxxxx>
> ---
> fs/btrfs/ioctl.c | 94 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 94 insertions(+)
>
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index 52b12ab9b82b..4fd61f191bba 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -388,6 +388,98 @@ static int btrfs_ioctl_fsgetxattr(struct file *file, void __user *arg)
> return 0;
> }
>
> +static int btrfs_ioctl_fssetxattr(struct file *file, void __user *arg)
> +{
> + struct inode *inode = file_inode(file);
> + struct btrfs_inode *binode = BTRFS_I(inode);
> + struct btrfs_root *root = binode->root;
> + struct btrfs_trans_handle *trans;
> + struct fsxattr fa;
> + unsigned oldflags;
> + unsigned old_i_flags;
> + int ret = 0;
> +
> + if (!inode_owner_or_capable(inode))
> + return -EPERM;
> +
> + if (btrfs_root_readonly(root))
> + return -EROFS;
> +
> + memset(&fa, 0, sizeof(fa));
> + if (copy_from_user(&fa, arg, sizeof(fa)))
> + return -EFAULT;
> +
> + ret = check_xflags(fa.fsx_xflags);
> + if (ret)
> + return ret;
> +
> + if (fa.fsx_extsize != 0 || fa.fsx_projid != 0 || fa.fsx_cowextsize != 0)
> + return -EOPNOTSUPP;
> +
> + ret = mnt_want_write_file(file);
> + if (ret)
> + return ret;
> +
> + inode_lock(inode);
> +
> + oldflags = binode->flags;
> + old_i_flags = inode->i_flags;
> +
> + /* We need the capabilities to change append-only or immutable inode */
> + if (((oldflags & (BTRFS_INODE_APPEND | BTRFS_INODE_IMMUTABLE)) ||
> + (fa.fsx_xflags & (FS_XFLAG_APPEND | FS_XFLAG_IMMUTABLE))) &&
> + !capable(CAP_LINUX_IMMUTABLE)) {
> + ret = -EPERM;
> + goto out_unlock;
> + }
> +
> + if (fa.fsx_xflags & FS_XFLAG_SYNC)
> + binode->flags |= BTRFS_INODE_SYNC;
> + else
> + binode->flags &= ~BTRFS_INODE_SYNC;
> + if (fa.fsx_xflags & FS_XFLAG_IMMUTABLE)
> + binode->flags |= BTRFS_INODE_IMMUTABLE;
> + else
> + binode->flags &= ~BTRFS_INODE_IMMUTABLE;
> + if (fa.fsx_xflags & FS_XFLAG_APPEND)
> + binode->flags |= BTRFS_INODE_APPEND;
> + else
> + binode->flags &= ~BTRFS_INODE_APPEND;
> + if (fa.fsx_xflags & FS_XFLAG_NODUMP)
> + binode->flags |= BTRFS_INODE_NODUMP;
> + else
> + binode->flags &= ~BTRFS_INODE_NODUMP;
> + if (fa.fsx_xflags & FS_XFLAG_NOATIME)
> + binode->flags |= BTRFS_INODE_NOATIME;
> + else
> + binode->flags &= ~BTRFS_INODE_NOATIME;
> +
> + /* 1 item for the inode */
> + trans = btrfs_start_transaction(root, 1);
> + if (IS_ERR(trans)) {
> + ret = PTR_ERR(trans);
> + goto out_drop;
> + }
> +
> + btrfs_sync_inode_flags_to_i_flags(inode);
> + inode_inc_iversion(inode);
> + inode->i_ctime = current_time(inode);
> + ret = btrfs_update_inode(trans, root, inode);
> +
> + btrfs_end_transaction(trans);
Shouldn't out_drop label be here?
Otherwise, above "goto out_drop" won't unlock nor restore the flag value.
> +
> + if (ret) {
> + binode->flags = oldflags;
> + inode->i_flags = old_i_flags;
> + }
> +
> +out_unlock:
> + inode_unlock(inode);
> +out_drop:
> + mnt_drop_write_file(file);
> + return ret;
> +}
> +
> static int btrfs_ioctl_getversion(struct file *file, int __user *arg)
> {
> struct inode *inode = file_inode(file);
> @@ -5620,6 +5712,8 @@ long btrfs_ioctl(struct file *file, unsigned int
> return btrfs_ioctl_set_features(file, argp);
> case FS_IOC_FSGETXATTR:
> return btrfs_ioctl_fsgetxattr(file, argp);
> + case FS_IOC_FSSETXATTR:
> + return btrfs_ioctl_fssetxattr(file, argp);
> }
>
> return -ENOTTY;
>
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