On Thu 28-03-13 15:40:20, Eric Sandeen wrote:
> This adds a new ioctl, EXT3_IOC_32BITHASH, which allows a
> userspace application to request 32-bit rather than 64-bit
> hashes from readdir on an indexed / dx / htree directory.
>
> Gluster had been relying on the top bits of the d_off being
> free; there are some reports that filling all 64 bits breaks
> Samba as well. The infrastructure to return 32-bit hashes
> already exists; NFS can turn it on, and it's turned on for
> 32-bit processes as well. So it's just a matter of flipping
> on the f_mode flag before readdir starts.
>
> Care needs to be taken that we don't change the FMODE flag
> after readdir has been started, so we make sure that
> filp->private_data has not yet been set before we set the flag.
> (Thanks Zach!).
>
> Pre-submission-fixes-by: Zach Brown <zab@xxxxxxxxxx>
> Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
> ---
>
> V2:
> fix "readir" typo
> rename goto target to *_out like others
> remove parameter; we can't really ever turn this back off once it's used.
> closing and reopening is the only way to get back to 64 bit hashes.
Looks good. Just one nit below:
> diff --git a/fs/ext3/ext3.h b/fs/ext3/ext3.h
> + case EXT3_IOC_32BITHASH: {
> + int err = 0;
> +
> + /* Serialize with readdir */
> + if ((err = mutex_lock_killable(&inode->i_mutex)))
> + return err;
> +
> + /* protect f_mode */
> + spin_lock(&filp->f_lock);
> +
> + /* Only valid for htree directories */
> + if (!S_ISDIR(inode->i_mode) || !is_dx_dir(inode)) {
Won't it be better to return ENOTDIR in !S_ISDIR case?
> + err = -EINVAL;
> + goto hash32bits_out;
> + }
> +
> + /* Have we already started readdir on this dx dir? */
> + if (filp->private_data) {
> + err = -EINVAL;
And here maybe EBUSY, but in this case I'm really undecided.
> + goto hash32bits_out;
> + }
> +
> + filp->f_mode |= FMODE_32BITHASH;
> +hash32bits_out:
> + spin_unlock(&filp->f_lock);
> + mutex_unlock(&inode->i_mutex);
> + return err;
> + }
> case FITRIM: {
>
> struct super_block *sb = inode->i_sb;
Honza
--
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
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