On 3/29/13 6:43 AM, Jan Kara wrote:
> 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:
Oh, of course, duh! I'll send V3, thanks.
-Eric
>> 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
>
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