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Message-ID: <4F93FED6.6090505@itwm.fraunhofer.de>
Date: Sun, 22 Apr 2012 14:51:34 +0200
From: Bernd Schubert <bernd.schubert@...m.fraunhofer.de>
To: Eric Sandeen <sandeen@...hat.com>
CC: linux-nfs@...r.kernel.org, linux-ext4@...r.kernel.org,
linux-fsdevel@...r.kernel.org, Fan Yong <yong.fan@...mcloud.com>,
bfields@...hat.com, Andreas Dilger <adilger@...mcloud.com>
Subject: Re: [PATCH 5 2/4] Return 32/64-bit dir name hash according to usage
type
On 04/20/2012 10:04 PM, Eric Sandeen wrote:
> On 1/9/12 7:21 AM, Bernd Schubert wrote:
>> From: Fan Yong <yong.fan@...mcloud.com>
>>
>> Traditionally ext2/3/4 has returned a 32-bit hash value from llseek()
>> to appease NFSv2, which can only handle a 32-bit cookie for seekdir()
>> and telldir(). However, this causes problems if there are 32-bit hash
>> collisions, since the NFSv2 server can get stuck resending the same
>> entries from the directory repeatedly.
>>
>> Allow ext4 to return a full 64-bit hash (both major and minor) for
>> telldir to decrease the chance of hash collisions. This still needs
>> integration on the NFS side.
>>
>> Patch-updated-by: Bernd Schubert <bernd.schubert@...m.fraunhofer.de>
>> (blame me if something is not correct)
>
> Bernd, I've merged this to ext3. Bruce thought maybe you were working
> on the same. Should I send mine?
That is perfectly fine with me.
>
> Also...
>
>> +/*
>> + * ext4_dir_llseek() based on generic_file_llseek() to handle both
>> + * non-htree and htree directories, where the "offset" is in terms
>> + * of the filename hash value instead of the byte offset.
>> + *
>> + * NOTE: offsets obtained *before* ext4_set_inode_flag(dir, EXT4_INODE_INDEX)
>> + * will be invalid once the directory was converted into a dx directory
>> + */
>> +loff_t ext4_dir_llseek(struct file *file, loff_t offset, int origin)
>
> ext4_llseek() worries about max offset for direct/indirect vs. extent-mapped
> files. Do we need to worry about the same thing in this function?
Hrmm, I just checked it and I think either is wrong. We only have to
care about non-dx directories, so ext4_readdir() applies, which limits
filp->f_pos < inode->i_size.
Going to send a patch tomorrow. Thanks for spotting this!
Cheers,
Bernd
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