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Subject: Re: [PATCH 03/11] Add support for per-file/inode stream ID
To: Shaun Tancheff <shaun.tancheff@seagate.com>
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From: Jens Axboe <axboe@fb.com>
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On 03/04/2016 11:53 AM, Shaun Tancheff wrote:
> What do you think of falling back to i_ino for applications which don't
> make use of setting stream_id yet?
>
> Something like this (or using a crc16 instead of the xor hack)?
>
> static inline unsigned int inode_streamid(struct inode *inode)
> {
> if (inode) {
> if (inode->i_streamid)
> return inode->i_streamid;
> return ((inode->i_ino >> 16) ^ inode->i_ino) & 0xFFFF;
> }
> return 0;
> }

If the device supports a high enough number of concurrently open 
streams, that might work fine. But if the mask ends up being 0x7, then I 
think it'll just introduce randomness into the whole thing.

But it's something that could be experimented with, certainly.

-- 
Jens Axboe