linux-ext4 - Re: [PATCH V1 00/17] ext4: Add inline data support.

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Date:	Thu, 27 Oct 2011 03:10:22 -0400
From:	Valdis.Kletnieks@...edu
To:	Tao Ma <tm@....ma>
Cc:	"Ted Ts'o" <tytso@....edu>,
	ext4 development <linux-ext4@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Andreas Dilger <adilger@...ger.ca>
Subject: Re: [PATCH V1 00/17] ext4: Add inline data support.

On Wed, 26 Oct 2011 15:32:24 +0800, Tao Ma said:

> Currently I use all the space between i_extra_isize and inode_size if
> inode_size = 256. For inode_size > 256, half of that space is used so as
> to leave some space for other xattrs.

I didn't check the code too closely - does this code DTRT if the user tries to
then attach a moby-sized xattr (or set of xattrs - if it's got a security.selinux
tag on it, and a security.capabilities xattr, and a user xattr or two, things are
going to be getting full).

> This is only a V1 and there are still something to do(e.g. I am thinking
> of using unused extent space), but I'd like to send it out earlier so
> that it can be reviewed ASAP.

If this works out, would it make sense to investigate doing this for all
tails in a V2?  So if your file was 4099 bytes long, you could save allocating
a second block.  Assuming random distribution of tail sizes, this wil save
an average of (space avail for tail)/(blocksize) per file.

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