On Tue 14-04-20 00:02:07, Josh Triplett wrote: > Is there a fundamental reason that ext4 *can't* or *shouldn't* support > inline data with 128-byte inodes? Well, where would we put it on disk? ext4 on-disk inode fills 128-bytes with 'osd2' union... Or do you mean we should put inline data in an external xattr block? Honza > As far as I can tell, the kernel ext4 implementation only allows inline > data with 256-byte or larger inodes, because it requires the system.data > xattr to exist, even if the actual data requires 60 bytes or less. (The > implementation in debugfs, on the other hand, handles inline data in > 128-byte inodes just fine. And it seems like it'd be fairly > straightforward to change the kernel implementation to support it as > well.) > > For filesystems that don't need to store xattrs in general, and can live > with the other limitations of 128-byte inodes, using a 128-byte inode > can save substantial space compared to a 256-byte inode (many megabytes > worth of inode tables, versus 4k for each file between 61-160 bytes), > and many small files or small directories would still fit in 60 bytes. -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
