Re: Fwd: [suggestion] Add verbose notification about inode-cache rebuild to kernel log

[Goffredo Baroncelli <kreijack@libero.it>]

On 05/09/2014 04:51 PM, David Sterba wrote:
> On Thu, May 08, 2014 at 04:22:13PM +0200, Tomáš Pružina wrote:
>> I ran into some troubles with inode-cache rebuilding on root fs after
>> filesystem was mounted without inode_cache, which stalls boot of my
>> box by several minutes.
>>
>> I boot from commandline like:
>> root=/dev/sda4 rootfstype=btrfs
>> rootflags=inode_cache,space_cache,autodefrag rw ...
>>
>> However when I manually remount root fs without inode_cache (for
>> example via kexec), it triggers cache rebuild at next mount which
>> takes several tens of minutes and mimick 'freeze' on boot.
>>
>> Would it be possible to put some printk saying that this is happening
>> so users don't get confused about it??
> 
> Adding the printk is probably a good thing, but I'd rather reconsider
> using inode_cache at all. IMO it's supposed to fix problems with inode
> numbers that we don't have.

IIRC, the problem is for the 32 bit system, were the API wants the inode number to be 32 bit..

In the past the inode_cache was introduced because the inode often reached 2^32 [1]

Because most modern hardware is 64 bit (with the exception of ARM ?), could be make sense to allow btrfs to work without inode_cache only on 64bit, loosing the possibility to be used on 32 bit system.

Instead when the inode_cache is used, btrfs still be compatible with both 32bit and 64bit systems.

How often a filesystem is moved between a 64bit and 32bit systems ?


[1] http://article.gmane.org/gmane.comp.file-systems.btrfs/9573
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