Re: Race between generic_forget_inode() and sync_sb_inodes()?

[Neil Brown <neilb@suse.de>]

Hi David,

On Friday November 30, dgc@sgi.com wrote:
> 
> 
> I came across this because I've been making changes to XFS to avoid the
> inode hash, and I've found that I need to remove the inode from the
> dirty list when setting I_WILL_FREE to avoid this race. I can't see
> how this race is avoided when inodes are hashed, so I'm wondering
> if we've just been lucky or there's something that I'm missing that
> means the above does not occur.

Looking at inode.c in 2.6.23-mm1, in generic_forget_inode, I see code:

	if (!hlist_unhashed(&inode->i_hash)) {
		if (!(inode->i_state & (I_DIRTY|I_SYNC)))
			list_move(&inode->i_list, &inode_unused);

so it looks to me like:
   If the inode is hashed and dirty, then move it (off the s_dirty
   list) to inode_unused.

So it seems to me that generic_forget_inode also finds it needs to
remove the inode from the dirty list when setting I_WILL_FREE.

Maybe we are looking at different kernel versions?  Maybe I
misunderstood your problem?

NeilBrown