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

From: Neil Brown
Date: Thu Nov 29 2007 - 17:07:37 EST



Hi David,

On Friday November 30, dgc@xxxxxxx 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
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/