From: Dave Chinner <dchinner@xxxxxxxxxx> If we want to split inode allocation up into a background chunk allocator and an indvidual free inode allocator, then we need to be able to guarantee that a free inode will be available before we take a log reservation for the free inode allocation. If we don't guarantee that we can allocate an inode before we reserve log space for the individual inode allocation, then we may reserve all the remaining log space for the free inode allocation and then not be able to reserve space for a ne winode chunk allocation in the log. This will cause an inode allocation deadlock. To avoid this deadlock, use a ticket system to guarantee an allocation has a reserved free inode before it proceeds to the transaction reservation for the allocation. This allows the free inode allocation to block waiting for background allocation to allocate more inode chunks in a sane and rational manner. The ticket system needs to be a per-allocation group ticket, as inodes are allocated and tracked at a per-AG granularity. Hence we need to restructure the inode allocation code to select an AG for the new inode as early as possible and then take a ticket on that AG. It is entirely possible that we can then get an ENOSPC error for the inode chunk allocation, so we must be able to fall all the way back to this ticket allocation loop to try another AG in this case. Hauling this AG selection loop out of the internal free inode allocation code might be sufficiently complex to warrant multiple setup patches by itself.... Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx> --- fs/xfs/xfs_ialloc.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/xfs/xfs_ialloc.h b/fs/xfs/xfs_ialloc.h index 68c0732..1da16f5 100644 --- a/fs/xfs/xfs_ialloc.h +++ b/fs/xfs/xfs_ialloc.h @@ -24,6 +24,8 @@ struct xfs_imap; struct xfs_mount; struct xfs_trans; +struct xfs_ialloc_ticket; + /* * Allocation parameters for inode allocation. */ -- 1.8.3.2 _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
