Re: [BUG] xfs/109 crashed 2k block size reflink enabled XFS

[Christoph Hellwig <hch@infradead.org>]

On Wed, Dec 07, 2016 at 10:35:03PM -0800, Darrick J. Wong wrote:
> I bet that assert is a result of the btree insert failing to find a new
> block to expand into.  I've felt for a while that we ought to yell ENOSPC
> louder when this happens, since I've hit it numerous times and grumbled
> about it not being obvious that we ran out of space.

Heh.  Took me a while to figure out what caused it last night as well.

> Anyway, XFS_AG_RESV_AGFL only gets a reservation if rmapbt=1 (or if you
> added an additional reservation after dinner), so if you're running
> reflink only then it's not surprising that it still runs out of space,
> since reflink=1 only reserves RESV_METADATA space.

I'm not running reflink only - this is the testcase from Eryu with
reflink and rmpbt for now.

But at that point I didn't add RESV_METADATA to xfs_bmbt_alloc_block.
With that one liner added xfs/109 seems to be doing fine so far, and
I've had it running for a few hours already today.  Note that this
is still without actually reserving additional block in
xfs_ag_resv_init, which is probably needed.