Re: [PATCH v2] xfs: set max_agbno to allow sparse alloc of last full inode chunk

[Carlos Maiolino <cem@kernel.org>]

On Fri, 09 Jan 2026 12:49:05 -0500, Brian Foster wrote:
> Sparse inode cluster allocation sets min/max agbno values to avoid
> allocating an inode cluster that might map to an invalid inode
> chunk. For example, we can't have an inode record mapped to agbno 0
> or that extends past the end of a runt AG of misaligned size.
> 
> The initial calculation of max_agbno is unnecessarily conservative,
> however. This has triggered a corner case allocation failure where a
> small runt AG (i.e. 2063 blocks) is mostly full save for an extent
> to the EOFS boundary: [2050,13]. max_agbno is set to 2048 in this
> case, which happens to be the offset of the last possible valid
> inode chunk in the AG. In practice, we should be able to allocate
> the 4-block cluster at agbno 2052 to map to the parent inode record
> at agbno 2048, but the max_agbno value precludes it.
> 
> [...]

Applied to for-next, thanks!

[1/1] xfs: set max_agbno to allow sparse alloc of last full inode chunk
      commit: c360004c0160dbe345870f59f24595519008926f

Best regards,
-- 
Carlos Maiolino <cem@kernel.org>