> From: Dave Chinner <dchinner@xxxxxxxxxx>
>
> The function xfs_bmap_isaeof() is used to indicate that an
> allocation is occurring at or past the end of file, and as such
> should be aligned to the underlying storage geometry if possible.
>
> Commit 27a3f8f ("xfs: introduce xfs_bmap_last_extent") changed the
> behaviour of this function for empty files - it turned off
> allocation alignment for this case accidentally. Hence large initial
> allocations from direct IO are not getting correctly aligned to the
> underlying geometry, and that is cause write performance to drop in
> alignment sensitive configurations.
>
> Fix it by considering allocation into empty files as requiring
> aligned allocation again.
>
> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
Ooops. The fix looks good,
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Might be worth cooking up a test for this, scsi_debug can expose
geometry, and we already have it wired to to large sector size
testing in xfstests.
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