xfs: expose block size in stat

For block size larger than page size, the unit of efficient IO is
the block size, not the page size. Leaving stat() to report
PAGE_SIZE as the block size causes test programs like fsx to issue
illegal ranges for operations that require block size alignment
(e.g. fallocate() insert range). Hence update the preferred IO size
to reflect the block size in this case.

This change is based on a patch originally from Dave Chinner.[1]

[1] https://lwn.net/ml/linux-fsdevel/[email protected]/

Signed-off-by: Pankaj Raghav <[email protected]>
Signed-off-by: Luis Chamberlain <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Acked-by: Darrick J. Wong <[email protected]>
Reviewed-by: Darrick J. Wong <[email protected]>
Reviewed-by: Dave Chinner <[email protected]>
Reviewed-by: Hannes Reinecke <[email protected]>
Reviewed-by: Daniel Gomez <[email protected]>
Reviewed-by: Matthew Wilcox (Oracle) <[email protected]>
Signed-off-by: Christian Brauner <[email protected]>

Author: Panky-codes

fs/xfs/xfs_iops.c

@@ -567,7 +567,7 @@ xfs_stat_blksize(
 			return 1U << mp->m_allocsize_log;
 	}
 
-	return PAGE_SIZE;
+	return max_t(uint32_t, PAGE_SIZE, mp->m_sb.sb_blocksize);
 }
 
 STATIC int