tree 61fb0bf8028df1bd79ea44c4376b213dcd70249a
parent 168316db3583253b9e5d46392e5b9d03d531406f
author Jan Kara <jack@suse.cz> 1486705856 -0500
committer Theodore Ts'o <tytso@mit.edu> 1486705856 -0500

ext4: fix stripe-unaligned allocations

When a filesystem is created using:

	mkfs.ext4 -b 4096 -E stride=512 <dev>

and we try to allocate 64MB extent, we will end up directly in
ext4_mb_complex_scan_group(). This is because the request is detected
as power-of-two allocation (so we start in ext4_mb_regular_allocator()
with ac_criteria == 0) however the check before
ext4_mb_simple_scan_group() refuses the direct buddy scan because the
allocation request is too large. Since cr == 0, the check whether we
should use ext4_mb_scan_aligned() fails as well and we fall back to
ext4_mb_complex_scan_group().

Fix the problem by checking for upper limit on power-of-two requests
directly when detecting them.

Reported-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>