Like 'io_opt', blk_stack_limits() should stack 'chunk_sectors' using
lcm_not_zero() rather than min_not_zero() -- otherwise the final
'chunk_sectors' could result in sub-optimal alignment of IO to
component devices in the IO stack.
Also, if 'chunk_sectors' isn't a multiple of 'physical_block_size'
then it is a bug in the driver and the device should be flagged as
'misaligned'.
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
---
block/blk-settings.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/block/blk-settings.c b/block/blk-settings.c
index 76a7e03bcd6c..b09642d5f15e 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -534,6 +534,7 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
t->io_min = max(t->io_min, b->io_min);
t->io_opt = lcm_not_zero(t->io_opt, b->io_opt);
+ t->chunk_sectors = lcm_not_zero(t->chunk_sectors, b->chunk_sectors);
/* Physical block size a multiple of the logical block size? */
if (t->physical_block_size & (t->logical_block_size - 1)) {
@@ -556,6 +557,13 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
ret = -1;
}
+ /* chunk_sectors a multiple of the physical block size? */
+ if (t->chunk_sectors & (t->physical_block_size - 1)) {
+ t->chunk_sectors = 0;
+ t->misaligned = 1;
+ ret = -1;
+ }
+
t->raid_partial_stripes_expensive =
max(t->raid_partial_stripes_expensive,
b->raid_partial_stripes_expensive);
@@ -594,10 +602,6 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
t->discard_granularity;
}
- if (b->chunk_sectors)
- t->chunk_sectors = min_not_zero(t->chunk_sectors,
- b->chunk_sectors);
-
t->zoned = max(t->zoned, b->zoned);
return ret;
}
--
2.15.0
--
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