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authorBoaz Harrosh <boaz@plexistor.com>2015-01-07 18:09:38 +0200
committerJens Axboe <axboe@fb.com>2015-01-13 21:59:15 -0700
commitc8fa31730fc72a83bad762112a872675b3e76886 (patch)
tree4ca498cb2c8e7899d13e29448fa105fcd6a23d45 /drivers/block/brd.c
parent937af5ecd0591e84ee54180fa97dcbe9bbe5fed6 (diff)
downloadop-kernel-dev-c8fa31730fc72a83bad762112a872675b3e76886.zip
op-kernel-dev-c8fa31730fc72a83bad762112a872675b3e76886.tar.gz
brd: Request from fdisk 4k alignment
Because of the direct_access() API which returns a PFN. partitions better start on 4K boundary, else offset ZERO of a partition will not be aligned and blk_direct_access() will fail the call. By setting blk_queue_physical_block_size(PAGE_SIZE) we can communicate this to fdisk and friends. The call to blk_queue_physical_block_size() is harmless and will not affect the Kernel behavior in any way. It is only for communication to user-mode. before this patch running fdisk on a default size brd of 4M the first sector offered is 34 (BAD), but after this patch it will be 40, ie 8 sectors aligned. Also when entering some random partition sizes the next partition-start sector is offered 8 sectors aligned after this patch. (Please note that with fdisk the user can still enter bad values, only the offered default values will be correct) Note that with bdev-size > 4M fdisk will try to align on a 1M boundary (above first-sector will be 2048), in any case. CC: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Boaz Harrosh <boaz@plexistor.com> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'drivers/block/brd.c')
-rw-r--r--drivers/block/brd.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index a7463c959..c01b921 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -486,10 +486,19 @@ static struct brd_device *brd_alloc(int i)
brd->brd_queue = blk_alloc_queue(GFP_KERNEL);
if (!brd->brd_queue)
goto out_free_dev;
+
blk_queue_make_request(brd->brd_queue, brd_make_request);
blk_queue_max_hw_sectors(brd->brd_queue, 1024);
blk_queue_bounce_limit(brd->brd_queue, BLK_BOUNCE_ANY);
+ /* This is so fdisk will align partitions on 4k, because of
+ * direct_access API needing 4k alignment, returning a PFN
+ * (This is only a problem on very small devices <= 4M,
+ * otherwise fdisk will align on 1M. Regardless this call
+ * is harmless)
+ */
+ blk_queue_physical_block_size(brd->brd_queue, PAGE_SIZE);
+
brd->brd_queue->limits.discard_granularity = PAGE_SIZE;
brd->brd_queue->limits.max_discard_sectors = UINT_MAX;
brd->brd_queue->limits.discard_zeroes_data = 1;
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