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authorMartin K. Petersen <martin.petersen@oracle.com>2012-01-11 16:27:11 +0100
committerJens Axboe <axboe@kernel.dk>2012-01-11 16:27:11 +0100
commitb1bd055d397e09f99dcef9b138ed104ff1812fcb (patch)
treee8e1d3d0b6a33859392bcba516933aff256dc4b4 /block/blk-settings.c
parentc98b2cc29af8e84e7364b53e9bb4cc7cfaf62555 (diff)
downloadlinux-linaro-stable-b1bd055d397e09f99dcef9b138ed104ff1812fcb.tar.gz
block: Introduce blk_set_stacking_limits function
Stacking driver queue limits are typically bounded exclusively by the capabilities of the low level devices, not by the stacking driver itself. This patch introduces blk_set_stacking_limits() which has more liberal metrics than the default queue limits function. This allows us to inherit topology parameters from bottom devices without manually tweaking the default limits in each driver prior to calling the stacking function. Since there is now a clear distinction between stacking and low-level devices, blk_set_default_limits() has been modified to carry the more conservative values that we used to manually set in blk_queue_make_request(). Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Acked-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-settings.c')
-rw-r--r--block/blk-settings.c32
1 files changed, 24 insertions, 8 deletions
diff --git a/block/blk-settings.c b/block/blk-settings.c
index fa1eb0449a05..d3234fc494ad 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -104,9 +104,7 @@ EXPORT_SYMBOL_GPL(blk_queue_lld_busy);
* @lim: the queue_limits structure to reset
*
* Description:
- * Returns a queue_limit struct to its default state. Can be used by
- * stacking drivers like DM that stage table swaps and reuse an
- * existing device queue.
+ * Returns a queue_limit struct to its default state.
*/
void blk_set_default_limits(struct queue_limits *lim)
{
@@ -114,13 +112,12 @@ void blk_set_default_limits(struct queue_limits *lim)
lim->max_integrity_segments = 0;
lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK;
lim->max_segment_size = BLK_MAX_SEGMENT_SIZE;
- lim->max_sectors = BLK_DEF_MAX_SECTORS;
- lim->max_hw_sectors = INT_MAX;
+ lim->max_sectors = lim->max_hw_sectors = BLK_SAFE_MAX_SECTORS;
lim->max_discard_sectors = 0;
lim->discard_granularity = 0;
lim->discard_alignment = 0;
lim->discard_misaligned = 0;
- lim->discard_zeroes_data = 1;
+ lim->discard_zeroes_data = 0;
lim->logical_block_size = lim->physical_block_size = lim->io_min = 512;
lim->bounce_pfn = (unsigned long)(BLK_BOUNCE_ANY >> PAGE_SHIFT);
lim->alignment_offset = 0;
@@ -131,6 +128,27 @@ void blk_set_default_limits(struct queue_limits *lim)
EXPORT_SYMBOL(blk_set_default_limits);
/**
+ * blk_set_stacking_limits - set default limits for stacking devices
+ * @lim: the queue_limits structure to reset
+ *
+ * Description:
+ * Returns a queue_limit struct to its default state. Should be used
+ * by stacking drivers like DM that have no internal limits.
+ */
+void blk_set_stacking_limits(struct queue_limits *lim)
+{
+ blk_set_default_limits(lim);
+
+ /* Inherit limits from component devices */
+ lim->discard_zeroes_data = 1;
+ lim->max_segments = USHRT_MAX;
+ lim->max_hw_sectors = UINT_MAX;
+
+ lim->max_sectors = BLK_DEF_MAX_SECTORS;
+}
+EXPORT_SYMBOL(blk_set_stacking_limits);
+
+/**
* blk_queue_make_request - define an alternate make_request function for a device
* @q: the request queue for the device to be affected
* @mfn: the alternate make_request function
@@ -165,8 +183,6 @@ void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn)
q->nr_batching = BLK_BATCH_REQ;
blk_set_default_limits(&q->limits);
- blk_queue_max_hw_sectors(q, BLK_SAFE_MAX_SECTORS);
- q->limits.discard_zeroes_data = 0;
/*
* by default assume old behaviour and bounce for any highmem page