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-rw-r--r--block/blk-settings.c21
1 files changed, 21 insertions, 0 deletions
diff --git a/block/blk-settings.c b/block/blk-settings.c
index 5d21239bc859..f1a1795a5683 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -113,6 +113,7 @@ void blk_set_default_limits(struct queue_limits *lim)
lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK;
lim->max_segment_size = BLK_MAX_SEGMENT_SIZE;
lim->max_sectors = lim->max_hw_sectors = BLK_SAFE_MAX_SECTORS;
+ lim->chunk_sectors = 0;
lim->max_write_same_sectors = 0;
lim->max_discard_sectors = 0;
lim->discard_granularity = 0;
@@ -277,6 +278,26 @@ void blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_hw_secto
EXPORT_SYMBOL(blk_queue_max_hw_sectors);
/**
+ * blk_queue_chunk_sectors - set size of the chunk for this queue
+ * @q: the request queue for the device
+ * @chunk_sectors: chunk sectors in the usual 512b unit
+ *
+ * Description:
+ * If a driver doesn't want IOs to cross a given chunk size, it can set
+ * this limit and prevent merging across chunks. Note that the chunk size
+ * must currently be a power-of-2 in sectors. Also note that the block
+ * layer must accept a page worth of data at any offset. So if the
+ * crossing of chunks is a hard limitation in the driver, it must still be
+ * prepared to split single page bios.
+ **/
+void blk_queue_chunk_sectors(struct request_queue *q, unsigned int chunk_sectors)
+{
+ BUG_ON(!is_power_of_2(chunk_sectors));
+ q->limits.chunk_sectors = chunk_sectors;
+}
+EXPORT_SYMBOL(blk_queue_chunk_sectors);
+
+/**
* blk_queue_max_discard_sectors - set max sectors for a single discard
* @q: the request queue for the device
* @max_discard_sectors: maximum number of sectors to discard