diff options
| -rw-r--r-- | block/ll_rw_blk.c | 33 |
1 files changed, 19 insertions, 14 deletions
diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c index 03d9c82b0fe7..0ef2971a9e82 100644 --- a/block/ll_rw_blk.c +++ b/block/ll_rw_blk.c @@ -625,26 +625,31 @@ static inline int ordered_bio_endio(struct request *rq, struct bio *bio, * Different hardware can have different requirements as to what pages * it can do I/O directly to. A low level driver can call * blk_queue_bounce_limit to have lower memory pages allocated as bounce - * buffers for doing I/O to pages residing above @page. By default - * the block layer sets this to the highest numbered "low" memory page. + * buffers for doing I/O to pages residing above @page. **/ void blk_queue_bounce_limit(request_queue_t *q, u64 dma_addr) { unsigned long bounce_pfn = dma_addr >> PAGE_SHIFT; - - /* - * set appropriate bounce gfp mask -- unfortunately we don't have a - * full 4GB zone, so we have to resort to low memory for any bounces. - * ISA has its own < 16MB zone. - */ - if (bounce_pfn < blk_max_low_pfn) { - BUG_ON(dma_addr < BLK_BOUNCE_ISA); + int dma = 0; + + q->bounce_gfp = GFP_NOIO; +#if BITS_PER_LONG == 64 + /* Assume anything <= 4GB can be handled by IOMMU. + Actually some IOMMUs can handle everything, but I don't + know of a way to test this here. */ + if (bounce_pfn < (0xffffffff>>PAGE_SHIFT)) + dma = 1; + q->bounce_pfn = max_low_pfn; +#else + if (bounce_pfn < blk_max_low_pfn) + dma = 1; + q->bounce_pfn = bounce_pfn; +#endif + if (dma) { init_emergency_isa_pool(); q->bounce_gfp = GFP_NOIO | GFP_DMA; - } else - q->bounce_gfp = GFP_NOIO; - - q->bounce_pfn = bounce_pfn; + q->bounce_pfn = bounce_pfn; + } } EXPORT_SYMBOL(blk_queue_bounce_limit); |