From: Tejun Heo Date: Tue, 4 Mar 2008 10:18:17 +0000 (+0100) Subject: block: separate out padding from alignment X-Git-Tag: v2.6.25-rc4~98^2~12 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e3790c7d42a545e8fe8b38b513613ca96687b670;p=linux-2.6 block: separate out padding from alignment Block layer alignment was used for two different purposes - memory alignment and padding. This causes problems in lower layers because drivers which only require memory alignment ends up with adjusted rq->data_len. Separate out padding such that padding occurs iff driver explicitly requests it. Tomo: restorethe code to update bio in blk_rq_map_user introduced by the commit 40b01b9bbdf51ae543a04744283bf2d56c4a6afa according to padding alignment. Signed-off-by: Tejun Heo Signed-off-by: FUJITA Tomonori Signed-off-by: Jens Axboe --- diff --git a/block/blk-map.c b/block/blk-map.c index f559832295..4e17dfd003 100644 --- a/block/blk-map.c +++ b/block/blk-map.c @@ -43,6 +43,7 @@ static int __blk_rq_map_user(struct request_queue *q, struct request *rq, void __user *ubuf, unsigned int len) { unsigned long uaddr; + unsigned int alignment; struct bio *bio, *orig_bio; int reading, ret; @@ -53,8 +54,8 @@ static int __blk_rq_map_user(struct request_queue *q, struct request *rq, * direct dma. else, set up kernel bounce buffers */ uaddr = (unsigned long) ubuf; - if (!(uaddr & queue_dma_alignment(q)) && - !(len & queue_dma_alignment(q))) + alignment = queue_dma_alignment(q) | q->dma_pad_mask; + if (!(uaddr & alignment) && !(len & alignment)) bio = bio_map_user(q, NULL, uaddr, len, reading); else bio = bio_copy_user(q, uaddr, len, reading); @@ -141,15 +142,20 @@ int blk_rq_map_user(struct request_queue *q, struct request *rq, /* * __blk_rq_map_user() copies the buffers if starting address - * or length isn't aligned. As the copied buffer is always - * page aligned, we know that there's enough room for padding. - * Extend the last bio and update rq->data_len accordingly. + * or length isn't aligned to dma_pad_mask. As the copied + * buffer is always page aligned, we know that there's enough + * room for padding. Extend the last bio and update + * rq->data_len accordingly. * * On unmap, bio_uncopy_user() will use unmodified * bio_map_data pointed to by bio->bi_private. */ - if (len & queue_dma_alignment(q)) { - unsigned int pad_len = (queue_dma_alignment(q) & ~len) + 1; + if (len & q->dma_pad_mask) { + unsigned int pad_len = (q->dma_pad_mask & ~len) + 1; + struct bio *bio = rq->biotail; + + bio->bi_io_vec[bio->bi_vcnt - 1].bv_len += pad_len; + bio->bi_size += pad_len; rq->extra_len += pad_len; } diff --git a/block/blk-settings.c b/block/blk-settings.c index da923fed1f..a9f37f530b 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -292,6 +292,23 @@ void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b) } EXPORT_SYMBOL(blk_queue_stack_limits); +/** + * blk_queue_dma_pad - set pad mask + * @q: the request queue for the device + * @mask: pad mask + * + * Set pad mask. Direct IO requests are padded to the mask specified. + * + * Appending pad buffer to a request modifies ->data_len such that it + * includes the pad buffer. The original requested data length can be + * obtained using blk_rq_raw_data_len(). + **/ +void blk_queue_dma_pad(struct request_queue *q, unsigned int mask) +{ + q->dma_pad_mask = mask; +} +EXPORT_SYMBOL(blk_queue_dma_pad); + /** * blk_queue_dma_drain - Set up a drain buffer for excess dma. * @q: the request queue for the device diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c index fe47922dd6..8f0e8f2bc6 100644 --- a/drivers/ata/libata-scsi.c +++ b/drivers/ata/libata-scsi.c @@ -862,9 +862,10 @@ static int ata_scsi_dev_config(struct scsi_device *sdev, struct request_queue *q = sdev->request_queue; void *buf; - /* set the min alignment */ + /* set the min alignment and padding */ blk_queue_update_dma_alignment(sdev->request_queue, ATA_DMA_PAD_SZ - 1); + blk_queue_dma_pad(sdev->request_queue, ATA_DMA_PAD_SZ - 1); /* configure draining */ buf = kmalloc(ATAPI_MAX_DRAIN, q->bounce_gfp | GFP_KERNEL); diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index b72526c13c..6f79d40dd3 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -362,6 +362,7 @@ struct request_queue unsigned long seg_boundary_mask; void *dma_drain_buffer; unsigned int dma_drain_size; + unsigned int dma_pad_mask; unsigned int dma_alignment; struct blk_queue_tag *queue_tags; @@ -701,6 +702,7 @@ extern void blk_queue_max_hw_segments(struct request_queue *, unsigned short); extern void blk_queue_max_segment_size(struct request_queue *, unsigned int); extern void blk_queue_hardsect_size(struct request_queue *, unsigned short); extern void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b); +extern void blk_queue_dma_pad(struct request_queue *, unsigned int); extern int blk_queue_dma_drain(struct request_queue *q, dma_drain_needed_fn *dma_drain_needed, void *buf, unsigned int size);