From 2237498f0b5c74768f688ebaf16eab2c708d5fdb Mon Sep 17 00:00:00 2001 From: Nicholas Bellinger Date: Tue, 11 Apr 2017 22:21:47 -0700 Subject: [PATCH] target/iblock: Convert WRITE_SAME to blkdev_issue_zeroout The people who are actively using iblock_execute_write_same_direct() are doing so in the context of ESX VAAI BlockZero, together with EXTENDED_COPY and COMPARE_AND_WRITE primitives. In practice though I've not seen any users of IBLOCK WRITE_SAME for anything other than VAAI BlockZero, so just using blkdev_issue_zeroout() when available, and falling back to iblock_execute_write_same() if the WRITE_SAME buffer contains anything other than zeros should be OK. (Hook up max_write_zeroes_sectors to signal LBPRZ feature bit in target_configure_unmap_from_queue - nab) Signed-off-by: Christoph Hellwig Reviewed-by: Martin K. Petersen Cc: Christoph Hellwig Cc: Mike Christie Cc: Hannes Reinecke Cc: Jens Axboe Signed-off-by: Nicholas Bellinger --- drivers/target/target_core_device.c | 2 +- drivers/target/target_core_iblock.c | 44 ++++++++++++++++++----------- 2 files changed, 28 insertions(+), 18 deletions(-) diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c index 8add07f387f9..a5762e601fa1 100644 --- a/drivers/target/target_core_device.c +++ b/drivers/target/target_core_device.c @@ -851,7 +851,7 @@ bool target_configure_unmap_from_queue(struct se_dev_attrib *attrib, attrib->unmap_granularity = q->limits.discard_granularity / block_size; attrib->unmap_granularity_alignment = q->limits.discard_alignment / block_size; - attrib->unmap_zeroes_data = 0; + attrib->unmap_zeroes_data = (q->limits.max_write_zeroes_sectors); return true; } EXPORT_SYMBOL(target_configure_unmap_from_queue); diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c index bb069ebe4aa6..b2044133d747 100644 --- a/drivers/target/target_core_iblock.c +++ b/drivers/target/target_core_iblock.c @@ -86,6 +86,7 @@ static int iblock_configure_device(struct se_device *dev) struct block_device *bd = NULL; struct blk_integrity *bi; fmode_t mode; + unsigned int max_write_zeroes_sectors; int ret = -ENOMEM; if (!(ib_dev->ibd_flags & IBDF_HAS_UDEV_PATH)) { @@ -129,7 +130,11 @@ static int iblock_configure_device(struct se_device *dev) * Enable write same emulation for IBLOCK and use 0xFFFF as * the smaller WRITE_SAME(10) only has a two-byte block count. */ - dev->dev_attrib.max_write_same_len = 0xFFFF; + max_write_zeroes_sectors = bdev_write_zeroes_sectors(bd); + if (max_write_zeroes_sectors) + dev->dev_attrib.max_write_same_len = max_write_zeroes_sectors; + else + dev->dev_attrib.max_write_same_len = 0xFFFF; if (blk_queue_nonrot(q)) dev->dev_attrib.is_nonrot = 1; @@ -415,28 +420,31 @@ iblock_execute_unmap(struct se_cmd *cmd, sector_t lba, sector_t nolb) } static sense_reason_t -iblock_execute_write_same_direct(struct block_device *bdev, struct se_cmd *cmd) +iblock_execute_zero_out(struct block_device *bdev, struct se_cmd *cmd) { struct se_device *dev = cmd->se_dev; struct scatterlist *sg = &cmd->t_data_sg[0]; - struct page *page = NULL; - int ret; + unsigned char *buf, zero = 0x00, *p = &zero; + int rc, ret; - if (sg->offset) { - page = alloc_page(GFP_KERNEL); - if (!page) - return TCM_OUT_OF_RESOURCES; - sg_copy_to_buffer(sg, cmd->t_data_nents, page_address(page), - dev->dev_attrib.block_size); - } + buf = kmap(sg_page(sg)) + sg->offset; + if (!buf) + return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE; + /* + * Fall back to block_execute_write_same() slow-path if + * incoming WRITE_SAME payload does not contain zeros. + */ + rc = memcmp(buf, p, cmd->data_length); + kunmap(sg_page(sg)); - ret = blkdev_issue_write_same(bdev, + if (rc) + return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE; + + ret = blkdev_issue_zeroout(bdev, target_to_linux_sector(dev, cmd->t_task_lba), target_to_linux_sector(dev, sbc_get_write_same_sectors(cmd)), - GFP_KERNEL, page ? page : sg_page(sg)); - if (page) - __free_page(page); + GFP_KERNEL, false); if (ret) return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE; @@ -472,8 +480,10 @@ iblock_execute_write_same(struct se_cmd *cmd) return TCM_INVALID_CDB_FIELD; } - if (bdev_write_same(bdev)) - return iblock_execute_write_same_direct(bdev, cmd); + if (bdev_write_zeroes_sectors(bdev)) { + if (!iblock_execute_zero_out(bdev, cmd)) + return 0; + } ibr = kzalloc(sizeof(struct iblock_req), GFP_KERNEL); if (!ibr)