From f6970ad31d42fceb38b5595cbad093a4d0bfcc43 Mon Sep 17 00:00:00 2001 From: Nicholas Bellinger Date: Wed, 7 Nov 2012 20:08:38 -0800 Subject: [PATCH] target/iblock: Add WRITE_SAME w/ UNMAP=0 emulation support This patch adds support for emulation of WRITE_SAME w/ UNMAP=0 within iblock_execute_write_same() backend code. The emulation uses a bio_add_page() call for each sector, and by default enforces a limit of max_write_same_len=0xFFFF (65536) sectors following what scsi_debug reports per default for MAXIMUM WRITE SAME LENGTH. It also sets max_write_same_len to the operational default at setup -> iblock_configure_device() time. (hch: Move unmap logic into iblock_execute_write_same_unmap + add check for single sector SGLs in iblock_execute_write_same) (mkp: Update comment for 0xFFFF magic constant) (nab: drop left-over max_write_same_len check in iblock_execute_write_same) Cc: Christoph Hellwig Cc: Martin K. Petersen Signed-off-by: Nicholas Bellinger --- drivers/target/target_core_iblock.c | 86 ++++++++++++++++++++++++++++++++++--- 1 file changed, 79 insertions(+), 7 deletions(-) diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c index 53f4501..6646046 100644 --- a/drivers/target/target_core_iblock.c +++ b/drivers/target/target_core_iblock.c @@ -151,6 +151,11 @@ static int iblock_configure_device(struct se_device *dev) pr_debug("IBLOCK: BLOCK Discard support available," " disabled by default\n"); } + /* + * 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; if (blk_queue_nonrot(q)) dev->dev_attrib.is_nonrot = 1; @@ -375,17 +380,20 @@ err: return ret; } +static struct bio *iblock_get_bio(struct se_cmd *, sector_t, u32); +static void iblock_submit_bios(struct bio_list *, int); +static void iblock_complete_cmd(struct se_cmd *); + static sense_reason_t -iblock_execute_write_same(struct se_cmd *cmd) +iblock_execute_write_same_unmap(struct se_cmd *cmd) { struct iblock_dev *ib_dev = IBLOCK_DEV(cmd->se_dev); - int ret; + int rc; - ret = blkdev_issue_discard(ib_dev->ibd_bd, cmd->t_task_lba, - spc_get_write_same_sectors(cmd), GFP_KERNEL, - 0); - if (ret < 0) { - pr_debug("blkdev_issue_discard() failed for WRITE_SAME\n"); + rc = blkdev_issue_discard(ib_dev->ibd_bd, cmd->t_task_lba, + spc_get_write_same_sectors(cmd), GFP_KERNEL, 0); + if (rc < 0) { + pr_warn("blkdev_issue_discard() failed: %d\n", rc); return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE; } @@ -393,6 +401,69 @@ iblock_execute_write_same(struct se_cmd *cmd) return 0; } +static sense_reason_t +iblock_execute_write_same(struct se_cmd *cmd) +{ + struct iblock_req *ibr; + struct scatterlist *sg; + struct bio *bio; + struct bio_list list; + sector_t block_lba = cmd->t_task_lba; + unsigned int sectors = spc_get_write_same_sectors(cmd); + + sg = &cmd->t_data_sg[0]; + + if (cmd->t_data_nents > 1 || + sg->length != cmd->se_dev->dev_attrib.block_size) { + pr_err("WRITE_SAME: Illegal SGL t_data_nents: %u length: %u" + " block_size: %u\n", cmd->t_data_nents, sg->length, + cmd->se_dev->dev_attrib.block_size); + return TCM_INVALID_CDB_FIELD; + } + + ibr = kzalloc(sizeof(struct iblock_req), GFP_KERNEL); + if (!ibr) + goto fail; + cmd->priv = ibr; + + bio = iblock_get_bio(cmd, block_lba, 1); + if (!bio) + goto fail_free_ibr; + + bio_list_init(&list); + bio_list_add(&list, bio); + + atomic_set(&ibr->pending, 1); + + while (sectors) { + while (bio_add_page(bio, sg_page(sg), sg->length, sg->offset) + != sg->length) { + + bio = iblock_get_bio(cmd, block_lba, 1); + if (!bio) + goto fail_put_bios; + + atomic_inc(&ibr->pending); + bio_list_add(&list, bio); + } + + /* Always in 512 byte units for Linux/Block */ + block_lba += sg->length >> IBLOCK_LBA_SHIFT; + sectors -= 1; + } + + iblock_submit_bios(&list, WRITE); + return 0; + +fail_put_bios: + while ((bio = bio_list_pop(&list))) + bio_put(bio); +fail_free_ibr: + kfree(ibr); +fail: + return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE; +} + enum { Opt_udev_path, Opt_readonly, Opt_force, Opt_err }; @@ -701,6 +772,7 @@ static struct sbc_ops iblock_sbc_ops = { .execute_rw = iblock_execute_rw, .execute_sync_cache = iblock_execute_sync_cache, .execute_write_same = iblock_execute_write_same, + .execute_write_same_unmap = iblock_execute_write_same_unmap, .execute_unmap = iblock_execute_unmap, }; -- 2.7.4