On Fri, 2011-10-14 at 07:29 -0400, Christoph Hellwig wrote:
> Do not block the submitting thread when handling a SYNCHRONIZE CACHE command,
> but implement it asynchronously by sending the FLUSH command ourself and
> calling transport_complete_sync_cache from the completion handler.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
>
Looks good.
Lightly tested with tcm_loop and committed with a minor comment fix for
iblock_emulate_sync_cache().
--nab
> Index: lio-core/drivers/target/target_core_iblock.c
> ===================================================================
> --- lio-core.orig/drivers/target/target_core_iblock.c 2011-10-13 12:16:31.756397481 +0200
> +++ lio-core/drivers/target/target_core_iblock.c 2011-10-13 12:19:49.127894821 +0200
> @@ -313,37 +313,42 @@ static unsigned long long iblock_emulate
> return blocks_long;
> }
>
> +static void iblock_end_io_flush(struct bio *bio, int err)
> +{
> + struct se_cmd *cmd = bio->bi_private;
> +
> + if (err)
> + pr_err("IBLOCK: cache flush failed: %d\n", err);
> +
> + if (cmd)
> + transport_complete_sync_cache(cmd, err == 0);
> + bio_put(bio);
> +}
> +
> /*
> - * Emulate SYCHRONIZE_CACHE_*
> + * Implement SYCHRONIZE CACHE. Note that we can handle lba ranges and must
> + * always flush the whole cache.
> */
> static void iblock_emulate_sync_cache(struct se_task *task)
> {
> struct se_cmd *cmd = task->task_se_cmd;
> struct iblock_dev *ib_dev = cmd->se_dev->dev_ptr;
> int immed = (cmd->t_task_cdb[1] & 0x2);
> - sector_t error_sector;
> - int ret;
> + struct bio *bio;
>
> /*
> * If the Immediate bit is set, queue up the GOOD response
> - * for this SYNCHRONIZE_CACHE op
> + * for this SYNCHRONIZE_CACHE op.
> */
> if (immed)
> transport_complete_sync_cache(cmd, 1);
>
> - /*
> - * blkdev_issue_flush() does not support a specifying a range, so
> - * we have to flush the entire cache.
> - */
> - ret = blkdev_issue_flush(ib_dev->ibd_bd, GFP_KERNEL, &error_sector);
> - if (ret != 0) {
> - pr_err("IBLOCK: block_issue_flush() failed: %d "
> - " error_sector: %llu\n", ret,
> - (unsigned long long)error_sector);
> - }
> -
> + bio = bio_alloc(GFP_KERNEL, 0);
> + bio->bi_end_io = iblock_end_io_flush;
> + bio->bi_bdev = ib_dev->ibd_bd;
> if (!immed)
> - transport_complete_sync_cache(cmd, ret == 0);
> + bio->bi_private = cmd;
> + submit_bio(WRITE_FLUSH, bio);
> }
>
> /*
> --
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