On 02/22/2013 06:35 AM, Nicholas A. Bellinger wrote:
> On Thu, 2013-02-21 at 13:57 +0800, Asias He wrote:
>> This patch adds support for emulation of WRITE_SAME w/ UNMAP=1 within
>> fd_execute_write_same_unmap() backend code.
>>
>> If the FILEIO backend is normal file, the emulation uses fallocate to
>> punch hole to reclaim the free space used by the file. If the FILEIO
>> backend is block device, the emulation uses blkdev_issue_discard().
>>
>> Tested with 512, 1k, 2k, and 4k block_sizes.
>>
>> Cc: Christoph Hellwig <hch@xxxxxx>
>> Cc: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
>> Cc: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
>> Signed-off-by: Asias He <asias@xxxxxxxxxx>
>> ---
>> drivers/target/target_core_file.c | 48 +++++++++++++++++++++++++++++++++++++++
>> 1 file changed, 48 insertions(+)
>>
>> diff --git a/drivers/target/target_core_file.c b/drivers/target/target_core_file.c
>> index 94383a5..2a9ce12 100644
>> --- a/drivers/target/target_core_file.c
>> +++ b/drivers/target/target_core_file.c
>> @@ -30,6 +30,7 @@
>> #include <linux/slab.h>
>> #include <linux/spinlock.h>
>> #include <linux/module.h>
>> +#include <linux/falloc.h>
>> #include <scsi/scsi.h>
>> #include <scsi/scsi_host.h>
>>
>> @@ -442,6 +443,52 @@ fd_execute_write_same(struct se_cmd *cmd)
>> }
>>
>> static sense_reason_t
>> +fd_execute_write_same_unmap(struct se_cmd *cmd)
>> +{
>> + struct se_device *se_dev = cmd->se_dev;
>> + struct fd_dev *fd_dev = FD_DEV(se_dev);
>> + struct file *file = fd_dev->fd_file;
>> + struct inode *inode = file->f_mapping->host;
>> + sector_t nolb = spc_get_write_same_sectors(cmd);
>> + int ret;
>> +
>> + if (!nolb) {
>> + target_complete_cmd(cmd, SAM_STAT_GOOD);
>> + return 0;
>> + }
>> +
>> + if (S_ISBLK(inode->i_mode)) {
>> + /* The backend is block device, use discard */
>> + struct block_device *bdev = inode->i_bdev;
>> +
>> + ret = blkdev_issue_discard(bdev, cmd->t_task_lba,
>> + nolb, GFP_KERNEL, 0);
>> + if (ret < 0) {
>> + pr_warn("FILEIO: blkdev_issue_discard() failed: %d\n",
>> + ret);
>> + return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
>> + }
>> + } else {
>> + /* The backend is normal file, use fallocate */
>> + loff_t pos = cmd->t_task_lba * se_dev->dev_attrib.block_size;
>> + unsigned int len = nolb * se_dev->dev_attrib.block_size;
>> + int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;
>> +
>> + if (!file->f_op->fallocate)
>> + return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
>> +
>> + ret = file->f_op->fallocate(file, mode, pos, len);
>> + if (ret < 0) {
>> + pr_warn("FILEIO: fallocate() failed: %d\n", ret);
>> + return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
>> + }
>> + }
>> +
>> + target_complete_cmd(cmd, GOOD);
>> + return 0;
>> +}
>> +
>
> So you'll also need to set the various dev->dev_attrib.*unmap* values
> for EVPD Block Limits at fd_configure_device() time.. Check out
> iblock_configure_device() to see how this is currently done for the
> underlying struct block_device case from request_queue->limits.
>
> For the fallocate() case, you'll need to add some sane defaults here
> too.
okay.
> As for the direct blkdev_issue_discard usage() within FILEIO code, I
> don't have a problem with it, but I'd really like to get hch's feedback
> here..
okay.
> --nab
>
>
>
>
>
>
>
>> +static sense_reason_t
>> fd_execute_rw(struct se_cmd *cmd)
>> {
>> struct scatterlist *sgl = cmd->t_data_sg;
>> @@ -600,6 +647,7 @@ static struct sbc_ops fd_sbc_ops = {
>> .execute_rw = fd_execute_rw,
>> .execute_sync_cache = fd_execute_sync_cache,
>> .execute_write_same = fd_execute_write_same,
>> + .execute_write_same_unmap = fd_execute_write_same_unmap,
>> };
>>
>> static sense_reason_t
>
>
--
Asias
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