On Thu, 2013-02-21 at 15:51 +0800, Asias He wrote:
> This patch adds support for emulation of UNMAP within
> fd_execute_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().
>
> TODO: fd_execute_unmap() is heavliy based on iblock_execute_unmap().
> Will split out and share the common code.
>
> 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 | 111 ++++++++++++++++++++++++++++++++++++++
> 1 file changed, 111 insertions(+)
>
> diff --git a/drivers/target/target_core_file.c b/drivers/target/target_core_file.c
> index 2a9ce12..b1359ef 100644
> --- a/drivers/target/target_core_file.c
> +++ b/drivers/target/target_core_file.c
> @@ -33,6 +33,7 @@
> #include <linux/falloc.h>
> #include <scsi/scsi.h>
> #include <scsi/scsi_host.h>
> +#include <asm/unaligned.h>
>
> #include <target/target_core_base.h>
> #include <target/target_core_backend.h>
> @@ -489,6 +490,115 @@ fd_execute_write_same_unmap(struct se_cmd *cmd)
> }
>
> static sense_reason_t
> +fd_execute_unmap(struct se_cmd *cmd)
> +{
> + struct se_device *dev = cmd->se_dev;
> + struct fd_dev *fd_dev = FD_DEV(dev);
> + struct file *file = fd_dev->fd_file;
> + struct inode *inode = file->f_mapping->host;
> + unsigned char *buf, *ptr = NULL;
> + sector_t lba;
> + int size;
> + u32 range;
> + sense_reason_t ret = 0;
> + int dl, bd_dl, err;
> +
> + /* We never set ANC_SUP */
> + if (cmd->t_task_cdb[1])
> + return TCM_INVALID_CDB_FIELD;
> +
> + if (cmd->data_length == 0) {
> + target_complete_cmd(cmd, SAM_STAT_GOOD);
> + return 0;
> + }
> +
> + if (cmd->data_length < 8) {
> + pr_warn("UNMAP parameter list length %u too small\n",
> + cmd->data_length);
> + return TCM_PARAMETER_LIST_LENGTH_ERROR;
> + }
> +
> + buf = transport_kmap_data_sg(cmd);
> + if (!buf)
> + return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
> +
> + dl = get_unaligned_be16(&buf[0]);
> + bd_dl = get_unaligned_be16(&buf[2]);
> +
> + size = cmd->data_length - 8;
> + if (bd_dl > size)
> + pr_warn("UNMAP parameter list length %u too small, ignoring bd_dl %u\n",
> + cmd->data_length, bd_dl);
> + else
> + size = bd_dl;
> +
> + if (size / 16 > dev->dev_attrib.max_unmap_block_desc_count) {
> + ret = TCM_INVALID_PARAMETER_LIST;
> + goto err;
> + }
> +
> + /* First UNMAP block descriptor starts at 8 byte offset */
> + ptr = &buf[8];
> + pr_debug("UNMAP: Sub: %s Using dl: %u bd_dl: %u size: %u"
> + " ptr: %p\n", dev->transport->name, dl, bd_dl, size, ptr);
> +
> + while (size >= 16) {
> + lba = get_unaligned_be64(&ptr[0]);
> + range = get_unaligned_be32(&ptr[8]);
> + pr_debug("UNMAP: Using lba: %llu and range: %u\n",
> + (unsigned long long)lba, range);
> +
> + if (range > dev->dev_attrib.max_unmap_lba_count) {
> + ret = TCM_INVALID_PARAMETER_LIST;
> + goto err;
> + }
> +
> + if (lba + range > dev->transport->get_blocks(dev) + 1) {
> + ret = TCM_ADDRESS_OUT_OF_RANGE;
> + goto err;
> + }
> +
> + if (S_ISBLK(inode->i_mode)) {
> + /* The backend is block device, use discard */
> + struct block_device *bdev = inode->i_bdev;
> +
> + err = blkdev_issue_discard(bdev, lba, range, GFP_KERNEL, 0);
> + if (err < 0) {
> + pr_err("FILEIO: blkdev_issue_discard() failed: %d\n",
> + err);
> + ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
> + goto err;
> + }
> + } else {
> + /* The backend is normal file, use fallocate */
> + loff_t pos = lba * dev->dev_attrib.block_size;
> + unsigned int len = range * dev->dev_attrib.block_size;
> + int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;
> +
> + if (!file->f_op->fallocate) {
> + ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
> + goto err;
> + }
> + err = file->f_op->fallocate(file, mode, pos, len);
> + if (err < 0) {
> + pr_warn("FILEIO: fallocate() failed: %d\n", err);
> + ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
> + goto err;
> + }
> + }
> +
Moving the if (S_ISBLK(inode->i_mode) { .. } else { .. } blocks into a
separate function that can be shared by fd_execute_write_same_unmap()
would save a few LOC here.
--nab
> + ptr += 16;
> + size -= 16;
> + }
> +
> +err:
> + transport_kunmap_data_sg(cmd);
> + if (!ret)
> + target_complete_cmd(cmd, GOOD);
> + return ret;
> +}
> +
> +static sense_reason_t
> fd_execute_rw(struct se_cmd *cmd)
> {
> struct scatterlist *sgl = cmd->t_data_sg;
> @@ -648,6 +758,7 @@ static struct sbc_ops fd_sbc_ops = {
> .execute_sync_cache = fd_execute_sync_cache,
> .execute_write_same = fd_execute_write_same,
> .execute_write_same_unmap = fd_execute_write_same_unmap,
> + .execute_unmap = fd_execute_unmap,
> };
>
> static sense_reason_t
--
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