On Fri, May 05, 2023 at 11:29:09PM -0700, Sarthak Kukreti wrote:
> Add support for provision requests to loopback devices.
> Loop devices will configure provision support based on
> whether the underlying block device/file can support
> the provision request and upon receiving a provision bio,
> will map it to the backing device/storage. For loop devices
> over files, a REQ_OP_PROVISION request will translate to
> an fallocate mode 0 call on the backing file.
>
> Signed-off-by: Sarthak Kukreti <sarthakkukreti@xxxxxxxxxxxx>
> ---
> drivers/block/loop.c | 42 ++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 42 insertions(+)
>
> diff --git a/drivers/block/loop.c b/drivers/block/loop.c
> index bc31bb7072a2..13c4b4f8b9c1 100644
> --- a/drivers/block/loop.c
> +++ b/drivers/block/loop.c
> @@ -327,6 +327,24 @@ static int lo_fallocate(struct loop_device *lo, struct request *rq, loff_t pos,
> return ret;
> }
>
> +static int lo_req_provision(struct loop_device *lo, struct request *rq, loff_t pos)
> +{
> + struct file *file = lo->lo_backing_file;
> + struct request_queue *q = lo->lo_queue;
> + int ret;
> +
> + if (!q->limits.max_provision_sectors) {
> + ret = -EOPNOTSUPP;
> + goto out;
> + }
> +
> + ret = file->f_op->fallocate(file, 0, pos, blk_rq_bytes(rq));
> + if (unlikely(ret && ret != -EINVAL && ret != -EOPNOTSUPP))
> + ret = -EIO;
> + out:
> + return ret;
> +}
> +
> static int lo_req_flush(struct loop_device *lo, struct request *rq)
> {
> int ret = vfs_fsync(lo->lo_backing_file, 0);
> @@ -488,6 +506,8 @@ static int do_req_filebacked(struct loop_device *lo, struct request *rq)
> FALLOC_FL_PUNCH_HOLE);
> case REQ_OP_DISCARD:
> return lo_fallocate(lo, rq, pos, FALLOC_FL_PUNCH_HOLE);
> + case REQ_OP_PROVISION:
> + return lo_req_provision(lo, rq, pos);
Hi Sarthak,
The only thing that stands out to me is the separate lo_req_provision()
helper here. It seems it might be a little cleaner to extend and reuse
lo_req_fallocate()..? But that's not something I feel strongly about, so
this all looks pretty good to me either way, FWIW.
Brian
> case REQ_OP_WRITE:
> if (cmd->use_aio)
> return lo_rw_aio(lo, cmd, pos, ITER_SOURCE);
> @@ -754,6 +774,25 @@ static void loop_sysfs_exit(struct loop_device *lo)
> &loop_attribute_group);
> }
>
> +static void loop_config_provision(struct loop_device *lo)
> +{
> + struct file *file = lo->lo_backing_file;
> + struct inode *inode = file->f_mapping->host;
> +
> + /*
> + * If the backing device is a block device, mirror its provisioning
> + * capability.
> + */
> + if (S_ISBLK(inode->i_mode)) {
> + blk_queue_max_provision_sectors(lo->lo_queue,
> + bdev_max_provision_sectors(I_BDEV(inode)));
> + } else if (file->f_op->fallocate) {
> + blk_queue_max_provision_sectors(lo->lo_queue, UINT_MAX >> 9);
> + } else {
> + blk_queue_max_provision_sectors(lo->lo_queue, 0);
> + }
> +}
> +
> static void loop_config_discard(struct loop_device *lo)
> {
> struct file *file = lo->lo_backing_file;
> @@ -1092,6 +1131,7 @@ static int loop_configure(struct loop_device *lo, fmode_t mode,
> blk_queue_io_min(lo->lo_queue, bsize);
>
> loop_config_discard(lo);
> + loop_config_provision(lo);
> loop_update_rotational(lo);
> loop_update_dio(lo);
> loop_sysfs_init(lo);
> @@ -1304,6 +1344,7 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
> }
>
> loop_config_discard(lo);
> + loop_config_provision(lo);
>
> /* update dio if lo_offset or transfer is changed */
> __loop_update_dio(lo, lo->use_dio);
> @@ -1830,6 +1871,7 @@ static blk_status_t loop_queue_rq(struct blk_mq_hw_ctx *hctx,
> case REQ_OP_FLUSH:
> case REQ_OP_DISCARD:
> case REQ_OP_WRITE_ZEROES:
> + case REQ_OP_PROVISION:
> cmd->use_aio = false;
> break;
> default:
> --
> 2.40.1.521.gf1e218fcd8-goog
>
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