[PATCH v3 3/3] loop: Add support for provision requests

Sarthak Kukreti
2023-04-14T00:02:57Z

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@chromium.org>
---
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);
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:
--
2.40.0.634.g4ca3ef3211-goog