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.
Caveat: For filesystems with copy-on-write semantics, REQ_OP_PROVISION will guarantee the success of only the next write to the provisioned range with a ENOSPC. Signed-off-by: Sarthak Kukreti <[email protected]> Signed-off-by: Mike Snitzer <[email protected]> --- drivers/block/loop.c | 39 ++++++++++++++++++++++++++++++++++++--- 1 file changed, 36 insertions(+), 3 deletions(-) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 9f2d412fc560..c84d4acdb18c 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -311,16 +311,20 @@ static int lo_fallocate(struct loop_device *lo, struct request *rq, loff_t pos, { /* * We use fallocate to manipulate the space mappings used by the image - * a.k.a. discard/zerorange. + * a.k.a. discard/provision/zerorange. */ struct file *file = lo->lo_backing_file; int ret; - mode |= FALLOC_FL_KEEP_SIZE; + if (mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE) && + !bdev_max_discard_sectors(lo->lo_device)) + return -EOPNOTSUPP; - if (!bdev_max_discard_sectors(lo->lo_device)) + if (mode == 0 && !bdev_max_provision_sectors(lo->lo_device)) return -EOPNOTSUPP; + mode |= FALLOC_FL_KEEP_SIZE; + ret = file->f_op->fallocate(file, mode, pos, blk_rq_bytes(rq)); if (unlikely(ret && ret != -EINVAL && ret != -EOPNOTSUPP)) return -EIO; @@ -488,6 +492,13 @@ 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: + /* + * fallocate() guarantees that the next writes to the + * provisioned range will succeed without ENOSPC but does not + * guarantee that every write to this range will succeed. + */ + return lo_fallocate(lo, rq, pos, 0); case REQ_OP_WRITE: if (cmd->use_aio) return lo_rw_aio(lo, cmd, pos, ITER_SOURCE); @@ -754,6 +765,25 @@ 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 +1122,7 @@ static int loop_configure(struct loop_device *lo, blk_mode_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 +1335,7 @@ 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); @@ -1857,6 +1889,7 @@ 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: -- 2.39.2
