Disable partition scan For some setups (multipath or dmraid) the in-kernel partition scan is pointless as the (block) partitions won't be used anywhere. Worse, it might trigger I/O errors as the partition table might not be accessible (eg for the passive path of a multipath device) or even invalid (eg for RAID0 dmraid). This patch allows to switch off the in-kernel partition scan by adding 'no_partition_scan' to the kernel commandline. Partitions scan can be allowed for individual disk by echoing a positive number into /sys/block/XXX/range and rescan the disk. Signed-off-by: Hannes Reinecke diff --git a/block/genhd.c b/block/genhd.c index 656c2c7..3d6a53b 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -173,6 +173,18 @@ static int exact_lock(dev_t devt, void *data) return 0; } +static int __read_mostly no_partition_scan; + +static int __init no_partition_scan_setup(char *str) +{ + no_partition_scan = 1; + printk(KERN_INFO "genhd: omit partition scan.\n"); + + return 1; +} + +__setup("no_partition_scan", no_partition_scan_setup); + /** * add_disk - add partitioning information to kernel list * @disk: per-device partitioning information @@ -186,6 +198,8 @@ void add_disk(struct gendisk *disk) int retval; disk->flags |= GENHD_FL_UP; + if (no_partition_scan) + disk->flags |= GENHD_FL_NO_PARTITION_SCAN; blk_register_region(MKDEV(disk->major, disk->first_minor), disk->minors, NULL, exact_match, exact_lock, disk); register_disk(disk); @@ -419,7 +433,27 @@ static ssize_t disk_range_show(struct device *dev, { struct gendisk *disk = dev_to_disk(dev); - return sprintf(buf, "%d\n", disk->minors); + return sprintf(buf, "%d\n", + (disk->flags & GENHD_FL_NO_PARTITION_SCAN ? 0 : disk->minors)); +} + +static ssize_t disk_range_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct gendisk *disk = dev_to_disk(dev); + int i; + + if (count > 0 && sscanf(buf, "%d", &i) > 0) { + if (i == 0) + disk->flags |= GENHD_FL_NO_PARTITION_SCAN; + else if (i <= disk->minors) + disk->flags &= ~GENHD_FL_NO_PARTITION_SCAN; + else + count = -EINVAL; + } + + return count; } static ssize_t disk_removable_show(struct device *dev, @@ -509,7 +543,7 @@ static ssize_t disk_fail_store(struct device *dev, #endif -static DEVICE_ATTR(range, S_IRUGO, disk_range_show, NULL); +static DEVICE_ATTR(range, S_IRUGO|S_IWUSR, disk_range_show, disk_range_store); static DEVICE_ATTR(removable, S_IRUGO, disk_removable_show, NULL); static DEVICE_ATTR(ro, S_IRUGO, disk_ro_show, NULL); static DEVICE_ATTR(size, S_IRUGO, disk_size_show, NULL); diff --git a/block/scsi_ioctl.c b/block/scsi_ioctl.c diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index 4225109..dfcdef1 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -72,7 +72,7 @@ static void blk_done(struct virtqueue *vq) static bool do_req(struct request_queue *q, struct virtio_blk *vblk, struct request *req) { - unsigned long num, out, in; + unsigned long num, out = 1, in = 1; struct virtblk_req *vbr; vbr = mempool_alloc(vblk->pool, GFP_ATOMIC); @@ -100,19 +100,26 @@ static bool do_req(struct request_queue *q, struct virtio_blk *vblk, /* This init could be done at vblk creation time */ sg_init_table(vblk->sg, VIRTIO_MAX_SG); sg_set_buf(&vblk->sg[0], &vbr->out_hdr, sizeof(vbr->out_hdr)); - num = blk_rq_map_sg(q, vbr->req, vblk->sg+1); - sg_set_buf(&vblk->sg[num+1], &vbr->status, sizeof(vbr->status)); - - if (rq_data_dir(vbr->req) == WRITE) { - vbr->out_hdr.type |= VIRTIO_BLK_T_OUT; - out = 1 + num; - in = 1; - } else { - vbr->out_hdr.type |= VIRTIO_BLK_T_IN; - out = 1; - in = 1 + num; + if (blk_pc_request(vbr->req)) { + sg_set_buf(&vblk->sg[out], &vbr->req->cmd, vbr->req->cmd_len); + out++; + } + num = blk_rq_map_sg(q, vbr->req, vblk->sg+out); + sg_set_buf(&vblk->sg[num+out], &vbr->status, sizeof(vbr->status)); + if (blk_pc_request(vbr->req)) { + sg_set_buf(&vblk->sg[num+out+1], &vbr->req->sense, 96); + in++; } + if (vbr->req->data_len) { + if (rq_data_dir(vbr->req) == WRITE) { + vbr->out_hdr.type |= VIRTIO_BLK_T_OUT; + out += num; + } else { + vbr->out_hdr.type |= VIRTIO_BLK_T_IN; + in += num; + } + } if (vblk->vq->vq_ops->add_buf(vblk->vq, vblk->sg, out, in, vbr)) { mempool_free(vbr, vblk->pool); return false; diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c diff --git a/fs/partitions/check.c b/fs/partitions/check.c index 7d6b34e..a73f6dc 100644 --- a/fs/partitions/check.c +++ b/fs/partitions/check.c @@ -485,6 +485,8 @@ int rescan_partitions(struct gendisk *disk, struct block_device *bdev) delete_partition(disk, p); if (disk->fops->revalidate_disk) disk->fops->revalidate_disk(disk); + if (disk->flags & GENHD_FL_NO_PARTITION_SCAN) + return 0; if (!get_capacity(disk) || !(state = check_partition(disk, bdev))) return 0; if (IS_ERR(state)) /* I/O error reading the partition table */ diff --git a/include/linux/genhd.h b/include/linux/genhd.h index 118216f..87c45ad 100644 --- a/include/linux/genhd.h +++ b/include/linux/genhd.h @@ -109,6 +109,7 @@ struct hd_struct { #define GENHD_FL_UP 16 #define GENHD_FL_SUPPRESS_PARTITION_INFO 32 #define GENHD_FL_FAIL 64 +#define GENHD_FL_NO_PARTITION_SCAN 128 #define BLK_SCSI_MAX_CMDS (256) #define BLK_SCSI_CMD_PER_LONG (BLK_SCSI_MAX_CMDS / (sizeof(long) * 8)) diff --git a/include/linux/virtio_blk.h b/include/linux/virtio_blk.h