Messages in this thread Patch in this message | | | Date | Wed, 27 Aug 2008 14:30:02 +0200 | From | Hannes Reinecke <> | Subject | Re: [PATCH] Disable partition scan |
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Hi all again,
Hannes Reinecke wrote: > Hi all, > > for some setups (eg dmraid or multipathing) the in-kernel partition scan > is pointless; the (block) partitions won't be used anywhere. Instead the > system will be using kpartx-generated device-mapper devices. > Worse, on some setups (RAID0 dmraid or active/passive multipath devices) > the in-kernel partition scan will generate plenty of I/O errors as the > partitions table might not be accessible or invalid for this device. > > This patch implements a new kernel command-line option 'no_partition_scan' > which will switch off the partition scan globally. The partition scan can > be re-enabled for individual devices by echoing any positive number smaller > than the number of minors into > /sys/class/block/XXX/range > > and rescanning the device. > > Please apply. > Yeah, cool. One should take care not to mangle to patches. Should teach me to use git properly. Oh well.
Corrected patch attached.
Cheers,
Hannes
-- Dr. Hannes Reinecke zSeries & Storage hare@suse.de +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: Markus Rex, HRB 16746 (AG Nürnberg) 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 <hare@suse.de>
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/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 | |