[linux-lvm] LVM support for LILO
Andi Kleen
ak at suse.de
Thu Sep 7 21:43:01 UTC 2000
On Thu, Sep 07, 2000 at 12:25:07PM -0600, Andreas Dilger wrote:
> Heinz,
> Michael Kellen and I have been working to add LILO support for booting
> from a LV (i.e. have /boot be an LV, and then not have ANY DOS partitions).
[...]
I did some similar work. I implemented an LVM_BMAP ioctl for LVM that
simply translates a given block to a (dev_t, blocknr in dev). lilo
simply does a normal FIOBMAP and then calls LVM_BMAP for every block
it gets. When the dev_t ever changes it complains loudly. Then it does
its normal work with the resulting blocks.
It works ok. The only problem is that a standard PV cannot be used for
booting, because it does leave any space for a MBR (it probably needs
a PV format revision that simply leaves 4K free)
> However, the main problem that we are having is that you cannot use
> an LV device major/minor to do anything with liblvm. All of the liblvm
> functions use an LV name, it would be good to add an ioctl which takes
> a dev_t (e.g. 0x3a01) and returns an LV name, or maybe an lv_t which
> we can use with liblvm. Along the same lines, it may be good to have
> an ioctl which takes a dev_t and returns a vg_t of the VG which this LV
> is a part of. Finally, it would be good to take the code out of lvm_map()
> which only does block/dev remapping (which lvm_map() will call), but
> which also be called by an ioctl like FIBMAP.
I'm just calling lvm_bmap from my ioctl. It is easy enough (patch against
2.2 appended)
--- include/linux/lvm.h.LVMBMAP Wed Aug 2 18:44:26 2000
+++ include/linux/lvm.h Thu Aug 10 01:29:14 2000
@@ -355,6 +355,10 @@
/* lock the logical volume manager */
#define LVM_LOCK_LVM _IO ( 0xfe, 0x100)
+
+/* bmap, argument lv_bmap_t */
+#define LV_BMAP _IOWR ( 0xfe, 0x51, 1)
+
/* END ioctls */
@@ -534,7 +538,10 @@
ulong new_pe;
} le_remap_req_t;
-
+typedef struct lv_bmap {
+ ulong lv_block;
+ dev_t lv_dev;
+} lv_bmap_t;
/*
* Structure Logical Volume (LV) Version 1
--- drivers/block/lvm.c.LVMBMAP Sun Jul 30 01:55:16 2000
+++ drivers/block/lvm.c Thu Aug 10 04:53:17 2000
@@ -1076,6 +1076,28 @@
*
********************************************************************/
+static int lvm_user_bmap(struct inode *inode, struct lv_bmap *user_result)
+{
+ struct buffer_head bh;
+ unsigned long block;
+ int err;
+
+ if (get_user(block, &user_result->lv_block))
+ return -EFAULT;
+
+ memset(&bh,0,sizeof bh);
+ bh.b_size = 512; /* XXX */
+ bh.b_rsector = block;
+ bh.b_dev = bh.b_rdev = inode->i_dev;
+ if ((err=lvm_map(&bh, READ)) < 0) {
+ printk("lvm map failed: %d\n", err);
+ return -EINVAL;
+ }
+
+ return put_user( kdev_t_to_nr(bh.b_rdev), &user_result->lv_dev) ||
+ put_user(bh.b_rsector, &user_result->lv_block) ? -EFAULT : 0;
+}
+
/*
* block device open routine
*/
@@ -1259,6 +1281,10 @@
vg[VG_BLK(minor)]->lv[LV_BLK(minor)]->lv_status = ( ulong) arg;
break;
+ case LV_BMAP:
+ /* turn logical block into (dev_t, block). non privileged. */
+ return lvm_user_bmap(inode, (struct lv_bmap *) arg);
+ break;
/* set allocation flags of a logical volume */
case LV_SET_ALLOCATION:
-Andi
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