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Date: Wed, 30 Jan 2008 17:25:03 -0600
From: Eric Sandeen <sandeen@...hat.com>
To: ext4 development <linux-ext4@...r.kernel.org>
Subject: [PATCH e2fsprogs] - detect LVM2 PVs in libblkid
The anaconda folks are now using blkid instead of hand-rolled
tests for filesystem type at install time, but they had one
more request:
Bugzilla Bug 409321: RFE: information on blkdevs "formatted" as PVs
https://bugzilla.redhat.com/show_bug.cgi?id=409321
The attached patch does the right thing for me on my sample
set of exactly 1 PV...
Any issues with reporting back something which is not actually
a filesystem ("lvm2pv") ?
[root@...t]# misc/blkid -c /dev/null /dev/sda2
/dev/sda2: UUID="guOQGdcOE3IafCm0190XkPZTy5fCEanQ" TYPE="lvm2pv"
[root@...t]# pvs -o pv_name,pv_uuid
PV PV UUID
/dev/sda2 guOQGd-cOE3-IafC-m019-0XkP-ZTy5-fCEanQ
Bits liberally stolen from lvm2 userspace.
Signed-off-by: Eric Sandeen <sandeen@...hat.com>
---
Index: e2fsprogs-1.40.5/lib/blkid/probe.h
===================================================================
--- e2fsprogs-1.40.5.orig/lib/blkid/probe.h
+++ e2fsprogs-1.40.5/lib/blkid/probe.h
@@ -531,6 +531,20 @@ struct hfs_mdb {
__u16 embed_blockcount;
} __attribute__((packed));
+/* this is lvm's label_header & pv_header combined. */
+
+#define LVM2_ID_LEN 32
+
+struct lvm2_pv_label_header {
+ /* label_header */
+ __u8 id[8]; /* LABELONE */
+ __u64 sector_xl; /* Sector number of this label */
+ __u32 crc_xl; /* From next field to end of sector */
+ __u32 offset_xl; /* Offset from start of struct to contents */
+ __u8 type[8]; /* LVM2 001 */
+ /* pv_header */
+ __u8 pv_uuid[LVM2_ID_LEN];
+} __attribute__ ((packed));
/*
* Byte swap functions
Index: e2fsprogs-1.40.5/lib/blkid/probe.c
===================================================================
--- e2fsprogs-1.40.5.orig/lib/blkid/probe.c
+++ e2fsprogs-1.40.5/lib/blkid/probe.c
@@ -895,6 +895,64 @@ static int probe_hfsplus(struct blkid_pr
return 1;
}
+#define LVM2_LABEL_SIZE 512
+static int lvm2_calc_crc(const void *buf, uint size)
+{
+ static const uint crctab[] = {
+ 0x00000000, 0x1db71064, 0x3b6e20c8, 0x26d930ac,
+ 0x76dc4190, 0x6b6b51f4, 0x4db26158, 0x5005713c,
+ 0xedb88320, 0xf00f9344, 0xd6d6a3e8, 0xcb61b38c,
+ 0x9b64c2b0, 0x86d3d2d4, 0xa00ae278, 0xbdbdf21c
+ };
+ uint i, crc = 0xf597a6cf;
+ const __u8 *data = (const __u8 *) buf;
+
+ for (i = 0; i < size; i++) {
+ crc ^= *data++;
+ crc = (crc >> 4) ^ crctab[crc & 0xf];
+ crc = (crc >> 4) ^ crctab[crc & 0xf];
+ }
+ return crc;
+}
+
+static int probe_lvm2(struct blkid_probe *probe,
+ struct blkid_magic *id __BLKID_ATTR((unused)),
+ unsigned char *buf)
+{
+ int sector = (id->bim_kboff) << 1;;
+ struct lvm2_pv_label_header *label;
+ label = (struct lvm2_pv_label_header *)buf;
+
+ /* buf is at 0k or 1k offset; find label inside */
+ if (memcmp(buf, "LABELONE", 8) == 0) {
+ label = (struct lvm2_pv_label_header *)buf;
+ } else if (memcmp(buf + 512, "LABELONE", 8) == 0) {
+ label = (struct lvm2_pv_label_header *)(buf + 512);
+ sector++;
+ } else {
+ return 1;
+ }
+
+ if (blkid_le64(label->sector_xl) != sector) {
+ DBG(DEBUG_PROBE,
+ printf("LVM2: label for sector %d found at sector %d\n",
+ blkid_le64(label->sector_xl), sector));
+ return 1;
+ }
+
+ if (lvm2_calc_crc(&label->offset_xl, LVM2_LABEL_SIZE -
+ ((void *)&label->offset_xl - (void *)label)) !=
+ blkid_le32(label->crc_xl)) {
+ DBG(DEBUG_PROBE,
+ printf("LVM2: label checksum incorrect at sector %d\n",
+ sector));
+ return 1;
+ }
+
+ blkid_set_tag(probe->dev, "UUID", label->pv_uuid, LVM2_ID_LEN);
+
+ return 0;
+}
/*
* BLKID_BLK_OFFS is at least as large as the highest bim_kboff defined
* in the type_array table below + bim_kbalign.
@@ -988,6 +1046,10 @@ static struct blkid_magic type_array[] =
{ "crypt_LUKS", 0, 0, 6, "LUKS\xba\xbe", probe_luks },
{ "squashfs", 0, 0, 4, "sqsh", 0 },
{ "squashfs", 0, 0, 4, "hsqs", 0 },
+ { "lvm2pv", 0, 0x218, 8, "LVM2 001", probe_lvm2 },
+ { "lvm2pv", 0, 0x018, 8, "LVM2 001", probe_lvm2 },
+ { "lvm2pv", 1, 0x018, 8, "LVM2 001", probe_lvm2 },
+ { "lvm2pv", 1, 0x218, 8, "LVM2 001", probe_lvm2 },
{ NULL, 0, 0, 0, NULL, NULL }
};
-
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