On Thu, 19 Nov 2009 15:40:21 +0000
"Trela, Maciej" <Maciej.Trela@xxxxxxxxx> wrote:
> Hello Neil,
> I made some research but unfortunately I couldn't find any other library except libparted.
> Assuming there are no other possibilities, do you think we could stay with the current solution or should I switch the patch to libparted?
>
> I have the impression that with libparted this simple patch would be much bigger (given the code size)...
>
Fair enough.
I have made some changes resulting in the following patch.
Thanks,
NeilBrown
>From 034b203a4754da7615d7b16bafeabfc4115dabea Mon Sep 17 00:00:00 2001
From: Trela, Maciej <Maciej.Trela@xxxxxxxxx>
Date: Tue, 8 Dec 2009 16:07:47 +1100
Subject: [PATCH] Check partition tables when creating array.
When creating an array, check if the devices have partition
tables and print a warning if the table or the partitions might be
destroyed by array creation.
Signed-off-by: NeilBrown <neilb@xxxxxxx>
---
Create.c | 17 +++++-
mdadm.h | 1 +
util.c | 176 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 191 insertions(+), 3 deletions(-)
diff --git a/Create.c b/Create.c
index 5b01b63..d104c05 100644
--- a/Create.c
+++ b/Create.c
@@ -375,11 +375,22 @@ int Create(struct supertype *st, char *mddev,
warn |= check_ext2(fd, dname);
warn |= check_reiser(fd, dname);
warn |= check_raid(fd, dname);
- if (st && strcmp(st->ss->name, "1.x") == 0 &&
+ if (strcmp(st->ss->name, "1.x") == 0 &&
+ st->minor_version >= 1)
+ /* metadata at front */
+ warn |= check_partitions(fd, dname, 0);
+ else if (level == 1 || level == LEVEL_CONTAINER)
+ /* partitions could be meaningful */
+ warn |= check_partitions(fd, dname, freesize*2);
+ else
+ /* partitions cannot be meaningful */
+ warn |= check_partitions(fd, dname, 0);
+ if (strcmp(st->ss->name, "1.x") == 0 &&
st->minor_version >= 1 &&
did_default &&
- level == 1) {
- warn = 1;
+ level == 1 &&
+ (warn & 1024) == 0) {
+ warn |= 1024;
fprintf(stderr, Name ": Note: this array has metadata at the start and\n"
" may not be suitable as a boot device. If you plan to\n"
" store '/' or '/boot' on this device please ensure that\n"
diff --git a/mdadm.h b/mdadm.h
index c7f864b..2bfe840 100644
--- a/mdadm.h
+++ b/mdadm.h
@@ -787,6 +787,7 @@ extern int parse_layout_faulty(char *layout);
extern int check_ext2(int fd, char *name);
extern int check_reiser(int fd, char *name);
extern int check_raid(int fd, char *name);
+extern int check_partitions(int fd, char *dname, unsigned long long freesize);
extern int get_mdp_major(void);
extern int dev_open(char *dev, int flags);
diff --git a/util.c b/util.c
index a0e4bcf..67c3550 100644
--- a/util.c
+++ b/util.c
@@ -65,6 +65,43 @@ struct blkpg_partition {
char volname[BLKPG_VOLNAMELTH]; /* volume label */
};
+/* partition table structures so we can check metadata position
+ * against the end of the last partition.
+ * Only handle MBR ant GPT partition tables.
+ */
+struct MBR_part_record {
+ __u8 bootable;
+ __u8 first_head;
+ __u8 first_sector;
+ __u8 first_cyl;
+ __u8 part_type;
+ __u8 last_head;
+ __u8 last_sector;
+ __u8 last_cyl;
+ __u32 first_sect_lba;
+ __u32 blocks_num;
+};
+
+struct GPT_part_entry {
+ unsigned char type_guid[16];
+ unsigned char partition_guid[16];
+ unsigned char starting_lba[8];
+ unsigned char ending_lba[8];
+ unsigned char attr_bits[8];
+ unsigned char name[72];
+};
+
+/* MBR/GPT magic numbers */
+#define MBR_SIGNATURE_MAGIC __cpu_to_le16(0xAA55)
+#define GPT_SIGNATURE_MAGIC __cpu_to_le64(0x5452415020494645ULL)
+
+#define MBR_SIGNATURE_OFFSET 510
+#define MBR_PARTITION_TABLE_OFFSET 446
+#define MBR_PARTITIONS 4
+#define MBR_GPT_PARTITION_TYPE 0xEE
+#define GPT_ALL_PARTITIONS_OFFSET 80
+#define GPT_ENTRY_SIZE_OFFSET 84
+
/*
* Parse a 128 bit uuid in 4 integers
* format is 32 hexx nibbles with options :.<space> separator
@@ -1096,6 +1133,145 @@ int get_dev_size(int fd, char *dname, unsigned long long *sizep)
return 1;
}
+
+/* Sets endofpart parameter to the last block used by the last GPT partition on the device.
+ * Returns: 1 if successful
+ * -1 for unknown partition type
+ * 0 for other errors
+ */
+static int get_gpt_last_partition_end(int fd, unsigned long long *endofpart)
+{
+ unsigned char buf[512];
+ unsigned char empty_gpt_entry[16]= {0};
+ struct GPT_part_entry *part;
+ unsigned long long curr_part_end;
+ unsigned all_partitions, entry_size;
+ int part_nr;
+
+ *endofpart = 0;
+
+ /* read GPT header */
+ lseek(fd, 512, SEEK_SET);
+ if (read(fd, buf, 512) != 512)
+ return 0;
+
+ /* get the number of partition entries and the entry size */
+ all_partitions = __le32_to_cpu(buf[GPT_ALL_PARTITIONS_OFFSET]);
+ entry_size = __le32_to_cpu(buf[GPT_ENTRY_SIZE_OFFSET]);
+
+ /* Check GPT signature*/
+ if (*((__u64*)buf) != GPT_SIGNATURE_MAGIC)
+ return -1;
+
+ /* sanity checks */
+ if (all_partitions > 1024 ||
+ entry_size > 512)
+ return -1;
+
+ /* read first GPT partition entries */
+ if (read(fd, buf, 512) != 512)
+ return 0;
+
+ part = (struct GPT_part_entry*)buf;
+
+ for (part_nr=0; part_nr < all_partitions; part_nr++) {
+ /* is this valid partition? */
+ if (memcmp(part->type_guid, empty_gpt_entry, 16) != 0) {
+ /* check the last lba for the current partition */
+ curr_part_end = __le64_to_cpu(*(__u64*)part->ending_lba);
+ if (curr_part_end > *endofpart)
+ *endofpart = curr_part_end;
+ }
+
+ part = (struct GPT_part_entry*)((unsigned char*)part + entry_size);
+
+ if ((unsigned char *)part >= buf + 512) {
+ if (read(fd, buf, 512) != 512)
+ return 0;
+ part = (struct GPT_part_entry*)buf;
+ }
+ }
+ return 1;
+}
+
+/* Sets endofpart parameter to the last block used by the last partition on the device.
+ * Returns: 1 if successful
+ * -1 for unknown partition type
+ * 0 for other errors
+ */
+static int get_last_partition_end(int fd, unsigned long long *endofpart)
+{
+ unsigned char boot_sect[512];
+ struct MBR_part_record *part;
+ unsigned long long curr_part_end;
+ int part_nr;
+ int retval = 0;
+
+ *endofpart = 0;
+
+ /* read MBR */
+ lseek(fd, 0, 0);
+ if (read(fd, boot_sect, 512) != 512)
+ goto abort;
+
+ /* check MBP signature */
+ if (*((__u16*)(boot_sect + MBR_SIGNATURE_OFFSET))
+ == MBR_SIGNATURE_MAGIC) {
+ retval = 1;
+ /* found the correct signature */
+ part = (struct MBR_part_record*)
+ (boot_sect + MBR_PARTITION_TABLE_OFFSET);
+
+ for (part_nr=0; part_nr < MBR_PARTITIONS; part_nr++) {
+ /* check for GPT type */
+ if (part->part_type == MBR_GPT_PARTITION_TYPE) {
+ retval = get_gpt_last_partition_end(fd, endofpart);
+ break;
+ }
+ /* check the last used lba for the current partition */
+ curr_part_end = __le32_to_cpu(part->first_sect_lba) +
+ __le32_to_cpu(part->blocks_num);
+ if (curr_part_end > *endofpart)
+ *endofpart = curr_part_end;
+
+ part++;
+ }
+ } else {
+ /* Unknown partition table */
+ retval = -1;
+ }
+ abort:
+ return retval;
+}
+
+int check_partitions(int fd, char *dname, unsigned long long freesize)
+{
+ /*
+ * Check where the last partition ends
+ */
+ unsigned long long endofpart;
+ int ret;
+
+ if ((ret = get_last_partition_end(fd, &endofpart)) > 0) {
+ /* There appears to be a partition table here */
+ if (freesize == 0) {
+ /* partitions will not be visible in new device */
+ fprintf(stderr,
+ Name ": partition table exists on %s but will be lost or\n"
+ " meaningless after creating array\n",
+ dname);
+ return 1;
+ } else if (endofpart > freesize) {
+ /* last partition overlaps metadata */
+ fprintf(stderr,
+ Name ": metadata will over-write last partition on %s.\n",
+ dname);
+ return 1;
+ }
+ }
+ return 0;
+}
+
void get_one_disk(int mdfd, mdu_array_info_t *ainf, mdu_disk_info_t *disk)
{
int d;
--
1.6.5.4
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