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authorBrian Behlendorf <[email protected]>2014-07-17 10:46:46 -0700
committerBrian Behlendorf <[email protected]>2016-03-10 14:04:58 -0800
commita9977b37ca7bd27ff28de435f8666e253ff6330e (patch)
tree6daf579f786201ccc7d9e79395fb4e4c210146f0 /cmd
parent1ee159f423b5eb3c4646b0ba2dd0fb359503ba90 (diff)
Relax MBR partition scanning requirement
When checking a whole disk to see if it can be safely added to the pool a variety of checks are done. One of those checks is to attempt to determine the partition information and scan all the partitions for existing filesystems. Since ZoL contains a EFI library this partition scanning is easy to do for GPT partitioned disks. However, for non-GPT partitioned disks (MBR/EBR) things are a bit harder. The lack of a convenient library means non-GPT partitioned disks will not have all their partitions checked. For this reason, the default behavior was to require the force option. For example: invalid vdev specification use '-f' to override the following errors: /dev/vdb does not contain an GPT label but it may contain partition information in the MBR. However in practice requiring the force option for this case is counter-intuitively less safe. The reason is because only the first error is returned. By passing the force option it will suppress this first warning and potentially others you were not aware of. Therefore this patch inverts the default behavior for non-GPT formated disks (unformatted, MBR/EBR, etc). If no GPT table is detected and there is no file system detected on the provided block device. Then it will be assumed that block device is safe to use. Longer term it would be nice to see MBR/EBR scanning added to the utilities. This should be fairly straight forward to do. However these days it's somewhat less critical because Linux defaults to GPT partition tables for devices 2TB or larger. Signed-off-by: Brian Behlendorf <[email protected]> Closes #2660 Closes #2274
Diffstat (limited to 'cmd')
-rw-r--r--cmd/zpool/zpool_vdev.c38
1 files changed, 17 insertions, 21 deletions
diff --git a/cmd/zpool/zpool_vdev.c b/cmd/zpool/zpool_vdev.c
index 54ca1b261..6469de1ce 100644
--- a/cmd/zpool/zpool_vdev.c
+++ b/cmd/zpool/zpool_vdev.c
@@ -399,8 +399,16 @@ check_slice(const char *path, blkid_cache cache, int force, boolean_t isspare)
}
/*
- * Validate a whole disk. Iterate over all slices on the disk and make sure
- * that none is in use by calling check_slice().
+ * Validate that a disk including all partitions are safe to use.
+ *
+ * For EFI labeled disks this can done relatively easily with the libefi
+ * library. The partition numbers are extracted from the label and used
+ * to generate the expected /dev/ paths. Each partition can then be
+ * checked for conflicts.
+ *
+ * For non-EFI labeled disks (MBR/EBR/etc) the same process is possible
+ * but due to the lack of a readily available libraries this scanning is
+ * not implemented. Instead only the device path as given is checked.
*/
static int
check_disk(const char *path, blkid_cache cache, int force,
@@ -411,34 +419,22 @@ check_disk(const char *path, blkid_cache cache, int force,
int err = 0;
int fd, i;
- /* This is not a wholedisk we only check the given partition */
if (!iswholedisk)
return (check_slice(path, cache, force, isspare));
- /*
- * When the device is a whole disk try to read the efi partition
- * label. If this is successful we safely check the all of the
- * partitions. However, when it fails it may simply be because
- * the disk is partitioned via the MBR. Since we currently can
- * not easily decode the MBR return a failure and prompt to the
- * user to use force option since we cannot check the partitions.
- */
if ((fd = open(path, O_RDONLY|O_DIRECT)) < 0) {
check_error(errno);
return (-1);
}
- if ((err = efi_alloc_and_read(fd, &vtoc)) != 0) {
+ /*
+ * Expected to fail for non-EFI labled disks. Just check the device
+ * as given and do not attempt to detect and scan partitions.
+ */
+ err = efi_alloc_and_read(fd, &vtoc);
+ if (err) {
(void) close(fd);
-
- if (force) {
- return (0);
- } else {
- vdev_error(gettext("%s does not contain an EFI "
- "label but it may contain partition\n"
- "information in the MBR.\n"), path);
- return (-1);
- }
+ return (check_slice(path, cache, force, isspare));
}
/*