>From 97bcb9eb8c34329a8ca1ec88fd89296e273ceb24 Mon Sep 17 00:00:00 2001
From: James Johnston <johnstonj.pub...@codenest.com>
Date: Thu, 17 Mar 2016 15:10:49 +0000
Subject: [PATCH] getroot: Correctly handle missing btrfs device identifiers.
The btrfs driver's BTRFS_IOC_FS_INFO ioctl only tells you the maximum
device ID and the number of devices. It does not tell you which
device IDs may no longer be allocated - for example, if a device is
later deleted from the file system, its device ID won't be allocated
any more.
You must then probe each device ID with BTRFS_IOC_DEV_INFO to see if
it is a valid device or not. It is not an error condition for this
ioctl to return ENODEV: it seems to mean that the device was deleted
by the user.
Signed-off-by: James Johnston <johnstonj.pub...@codenest.com>
---
grub-core/osdep/linux/getroot.c | 26 ++++++++++++++++++++------
1 file changed, 20 insertions(+), 6 deletions(-)
diff --git a/grub-core/osdep/linux/getroot.c b/grub-core/osdep/linux/getroot.c
index 10480b6..852f3a2 100644
--- a/grub-core/osdep/linux/getroot.c
+++ b/grub-core/osdep/linux/getroot.c
@@ -242,15 +242,29 @@ grub_find_root_devices_from_btrfs (const char *dir)
struct btrfs_ioctl_dev_info_args devi;
memset (&devi, 0, sizeof (devi));
devi.devid = i;
+ /* We have to probe all possible device IDs, since btrfs doesn't
+ give us a list of all the valid ones. */
if (ioctl (fd, BTRFS_IOC_DEV_INFO, &devi) < 0)
{
- close (fd);
- free (ret);
- return NULL;
+ /* ENODEV is normal, e.g. if the first device is deleted from
+ an array. */
+ int last_error = errno;
+ if (last_error != ENODEV)
+ {
+ grub_util_warn(_("btrfs device info could not be read "
+ "for %s, device %d: errno %d"), dir, i,
+ last_error);
+ close (fd);
+ free (ret);
+ return NULL;
+ }
+ }
+ else
+ {
+ ret[j++] = xstrdup ((char *) devi.path);
+ if (j >= fsi.num_devices)
+ break;
}
- ret[j++] = xstrdup ((char *) devi.path);
- if (j >= fsi.num_devices)
- break;
}
close (fd);
ret[j] = 0;
--
1.9.5.msysgit.1
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