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Add btrfs probing support, currently only in the single-device case. 

* kern/emu/getroot.c (find_root_device_from_mountinfo): New
function.
(grub_guess_root_device): Call find_root_device_from_mountinfo
before looking in /dev.
This commit is contained in:
Colin Watson 2010-06-01 18:30:20 +01:00
parent b1d17e10e0 0d9ff59345
commit bde4a9ac1d
2 changed files with 95 additions and 0 deletions
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9
ChangeLog
View File

@ -1,3 +1,12 @@
2010-06-01 Colin Watson <cjwatson@ubuntu.com>
Add btrfs probing support, currently only in the single-device case.
* kern/emu/getroot.c (find_root_device_from_mountinfo): New
function.
(grub_guess_root_device): Call find_root_device_from_mountinfo
before looking in /dev.
2010-05-31 Vladimir Serbinenko <phcoder@gmail.com>
* disk/i386/pc/biosdisk.c (grub_biosdisk_open): Use

86
kern/emu/getroot.c
View File

@ -80,6 +80,86 @@ xgetcwd (void)
return path;
}
#ifdef __linux__
/* Statting something on a btrfs filesystem always returns a virtual device
major/minor pair rather than the real underlying device, because btrfs
can span multiple underlying devices (and even if it's currently only
using a single device it can be dynamically extended onto another). We
can't deal with the multiple-device case yet, but in the meantime, we can
at least cope with the single-device case by scanning
/proc/self/mountinfo. */
static char *
find_root_device_from_mountinfo (const char *dir)
{
FILE *fp;
char *buf = NULL;
size_t len = 0;
char *ret = NULL;
fp = fopen ("/proc/self/mountinfo", "r");
if (! fp)
return NULL; /* fall through to other methods */
while (getline (&buf, &len, fp) > 0)
{
int mnt_id, parent_mnt_id;
unsigned int major, minor;
char enc_root[PATH_MAX], enc_path[PATH_MAX];
int count;
size_t enc_path_len;
const char *sep;
char fstype[PATH_MAX], device[PATH_MAX];
struct stat st;
if (sscanf (buf, "%d %d %u:%u %s %s%n",
&mnt_id, &parent_mnt_id, &major, &minor, enc_root, enc_path,
&count) < 6)
continue;
if (strcmp (enc_root, "/") != 0)
continue; /* only a subtree is mounted */
enc_path_len = strlen (enc_path);
if (strncmp (dir, enc_path, enc_path_len) != 0 ||
(dir[enc_path_len] && dir[enc_path_len] != '/'))
continue;
/* This is a parent of the requested directory. /proc/self/mountinfo
is in mount order, so it must be the closest parent we've
encountered so far. If it's virtual, return its device node;
otherwise, carry on to try to find something closer. */
free (ret);
ret = NULL;
if (major != 0)
continue; /* not a virtual device */
sep = strstr (buf + count, " - ");
if (!sep)
continue;
sep += sizeof (" - ") - 1;
if (sscanf (sep, "%s %s", fstype, device) != 2)
continue;
if (stat (device, &st) < 0)
continue;
if (!S_ISBLK (st.st_mode))
continue; /* not a block device */
ret = strdup (device);
}
free (buf);
fclose (fp);
return ret;
}
#endif /* __linux__ */
#ifdef __MINGW32__
static char *
@ -366,6 +446,12 @@ grub_guess_root_device (const char *dir)
#else /* !__GNU__ */
struct stat st;
#ifdef __linux__
os_dev = find_root_device_from_mountinfo (dir);
if (os_dev)
return os_dev;
#endif /* __linux__ */
if (stat (dir, &st) < 0)
grub_util_error ("cannot stat `%s'", dir);