From: Davidlohr Bueso <dave@xxxxxxx>
Add support for loop devices to add partitions. For now we make use of the max_part parameter from the loop kernel module,
otherwise the feature is disabled.
Below an example output:
root@offbook:~/projects/util-linux/partx# ./partx images-pt/dos+bsd.img
# 1: 32- 7679 ( 7648 sectors, 3 MB)
# 2: 7680- 16383 ( 8704 sectors, 4 MB)
# 5: 7936- 12799 ( 4864 sectors, 2 MB)
# 6: 12544- 16127 ( 3584 sectors, 1 MB)
root@offbook:~/projects/util-linux/partx# ./partx -a -n 1:5 images-pt/dos+bsd.img
root@offbook:~/projects/util-linux/partx# ls /dev/loop0* -ltr
brw-rw---- 1 root disk 7, 0 2011-08-15 00:07 /dev/loop0
brw-rw---- 1 root disk 7, 5 2011-08-15 00:07 /dev/loop0p5
brw-rw---- 1 root disk 7, 2 2011-08-15 00:07 /dev/loop0p2
brw-rw---- 1 root disk 7, 1 2011-08-15 00:07 /dev/loop0p1
Signed-off-by: Davidlohr Bueso <dave@xxxxxxx>
---
partx/Makefile.am | 2 +
partx/partx.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++++++---
2 files changed, 75 insertions(+), 4 deletions(-)
diff --git a/partx/Makefile.am b/partx/Makefile.am
index 6a72942..080bc47 100644
--- a/partx/Makefile.am
+++ b/partx/Makefile.am
@@ -11,6 +11,8 @@ partx_SOURCES = partx.c partx.h \
$(top_srcdir)/lib/at.c \
$(top_srcdir)/lib/mbsalign.c \
$(top_srcdir)/lib/strutils.c \
+ $(top_srcdir)/lib/canonicalize.c \
+ $(top_srcdir)/lib/loopdev.c \
$(top_srcdir)/lib/linux_version.c
partx_CFLAGS = -I$(ul_libblkid_incdir)
diff --git a/partx/partx.c b/partx/partx.c
index 0b35f9f..d0e40c7 100644
--- a/partx/partx.c
+++ b/partx/partx.c
@@ -31,6 +31,7 @@
#include "xalloc.h"
#include "partx.h"
#include "sysfs.h"
+#include "loopdev.h"
#include "at.h"
/* this is the default upper limit, could be modified by --nr */
@@ -88,7 +89,49 @@ static int columns[__NCOLUMNS], ncolumns;
static int verbose;
static int partx_flags;
+static struct loopdev_cxt lc;
+static int loopdev = 0;
+/*
+ * Check if the kernel supports partitioned loop devices.
+ * In a near future (around linux 3.2, hopefully) this will come
+ * always out of the box, until then we need to check.
+ */
+static int loopmod_supports_parts(void)
+{
+ int rc, ret = 0;
+ FILE *f = fopen("/sys/module/loop/parameters/max_part", "r");
+
+ if (!f)
+ return 0;
+ rc = fscanf(f, "%d", &ret);
+ fclose(f);
+ return ret;
+}
+
+static void assoc_loopdev(const char *fname)
+{
+ int rc;
+
+ loopcxt_init(&lc, 0);
+
+ rc = loopcxt_find_unused(&lc);
+ if (rc)
+ err(EXIT_FAILURE, "failed to find unused device");
+
+ if (verbose)
+ printf("Trying to use '%s' for the loop device\n", loopcxt_get_device(&lc));
+
+ if (loopcxt_set_backing_file(&lc, fname))
+ err(EXIT_FAILURE, "failed to set backing file");
+
+ rc = loopcxt_setup_device(&lc);
+
+ if (rc == -EBUSY)
+ err(EXIT_FAILURE, "failed to setup device for %s", fname);
+
+ loopdev = 1;
+}
static inline int get_column_id(int num)
{
@@ -278,6 +321,7 @@ static int del_parts(int fd, const char *device, dev_t devno,
return rc;
}
+
static void add_parts_warnx(const char *device, int first, int last)
{
if (first == last)
@@ -288,7 +332,7 @@ static void add_parts_warnx(const char *device, int first, int last)
}
static int add_parts(int fd, const char *device,
- blkid_partlist ls, int lower, int upper)
+ blkid_partlist ls, int lower, int upper)
{
int i, nparts, rc = 0, errfirst = 0, errlast = 0;
@@ -338,6 +382,19 @@ static int add_parts(int fd, const char *device,
if (errfirst)
add_parts_warnx(device, errfirst, errlast);
+
+ /* the kernel adds *all* loopdev partitions, so we should delete
+ any extra, unwanted ones, when the -n option is passed */
+ if (loopdev && (lower || upper)) {
+ for (i = 0; i < nparts; i++) {
+ blkid_partition par = blkid_partlist_get_partition(ls, i);
+ int n = blkid_partition_get_partno(par);
+
+ if (n < lower || n > upper)
+ partx_del_partition(fd, n);
+ }
+ }
+
return rc;
}
@@ -800,14 +857,23 @@ int main(int argc, char **argv)
if (what == ACT_ADD || what == ACT_DELETE) {
struct stat x;
- if (stat(wholedisk, &x) || !S_ISBLK(x.st_mode))
- errx(EXIT_FAILURE, _("%s: not a block device"), wholedisk);
+ if (stat(wholedisk, &x) || !S_ISBLK(x.st_mode)) {
+ /* not a blkdev, try to associate it to a loop device */
+ if (!loopmod_supports_parts())
+ errx(EXIT_FAILURE, _("%s: does not support loop device partitions"),
+ wholedisk);
+ assoc_loopdev(wholedisk);
+ wholedisk = xstrdup(lc.device);
+ }
}
if ((fd = open(wholedisk, O_RDONLY)) == -1)
err(EXIT_FAILURE, _("%s: open failed"), wholedisk);
- if (what == ACT_DELETE)
+ if (what == ACT_DELETE) {
+ if (loopdev)
+ errx(EXIT_FAILURE, _("%s: cannot delete partitions"), wholedisk);
rc = del_parts(fd, wholedisk, disk_devno, lower, upper);
+ }
else {
blkid_probe pr = blkid_new_probe();
blkid_partlist ls = NULL;
@@ -846,6 +912,9 @@ int main(int argc, char **argv)
blkid_free_probe(pr);
}
+ if (loopdev)
+ loopcxt_deinit(&lc);
+
close(fd);
return rc ? EXIT_FAILURE : EXIT_SUCCESS;
}
--
1.7.4.1
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