Libguestfs - Oct 2015 - [PATCHv2] Added btrfs support for vfs_min_size.

---
 daemon/btrfs.c       | 72 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 daemon/daemon.h      |  1 +
 daemon/fs-min-size.c | 33 ++++++++++++++++++++----
 generator/actions.ml |  6 ++++-
 4 files changed, 106 insertions(+), 6 deletions(-)

diff --git a/daemon/btrfs.c b/daemon/btrfs.c
index ddb029d..1e0a9a2 100644
--- a/daemon/btrfs.c
+++ b/daemon/btrfs.c
@@ -2190,3 +2190,75 @@ do_btrfs_replace (const char *srcdev, const char
*targetdev,

   return 0;
 }
+
+/* btrfs command add a new command
+ * inspect-internal min-dev-size <path>
+ * since v4.2
+ * We could check whether 'btrfs' supports
+ * 'min-dev-size' command by checking the output of
+ * 'btrfs --help' command.
+ */
+static int
+test_btrfs_min_dev_size (void)
+{
+  CLEANUP_FREE char *err = NULL, *out = NULL;
+  static int result = -1;
+  const char *cmd_pattern = "btrfs inspect-internal min-dev-size";
+  int r;
+
+  if (result != -1)
+    return result;
+
+  r = commandr (&out, &err, str_btrfs, "--help", NULL);
+
+  if (r == -1) {
+    reply_with_error ("btrfs: %s", err);
+    return -1;
+  }
+
+  if (strstr (out, cmd_pattern) == NULL)
+    result = 0;
+  else
+    result = 1;
+
+  return result;
+}
+
+int64_t
+btrfs_minimum_size (const char *path)
+{
+  CLEANUP_FREE char *err = NULL, *out = NULL;
+  int64_t ret = 0;
+  int r;
+  int min_size_supported = test_btrfs_min_dev_size ();
+
+  if (min_size_supported == -1)
+    return -1;
+  else if (min_size_supported == 0)
+    NOT_SUPPORTED (-1, "'btrfs inspect-internal min-dev-size' \
+                        needs btrfs-progs >= 4.2");
+
+  r = command (&out, &err, str_btrfs, "inspect-internal",
+               "min-dev-size", sysroot_path (path), NULL);
+
+  if (r == -1) {
+    reply_with_error ("%s", err);
+    return -1;
+  }
+
+#if __WORDSIZE == 64
+#define XSTRTOD64 xstrtol
+#else
+#define XSTRTOD64 xstrtoll
+#endif
+
+  if (XSTRTOD64 (out, NULL, 10, &ret, NULL) != LONGINT_OK) {
+    reply_with_error ("cannot parse minimum size");
+    return -1;
+  }
+
+#undef XSTRTOD64
+
+  return ret;
+}
+
diff --git a/daemon/daemon.h b/daemon/daemon.h
index 8bcc9bd..4a969dd 100644
--- a/daemon/daemon.h
+++ b/daemon/daemon.h
@@ -280,6 +280,7 @@ extern char *btrfs_get_label (const char *device);
 extern int btrfs_set_label (const char *device, const char *label);
 extern int btrfs_set_uuid (const char *device, const char *uuid);
 extern int btrfs_set_uuid_random (const char *device);
+extern int64_t btrfs_minimum_size (const char *path);

 /*-- in ntfs.c --*/
 extern char *ntfs_get_label (const char *device);
diff --git a/daemon/fs-min-size.c b/daemon/fs-min-size.c
index 4f93f8c..e43237b 100644
--- a/daemon/fs-min-size.c
+++ b/daemon/fs-min-size.c
@@ -18,19 +18,35 @@

 #include <config.h>

-#include <stdio.h>
-#include <stdlib.h>
-#include <unistd.h>
-
 #include "daemon.h"
 #include "actions.h"

+static char*
+get_mount_point (const char *device)
+{
+  CLEANUP_FREE_STRING_LIST char **mountpoints = do_mountpoints();
+  size_t i;
+
+  if (mountpoints == NULL) {
+    reply_with_error ("cannot get mountpoints");
+    return NULL;
+  }
+
+  for (i = 0; mountpoints[i] != NULL; i += 2) {
+    if (STREQ (mountpoints[i], device))
+      return strdup (mountpoints[i + 1]);
+  }
+
+  reply_with_error ("device not mounted: %s", device);
+  return NULL;
+}
+
 int64_t
 do_vfs_minimum_size (const mountable_t *mountable)
 {
   int64_t r;

-  /* How we set the label depends on the filesystem type. */
+  /* How we get minimum size depends on the filesystem type. */
   CLEANUP_FREE char *vfs_type = do_vfs_type (mountable);
   if (vfs_type == NULL)
     return -1;
@@ -41,6 +57,13 @@ do_vfs_minimum_size (const mountable_t *mountable)
   else if (STREQ (vfs_type, "ntfs"))
     r = ntfs_minimum_size (mountable->device);

+  else if (STREQ (vfs_type, "btrfs")) {
+    CLEANUP_FREE char *path = get_mount_point (mountable->device);
+    if (path == NULL)
+      return -1;
+    r = btrfs_minimum_size (path);
+  }
+
   else
     NOT_SUPPORTED (-1, "don't know how to get minimum size of
'%s' filesystems",
                    vfs_type);
diff --git a/generator/actions.ml b/generator/actions.ml
index 62176ab..8832410 100644
--- a/generator/actions.ml
+++ b/generator/actions.ml
@@ -12761,6 +12761,10 @@ To read the UUID on a filesystem, call
C<guestfs_vfs_uuid>." };
       InitPartition, IfAvailable "ntfsprogs", TestRun(
         [["mkfs"; "ntfs"; "/dev/sda1";
""; "NOARG"; ""; ""; "NOARG"];
          ["vfs_minimum_size"; "/dev/sda1"]]), [];
+      InitPartition, Always, TestRun (
+        [["mkfs"; "btrfs"; "/dev/sda1";
""; "NOARG"; ""; ""; "NOARG"];
+         ["mount"; "/dev/sda1"; "/"];
+         ["vfs_minimum_size"; "/dev/sda1"]]), [];
     ];
     shortdesc = "get minimum filesystem size";
     longdesc = "\
@@ -12770,7 +12774,7 @@ This is the minimum possible size for filesystem
shrinking.
 If getting minimum size of specified filesystem is not supported,
 this will fail and set errno as ENOTSUP.

-See also L<ntfsresize(8)>, L<resize2fs(8)>." };
+See also L<ntfsresize(8)>, L<resize2fs(8)>,
L<btrfs(8)>." };

 ]

--
1.8.3.1

On Fri, Oct 23, 2015 at 07:53:58PM +0300, Maxim Perevedentsev
wrote:
> --- a/daemon/fs-min-size.c
> +++ b/daemon/fs-min-size.c
> @@ -18,19 +18,35 @@
> 
>  #include <config.h>
> 
> -#include <stdio.h>
> -#include <stdlib.h>
> -#include <unistd.h>
> -
Not sure why these were removed.  Almost any file should include
<stdio.h> and probably <stdlib.h>.

<unistd.h> is needed for most system calls.  Also <string.h> is
needed
in this file because it calls strdup.

Don't depend on implicit #includes in "daemon.h".
> +  for (i = 0; mountpoints[i] != NULL; i += 2) {
> +    if (STREQ (mountpoints[i], device))
> +      return strdup (mountpoints[i + 1]);
You need to check the return value of strdup in case there was an
allocation error.  The mountpoints string is (to some extent) under
end-user control, and if the call to strdup were to return NULL
libguestfs would hang.

Also 'daemon/btrfs.c' has a rogue newline at the end of the file,
which git complains about.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
virt-builder quickly builds VMs from scratch
http://libguestfs.org/virt-builder.1.html