From 858a9de29722742e6d9fb59fccb8b47050fd30be Mon Sep 17 00:00:00 2001
From: Maxim Perevedentsev <mperevedentsev@virtuozzo.com>
Date: Tue, 27 Oct 2015 17:55:40 +0300
Subject: [PATCH] Added btrfs support to vfs_minimum_size.

---
 daemon/btrfs.c       | 71 ++++++++++++++++++++++++++++++++++++++++++++
 daemon/daemon.h      |  1 +
 daemon/fs-min-size.c | 34 ++++++++++++++++++++-
 generator/actions.ml |  6 +++-
 4 files changed, 110 insertions(+), 2 deletions(-)

diff --git a/daemon/btrfs.c b/daemon/btrfs.c
index ddb029d1b..652a17ee5 100644
--- a/daemon/btrfs.c
+++ b/daemon/btrfs.c
@@ -2190,3 +2190,74 @@ 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 8bcc9bd56..4a969ddd5 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 4f93f8cab..ca71c4d5e 100644
--- a/daemon/fs-min-size.c
+++ b/daemon/fs-min-size.c
@@ -25,12 +25,37 @@
 #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;
+  char *path;
+
+  if (mountpoints == NULL) {
+    reply_with_error ("cannot get mountpoints");
+    return NULL;
+  }
+
+  for (i = 0; mountpoints[i] != NULL; i += 2) {
+    if (STREQ (mountpoints[i], device)) {
+      path = strdup (mountpoints[i + 1]);
+      if (path == NULL)
+        reply_with_perror ("strdup");
+      return path;
+    }
+  }
+
+  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 +66,13 @@ 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 62176abb0..8832410ac 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)>." };
 
 ]