From: Karel Zak <kzak@redhat.com>
Date: Thu, 8 Apr 2010 14:38:23 +0000 (+0200)
Subject: mount: use auto-loopdev for all known filesystems
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=556c9641f01eb9c6d1c5b4ae3c6cdd4f9395d34d;p=util-linux

mount: use auto-loopdev for all known filesystems

The commit e580266914734898999f652025f9c7141023df66 introduced
"automatically detect and loop-mount regular files". This should be
used only for filesystems that require block devices.

All known filesystems in libblkid depend block devices, so we can
use blkid_known_fstype() as a filter for this feature.

Signed-off-by: Karel Zak <kzak@redhat.com>
---

diff --git a/mount/mount.8 b/mount/mount.8
index 9675cc62..06ea3acd 100644
--- a/mount/mount.8
+++ b/mount/mount.8
@@ -2560,13 +2560,14 @@ will try to find some unused loop device and use that, for example
 The mount command
 .B automatically
 creates a loop device from a regular file if a filesystem type is
-not specified, for example:
+not specified or the filesystem is known for libblkid, for example:
 .RS
 .sp
 .B "mount /tmp/disk.img /mnt"
 .sp
+.B "mount -t ext3 /tmp/disk.img /mnt"
+.sp
 .RE
-
 This type of mount knows about four options, namely
 .BR loop ", " offset ", " sizelimit " and " encryption ,
 that are really options to
diff --git a/mount/mount.c b/mount/mount.c
index 7a5ea06d..8cab2e8a 100644
--- a/mount/mount.c
+++ b/mount/mount.c
@@ -1120,16 +1120,15 @@ loop_check(const char **spec, const char **type, int *flags,
   *loopfile = *spec;
 
   /* Automatically create a loop device from a regular file if a filesystem
-   * is not specified.
+   * is not specified or the filesystem is known for libblkid (these
+   * filesystems work with block devices only).
    *
    * Note that there is not a restriction (on kernel side) that prevents regular
    * file as a mount(2) source argument. A filesystem that is able to mount
    * regular files could be implemented.
-   *
-   * If the filesystem type is specified than "-o loop" is required to create a
-   * loop device.
    */
-  if (!*loop && (!*type || strcmp(*type, "auto") == 0)) {
+  if (!*loop && (!*type || strcmp(*type, "auto") == 0 ||
+			   fsprobe_known_fstype(*type))) {
     struct stat st;
     if (stat(*loopfile, &st) == 0)
       *loop = S_ISREG(st.st_mode);