blkid: Optimize devicemapper support

This commit works by removing all calls from libdevmapper altogether,
and using the standard support for "normal" non-dm devices.

It depends on dm devices being placed in /dev/mapper (but the previous
code had this dependency anyway), and /proc/partitions containing dm
devices.

We don't actually rip out the libdevmapper code in this commit, but
just disable it via #undef HAVE_DEVMAPPER, just so it's easier to
review and understand the fundamental code changes.  A subsequent
commit will remove the libdevmapper code, as well as unexport
the blkid_devdirs string array.

Thanks to Karel Zak for inspiring me to look at the dm code in blkid,
so I could realize how much it deserved to ripped out by its roots.  :-)

[kzak@redhat.com: port from e2fsprogs to util-linux-ng tree]

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Karel Zak <kzak@redhat.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/libs/blkid/src/blkidP.h b/libs/blkid/src/blkidP.h
index 6ae046e00..3c55a5b07 100644
--- a/libs/blkid/src/blkidP.h
+++ b/libs/blkid/src/blkidP.h
@@ -228,6 +228,13 @@ extern void blkid_debug_dump_dev(blkid_dev dev);
 extern void blkid_debug_dump_tag(blkid_tag tag);
 #endif
 
+/* devno.c */
+struct dir_list {
+	char	*name;
+	struct dir_list *next;
+};
+extern void blkid__scan_dir(char *, dev_t, struct dir_list **, char **);
+
 /* lseek.c */
 extern blkid_loff_t blkid_llseek(int fd, blkid_loff_t offset, int whence);