df,find_mount_point: optionally don't ignore rootfs

Signed-off-by: Lauri Kasanen <curaga@operamail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

3 files changed, 21 insertions, 2 deletions

diff --git a/coreutils/df.c b/coreutils/df.c
index af9b77b23..70fd1f4fd 100644
--- a/coreutils/df.c
+++ b/coreutils/df.c
@@ -160,7 +160,7 @@ int df_main(int argc UNUSED_PARAM, char **argv)
                         }
 
                         /* GNU coreutils 6.10 skips certain mounts, try to be compatible.  */
-                        if (strcmp(device, "rootfs") == 0)
+                        if (ENABLE_FEATURE_SKIP_ROOTFS && strcmp(device, "rootfs") == 0)
                                 continue;
 
 #ifdef WHY_WE_DO_IT_FOR_DEV_ROOT_ONLY
diff --git a/libbb/Config.src b/libbb/Config.src
index 85892d3fe..dfb897d5f 100644
--- a/libbb/Config.src
+++ b/libbb/Config.src
@@ -161,6 +161,25 @@ config FEATURE_COPYBUF_KB
           Bigger buffers will be allocated with mmap, with fallback to 4 kb
           stack buffer if mmap fails.
 
+config FEATURE_SKIP_ROOTFS
+        bool "Skip rootfs in mount table"
+        default y
+        help
+          Ignore rootfs entry in mount table.
+
+          In Linux, kernel has a special filesystem, rootfs, which is initially
+          mounted on /. It contains initramfs data, if kernel is configured
+          to have one. Usually, another file system is mounted over / early
+          in boot process, and therefore most tools which manipulate
+          mount table, such as df, will skip rootfs entry.
+
+          However, some systems do not mount anything on /.
+          If you need to configure busybox for one of these systems,
+          you may find useful to turn this option off to make df show
+          initramfs statistic.
+
+          Otherwise, choose Y.
+
 config MONOTONIC_SYSCALL
         bool "Use clock_gettime(CLOCK_MONOTONIC) syscall"
         default n
diff --git a/libbb/find_mount_point.c b/libbb/find_mount_point.c
index 361698a6b..56637ad92 100644
--- a/libbb/find_mount_point.c
+++ b/libbb/find_mount_point.c
@@ -43,7 +43,7 @@ struct mntent* FAST_FUNC find_mount_point(const char *name, int subdir_too)
                 /* rootfs mount in Linux 2.6 exists always,
                  * and it makes sense to always ignore it.
                  * Otherwise people can't reference their "real" root! */
-                if (strcmp(mountEntry->mnt_fsname, "rootfs") == 0)
+                if (ENABLE_FEATURE_SKIP_ROOTFS && strcmp(mountEntry->mnt_fsname, "rootfs") == 0)
                         continue;
 
                 if (strcmp(name, mountEntry->mnt_dir) == 0