From 6625b74e90a0b6918c90c408215e76719e459883 Mon Sep 17 00:00:00 2001

From: Daniel Drake <dsd@laptop.org>

Date: Wed, 11 Apr 2012 23:00:43 +0100

Subject: [PATCH] rootfs-block: avoid remount when options don't change

Mounting, unmounting and then mounting a disk partition takes some

time.

On embedded systems such as OLPC XO where we disable fsck and fstab

reading, the root options are not going to change throughout the

mount_root() function, so remounting is time consuming and without

change.

Detect and optimize for this case so that the filesystem is only

mounted once.

---

 modules.d/95rootfs-block/mount-root.sh |   12 ++++++++----

 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/modules.d/95rootfs-block/mount-root.sh b/modules.d/95rootfs-block/mount-root.sh

index 2c89431..aef99ae 100755

--- a/modules.d/95rootfs-block/mount-root.sh

+++ b/modules.d/95rootfs-block/mount-root.sh

@@ -98,20 +98,24 @@ mount_root() {

     # them; rflags is guaranteed to not be empty

     rflags="${rootopts:+"${rootopts},"}${rflags}"

-    umount "$NEWROOT"

-

     # backslashes are treated as escape character in fstab

     # esc_root=$(echo ${root#block:} | sed 's,\\,\\\\,g')

     # printf '%s %s %s %s 1 1 \n' "$esc_root" "$NEWROOT" "$rootfs" "$rflags" >/etc/fstab

+    ran_fsck=0

     if [ -z "$fastboot" -a "$READONLY" != "yes" ] && ! strstr "${rflags},${rootopts}" _netdev; then

+        umount "$NEWROOT"

         fsck_single "${root#block:}" "$rootfs" "$fsckoptions"

         _ret=$?

         [ $_ret -ne 255 ] && echo $_ret >/run/initramfs/root-fsck

+        ran_fsck=1

     fi

-    info "Remounting ${root#block:} with -o ${rflags}"

-    mount -t "$rootfs" -o "$rflags" "${root#block:}" "$NEWROOT" 2>&1 | vinfo

+    if [ -n "$rootopts" -o "$ran_fsck" = "1" ]; then

+        info "Remounting ${root#block:} with -o ${rflags}"

+        umount "$NEWROOT" &>/dev/null

+        mount -t "$rootfs" -o "$rflags" "${root#block:}" "$NEWROOT" 2>&1 | vinfo

+    fi

     [ -f "$NEWROOT"/forcefsck ] && rm -f "$NEWROOT"/forcefsck 2>/dev/null

     [ -f "$NEWROOT"/.autofsck ] && rm -f "$NEWROOT"/.autofsck 2>/dev/null