| Message ID | 1415815266-21733-1-git-send-email-dywi@mailerd.de |
|---|---|
| State | Not Applicable |
| Headers | show |
André, All, On 2014-11-12 19:01 +0100, André Erdmann spake thusly: > systemd runs "/bin/mount MOUNTPOINT -o remount" for remounting > the rootfs (and others like /usr, /proc, ...) [0]. This is supposed > to remount the rootfs in rw/ro mode depending on /etc/fstab. > > busybox' mount -o remount command, however, complety ignores fstab > and reads the mount options from /proc/mounts only (+ cmdline "-o ...") [1], > so "mount / -o remount" is a no-op. > > This commit adds a patch that causes systemd's remount-fs to pass the > options from /etc/fstab to the mount command. > > References: > [0] http://cgit.freedesktop.org/systemd/systemd/tree/src/remount-fs/remount-fs.c?id=v217 (line 99) > [1] http://git.busybox.net/busybox/tree/util-linux/mount.c?h=1_22_stable (line 2133) > > Signed-off-by: André Erdmann <dywi@mailerd.de> Forwarding it on behalf of Eric: http://lists.busybox.net/pipermail/buildroot/2014-November/112134.html Tested-by: Eric Limpens <limpens@gmail.com> Regards, Yann E. MORIN. > --- > > Notes: > * selecting BR2_PACKAGE_UTIL_LINUX_MOUNT=y would also fix remounting, > but that also requires BR2_PACKAGE_UTIL_LINUX_BINARIES=y... > > * passing all options to mount rather than checking for "rw"/ro" > (hasmntopt(...,"ro")==NULL) makes remount-fs behave identical > regardless of whether util-linux' or busybox' mount is used > (remount-fs also remounts /proc etc.) > > * a systemd-based buildroot config ignores BR2_TARGET_GENERIC_REMOUNT_ROOTFS_RW > This is not changed by this commit, but the rootfs is now always rw unless > /etc/fstab gets replaced by a a postbuild script / rootfs overlay. > > By the way, I have a script for generating /etc/fstab, which could be useful > for dealing with remount-ro/rw and systemd-specific mounts (and maybe genimages). > Tell me if there's any interest in getting this integrated into buildroot. > > You can view it here > https://gist.github.com/dywisor/62d41835c2dff043f794#file-mkfstab-bash-L17-L96 > (not the latest revision, but sufficient for getting an overview.) > --- > ...t-fs-pass-options-from-fstab-to-bin-mount.patch | 63 ++++++++++++++++++++++ > 1 file changed, 63 insertions(+) > create mode 100644 package/systemd/0005-remount-fs-pass-options-from-fstab-to-bin-mount.patch > > diff --git a/package/systemd/0005-remount-fs-pass-options-from-fstab-to-bin-mount.patch b/package/systemd/0005-remount-fs-pass-options-from-fstab-to-bin-mount.patch > new file mode 100644 > index 0000000..c6dc661 > --- /dev/null > +++ b/package/systemd/0005-remount-fs-pass-options-from-fstab-to-bin-mount.patch > @@ -0,0 +1,63 @@ > +From 7bc0901a00e78f22f97dbd3f85c7a19d9a78e7a1 Mon Sep 17 00:00:00 2001 > +From: =?UTF-8?q?Andr=C3=A9=20Erdmann?= <dywi@mailerd.de> > +Date: Wed, 12 Nov 2014 17:45:46 +0100 > +Subject: [PATCH 1/1] remount-fs: pass options from fstab to /bin/mount > +MIME-Version: 1.0 > +Content-Type: text/plain; charset=UTF-8 > +Content-Transfer-Encoding: 8bit > + > +busybox mount -o remount reads the mount options from /proc/mounts (or mtab); > +Executing "/bin/mount / -o remount" has no effect when /bin/mount is linked > +to busybox. > + > +remount-fs already reads the options from /etc/fstab, > +so simply pass them to the mount command. > + > +Signed-off-by: André Erdmann <dywi@mailerd.de> > +--- > + src/remount-fs/remount-fs.c | 11 ++++++++++- > + 1 file changed, 10 insertions(+), 1 deletion(-) > + > +diff --git a/src/remount-fs/remount-fs.c b/src/remount-fs/remount-fs.c > +index cd7cfe7..f63f009 100644 > +--- a/src/remount-fs/remount-fs.c > ++++ b/src/remount-fs/remount-fs.c > +@@ -20,6 +20,7 @@ > + ***/ > + > + #include <unistd.h> > ++#include <stdlib.h> > + #include <fcntl.h> > + #include <errno.h> > + #include <string.h> > +@@ -93,18 +94,26 @@ int main(int argc, char *argv[]) { > + } > + > + if (pid == 0) { > ++ char *opts_str; > + const char *arguments[5]; > + /* Child */ > + > ++ opts_str = strappend("remount,", me->mnt_opts); > ++ if (opts_str == NULL) { > ++ log_error("Failed to get remount opts"); > ++ _exit(EXIT_FAILURE); > ++ } > ++ > + arguments[0] = "/bin/mount"; > + arguments[1] = me->mnt_dir; > + arguments[2] = "-o"; > +- arguments[3] = "remount"; > ++ arguments[3] = opts_str; > + arguments[4] = NULL; > + > + execv("/bin/mount", (char **) arguments); > + > + log_error("Failed to execute /bin/mount: %m"); > ++ free(opts_str); > + _exit(EXIT_FAILURE); > + } > + > +-- > +2.1.3 > + > -- > 2.1.3 > > _______________________________________________ > buildroot mailing list > buildroot@busybox.net > http://lists.busybox.net/mailman/listinfo/buildroot
diff --git a/package/systemd/0005-remount-fs-pass-options-from-fstab-to-bin-mount.patch b/package/systemd/0005-remount-fs-pass-options-from-fstab-to-bin-mount.patch new file mode 100644 index 0000000..c6dc661 --- /dev/null +++ b/package/systemd/0005-remount-fs-pass-options-from-fstab-to-bin-mount.patch @@ -0,0 +1,63 @@ +From 7bc0901a00e78f22f97dbd3f85c7a19d9a78e7a1 Mon Sep 17 00:00:00 2001 +From: =?UTF-8?q?Andr=C3=A9=20Erdmann?= <dywi@mailerd.de> +Date: Wed, 12 Nov 2014 17:45:46 +0100 +Subject: [PATCH 1/1] remount-fs: pass options from fstab to /bin/mount +MIME-Version: 1.0 +Content-Type: text/plain; charset=UTF-8 +Content-Transfer-Encoding: 8bit + +busybox mount -o remount reads the mount options from /proc/mounts (or mtab); +Executing "/bin/mount / -o remount" has no effect when /bin/mount is linked +to busybox. + +remount-fs already reads the options from /etc/fstab, +so simply pass them to the mount command. + +Signed-off-by: André Erdmann <dywi@mailerd.de> +--- + src/remount-fs/remount-fs.c | 11 ++++++++++- + 1 file changed, 10 insertions(+), 1 deletion(-) + +diff --git a/src/remount-fs/remount-fs.c b/src/remount-fs/remount-fs.c +index cd7cfe7..f63f009 100644 +--- a/src/remount-fs/remount-fs.c ++++ b/src/remount-fs/remount-fs.c +@@ -20,6 +20,7 @@ + ***/ + + #include <unistd.h> ++#include <stdlib.h> + #include <fcntl.h> + #include <errno.h> + #include <string.h> +@@ -93,18 +94,26 @@ int main(int argc, char *argv[]) { + } + + if (pid == 0) { ++ char *opts_str; + const char *arguments[5]; + /* Child */ + ++ opts_str = strappend("remount,", me->mnt_opts); ++ if (opts_str == NULL) { ++ log_error("Failed to get remount opts"); ++ _exit(EXIT_FAILURE); ++ } ++ + arguments[0] = "/bin/mount"; + arguments[1] = me->mnt_dir; + arguments[2] = "-o"; +- arguments[3] = "remount"; ++ arguments[3] = opts_str; + arguments[4] = NULL; + + execv("/bin/mount", (char **) arguments); + + log_error("Failed to execute /bin/mount: %m"); ++ free(opts_str); + _exit(EXIT_FAILURE); + } + +-- +2.1.3 +
systemd runs "/bin/mount MOUNTPOINT -o remount" for remounting the rootfs (and others like /usr, /proc, ...) [0]. This is supposed to remount the rootfs in rw/ro mode depending on /etc/fstab. busybox' mount -o remount command, however, complety ignores fstab and reads the mount options from /proc/mounts only (+ cmdline "-o ...") [1], so "mount / -o remount" is a no-op. This commit adds a patch that causes systemd's remount-fs to pass the options from /etc/fstab to the mount command. References: [0] http://cgit.freedesktop.org/systemd/systemd/tree/src/remount-fs/remount-fs.c?id=v217 (line 99) [1] http://git.busybox.net/busybox/tree/util-linux/mount.c?h=1_22_stable (line 2133) Signed-off-by: André Erdmann <dywi@mailerd.de> --- Notes: * selecting BR2_PACKAGE_UTIL_LINUX_MOUNT=y would also fix remounting, but that also requires BR2_PACKAGE_UTIL_LINUX_BINARIES=y... * passing all options to mount rather than checking for "rw"/ro" (hasmntopt(...,"ro")==NULL) makes remount-fs behave identical regardless of whether util-linux' or busybox' mount is used (remount-fs also remounts /proc etc.) * a systemd-based buildroot config ignores BR2_TARGET_GENERIC_REMOUNT_ROOTFS_RW This is not changed by this commit, but the rootfs is now always rw unless /etc/fstab gets replaced by a a postbuild script / rootfs overlay. By the way, I have a script for generating /etc/fstab, which could be useful for dealing with remount-ro/rw and systemd-specific mounts (and maybe genimages). Tell me if there's any interest in getting this integrated into buildroot. You can view it here https://gist.github.com/dywisor/62d41835c2dff043f794#file-mkfstab-bash-L17-L96 (not the latest revision, but sufficient for getting an overview.) --- ...t-fs-pass-options-from-fstab-to-bin-mount.patch | 63 ++++++++++++++++++++++ 1 file changed, 63 insertions(+) create mode 100644 package/systemd/0005-remount-fs-pass-options-from-fstab-to-bin-mount.patch