The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-4.19.y git checkout FETCH_HEAD git cherry-pick -x 21528c69a0d8483f7c6345b1a0bc8d8975e9a172 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024012238-coke-debrief-5c9b@gregkh' --subject-prefix 'PATCH 4.19.y' HEAD^..

Possible dependencies:

21528c69a0d8 ("rootfs: Fix support for rootfstype= when root= is given") 037f11b4752f ("mnt_init(): call shmem_init() unconditionally") fd3e007f6c6a ("don't bother with registering rootfs") 14a253ce4210 ("init_rootfs(): don't bother with init_ramfs_fs()") 9bc61ab18b1d ("vfs: Introduce fs_context, switch vfs_kern_mount() to it.") 505b050fdf42 ("Merge branch 'mount.part1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 21528c69a0d8483f7c6345b1a0bc8d8975e9a172 Mon Sep 17 00:00:00 2001 From: Stefan Berger stefanb@linux.ibm.com Date: Sun, 19 Nov 2023 20:12:48 -0500 Subject: [PATCH] rootfs: Fix support for rootfstype= when root= is given

Documentation/filesystems/ramfs-rootfs-initramfs.rst states:

If CONFIG_TMPFS is enabled, rootfs will use tmpfs instead of ramfs by default. To force ramfs, add "rootfstype=ramfs" to the kernel command line.

This currently does not work when root= is provided since then saved_root_name contains a string and rootfstype= is ignored. Therefore, ramfs is currently always chosen when root= is provided.

The current behavior for rootfs's filesystem is:

root= | rootfstype= | chosen rootfs filesystem ------------+-------------+-------------------------- unspecified | unspecified | tmpfs unspecified | tmpfs | tmpfs unspecified | ramfs | ramfs provided | ignored | ramfs

rootfstype= should be respected regardless whether root= is given, as shown below:

root= | rootfstype= | chosen rootfs filesystem ------------+-------------+-------------------------- unspecified | unspecified | tmpfs (as before) unspecified | tmpfs | tmpfs (as before) unspecified | ramfs | ramfs (as before) provided | unspecified | ramfs (compatibility with before) provided | tmpfs | tmpfs (new) provided | ramfs | ramfs (new)

This table represents the new behavior.

Fixes: 6e19eded3684 ("initmpfs: use initramfs if rootfstype= or root= specified") Cc: stable@vger.kernel.org Signed-off-by: Rob Landley rob@landley.net Link: https://lore.kernel.org/lkml/8244c75f-445e-b15b-9dbf-266e7ca666e2@landley.ne... Reviewed-and-Tested-by: Mimi Zohar zohar@linux.ibm.com Signed-off-by: Stefan Berger stefanb@linux.ibm.com Link: https://lore.kernel.org/r/20231120011248.396012-1-stefanb@linux.ibm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

diff --git a/init/do_mounts.c b/init/do_mounts.c index 5fdef94f0864..279ad28bf4fb 100644 --- a/init/do_mounts.c +++ b/init/do_mounts.c @@ -510,7 +510,10 @@ struct file_system_type rootfs_fs_type = {

void __init init_rootfs(void) { - if (IS_ENABLED(CONFIG_TMPFS) && !saved_root_name[0] && - (!root_fs_names || strstr(root_fs_names, "tmpfs"))) - is_tmpfs = true; + if (IS_ENABLED(CONFIG_TMPFS)) { + if (!saved_root_name[0] && !root_fs_names) + is_tmpfs = true; + else if (root_fs_names && !!strstr(root_fs_names, "tmpfs")) + is_tmpfs = true; + } }