From 6e19eded3684dc184181093af3bff2ff440f5b53 Mon Sep 17 00:00:00 2001 From: Rob Landley Date: Wed, 11 Sep 2013 14:26:13 -0700 Subject: [PATCH] initmpfs: use initramfs if rootfstype= or root= specified Command line option rootfstype=ramfs to obtain old initramfs behavior, and use ramfs instead of tmpfs for stub when root= defined (for cosmetic reasons). [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Rob Landley Cc: Jeff Layton Cc: Jens Axboe Cc: Stephen Warren Cc: Rusty Russell Cc: Jim Cromie Cc: Sam Ravnborg Cc: Greg Kroah-Hartman Cc: "Eric W. Biederman" Cc: Alexander Viro Cc: "H. Peter Anvin" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- .../filesystems/ramfs-rootfs-initramfs.txt | 4 ++++ init/do_mounts.c | 15 +++++++++++---- 2 files changed, 15 insertions(+), 4 deletions(-) diff --git a/Documentation/filesystems/ramfs-rootfs-initramfs.txt b/Documentation/filesystems/ramfs-rootfs-initramfs.txt index 59b4a0962e0f..b176928e6963 100644 --- a/Documentation/filesystems/ramfs-rootfs-initramfs.txt +++ b/Documentation/filesystems/ramfs-rootfs-initramfs.txt @@ -79,6 +79,10 @@ to just make sure certain lists can't become empty. Most systems just mount another filesystem over rootfs and ignore it. The amount of space an empty instance of ramfs takes up is tiny. +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. + What is initramfs? ------------------ diff --git a/init/do_mounts.c b/init/do_mounts.c index e27908b949d4..a51cddc2ff8c 100644 --- a/init/do_mounts.c +++ b/init/do_mounts.c @@ -591,16 +591,20 @@ out: sys_chroot("."); } +static bool is_tmpfs; static struct dentry *rootfs_mount(struct file_system_type *fs_type, int flags, const char *dev_name, void *data) { static unsigned long once; + void *fill = ramfs_fill_super; if (test_and_set_bit(0, &once)) return ERR_PTR(-ENODEV); - return mount_nodev(fs_type, flags, data, - IS_ENABLED(CONFIG_TMPFS) ? shmem_fill_super : ramfs_fill_super); + if (IS_ENABLED(CONFIG_TMPFS) && is_tmpfs) + fill = shmem_fill_super; + + return mount_nodev(fs_type, flags, data, fill); } static struct file_system_type rootfs_fs_type = { @@ -616,10 +620,13 @@ int __init init_rootfs(void) if (err) return err; - if (IS_ENABLED(CONFIG_TMPFS)) + if (IS_ENABLED(CONFIG_TMPFS) && !saved_root_name[0] && + (!root_fs_names || strstr(root_fs_names, "tmpfs"))) { err = shmem_init(); - else + is_tmpfs = true; + } else { err = init_ramfs_fs(); + } if (err) unregister_filesystem(&rootfs_fs_type); -- 2.20.1