[RFC PATCH] rootfs: force mounting rootfs as tmpfs
From: Mimi Zohar <hidden>
Date: 2018-01-30 21:46:26
Also in:
lkml
Subsystem:
documentation, filesystems (vfs and infrastructure), the rest · Maintainers:
Jonathan Corbet, Alexander Viro, Christian Brauner, Linus Torvalds
Commit 16203a7a9422 ("initmpfs: make rootfs use tmpfs when CONFIG_TMPFS
enabled") introduced using tmpfs as the rootfs filesystem. The use of
tmpfs is limited to systems that do not specify "root=" on the boot
command line.
Without the check "!saved_root_name[0]", rootfs uses tmpfs. As there
must be a valid reason for this check, this patch introduces a new boot
command line option named "noramfs" to force rootfs to use tmpfs.
Signed-off-by: Mimi Zohar <redacted>
---
Documentation/admin-guide/kernel-parameters.txt | 2 ++
init/do_mounts.c | 15 +++++++++++++--
2 files changed, 15 insertions(+), 2 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 6571fbfdb2a1..fd82df2ff150 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt@@ -2733,6 +2733,8 @@ nopcid [X86-64] Disable the PCID cpu feature. + noramfs Don't use ramfs for rootfs, use tmpfs. + norandmaps Don't use address space randomization. Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
diff --git a/init/do_mounts.c b/init/do_mounts.c
index 7cf4f6dafd5f..74d8bfcd1294 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c@@ -315,6 +315,16 @@ static int __init root_data_setup(char *str) return 1; } +static bool force_tmpfs; +static int __init force_tmpfs_setup(char *str) +{ + if (*str) + return 0; + force_tmpfs = true; + return 1; + +} + static char * __initdata root_fs_names; static int __init fs_names_setup(char *str) {
@@ -332,6 +342,7 @@ static int __init root_delay_setup(char *str) __setup("rootflags=", root_data_setup); __setup("rootfstype=", fs_names_setup); __setup("rootdelay=", root_delay_setup); +__setup("noramfs", force_tmpfs_setup); static void __init get_fs_names(char *page) {
@@ -632,8 +643,8 @@ int __init init_rootfs(void) if (err) return err; - if (IS_ENABLED(CONFIG_TMPFS) && !saved_root_name[0] && - (!root_fs_names || strstr(root_fs_names, "tmpfs"))) { + if (IS_ENABLED(CONFIG_TMPFS) && (force_tmpfs || (!saved_root_name[0] && + (!root_fs_names || strstr(root_fs_names, "tmpfs"))))) { err = shmem_init(); is_tmpfs = true; } else {
--
2.7.5
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