Change the root filesystem to tmpfs. Doing this makes having a system on
tmpfs much easier, while allowing to discard the now unnecessary ramfs.
Having the rootfs on tmpfs allows to safely run e.g. a rescue system without
using tricks. You might even include the rescue system into the kernel.
This is a rework of Al Boldi's "[PATCH] initramfs: Allow rootfs to use
tmpfs instead of ramfs". All the fame belongs to him, the bugs belong to me.
Signed-Off-By: Bodo Eggert <[email protected]>
diff -Xdontdiff -pruN linux-2.6.22.base/fs/Kconfig linux-2.6.22.tmpfsroot/fs/Kconfig
--- linux-2.6.22.base/fs/Kconfig 2007-07-12 14:05:16.000000000 +0200
+++ linux-2.6.22.tmpfsroot/fs/Kconfig 2007-07-12 15:10:09.000000000 +0200
@@ -989,6 +989,22 @@ config TMPFS_POSIX_ACL
If you don't know what Access Control Lists are, say N.
+config TMPFS_ROOT
+ bool "Use tmpfs instrad of ramfs for initramfs"
+ depends on TMPFS
+ default n
+ help
+ This replaces the ramfs used for unpacking the cpio images
+ with tmpfs, thereby allowing swapping these contents to disk and
+ adding size limit support.
+
+ Side effect:
+ This is useful only if you don't plan on mounting a different
+ root filesystem. Therefore it will change the default of the
+ root= parameter to "rootfs".
+
+ If unsure, say N
+
config HUGETLBFS
bool "HugeTLB file system support"
depends on X86 || IA64 || PPC64 || SPARC64 || SUPERH || BROKEN
@@ -1003,7 +1019,7 @@ config HUGETLB_PAGE
def_bool HUGETLBFS
config RAMFS
- bool
+ bool "Ramfs file system support" if TMPFS_ROOT
default y
---help---
Ramfs is a file system which keeps all files in RAM. It allows
diff -Xdontdiff -pruN linux-2.6.22.base/fs/ramfs/inode.c linux-2.6.22.tmpfsroot/fs/ramfs/inode.c
--- linux-2.6.22.base/fs/ramfs/inode.c 2007-07-12 14:05:17.000000000 +0200
+++ linux-2.6.22.tmpfsroot/fs/ramfs/inode.c 2007-07-12 15:01:32.000000000 +0200
@@ -189,6 +189,13 @@ int ramfs_get_sb(struct file_system_type
return get_sb_nodev(fs_type, flags, data, ramfs_fill_super, mnt);
}
+static struct file_system_type ramfs_fs_type = {
+ .name = "ramfs",
+ .get_sb = ramfs_get_sb,
+ .kill_sb = kill_litter_super,
+};
+
+#ifdef CONFIG_RAMFS_ROOTFS
static int rootfs_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data, struct vfsmount *mnt)
{
@@ -196,17 +203,18 @@ static int rootfs_get_sb(struct file_sys
mnt);
}
-static struct file_system_type ramfs_fs_type = {
- .name = "ramfs",
- .get_sb = ramfs_get_sb,
- .kill_sb = kill_litter_super,
-};
static struct file_system_type rootfs_fs_type = {
.name = "rootfs",
.get_sb = rootfs_get_sb,
.kill_sb = kill_litter_super,
};
+int __init init_rootfs(void)
+{
+ return register_filesystem(&rootfs_fs_type);
+}
+#endif
+
static int __init init_ramfs_fs(void)
{
return register_filesystem(&ramfs_fs_type);
@@ -220,9 +228,4 @@ static void __exit exit_ramfs_fs(void)
module_init(init_ramfs_fs)
module_exit(exit_ramfs_fs)
-int __init init_rootfs(void)
-{
- return register_filesystem(&rootfs_fs_type);
-}
-
MODULE_LICENSE("GPL");
diff -Xdontdiff -pruN linux-2.6.22.base/init/do_mounts.c linux-2.6.22.tmpfsroot/init/do_mounts.c
--- linux-2.6.22.base/init/do_mounts.c 2007-07-12 15:04:48.000000000 +0200
+++ linux-2.6.22.tmpfsroot/init/do_mounts.c 2007-07-12 14:53:07.000000000 +0200
@@ -24,7 +24,11 @@ int __initdata rd_doload; /* 1 = load RA
int root_mountflags = MS_RDONLY | MS_SILENT;
char * __initdata root_device_name;
+#ifdef CONFIG_TMPFS_ROOT
+static char __initdata saved_root_name[64] = "rootfs";
+#else
static char __initdata saved_root_name[64];
+#endif
dev_t ROOT_DEV;
diff -Xdontdiff -pruN linux-2.6.22.base/mm/shmem.c linux-2.6.22.tmpfsroot/mm/shmem.c
--- linux-2.6.22.base/mm/shmem.c 2007-07-12 14:05:25.000000000 +0200
+++ linux-2.6.22.tmpfsroot/mm/shmem.c 2007-07-12 15:01:32.000000000 +0200
@@ -2369,6 +2369,8 @@ static void init_once(void *foo, struct
static int init_inodecache(void)
{
+ if (shmem_inode_cachep)
+ return 0;
shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
sizeof(struct shmem_inode_info),
0, 0, init_once, NULL);
@@ -2582,6 +2584,34 @@ put_memory:
return ERR_PTR(error);
}
+#ifdef CONFIG_TMPFS_ROOT
+static int rootfs_get_sb(struct file_system_type *fs_type,
+ int flags, const char *dev_name, void *data, struct vfsmount *mnt)
+{
+ return get_sb_nodev(fs_type, flags|MS_NOUSER, data, shmem_fill_super,
+ mnt);
+}
+
+/*static struct super_block *rootfs_get_sb(struct file_system_type *fs_type,
+ int flags, const char *dev_name, void *data)
+{
+ return get_sb_single(fs_type, flags, data, shmem_fill_super);
+}*/
+
+static struct file_system_type rootfs_fs_type = {
+ .name = "rootfs",
+ .get_sb = rootfs_get_sb,
+ .kill_sb = kill_litter_super,
+};
+
+int __init init_rootfs(void)
+{
+ if (init_inodecache())
+ panic("Can't initialize shm inode cache");
+ return register_filesystem(&rootfs_fs_type);
+}
+#endif
+
/*
* shmem_zero_setup - setup a shared anonymous mapping
*
-
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