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    SubjectRe: [PATCH] use tmpfs for rootfs v2
    On Thu, Oct 16, 2008 at 10:39 AM, Bodo Eggert <7eggert@gmx.de> wrote:
    > This patch allows chosing tmpfs instead of ramfs for the root filesystem.
    > Having tmpfs is usefull for running systems from RAM, because it does not
    > risk deadlocking the system and possibly allows swapping. Using tmpfs
    > increases the kernel by 10 bytes on x86_64.
    >
    > Having tmpfs as the root filesystem allows you to get rid of the now unused
    > ramfs and free some kernel memory. On my system, that's about 5198 bytes
    > compared to having a ramfs root.
    >
    > Off cause you can mount tmpfs and move around the data, but this is slower
    > (having to copy around the data), more error-prone and it uses more memory.
    > Besides that, I don't see the point in explicitely doing the wrong thing
    > and then having everybody fix it.
    >
    >
    > Signed-off-by: Bodo Eggert <7eggert@gmx.de>
    >
    > ---
    > Changes to v1: Include the change to the Makefile.
    >
    > Some numbers for my system: (from make and from size vmlinux)
    >
    > Setup is 10716 bytes (padded to 10752 bytes).
    > System is 2659 kB
    > text data bss dec hex filename
    > 5341667 874212 562992 6778871 676ff7 vmlinux
    >
    > having TMPFS_IS_ROOT:
    > Setup is 10716 bytes (padded to 10752 bytes).
    > System is 2659 kB
    > text data bss dec hex filename
    > 5341677 874212 562992 6778881 677001 vmlinux
    > +10
    >
    > not having ramfs:
    > Setup is 10716 bytes (padded to 10752 bytes).
    > System is 2659 kB
    > text data bss dec hex filename
    > 5336733 873948 562992 6773673 675ba9 vmlinux
    > -4934 -264
    >
    >
    > fs/Kconfig | 21 +++++++++++++++++++++
    > fs/Makefile | 2 +-
    > fs/ramfs/inode.c | 39 +++++++++++++++++++++------------------
    > mm/shmem.c | 26 ++++++++++++++++++++++++++
    > 4 files changed, 69 insertions(+), 19 deletions(-)
    >
    > diff -pruNXdontdiff linux-2.6.27.2-numlock/fs/Kconfig linux-2.6.27.3-tmpfs/fs/Kconfig
    > --- linux-2.6.27.2-numlock/fs/Kconfig 2008-10-10 13:18:34.000000000 +0200
    > +++ linux-2.6.27.3-tmpfs/fs/Kconfig 2008-10-11 15:42:21.000000000 +0200
    > @@ -953,6 +953,27 @@ 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 && SHMEM
    > + default n
    > + help
    > + This replaces the ramfs used for unpacking the cpio images
    > + with tmpfs.
    > +
    > + If unsure, say N
    > +
    > +config RAMFS
    > + bool "Ramfs file system support" if TMPFS_ROOT
    > + default y
    > + ---help---
    > + Ramfs is a file system which keeps all files in RAM. Unlike tmpfs,
    > + it cannot be swapped to disk, and it has the risk of deadlocking
    > + the system by using all memory.
    > +
    > + Ramfs is used for booting the system and unpacking the cpio if
    > + TMPFS_ROOT is not set.
    > +
    > config HUGETLBFS
    > bool "HugeTLB file system support"
    > depends on X86 || IA64 || PPC64 || SPARC64 || (SUPERH && MMU) || \
    > diff -pruNXdontdiff linux-2.6.27.2-numlock/fs/ramfs/inode.c linux-2.6.27.3-tmpfs/fs/ramfs/inode.c
    > --- linux-2.6.27.2-numlock/fs/ramfs/inode.c 2008-07-13 23:51:29.000000000 +0200
    > +++ linux-2.6.27.3-tmpfs/fs/ramfs/inode.c 2008-10-11 15:50:03.000000000 +0200
    > @@ -190,6 +190,13 @@ 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,
    > +};
    > +
    > +#ifndef 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)
    > {
    > @@ -197,30 +204,12 @@ 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,
    > };
    >
    > -static int __init init_ramfs_fs(void)
    > -{
    > - return register_filesystem(&ramfs_fs_type);
    > -}
    > -
    > -static void __exit exit_ramfs_fs(void)
    > -{
    > - unregister_filesystem(&ramfs_fs_type);
    > -}
    > -
    > -module_init(init_ramfs_fs)
    > -module_exit(exit_ramfs_fs)
    > -
    > int __init init_rootfs(void)
    > {
    > int err;
    > @@ -235,5 +224,19 @@ int __init init_rootfs(void)
    >
    > return err;
    > }
    > +#endif
    > +
    > +static int __init init_ramfs_fs(void)
    > +{
    > + return register_filesystem(&ramfs_fs_type);
    > +}
    > +
    > +static void __exit exit_ramfs_fs(void)
    > +{
    > + unregister_filesystem(&ramfs_fs_type);
    > +}
    > +
    > +module_init(init_ramfs_fs)
    > +module_exit(exit_ramfs_fs)
    >
    > MODULE_LICENSE("GPL");
    > diff -pruNXdontdiff linux-2.6.27.2-numlock/mm/shmem.c linux-2.6.27.3-tmpfs/mm/shmem.c
    > --- linux-2.6.27.2-numlock/mm/shmem.c 2008-10-10 13:18:47.000000000 +0200
    > +++ linux-2.6.27.3-tmpfs/mm/shmem.c 2008-10-11 16:05:52.000000000 +0200
    > @@ -2366,6 +2366,10 @@ static void init_once(void *foo)
    >
    > static int init_inodecache(void)
    > {
    > +#ifdef CONFIG_TMPFS_ROOT
    > + if (shmem_inode_cachep)
    > + return 0;
    > +#endif
    > shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
    > sizeof(struct shmem_inode_info),
    > 0, SLAB_PANIC, init_once);
    > @@ -2583,6 +2587,28 @@ 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, data, shmem_fill_super, mnt);
    > +}
    > +
    > +
    > + 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
    > * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
    > diff -pruNXdontdiff linux-2.6.27.2-numlock/fs/Makefile linux-2.6.27.3-tmpfs/fs/Makefile
    > --- linux-2.6.27.2-numlock/fs/Makefile 2008-10-16 19:25:20.000000000 +0200
    > +++ linux-2.6.27.3-tmpfs/fs/Makefile 2008-10-16 19:24:00.000000000 +0200
    > @@ -67,6 +67,7 @@ obj-$(CONFIG_PROFILING) += dcookies.o
    > obj-$(CONFIG_DLM) += dlm/
    >
    > # Do not add any filesystems before this line
    > +obj-$(CONFIG_RAMFS) += ramfs/
    > obj-$(CONFIG_REISERFS_FS) += reiserfs/
    > obj-$(CONFIG_EXT3_FS) += ext3/ # Before ext2 so root fs can be ext3
    > obj-$(CONFIG_EXT4DEV_FS) += ext4/ # Before ext2 so root fs can be ext4dev
    > @@ -74,7 +75,6 @@ obj-$(CONFIG_JBD) += jbd/
    > obj-$(CONFIG_JBD2) += jbd2/
    > obj-$(CONFIG_EXT2_FS) += ext2/
    > obj-$(CONFIG_CRAMFS) += cramfs/
    > -obj-y += ramfs/
    > obj-$(CONFIG_HUGETLBFS) += hugetlbfs/
    > obj-$(CONFIG_CODA_FS) += coda/
    > obj-$(CONFIG_MINIX_FS) += minix/

    Haven't gotten the hang of attaching patches inline using gmail yet.
    Here is a patch ontop of the previous one that fixes whitespace problems
    pointed out by checkpatch.pl. It is based on 2.7.27
    3fa8749e584b55f1180411ab1b51117190bac1e5

    It is also available here:
    http://www.digitalprognosis.com/opensource/patches/linux-2.6/0001-Cleanup-the-whitespace-to-be-checkpatch-compliant.patch

    --
    Jeff Schroeder

    Don't drink and derive, alcohol and analysis don't mix.
    http://www.digitalprognosis.com
    From e1fe0b8129d1769c834bff4262bab356e8d444bb Mon Sep 17 00:00:00 2001
    From: Jeff Schroeder <jeffschroeder@computer.org>
    Date: Thu, 16 Oct 2008 13:47:20 -0700
    Subject: [PATCH] Cleanup the whitespace to be checkpatch compliant

    Applies ontop of: http://lkml.org/lkml/diff/2008/10/16/388/1
    Signed-off-by: Jeff Schroeder <jeffschroeder@computer.org>
    ---
    mm/shmem.c | 30 +++++++++++++++---------------
    1 files changed, 15 insertions(+), 15 deletions(-)

    diff --git a/mm/shmem.c b/mm/shmem.c
    index a1d2042..d1b3cd8 100644
    --- a/mm/shmem.c
    +++ b/mm/shmem.c
    @@ -2594,21 +2594,21 @@ static int rootfs_get_sb(struct file_system_type *fs_type,
    return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt);
    }

    -
    - 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
    -
    +
    +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
    * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
    --
    1.5.4.3
    \
     
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      Last update: 2008-10-16 23:05    [W:4.100 / U:0.060 seconds]
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