* [PATCH 1/5] initmpfs v2: replace MS_NOUSER in initramfs
2013-07-16 23:45 [PATCH 0/5] initmpfs v2: use tmpfs instead of ramfs for rootfs Rob Landley
@ 2013-07-16 23:45 ` Rob Landley
2013-07-16 23:45 ` [PATCH 2/5] initmpfs v2: Move bdi setup from init_rootfs to init_ramfs Rob Landley
` (3 subsequent siblings)
4 siblings, 0 replies; 12+ messages in thread
From: Rob Landley @ 2013-07-16 23:45 UTC (permalink / raw)
To: linux-kernel; +Cc: Al Viro, Eric W. Biederman, Andrew Morton
From: Rob Landley <rob@landley.net>
Mounting MS_NOUSER prevents --bind mounts from rootfs. Prevent new rootfs
mounts with a different mechanism that doesn't affect bind mounts.
Signed-off-by: Rob Landley <rob@landley.net>
---
fs/ramfs/inode.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/fs/ramfs/inode.c b/fs/ramfs/inode.c
index c24f1e1..14b9c35 100644
--- a/fs/ramfs/inode.c
+++ b/fs/ramfs/inode.c
@@ -247,7 +247,12 @@ struct dentry *ramfs_mount(struct file_system_type *fs_type,
static struct dentry *rootfs_mount(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data)
{
- return mount_nodev(fs_type, flags|MS_NOUSER, data, ramfs_fill_super);
+ static unsigned long once;
+
+ if (test_and_set_bit(1, &once))
+ return ERR_PTR(-ENODEV);
+
+ return mount_nodev(fs_type, flags, data, ramfs_fill_super);
}
static void ramfs_kill_sb(struct super_block *sb)
^ permalink raw reply [flat|nested] 12+ messages in thread* [PATCH 2/5] initmpfs v2: Move bdi setup from init_rootfs to init_ramfs
2013-07-16 23:45 [PATCH 0/5] initmpfs v2: use tmpfs instead of ramfs for rootfs Rob Landley
2013-07-16 23:45 ` [PATCH 1/5] initmpfs v2: replace MS_NOUSER in initramfs Rob Landley
@ 2013-07-16 23:45 ` Rob Landley
2013-07-16 23:45 ` [PATCH 3/5] initmpfs v2: Move rootfs code from fs/ramfs/ to init/ Rob Landley
` (2 subsequent siblings)
4 siblings, 0 replies; 12+ messages in thread
From: Rob Landley @ 2013-07-16 23:45 UTC (permalink / raw)
To: linux-kernel; +Cc: Al Viro, Eric W. Biederman, Andrew Morton
From: Rob Landley <rob@landley.net>
Even though ramfs hasn't got a backing device, commit e0bf68ddec4f added one
anyway, and put the initialization in init_rootfs() since that's the first
user, leaving it out of init_ramfs() to avoid duplication.
But initmpfs uses init_tmpfs() instead, so move the init into the filesystem's
init function, add a "once" guard to prevent duplicate initialization, and
call the filesystem init from rootfs init.
This goes part of the way to allowing ramfs to be built as a module.
Signed-off-by: Rob Landley <rob@landley.net>
---
fs/ramfs/inode.c | 23 ++++++++++++++++++-----
1 file changed, 18 insertions(+), 5 deletions(-)
--- initold/fs/ramfs/inode.c 2013-06-28 15:12:03.205879730 -0500
+++ initold2/fs/ramfs/inode.c 2013-06-28 15:12:12.425880115 -0500
@@ -275,21 +275,34 @@
static int __init init_ramfs_fs(void)
{
- return register_filesystem(&ramfs_fs_type);
+ static unsigned long once;
+ int err;
+
+ if (test_and_set_bit(1, &once))
+ return 0;
+
+ err = bdi_init(&ramfs_backing_dev_info);
+ if (err)
+ return err;
+
+ err = register_filesystem(&ramfs_fs_type);
+ if (err)
+ bdi_destroy(&ramfs_backing_dev_info);
+
+ return err;
}
module_init(init_ramfs_fs)
int __init init_rootfs(void)
{
- int err;
+ int err = register_filesystem(&rootfs_fs_type);
- err = bdi_init(&ramfs_backing_dev_info);
if (err)
return err;
- err = register_filesystem(&rootfs_fs_type);
+ err = init_ramfs_fs();
if (err)
- bdi_destroy(&ramfs_backing_dev_info);
+ unregister_filesystem(&rootfs_fs_type);
return err;
}
^ permalink raw reply [flat|nested] 12+ messages in thread* [PATCH 3/5] initmpfs v2: Move rootfs code from fs/ramfs/ to init/
2013-07-16 23:45 [PATCH 0/5] initmpfs v2: use tmpfs instead of ramfs for rootfs Rob Landley
2013-07-16 23:45 ` [PATCH 1/5] initmpfs v2: replace MS_NOUSER in initramfs Rob Landley
2013-07-16 23:45 ` [PATCH 2/5] initmpfs v2: Move bdi setup from init_rootfs to init_ramfs Rob Landley
@ 2013-07-16 23:45 ` Rob Landley
2013-07-16 23:45 ` [PATCH 4/5] initmpfs v2: Make rootfs use tmpfs when CONFIG_TMPFS enabled Rob Landley
2013-07-16 23:45 ` [PATCH 5/5] initmpfs v2: Use initramfs if rootfstype= or root= specified Rob Landley
4 siblings, 0 replies; 12+ messages in thread
From: Rob Landley @ 2013-07-16 23:45 UTC (permalink / raw)
To: linux-kernel
Cc: linux-fsdevel, Jeff Layton, Jens Axboe, Stephen Warren,
Rusty Russell, Jim Cromie, Sam Ravnborg, Greg Kroah-Hartman,
Andrew Morton, Eric W. Biederman, Alexander Viro
From: Rob Landley <rob@landley.net>
When the rootfs code was a wrapper around ramfs, having them in the same
file made sense. Now that it can wrap another filesystem type, move it
in with the init code instead.
This also allows a subsequent patch to access rootfstype= command line arg.
Signed-off-by: Rob Landley <rob@landley.net>
---
fs/namespace.c | 2 +-
fs/ramfs/inode.c | 32 +-------------------------------
include/linux/init.h | 1 +
include/linux/ramfs.h | 2 +-
init/do_mounts.c | 32 ++++++++++++++++++++++++++++++++
5 files changed, 36 insertions(+), 33 deletions(-)
--- initold/fs/namespace.c 2013-06-28 15:09:19.389872904 -0500
+++ initold2/fs/namespace.c 2013-06-28 15:16:05.261889820 -0500
@@ -17,7 +17,7 @@
#include <linux/security.h>
#include <linux/idr.h>
#include <linux/acct.h> /* acct_auto_close_mnt */
-#include <linux/ramfs.h> /* init_rootfs */
+#include <linux/init.h> /* init_rootfs */
#include <linux/fs_struct.h> /* get_fs_root et.al. */
#include <linux/fsnotify.h> /* fsnotify_vfsmount_delete */
#include <linux/uaccess.h>
--- initold/fs/ramfs/inode.c 2013-06-28 15:15:37.549888666 -0500
+++ initold2/fs/ramfs/inode.c 2013-06-28 15:16:05.273889820 -0500
@@ -244,17 +244,6 @@
return mount_nodev(fs_type, flags, data, ramfs_fill_super);
}
-static struct dentry *rootfs_mount(struct file_system_type *fs_type,
- int flags, const char *dev_name, void *data)
-{
- static unsigned long once;
-
- if (test_and_set_bit(1, &once))
- return ERR_PTR(-ENODEV);
-
- return mount_nodev(fs_type, flags, data, ramfs_fill_super);
-}
-
static void ramfs_kill_sb(struct super_block *sb)
{
kfree(sb->s_fs_info);
@@ -267,13 +256,8 @@
.kill_sb = ramfs_kill_sb,
.fs_flags = FS_USERNS_MOUNT,
};
-static struct file_system_type rootfs_fs_type = {
- .name = "rootfs",
- .mount = rootfs_mount,
- .kill_sb = kill_litter_super,
-};
-static int __init init_ramfs_fs(void)
+int __init init_ramfs_fs(void)
{
static unsigned long once;
int err;
@@ -292,17 +276,3 @@
return err;
}
module_init(init_ramfs_fs)
-
-int __init init_rootfs(void)
-{
- int err = register_filesystem(&rootfs_fs_type);
-
- if (err)
- return err;
-
- err = init_ramfs_fs();
- if (err)
- unregister_filesystem(&rootfs_fs_type);
-
- return err;
-}
--- initold/include/linux/init.h 2013-06-28 15:09:19.517872909 -0500
+++ initold2/include/linux/init.h 2013-06-28 15:16:05.321889821 -0500
@@ -153,6 +153,7 @@
void setup_arch(char **);
void prepare_namespace(void);
void __init load_default_modules(void);
+int __init init_rootfs(void);
extern void (*late_time_init)(void);
--- initold/include/linux/ramfs.h 2013-06-28 15:09:19.537872910 -0500
+++ initold2/include/linux/ramfs.h 2013-06-28 15:16:05.513889832 -0500
@@ -25,7 +25,7 @@
extern const struct file_operations ramfs_file_operations;
extern const struct vm_operations_struct generic_file_vm_ops;
-extern int __init init_rootfs(void);
+extern int __init init_ramfs_fs(void);
int ramfs_fill_super(struct super_block *sb, void *data, int silent);
--- initold/init/do_mounts.c 2013-06-28 15:09:19.585872913 -0500
+++ initold2/init/do_mounts.c 2013-06-28 15:16:05.561889831 -0500
@@ -26,6 +26,7 @@
#include <linux/async.h>
#include <linux/fs_struct.h>
#include <linux/slab.h>
+#include <linux/ramfs.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_fs_sb.h>
@@ -588,3 +589,34 @@
sys_mount(".", "/", NULL, MS_MOVE, NULL);
sys_chroot(".");
}
+
+static struct dentry *rootfs_mount(struct file_system_type *fs_type,
+ int flags, const char *dev_name, void *data)
+{
+ static unsigned long once;
+
+ if (test_and_set_bit(1, &once))
+ return ERR_PTR(-ENODEV);
+
+ return mount_nodev(fs_type, flags, data, ramfs_fill_super);
+}
+
+static struct file_system_type rootfs_fs_type = {
+ .name = "rootfs",
+ .mount = rootfs_mount,
+ .kill_sb = kill_litter_super,
+};
+
+int __init init_rootfs(void)
+{
+ int err = register_filesystem(&rootfs_fs_type);
+
+ if (err)
+ return err;
+
+ err = init_ramfs_fs();
+ if (err)
+ unregister_filesystem(&rootfs_fs_type);
+
+ return err;
+}
diff --git a/fs/ramfs/inode.c b/fs/ramfs/inode.c
index c24f1e1..3b9f114 100644
^ permalink raw reply [flat|nested] 12+ messages in thread* [PATCH 4/5] initmpfs v2: Make rootfs use tmpfs when CONFIG_TMPFS enabled.
2013-07-16 23:45 [PATCH 0/5] initmpfs v2: use tmpfs instead of ramfs for rootfs Rob Landley
` (2 preceding siblings ...)
2013-07-16 23:45 ` [PATCH 3/5] initmpfs v2: Move rootfs code from fs/ramfs/ to init/ Rob Landley
@ 2013-07-16 23:45 ` Rob Landley
2013-07-16 23:45 ` [PATCH 5/5] initmpfs v2: Use initramfs if rootfstype= or root= specified Rob Landley
4 siblings, 0 replies; 12+ messages in thread
From: Rob Landley @ 2013-07-16 23:45 UTC (permalink / raw)
To: linux-kernel
Cc: linux-mm, Al Viro, Greg Kroah-Hartman, Jens Axboe,
Stephen Warren, Andrew Morton, Hugh Dickins
From: Rob Landley <rob@landley.net>
Conditionally call the appropriate fs_init function and fill_super functions.
Add a use once guard to shmem_init() to simply succeed on a second call.
(Note that IS_ENABLED() is a compile time constant so dead code elimination
removes unused function calls when CONFIG_TMPFS is disabled.)
Signed-off-by: Rob Landley <rob@landley.net>
---
init/do_mounts.c | 10 ++++++++--
mm/shmem.c | 4 ++++
2 files changed, 12 insertions(+), 2 deletions(-)
--- initold/init/do_mounts.c 2013-06-27 00:02:26.283442977 -0500
+++ initwork/init/do_mounts.c 2013-06-27 00:45:21.599550312 -0500
@@ -27,6 +27,7 @@
#include <linux/fs_struct.h>
#include <linux/slab.h>
#include <linux/ramfs.h>
+#include <linux/shmem_fs.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_fs_sb.h>
@@ -598,7 +597,8 @@
if (test_and_set_bit(1, &once))
return ERR_PTR(-ENODEV);
- return mount_nodev(fs_type, flags, data, ramfs_fill_super);
+ return mount_nodev(fs_type, flags, data,
+ IS_ENABLED(CONFIG_TMPFS) ? shmem_fill_super : ramfs_fill_super);
}
static struct file_system_type rootfs_fs_type = {
@@ -614,7 +614,11 @@
if (err)
return err;
- err = init_ramfs_fs();
+ if (IS_ENABLED(CONFIG_TMPFS))
+ err = shmem_init();
+ else
+ err = init_ramfs_fs();
+
if (err)
unregister_filesystem(&rootfs_fs_type);
--- initold/mm/shmem.c 2013-06-25 13:09:22.215743137 -0500
+++ initwork/mm/shmem.c 2013-06-27 00:16:58.195479317 -0500
@@ -2816,6 +2816,10 @@
{
int error;
+ /* If rootfs called this, don't re-init */
+ if (shmem_inode_cachep)
+ return 0;
+
error = bdi_init(&shmem_backing_dev_info);
if (error)
goto out4;
^ permalink raw reply [flat|nested] 12+ messages in thread* [PATCH 5/5] initmpfs v2: Use initramfs if rootfstype= or root= specified.
2013-07-16 23:45 [PATCH 0/5] initmpfs v2: use tmpfs instead of ramfs for rootfs Rob Landley
` (3 preceding siblings ...)
2013-07-16 23:45 ` [PATCH 4/5] initmpfs v2: Make rootfs use tmpfs when CONFIG_TMPFS enabled Rob Landley
@ 2013-07-16 23:45 ` Rob Landley
2013-07-19 19:57 ` Andrew Morton
4 siblings, 1 reply; 12+ messages in thread
From: Rob Landley @ 2013-07-16 23:45 UTC (permalink / raw)
To: linux-kernel
Cc: Al Viro, Greg Kroah-Hartman, Jens Axboe, Stephen Warren, Andrew Morton
From: Rob Landley <rob@landley.net>
Command line option rootfstype=ramfs to obtain old initramfs behavior,
and use ramfs instead of tmpfs for stub when root= defined (for cosmetic
reasons).
Signed-off-by: Rob Landley <rob@landley.net>
---
init/do_mounts.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
--- initold/init/do_mounts.c 2013-06-29 13:27:00.485256840 -0500
+++ initwork/init/do_mounts.c 2013-06-29 13:34:17.925275072 -0500
@@ -591,16 +591,20 @@
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(1, &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 = {
@@ -616,9 +620,12 @@
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)
^ permalink raw reply [flat|nested] 12+ messages in thread* Re: [PATCH 5/5] initmpfs v2: Use initramfs if rootfstype= or root= specified.
2013-07-16 23:45 ` [PATCH 5/5] initmpfs v2: Use initramfs if rootfstype= or root= specified Rob Landley
@ 2013-07-19 19:57 ` Andrew Morton
2013-07-26 4:12 ` Rob Landley
0 siblings, 1 reply; 12+ messages in thread
From: Andrew Morton @ 2013-07-19 19:57 UTC (permalink / raw)
To: Rob Landley
Cc: linux-kernel, Al Viro, Greg Kroah-Hartman, Jens Axboe, Stephen Warren
On Tue, 16 Jul 2013 16:45:39 -0700 (PDT) Rob Landley <rob@landley.net> wrote:
> Command line option rootfstype=ramfs to obtain old initramfs behavior,
> and use ramfs instead of tmpfs for stub when root= defined (for cosmetic
> reasons).
Could we get a Documentation/kernel-parameters.txt update please?
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH 5/5] initmpfs v2: Use initramfs if rootfstype= or root= specified.
2013-07-19 19:57 ` Andrew Morton
@ 2013-07-26 4:12 ` Rob Landley
0 siblings, 0 replies; 12+ messages in thread
From: Rob Landley @ 2013-07-26 4:12 UTC (permalink / raw)
To: Andrew Morton
Cc: linux-kernel, Al Viro, Greg Kroah-Hartman, Jens Axboe, Stephen Warren
On 07/19/2013 02:57:18 PM, Andrew Morton wrote:
> On Tue, 16 Jul 2013 16:45:39 -0700 (PDT) Rob Landley
> <rob@landley.net> wrote:
>
> > Command line option rootfstype=ramfs to obtain old initramfs
> behavior,
> > and use ramfs instead of tmpfs for stub when root= defined (for
> cosmetic
> > reasons).
>
> Could we get a Documentation/kernel-parameters.txt update please?
Sorry for the delay, traveling. Behind on email...
"rootfstype" is already documented in kernel parameters:
rootfstype= [KNL] Set root filesystem type
I just applied the existing definition to initramfs now that it has
more than one filesystem option there. Do you want me to add a special
case here to say that rootfstype= still works when the root filesystem
is initramfs? Or would it instead make more sense to add:
Signed-off-by: Rob Landley <rob@landley.net>
Document that rootfstype= applies to initmpfs too.
--- a/Documentation/filesystems/ramfs-rootfs-initramfs.txt
+++ b/Documentation/filesystems/ramfs-rootfs-initramfs.txt
@@ -79,6 +79,9 @@ 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?
------------------
(What I _didn't_ do yet is hook up rootflags= to initmpfs, so you can
specify size= as something other than 50%. Partly because if you have
an empty cpio archive and the rootflags= applies to ext3 or something,
those flags could potentially confuse tmpfs with unknown options and
throw errors. And partly because mount -o remount,size=20% works fine
after the fact, so it's not time critical and I easily can do a
follow-up patch. The one potential downside is if you want to have a
cpio archive eat more than 50% of the kernel's memory, it'll fail to
extract into tmpfs with the size limits. But the rootfstype=ramfs
downgrade also works around that for now...)
There are a number of follow up patches I could do, but the basic
functionality doesn't depend on them...
Rob
^ permalink raw reply [flat|nested] 12+ messages in thread