initmpfs: make rootfs use tmpfs when CONFIG_TMPFS enabled
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>
Cc: Jeff Layton <jlayton@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Stephen Warren <swarren@nvidia.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jim Cromie <jim.cromie@gmail.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/init/do_mounts.c b/init/do_mounts.c
index 5d8d48f..e27908b 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -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 +599,8 @@
if (test_and_set_bit(0, &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 +616,11 @@
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);
diff --git a/mm/shmem.c b/mm/shmem.c
index a1b8bf4..8297623 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2819,6 +2819,10 @@
{
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;