initmpfs: make rootfs use tmpfs when CONFIG_TMPFS enabled (16203a7a) · Commits · 戴 / test

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>

init/do_mounts.c

+8 −2

Original line number	Diff line number	Diff line
		@@ -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 @@ static struct dentry rootfs_mount(struct file_system_type fs_type,
		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 @@ int __init init_rootfs(void)
		if (err)
		return err;

		if (IS_ENABLED(CONFIG_TMPFS))
		err = shmem_init();
		else
		err = init_ramfs_fs();

		if (err)
		unregister_filesystem(&rootfs_fs_type);

mm/shmem.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -2819,6 +2819,10 @@ int __init shmem_init(void)
		{
		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;

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