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@@ -0,0 +1,57 @@
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+From 9a18df7a71bfa620b1278777d64783a359d7eb4e Mon Sep 17 00:00:00 2001
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+From: Thorsten Glaser <tg@mirbsd.org>
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+Date: Sun, 4 May 2014 01:37:54 +0200
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+Subject: [PATCH] mount tmpfs-as-rootfs (initramfs) with -o
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+ nr_blocks=0,nr_inodes=0
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+
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+I would have preferred to write this patch to be able to pass
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+rootflags=nr_blocks=0,nr_inodes=0 on the kernel command line,
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+and then hand these rootflags over to the initramfs (tmpfs)
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+mount in the same way the kernel hands them over to the block
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+device rootfs mount. But at least the Debian/m68k initrd also
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+parses $rootflags from the environment and adds it to the call
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+to the user-space mount for the eventual root device, which
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+would make the kernel command line rootflags option be used in
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+both places (tmpfs and e.g. ext4) which is guaranteed to error
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+out in at least one of them.
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+
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+This change is intended to aid people in a setup where the
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+initrd is the final root filesystem, i.e. not mounted over.
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+This is especially useful in automated tests running on qemu
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+for boards with constrained memory (e.g. 64 MiB on sh4).
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+
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+Considering that the initramfs is normally emptied out then
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+overmounted, this change is probably safe for setups where
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+initramfs just hosts early userspace, too, since the tmpfs
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+backing it is not accessible any more later on, AFAICT.
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+
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+Signed-off-by: Thorsten Glaser <tg@mirbsd.org>
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+---
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+ init/do_mounts.c | 4 ++++
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+ 1 file changed, 4 insertions(+)
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+
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+diff --git a/init/do_mounts.c b/init/do_mounts.c
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+index 82f2288..55a4cfe 100644
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+--- a/init/do_mounts.c
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++++ b/init/do_mounts.c
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+@@ -594,6 +594,7 @@ out:
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+ }
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+
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+ static bool is_tmpfs;
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++static char tmpfs_rootflags[] = "nr_blocks=0,nr_inodes=0";
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+ static struct dentry *rootfs_mount(struct file_system_type *fs_type,
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+ int flags, const char *dev_name, void *data)
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+ {
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+@@ -606,6 +607,9 @@ static struct dentry *rootfs_mount(struct file_system_type *fs_type,
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+ if (IS_ENABLED(CONFIG_TMPFS) && is_tmpfs)
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+ fill = shmem_fill_super;
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+
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++ if (is_tmpfs)
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++ data = tmpfs_rootflags;
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++
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+ return mount_nodev(fs_type, flags, data, fill);
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+ }
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+
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+--
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+2.0.0.rc0
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+
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Waldemar Brodkorb