On Thu, Mar 20, 2025 at 08:28:23PM +0100, Julian Stecklina via B4 Relay wrote:
> From: Julian Stecklina <julian.stecklina@xxxxxxxxxxxxxxxxxxxxx>
>
> Add erofs detection to the initrd mount code. This allows systems to
> boot from an erofs-based initrd in the same way as they can boot from
> a squashfs initrd.
>
> Just as squashfs initrds, erofs images as initrds are a good option
> for systems that are memory-constrained.
>
> Signed-off-by: Julian Stecklina <julian.stecklina@xxxxxxxxxxxxxxxxxxxxx>
> ---
> init/do_mounts_rd.c | 19 +++++++++++++++++++
> 1 file changed, 19 insertions(+)
>
> diff --git a/init/do_mounts_rd.c b/init/do_mounts_rd.c
> index ac021ae6e6fa78c7b7828a78ab2fa3af3611bef3..7c3f8b45b5ed2eea3c534d7f2e65608542009df5 100644
> --- a/init/do_mounts_rd.c
> +++ b/init/do_mounts_rd.c
> @@ -11,6 +11,7 @@
>
> #include "do_mounts.h"
> #include "../fs/squashfs/squashfs_fs.h"
> +#include "../fs/erofs/erofs_fs.h"
>
> #include <linux/decompress/generic.h>
>
> @@ -47,6 +48,7 @@ static int __init crd_load(decompress_fn deco);
> * romfs
> * cramfs
> * squashfs
> + * erofs
> * gzip
> * bzip2
> * lzma
> @@ -63,6 +65,7 @@ identify_ramdisk_image(struct file *file, loff_t pos,
> struct romfs_super_block *romfsb;
> struct cramfs_super *cramfsb;
> struct squashfs_super_block *squashfsb;
> + struct erofs_super_block *erofsb;
> int nblocks = -1;
> unsigned char *buf;
> const char *compress_name;
> @@ -77,6 +80,7 @@ identify_ramdisk_image(struct file *file, loff_t pos,
> romfsb = (struct romfs_super_block *) buf;
> cramfsb = (struct cramfs_super *) buf;
> squashfsb = (struct squashfs_super_block *) buf;
> + erofsb = (struct erofs_super_block *) buf;
> memset(buf, 0xe5, size);
>
> /*
> @@ -165,6 +169,21 @@ identify_ramdisk_image(struct file *file, loff_t pos,
> goto done;
> }
>
> + /* Try erofs */
> + pos = (start_block * BLOCK_SIZE) + EROFS_SUPER_OFFSET;
> + kernel_read(file, buf, size, &pos);
> +
> + if (erofsb->magic == EROFS_SUPER_MAGIC_V1) {
le32_to_cpu(erofsb->magic)
> + printk(KERN_NOTICE
> + "RAMDISK: erofs filesystem found at block %d\n",
> + start_block);
> +
> + nblocks = ((erofsb->blocks << erofsb->blkszbits) + BLOCK_SIZE - 1)
> + >> BLOCK_SIZE_BITS;
le32_to_cpu(erofsb->blocks)
> +
> + goto done;
> + }
> +
> printk(KERN_NOTICE
> "RAMDISK: Couldn't find valid RAM disk image starting at %d.\n",
> start_block);
>
This seems to be broken for cramfs and minix, too.
Thomas
