[PATCH] blkid: allow up to 64k erofs block sizes

[PATCH] blkid: allow up to 64k erofs block sizes

[Eric Sandeen]

Today, mkfs.erofs defaults to page size for block size, but blkid
does not recognize this. Increase the limit to 64k.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
---

(There might be strange arches out there > 64k but I don't know if
erofs really works with blocks that big, so for now let's just
limit it to 64k?)

diff --git a/libblkid/src/superblocks/erofs.c b/libblkid/src/superblocks/erofs.c
index 05822460b..89620db47 100644
--- a/libblkid/src/superblocks/erofs.c
+++ b/libblkid/src/superblocks/erofs.c
@@ -73,8 +73,8 @@ static int probe_erofs(blkid_probe pr, const struct blkid_idmag *mag)
 	if (!sb)
 		return errno ? -errno : BLKID_PROBE_NONE;
 
-	/* EROFS is restricted to 4KiB block size */
-	if (sb->blkszbits > 31 || (1U << sb->blkszbits) > 4096)
+	/* block size must be between 512 and 64k */
+	if (sb->blkszbits > 31 || (1U << sb->blkszbits) > 65536)
 		return BLKID_PROBE_NONE;
 
 	if (!erofs_verify_checksum(pr, mag, sb))

Re: [PATCH] blkid: allow up to 64k erofs block sizes

[Gao Xiang]

Hi Eric,

On Thu, Jan 23, 2025 at 01:17:10PM -0600, Eric Sandeen wrote:
> Today, mkfs.erofs defaults to page size for block size, but blkid
> does not recognize this. Increase the limit to 64k.
> 
> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
> ---
> 
> (There might be strange arches out there > 64k but I don't know if
> erofs really works with blocks that big, so for now let's just
> limit it to 64k?)
> 
> diff --git a/libblkid/src/superblocks/erofs.c b/libblkid/src/superblocks/erofs.c
> index 05822460b..89620db47 100644
> --- a/libblkid/src/superblocks/erofs.c
> +++ b/libblkid/src/superblocks/erofs.c
> @@ -73,8 +73,8 @@ static int probe_erofs(blkid_probe pr, const struct blkid_idmag *mag)
>  	if (!sb)
>  		return errno ? -errno : BLKID_PROBE_NONE;
>  
> -	/* EROFS is restricted to 4KiB block size */
> -	if (sb->blkszbits > 31 || (1U << sb->blkszbits) > 4096)
> +	/* block size must be between 512 and 64k */
> +	if (sb->blkszbits > 31 || (1U << sb->blkszbits) > 65536)

I think it should be

	if (sb->blkszbits < 9 || ..

?

Also (1U << sb->blkszbits) might be overflowed, so just use
sb->blkszbits > 16.

Otherwise it looks good to me.

Thanks,
Gao Xiang

>  		return BLKID_PROBE_NONE;
>  
>  	if (!erofs_verify_checksum(pr, mag, sb))
> 

[PATCH V2] blkid: allow up to 64k erofs block sizes

[Eric Sandeen]

Today, mkfs.erofs defaults to page size for block size, but blkid
does not recognize this. Increase the limit to 64k.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
---

V2: Test for too-small blocksize, and simplify too-large blocksize
test.  (the prior > 31 || <shift test> was probably just avoiding
a shift overflow but there's really no reason, so just look directly
at blkszbits)

(There might be strange arches out there > 64k but I don't know if
erofs really works with blocks that big, so for now let's just
limit it to 64k?)

diff --git a/libblkid/src/superblocks/erofs.c b/libblkid/src/superblocks/erofs.c
index 05822460b..89620db47 100644
--- a/libblkid/src/superblocks/erofs.c
+++ b/libblkid/src/superblocks/erofs.c
@@ -73,8 +73,8 @@ static int probe_erofs(blkid_probe pr, const struct blkid_idmag *mag)
 	if (!sb)
 		return errno ? -errno : BLKID_PROBE_NONE;
 
-	/* EROFS is restricted to 4KiB block size */
-	if (sb->blkszbits > 31 || (1U << sb->blkszbits) > 4096)
+	/* block size must be between 512 and 64k */
+	if (sb->blkszbits < 9 || sb->blkszbits > 16)
 		return BLKID_PROBE_NONE;
 
 	if (!erofs_verify_checksum(pr, mag, sb))

Re: [PATCH V2] blkid: allow up to 64k erofs block sizes

[Gao Xiang]

On Fri, Jan 24, 2025 at 08:37:12AM -0600, Eric Sandeen wrote:
> Today, mkfs.erofs defaults to page size for block size, but blkid
> does not recognize this. Increase the limit to 64k.
> 
> Signed-off-by: Eric Sandeen <sandeen@redhat.com>

Reviewed-by: Gao Xiang <xiang@kernel.org>

Thanks,
Gao Xiang

Re: [PATCH V2] blkid: allow up to 64k erofs block sizes

[Karel Zak]

On Sat, Jan 25, 2025 at 11:19:59PM GMT, Gao Xiang wrote:
> On Fri, Jan 24, 2025 at 08:37:12AM -0600, Eric Sandeen wrote:
> > Today, mkfs.erofs defaults to page size for block size, but blkid
> > does not recognize this. Increase the limit to 64k.
> > 
> > Signed-off-by: Eric Sandeen <sandeen@redhat.com>
> 
> Reviewed-by: Gao Xiang <xiang@kernel.org>

Applied, thanks!

    Karel

-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com