lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Mon, 24 Jun 2013 18:08:44 +1000
From:	Dave Chinner <>
To:	Theodore Ts'o <>, Eric Sandeen <>,
	Andreas Dilger <>,
	Namjae Jeon <>,
	"" <>,
	"" <>,
	"" <>,
	"" <>,
	"" <>,
	Namjae Jeon <>
Subject: Re: [PATCH 0/3] ext4: introduce two new ioctls

On Sun, Jun 23, 2013 at 11:12:35PM -0400, Theodore Ts'o wrote:
> On Mon, Jun 24, 2013 at 12:44:59PM +1000, Dave Chinner wrote:
> > 
> > Hence, at minimum, this should be a fallocate() operation, not a ext4
> > specific ioctl as it is relatively trivial to implement on most
> > extent based filesystems.
> The fallocate() uses a units of bytes for the offset and length; would
> a FALLOC_FL_COLLAPSE_RANGE be guaranteed to work on any arbitrary
> offset and length?  Or would it only work if the offset and length are
> multiples of the file system blocksize?

There's nothing stopping us from restricting the offset/len to
specific alignments if the operation cannot be done on arbitrary
byte ranges. We do that for direct IO, and the sky hasn't fallen

> The the EXT4_IOC_TRUNCATE_BLOCK_RANGE interface solves this problem by
> using units of file system blocks (i.e., __u32 start_block), but that
> raises another issue, which is it forces the user space program to
> somehow figure out the file system block size, which seems a bit nasty.

Yeah, exactly. We can do that internally very easily, and EINVAL can
be returned when the alignment is bad just like we do for direct

But, well, I pine for a generic XFS_IOC_DIOINFO interface so the
filesystem can tell users about alignment restrictions....


Dave Chinner
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to
More majordomo info at

Powered by blists - more mailing lists