lists.openwall.net   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  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:	Thu, 19 Jul 2012 08:42:12 -0700
From:	Andreas Dilger <aedilger@...il.com>
To:	Wang Sheng-Hui <shhuiw@...il.com>
Cc:	ext4 development <linux-ext4@...r.kernel.org>
Subject: Re: One question about ext4_fallocate


On 2012-07-19, at 7:51 AM, Wang Sheng-Hui wrote:
> I have one question about ext4_fallocate:
> 	For its parameters, offset & len, it will preallocate
> 	one space with length >= len, right?
> 
> From the code:
> 	map.m_lblk = offset >> blkbits;
> 	/*
> 	 * We can't just convert len to max_blocks because
> 	 * If blocksize = 4096 offset = 3072 and len = 2048
> 	 */
> 	max_blocks = (EXT4_BLOCK_ALIGN(len + offset, blkbits) >> blkbits)
> 		- map.m_lblk;
> 
> We can see that the target space is enlarged to the (floor, ceiling) of 
> (offset, offset+len). Right?
> 
> If I'm wrong, please correct me.

A whole block has to be allocated for fallocate, but if KEEP_SIZE is not used, the i_size should be changed to match the actual requested size.

Cheers, Andreas





--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Powered by blists - more mailing lists