From: Eric Sandeen <sandeen@sandeen.net>
To: mingz@ele.uri.edu
Cc: linux-xfs@oss.sgi.com
Subject: Re: how to understand allocsp
Date: Thu, 24 Aug 2006 15:53:04 -0500 [thread overview]
Message-ID: <44EE11B0.7010208@sandeen.net> (raw)
In-Reply-To: <1156450310.2700.85.camel@localhost.localdomain>
Ming Zhang wrote:
> Hi All
>
> Play with xfs_io and feel confused about this allocsp.
>
> Starting with a empty file.
>
I honestly never keep this all straight without going back to the code,
but I'd start by looking at the comments for, and code in,
xfs_change_file_space and xfs_alloc_file_space.
/*
* XFS_IOC_RESVSP and XFS_IOC_UNRESVSP will reserve or unreserve
* file space.
* These calls do NOT zero the data space allocated to the file,
* nor do they change the file size.
*
* XFS_IOC_ALLOCSP and XFS_IOC_FREESP will allocate and free file
* space.
* These calls cause the new file data to be zeroed and the file
* size to be changed.
*/
The semantics of all this could be clearer, IMHO.
-Eric
next prev parent reply other threads:[~2006-08-24 20:53 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-08-24 20:11 how to understand allocsp Ming Zhang
2006-08-24 20:53 ` Eric Sandeen [this message]
2006-08-24 21:01 ` Ming Zhang
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