From: Bryan Henderson <hbryan@us.ibm.com>
To: Jeff Mahoney <jeffm@suse.com>
Cc: "Kathy KN (HK)" <kathy.kn@gmail.com>, linux-fsdevel@vger.kernel.org
Subject: Re: Access content of file via inodes
Date: Wed, 6 Apr 2005 10:57:43 -0700 [thread overview]
Message-ID: <OF4FAAF477.1C901285-ON85256FDB.006171CD-88256FDB.00623672@us.ibm.com> (raw)
In-Reply-To: <4253410C.20405@suse.com>
>What I meant by
>> via blocks is to gain knowledge of the physical blocks used by the
inodes
>> and retrieve the content from it directly, by accessing b_data.
>
>The problem with that approach is that some filesystems may store part
>of the file outside of a complete block.
There's an even more basic problem with this approach: The question is
specifically about the filesystem-type-independent layer above the VFS
interface. At this layer, you don't even know that there is a block
device involved. And if you do, you don't know that the filesystem driver
uses the buffer cache to access it. And if you do know that it uses the
buffer cache, you don't know that the file data you're looking for is
presently in the buffer cache, or how to get it there if it isn't.
If you believe in the layering at all, the only interface you can consider
at this layer for getting at file data is VFS ->read.
--
Bryan Henderson San Jose California
IBM Almaden Research Center Filesystems
next prev parent reply other threads:[~2005-04-06 17:57 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-04-05 1:23 Access content of file via inodes Kathy KN
2005-04-05 7:22 ` Christoph Hellwig
2005-04-05 17:53 ` Bryan Henderson
2005-04-06 1:27 ` Kathy KN (HK)
2005-04-06 1:53 ` Jeff Mahoney
2005-04-06 17:57 ` Bryan Henderson [this message]
2005-04-06 7:54 ` Anton Altaparmakov
2005-04-06 11:33 ` Anton Altaparmakov
2005-04-06 13:09 ` Jeffrey Mahoney
2005-04-07 5:25 ` Kathy KN (HK)
2005-04-07 6:47 ` Jeffrey Mahoney
2005-04-07 8:09 ` Anton Altaparmakov
2005-04-05 19:01 ` Jeff Mahoney
2005-04-06 1:32 ` Kathy KN (HK)
2005-04-06 1:50 ` Jeff Mahoney
2005-04-08 6:01 ` Kathy KN (HK)
2005-04-08 8:17 ` Anton Altaparmakov
2005-05-27 19:13 ` Martin Jambor
2005-05-28 15:57 ` Anton Altaparmakov
2005-05-28 21:44 ` Martin Jambor
2005-05-29 7:26 ` Anton Altaparmakov
2005-05-30 21:51 ` Martin Jambor
2005-05-30 22:19 ` Anton Altaparmakov
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