Re: [PATCH 1/4] vfs: vfs-level fiemap interface

[Christoph Hellwig <hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>]

On Tue, Oct 07, 2008 at 02:52:19PM -0400, Theodore Tso wrote:
> Right, thanks.  This time in proper English.  :-)
> 
>     * FIEMAP_EXTENT_ENCODED
> 
>     This extent does not consist of plain filesystem blocks but is
>     encoded (e.g. encrypted or compressed).  Reading the data in this
>     extent via I/O to the block device will have undefined results.
> 
>     Note that it is *always* undefined to try to update the data
>     in-place by writing to the indicated location without the
>     assistance of the filesystem, or to access the data using the
>     information returned by the FIEMAP interface while the filesystem
>     is mounted.  In other words, user applications may only read the
>     extent data via I/O to the block device while the filesystem is
>     unmounted, and then only if the FIEMAP_EXTENT_ENCODED flag is
>     clear; user applications must not try reading or writing to the
>     filesystem via the block device under any other circumstances.

Looks good!

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