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***** SUSPECTED SPAM ***** Re: [PATCH 47/49] xfs: Add read-only support

To: Mark Tinguely <tinguely@xxxxxxx>
Subject: ***** SUSPECTED SPAM ***** Re: [PATCH 47/49] xfs: Add read-only support for dirent filetype field
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Mon, 12 Aug 2013 10:33:37 +1000
Cc: xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
Importance: Low
In-reply-to: <52016716.3080807@xxxxxxx>
References: <1374216324-8781-1-git-send-email-david@xxxxxxxxxxxxx> <1374216324-8781-48-git-send-email-david@xxxxxxxxxxxxx> <52016716.3080807@xxxxxxx>
User-agent: Mutt/1.5.21 (2010-09-15)
On Tue, Aug 06, 2013 at 04:13:58PM -0500, Mark Tinguely wrote:
> On 07/19/13 01:45, Dave Chinner wrote:
> >From: Dave Chinner<dchinner@xxxxxxxxxx>
> >
> >Add support for the file type field in directory entries so that
> >readdir can return the type of the inode the dirent points to to
> >userspace without first having to read the inode off disk.
> >
> >The encoding of the type field is a single byte that is added to the
> >end of the directory entry name length. For all intents and
> >purposes, it appends a "hidden" byte to the name field which
> >contains the type information. As the directory entry is already of
> >dynamic size, helpers are already required to access and decode the
> >direct entry structures.
> >
> >Hence the relevent extraction and iteration helpers are updated to
> >understand the hidden byte.  Helpers for reading and writing the
> >filetype field from the directory entries are also added. Only the
> >read helpers are used by this patch.  It also adds all the code
> >necessary to read the type information out of the dirents on disk.
> >
> >Further we add the superblock feature bit and helpers to indicate
> >that we understand the on-disk format change. This is not a
> >compatible change - existing kernels cannot read the new format
> >successfully - so an incompatible feature flag is added. We don't
> >yet allow filesystems to mount with this flag yet - that will be
> >added once write support is added.
> >
> >Finally, the code to take the type from the VFS, convert it to an
> >XFS on-disk type and put it into the xfs_name structures passed
> >around is added, but the directory code does not use this field yet.
> >That will be in the next patch.
> >
> >Signed-off-by: Dave Chinner<dchinner@xxxxxxxxxx>
> >---
> Same as kernel patch (48/49) - written to support only v3 inodes. This
> should support v2 and v3 inodes.

It's a directory entry format change - it has nothing to do with the
version of the inode.


Dave Chinner

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