Re: [PATCH] relayfs redux for 2.6.10: lean and mean

From: Peter Williams
Date: Thu Jan 20 2005 - 21:17:16 EST


Karim Yaghmour wrote:
Greg KH wrote:

Hm, how about this idea for cutting about 500 more lines from the code:

Why not drop the "fs" part of relayfs and just make the code a set of
struct file_operations. That way you could have "relayfs-like" files in
any ram based file system that is being used. Then, a user could use
these fops and assorted interface to create debugfs or even procfs files
using this type of interface.

As relayfs really is almost the same (conceptually wise) as debugfs as
far as concept of what kinds of files will be in there (nothing anyone
would ever rely on for normal operations, but for debugging only) this
keeps users and developers from having to spread their debugging and
instrumenting files from accross two different file systems.


However this assumes that the users of relayfs are not going to want
it during normal system operation. This is an assumption that fails
with at least LTT as it is targeted at sysadmins, application developers
and power users who need to be able to trace their systems at any time.

I don't mind piggy-backing off another fs, if it makes sense, but
unlike debugfs, relayfs is meant for general use, and all files in there
are of the same type: relay channels for dumping huge amounts of data
to user-space. It seems to me the target audience and basic idea (relay
channels only in the fs) are different, but let me know if there's a
compeling argument for doing this in another way without making it too
confusing for users of those special "files" (IOW, when this starts
being used in distros, it'll be more straightforward for users to
understand if all files in a mounted fs behave a certain way than if
they have certain "odd" files in certain directories, even if it's
/proc.)

Perhaps the logical solution is to implement debugfs in terms of relayfs?

Peter
--
Peter Williams pwil3058@xxxxxxxxxxxxxx

"Learning, n. The kind of ignorance distinguishing the studious."
-- Ambrose Bierce
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