Re: Kernel bug: Bad page state: related to generic symlink code andmmap

From: Mika Penttilä
Date: Fri Aug 19 2005 - 14:16:20 EST


Al Viro wrote:

On Fri, Aug 19, 2005 at 05:53:32PM +0100, Al Viro wrote:


I'm taking NFS helpers to libfs.c and switching ncpfs to them. IMO that's
better than copying the damn thing and other network filesystems might have
the same needs eventually...



[something like this - completely untested]

* stray_page_get_link(inode, filler) - returns ERR_PTR(error) or pointer
to symlink body. Said symlink body sits in a page at offset equal to
offsetof(page, struct stray_page_link). filler() is expected to put it
at such offset. Page is cached.

* stray_page_put_link() - ->put_link() suitable for links obtained from
stray_page_get_link(). Unlike the usual pagecache-based variants, this
sucker does _not_ rely on page staying cached.

* nfs and ncpfs switched to the helpers above.

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
----



Just out of curiosity - what protects even local filesystems against concurrent truncate and symlink resolving when using the page cache helpers?

--Mika

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