From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CB6781A0BCA; Thu, 12 Sep 2024 11:08:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726139292; cv=none; b=mn4tFVC/u4g3mR7nbPy1HJcsTMOSklcioG27L3wRDEyxkMF9KFEx2jorW1NXgA6X/oGGOy/vgjp9/2FZFv8d/BWp3DPvb2/RXIFVx7XDUB1ZUTGPfWKqHZvgn7h2GhTwf/nnJ0Ta0Ufrbf9yjmZWweRYIR96XaOnnLxKz+Io0e4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726139292; c=relaxed/simple; bh=GbxUJ4J25O2ocZfy3OfLzH7S3aVFRnG3v9CiZA2JkeA=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=TilitmI9WILMtv9siN0QM5iWAJc0eVc/svZoKo8WseVJ8aVag4bGc84ioa9bqAfOyZ61vLwpTsXMjWodZFXWGrjrQrjz4evX+/ZHgnM52Wckb0a3ijqQLJwnGnEiWd2L5FygrND0zbTP2MH6FD6PWxW4hYzw0+AxExXYDK1AXh8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=dHfnTu53; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="dHfnTu53" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8C721C4CEC3; Thu, 12 Sep 2024 11:08:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1726139291; bh=GbxUJ4J25O2ocZfy3OfLzH7S3aVFRnG3v9CiZA2JkeA=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=dHfnTu531Ihq75RxEH3OVvbYqzWjWbrqlzHVnGkNOG9zq8LTkJ2MfpGGBVLYCcV91 A8sHyofeY8dg+QSUT2ahN+/WBUFSXaCWy+xovU4TtZFlj8DLN5ohJLF50iWELad2Jl BTxKkWwliGXs6r1WgOD7NDrQ3htuaDDZ+edo0tokI6cdbUe2uPwHFh6dq4V+jwPKEe NduaSH/D4lFdPz430svLf1nf98WYok7jT7goIKMIpvFjpHpNrzrbMkVW2EV9jZ6d2X uW1eT9KaQRQx4aTuWV4xxf197TFy2QO3Ua1z3t9/tvXnFAmd0HeW+Y6ysdc5bXgXK5 pq5jtIENQ+pkA== Message-ID: Subject: Re: [PATCH v1 0/4] Fixup NLM and kNFSD file lock callbacks From: Jeff Layton To: Benjamin Coddington , Chuck Lever , Amir Goldstein , Neil Brown , Trond Myklebust , Anna Schumaker , Jonathan Corbet , Andreas Gruenbacher , Mark Fasheh , Joel Becker , Joseph Qi , Alexander Viro , Christian Brauner , Jan Kara , Alexander Ahring Oder Aring Cc: linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, gfs2@lists.linux.dev, ocfs2-devel@lists.linux.dev Date: Thu, 12 Sep 2024 07:08:07 -0400 In-Reply-To: References: Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv 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linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Wed, 2024-09-11 at 15:42 -0400, Benjamin Coddington wrote: > Last year both GFS2 and OCFS2 had some work done to make their locking mo= re > robust when exported over NFS. Unfortunately, part of that work caused b= oth > NLM (for NFS v3 exports) and kNFSD (for NFSv4.1+ exports) to no longer se= nd > lock notifications to clients. >=20 > This in itself is not a huge problem because most NFS clients will still > poll the server in order to acquire a conflicted lock, but now that I've > noticed it I can't help but try to fix it because there are big advantage= s > for setups that might depend on timely lock notifications, and we've > supported that as a feature for a long time. >=20 > Its important for NLM and kNFSD that they do not block their kernel threa= ds > inside filesystem's file_lock implementations because that can produce > deadlocks. We used to make sure of this by only trusting that > posix_lock_file() can correctly handle blocking lock calls asynchronously= , > so the lock managers would only setup their file_lock requests for async > callbacks if the filesystem did not define its own lock() file operation. >=20 > However, when GFS2 and OCFS2 grew the capability to correctly > handle blocking lock requests asynchronously, they started signalling thi= s > behavior with EXPORT_OP_ASYNC_LOCK, and the check for also trusting > posix_lock_file() was inadvertently dropped, so now most filesystems no > longer produce lock notifications when exported over NFS. >=20 > I tried to fix this by simply including the old check for lock(), but the > resulting include mess and layering violations was more than I could acce= pt. > There's a much cleaner way presented here using an fop_flag, which while > potentially flag-greedy, greatly simplifies the problem and grooms the > way for future uses by both filesystems and lock managers alike. >=20 > Criticism welcomed, > Ben >=20 > Benjamin Coddington (4): > fs: Introduce FOP_ASYNC_LOCK > gfs2/ocfs2: set FOP_ASYNC_LOCK > NLM/NFSD: Fix lock notifications for async-capable filesystems > exportfs: Remove EXPORT_OP_ASYNC_LOCK >=20 > Documentation/filesystems/nfs/exporting.rst | 7 ------- > fs/gfs2/export.c | 1 - > fs/gfs2/file.c | 2 ++ > fs/lockd/svclock.c | 5 ++--- > fs/nfsd/nfs4state.c | 19 ++++--------------- > fs/ocfs2/export.c | 1 - > fs/ocfs2/file.c | 2 ++ > include/linux/exportfs.h | 13 ------------- > include/linux/filelock.h | 5 +++++ > include/linux/fs.h | 2 ++ > 10 files changed, 17 insertions(+), 40 deletions(-) >=20 Thanks for fixing this up, Ben! Reviewed-by: Jeff Layton