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From: Jan Harkes <jaharkes@cs.cmu.edu>
To: Amir Goldstein <amir73il@gmail.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>,
	Christian Brauner <brauner@kernel.org>,
	linux-unionfs@vger.kernel.org,
	Chuck Lever <chuck.lever@oracle.com>,
	Jeff Layton <jlayton@kernel.org>, Jan Kara <jack@suse.cz>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	David Howells <dhowells@redhat.com>
Subject: Re: [PATCH 09/15] fs: move file_start_write() into vfs_iter_write()
Date: Wed, 15 Nov 2023 20:07:53 -0500	[thread overview]
Message-ID: <20231116010753.f3nptj4urhfcynnt@cs.cmu.edu> (raw)
In-Reply-To: <CAOQ4uxjcnwuF1gMxe64WLODGA_MyAy8x-DtqkCUxqVQKk3Xbng@mail.gmail.com>

On Wed, Nov 15, 2023 at 11:01:39AM +0200, Amir Goldstein wrote:
> On Wed, Nov 15, 2023 at 1:42 AM Jan Harkes <jaharkes@cs.cmu.edu> wrote:
> >  * Since freeze protection behaves as a lock, users have to preserve
> >  * ordering of freeze protection and other filesystem locks. Generally,
> >  * freeze protection should be the outermost lock. In particular, we
> >  * have:
> >  *
> >  * sb_start_write
> >  *   -> i_mutex                 (write path, truncate, directory ops,
> >  *   ...)
> >  *   -> s_umount                (freeze_super, thaw_super)
> >
> 
> This describes the locking order within a specific fs.
> host_file is not in the same fs as code_inode.
> 
> IIUC, host_file is a sort of backing file for the code inode.
> In cases like this, as in cachefiles and overlayfs, it is best
> to order all backing fs locks strictly after all the frontend fs locks.
> See ovl_write_iter() for example.
> 
> IOW, the new lock ordering is preferred:
> file_start_write(coda_file)
>   inode_lock(code_inode)
>     file_start_write(host_file)
>       inode_lock(host_inode)

Well, if everybody else is doing it, I guess it must be ok.

Jan

  reply	other threads:[~2023-11-16  1:07 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-11-14 15:32 [PATCH 00/15] Tidy up file permission hooks Amir Goldstein
2023-11-14 15:32 ` [PATCH 01/15] ovl: add permission hooks outside of do_splice_direct() Amir Goldstein
2023-11-14 15:32 ` [PATCH 02/15] splice: remove permission hook from do_splice_direct() Amir Goldstein
2023-11-14 15:32 ` [PATCH 03/15] splice: move permission hook out of splice_direct_to_actor() Amir Goldstein
2023-11-14 16:08   ` Chuck Lever
2023-11-14 15:32 ` [PATCH 04/15] splice: move permission hook out of splice_file_to_pipe() Amir Goldstein
2023-11-14 15:32 ` [PATCH 05/15] splice: remove permission hook from iter_file_splice_write() Amir Goldstein
2023-11-14 15:32 ` [PATCH 06/15] remap_range: move permission hooks out of do_clone_file_range() Amir Goldstein
2023-11-14 15:32 ` [PATCH 07/15] remap_range: move file_start_write() to after permission hook Amir Goldstein
2023-11-14 15:32 ` [PATCH 08/15] btrfs: " Amir Goldstein
2023-11-14 15:32 ` [PATCH 09/15] fs: move file_start_write() into vfs_iter_write() Amir Goldstein
2023-11-14 23:42   ` Jan Harkes
2023-11-15  9:01     ` Amir Goldstein
2023-11-16  1:07       ` Jan Harkes [this message]
2023-11-14 15:32 ` [PATCH 10/15] fs: move permission hook out of do_iter_write() Amir Goldstein
2023-11-14 15:32 ` [PATCH 11/15] fs: move permission hook out of do_iter_read() Amir Goldstein
2023-11-14 15:32 ` [PATCH 12/15] fs: move kiocb_start_write() into vfs_iocb_iter_write() Amir Goldstein
2023-11-17 19:46   ` Josef Bacik
2023-11-18  9:08     ` Amir Goldstein
2023-11-14 15:35 ` [PATCH 00/15] Tidy up file permission hooks Amir Goldstein
2023-11-17 19:44 ` Josef Bacik
2023-11-18  6:59   ` Amir Goldstein
2023-11-21 11:07     ` Amir Goldstein
2023-11-21 15:41       ` Christian Brauner
2023-11-17 20:34 ` Josef Bacik
2023-11-14 15:33 Amir Goldstein
2023-11-14 15:33 ` [PATCH 09/15] fs: move file_start_write() into vfs_iter_write() Amir Goldstein

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