From: Al Viro <viro@zeniv.linux.org.uk>
To: Christoph Hellwig <hch@lst.de>
Cc: linux-fsdevel@vger.kernel.org,
Christian Brauner <brauner@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Namjae Jeon <linkinjeon@kernel.org>,
David Sterba <dsterba@suse.com>,
David Howells <dhowells@redhat.com>,
Miklos Szeredi <miklos@szeredi.hu>,
Amir Goldstein <amir73il@gmail.com>,
Trond Myklebust <trond.myklebust@hammerspace.com>,
Bob Peterson <rpeterso@redhat.com>,
Steve French <sfrench@samba.org>,
Luis Chamberlain <mcgrof@kernel.org>
Subject: Re: [PATCH 04/15] hfsplus: switch to rcu-delayed unloading of nls and freeing ->s_fs_info
Date: Mon, 2 Oct 2023 19:09:25 +0100 [thread overview]
Message-ID: <20231002180925.GZ800259@ZenIV> (raw)
In-Reply-To: <20231002072143.GU800259@ZenIV>
On Mon, Oct 02, 2023 at 08:21:43AM +0100, Al Viro wrote:
> On Mon, Oct 02, 2023 at 08:14:01AM +0100, Al Viro wrote:
> > On Mon, Oct 02, 2023 at 08:49:12AM +0200, Christoph Hellwig wrote:
> > > Instead of all this duplicatio in the file system, can we please just
> > > add a
> > >
> > > struct nls_table *s_nls;
> > >
> > > to struct super_block and RCU free it in common code and drop all the
> > > code in the file systems?
> >
> > It makes no sense for most of the filesystems, for one thing (note that
> > any use in ->lookup() does not warrant rcu delays). What's more,
> > how do you formulate the rules for what goes in that field when filesystem
> > uses more than one nls_table?
>
> Consider e.g. HFS; two separate nls_table (nls_disk, nls_io), neither needs
> RCU delays of any sort. On VFAT, for that matter - again, two tables,
> one needs RCU delay, another doesn't (both get dropped from the same
> helper, so both get it).
BTW, is there any reason not to have synchronize_rcu() in delete_module(2),
just before calling ->exit()?
It's not a hot path, unless something really weird is going on, and it
would get rid of the need to delay unload_nls() calls...
next prev parent reply other threads:[~2023-10-02 18:09 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-02 2:28 [RFC][PATCHES] fixes in methods exposed to rcu pathwalk Al Viro
2023-10-02 2:28 ` Al Viro
2023-10-02 2:29 ` [PATCH 01/15] rcu pathwalk: prevent bogus hard errors from may_lookup() Al Viro
2023-10-02 2:30 ` [PATCH 02/15] exfat: move freeing sbi, upcase table and dropping nls into rcu-delayed helper Al Viro
2023-10-02 16:10 ` Linus Torvalds
2023-10-02 18:04 ` Al Viro
2023-10-02 2:30 ` [PATCH 03/15] affs: free affs_sb_info with kfree_rcu() Al Viro
2023-10-02 2:31 ` [PATCH 04/15] hfsplus: switch to rcu-delayed unloading of nls and freeing ->s_fs_info Al Viro
2023-10-02 6:49 ` Christoph Hellwig
2023-10-02 7:14 ` Al Viro
2023-10-02 7:21 ` Al Viro
2023-10-02 18:09 ` Al Viro [this message]
2023-10-04 19:04 ` Linus Torvalds
2023-10-04 19:06 ` Linus Torvalds
2023-10-02 2:31 ` [PATCH 05/15] cifs_get_link(): bail out in unsafe case Al Viro
2023-10-02 2:32 ` [PATCH 06/15] procfs: move dropping pde and pid from ->evict_inode() to ->free_inode() Al Viro
2023-10-02 2:33 ` [PATCH 07/15] procfs: make freeing proc_fs_info rcu-delayed Al Viro
2023-10-02 2:33 ` [PATCH 08/15] gfs2: fix an oops in gfs2_permission() Al Viro
2023-10-02 11:46 ` Bob Peterson
2023-10-02 12:59 ` Al Viro
2023-10-02 14:16 ` Al Viro
2023-10-03 14:46 ` Andreas Grünbacher
2023-10-02 2:34 ` [PATCH 09/15] nfs: make nfs_set_verifier() safe for use in RCU pathwalk Al Viro
2023-10-02 2:34 ` [PATCH 10/15] nfs: fix UAF on pathwalk running into umount Al Viro
2023-10-02 2:35 ` [PATCH 11/15] fuse: fix UAF in rcu pathwalks Al Viro
2023-10-02 2:35 ` [PATCH 12/15] afs: fix __afs_break_callback() / afs_drop_open_mmap() race Al Viro
2023-10-02 2:36 ` [PATCH 13/15] overlayfs: move freeing ovl_entry past rcu delay Al Viro
2023-10-02 2:36 ` [PATCH 14/15] ovl_dentry_revalidate_common(): fetch inode once Al Viro
2023-10-02 2:37 ` [PATCH 15/15] overlayfs: make use of ->layers safe in rcu pathwalk Al Viro
2023-10-02 6:40 ` Amir Goldstein
2023-10-02 7:23 ` Al Viro
2023-10-02 8:53 ` Amir Goldstein
2023-10-03 20:47 ` Al Viro
2023-10-02 5:47 ` [PATCH 14/15] ovl_dentry_revalidate_common(): fetch inode once Amir Goldstein
2023-10-02 5:56 ` Amir Goldstein
2023-10-02 14:47 ` Amir Goldstein
2023-10-02 5:51 ` [PATCH 13/15] overlayfs: move freeing ovl_entry past rcu delay Amir Goldstein
2023-10-02 2:52 ` [RFC][PATCHES] fixes in methods exposed to rcu pathwalk Al Viro
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