From: Al Viro <viro@zeniv.linux.org.uk>
To: NeilBrown <neilb@suse.de>
Cc: Christian Brauner <brauner@kernel.org>, Jan Kara <jack@suse.cz>,
Linus Torvalds <torvalds@linux-foundation.org>,
Jeff Layton <jlayton@kernel.org>,
Dave Chinner <david@fromorbit.com>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 08/19] VFS: introduce lookup_and_lock() and friends
Date: Fri, 7 Feb 2025 20:22:35 +0000 [thread overview]
Message-ID: <20250207202235.GH1977892@ZenIV> (raw)
In-Reply-To: <20250206054504.2950516-9-neilb@suse.de>
On Thu, Feb 06, 2025 at 04:42:45PM +1100, NeilBrown wrote:
> lookup_and_lock() combines locking the directory and performing a lookup
> prior to a change to the directory.
> Abstracting this prepares for changing the locking requirements.
>
> done_lookup_and_lock() provides the inverse of putting the dentry and
> unlocking.
>
> For "silly_rename" we will need to lookup_and_lock() in a directory that
> is already locked. For this purpose we add LOOKUP_PARENT_LOCKED.
Ewww... I do realize that such things might appear in intermediate
stages of locking massage, but they'd better be _GONE_ by the end of it.
Conditional locking of that sort is really asking for trouble.
If nothing else, better split the function in two variants and document
the differences; that kind of stuff really does not belong in arguments.
If you need it to exist through the series, that is - if not, you should
just leave lookup_one_qstr() for the "locked" case from the very beginning.
> This functionality is exported as lookup_and_lock_one() which takes a
> name and len rather than a qstr.
... for the sake of ...?
next prev parent reply other threads:[~2025-02-07 20:22 UTC|newest]
Thread overview: 83+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-06 5:42 [PATCH 00/19 v7?] RFC: Allow concurrent and async changes in a directory NeilBrown
2025-02-06 5:42 ` [PATCH 01/19] VFS: introduce vfs_mkdir_return() NeilBrown
2025-02-06 12:24 ` Christian Brauner
2025-02-06 23:52 ` NeilBrown
2025-02-06 13:52 ` Jeff Layton
2025-02-06 23:57 ` NeilBrown
2025-02-07 19:45 ` Al Viro
2025-02-10 4:36 ` NeilBrown
2025-02-06 5:42 ` [PATCH 02/19] VFS: use global wait-queue table for d_alloc_parallel() NeilBrown
2025-02-07 19:32 ` Al Viro
2025-02-10 4:58 ` NeilBrown
2025-02-10 5:15 ` Al Viro
2025-02-11 23:35 ` NeilBrown
2025-02-12 0:25 ` Al Viro
2025-02-12 1:46 ` NeilBrown
2025-02-06 5:42 ` [PATCH 03/19] VFS: use d_alloc_parallel() in lookup_one_qstr_excl() and rename it NeilBrown
2025-02-06 14:30 ` Jeff Layton
2025-02-07 0:04 ` NeilBrown
2025-02-07 0:23 ` Jeff Layton
2025-02-07 20:01 ` Al Viro
2025-02-06 5:42 ` [PATCH 04/19] VFS: change kern_path_locked() and user_path_locked_at() to never return negative dentry NeilBrown
2025-02-06 12:31 ` Christian Brauner
2025-02-06 13:09 ` Christian Brauner
2025-02-07 0:08 ` NeilBrown
2025-02-06 5:42 ` [PATCH 05/19] VFS: add common error checks to lookup_one_qstr() NeilBrown
2025-02-06 12:33 ` Christian Brauner
2025-02-07 20:14 ` Al Viro
2025-02-09 20:23 ` Al Viro
2025-02-06 5:42 ` [PATCH 06/19] VFS: repack DENTRY_ flags NeilBrown
2025-02-06 12:34 ` (subset) " Christian Brauner
2025-02-06 5:42 ` [PATCH 07/19] VFS: repack LOOKUP_ bit flags NeilBrown
2025-02-06 12:44 ` Christian Brauner
2025-02-07 0:24 ` NeilBrown
2025-02-06 12:54 ` (subset) " Christian Brauner
2025-02-06 5:42 ` [PATCH 08/19] VFS: introduce lookup_and_lock() and friends NeilBrown
2025-02-06 13:49 ` Christian Brauner
2025-02-07 1:28 ` NeilBrown
2025-02-07 20:22 ` Al Viro [this message]
2025-02-08 23:18 ` Al Viro
2025-02-12 5:22 ` NeilBrown
2025-02-12 15:51 ` Al Viro
2025-02-12 20:11 ` Al Viro
2025-02-12 4:49 ` NeilBrown
2025-02-06 5:42 ` [PATCH 09/19] VFS: add _async versions of the various directory modifying inode_operations NeilBrown
2025-02-06 13:15 ` Christian Brauner
2025-02-07 1:46 ` NeilBrown
2025-02-07 22:41 ` Al Viro
2025-02-09 1:09 ` Al Viro
2025-02-09 4:57 ` Al Viro
2025-02-06 5:42 ` [PATCH 10/19] VFS: introduce inode flags to report locking needs for directory ops NeilBrown
2025-02-06 13:22 ` Christian Brauner
2025-02-07 2:01 ` NeilBrown
2025-02-06 5:42 ` [PATCH 11/19] VFS: Add ability to exclusively lock a dentry and use for create/remove operations NeilBrown
2025-02-08 1:38 ` Al Viro
2025-02-09 6:40 ` Al Viro
2025-02-06 5:42 ` [PATCH 12/19] VFS: enhance d_splice_alias to accommodate shared-lock updates NeilBrown
2025-02-06 5:42 ` [PATCH 13/19] VFS: lock dentry for ->revalidate to avoid races with rename etc NeilBrown
2025-02-07 20:28 ` Al Viro
2025-02-07 20:35 ` Al Viro
2025-02-08 1:30 ` Al Viro
2025-02-08 1:35 ` Al Viro
2025-02-12 21:22 ` Al Viro
2025-02-06 5:42 ` [PATCH 14/19] VFS: Ensure no async updates happening in directory being removed NeilBrown
2025-02-06 14:06 ` Christian Brauner
2025-02-07 2:17 ` NeilBrown
2025-02-07 21:06 ` Al Viro
2025-02-08 22:06 ` Al Viro
2025-02-08 22:30 ` Linus Torvalds
2025-02-08 22:34 ` Linus Torvalds
2025-02-08 23:25 ` Al Viro
2025-02-06 5:42 ` [PATCH 15/19] VFS: Change lookup_and_lock() to use shared lock when possible NeilBrown
2025-02-06 5:42 ` [PATCH 16/19] VFS: add lookup_and_lock_rename() NeilBrown
2025-02-07 21:21 ` Al Viro
2025-02-06 5:42 ` [PATCH 17/19] nfsd: use lookup_and_lock_one() and lookup_and_lock_rename_one() NeilBrown
2025-02-06 5:42 ` [PATCH 18/19] nfs: change mkdir inode_operation to mkdir_async NeilBrown
2025-02-06 5:42 ` [PATCH 19/19] nfs: switch to _async for all directory ops NeilBrown
2025-02-13 3:51 ` Al Viro
2025-02-13 4:09 ` Al Viro
2025-02-13 18:01 ` Al Viro
2025-02-06 14:36 ` [PATCH 00/19 v7?] RFC: Allow concurrent and async changes in a directory Christian Brauner
2025-02-06 15:36 ` John Stoffel
2025-02-07 2:18 ` NeilBrown
2025-02-09 23:33 ` Al Viro
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