From: Phillip Wood <firstname.lastname@example.org>
To: "Michal Suchánek" <email@example.com>, "Duy Nguyen" <firstname.lastname@example.org>
Cc: Git Mailing List <email@example.com>,
Eric Sunshine <firstname.lastname@example.org>,
Marketa Calabkova <email@example.com>,
Junio C Hamano <firstname.lastname@example.org>
Subject: Re: [PATCH 2/2] setup: don't fail if commondir reference is deleted.
Date: Thu, 21 Feb 2019 17:07:50 +0000 [thread overview]
Message-ID: <email@example.com> (raw)
On 21/02/2019 13:50, Michal Suchánek wrote:
> On Thu, 21 Feb 2019 17:50:38 +0700
> Duy Nguyen <firstname.lastname@example.org> wrote:
>> On Tue, Feb 19, 2019 at 12:05 AM Michal Suchanek <email@example.com> wrote:
>>> When adding wotktrees git can die in get_common_dir_noenv while
>>> examining existing worktrees because the commondir file does not exist.
>>> Rather than testing if the file exists before reading it handle ENOENT.
>> I don't think we could go around fixing every access to incomplete
>> worktrees like this. If this is because of racy 'worktree add', then
>> perhaps a better solution is make it absolutely clear it's not ready
>> for anybody to access.
>> For example, we can suffix the worktree directory name with ".lock"
>> and make sure get_worktrees() ignores entries ending with ".lock".
>> That should protect other commands while 'worktree add' is still
>> running. Only when the worktree is complete that 'worktree add' should
>> rename the directory to lose ".lock" and run external commands like
>> git-checkout to populate the worktree.
> The problem is we don't forbid worktree names ending with ".lock".
> Which means that if we start to forbid them now existing worktrees
> might become inaccessible.
I think it is also racy as the renaming breaks the use of mkdir erroring
out if the directory already exists. One solution is to have a lock
entry in $GIT_COMMON_DIR/worktree-locks and make sure the code that
iterates over the entries in $GIT_COMMON_DIR/worktrees skips any that
have a corresponding ignores in $GIT_COMMON_DIR/worktree-locks. If the
worktree-locks/<dir> is created before worktree/<dir> then it should be
race free (you will have to remove the lock if the real entry cannot be
created and then increment the counter and try again). Entries could
also be locked on removal to prevent a race there.
next prev parent reply other threads:[~2019-02-21 17:07 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-18 17:04 [PATCH 0/2] worktree add race fix Michal Suchanek
2019-02-18 17:04 ` [PATCH 1/2] worktree: fix worktree add race Michal Suchanek
2019-02-18 17:04 ` [PATCH 2/2] setup: don't fail if commondir reference is deleted Michal Suchanek
2019-02-18 21:00 ` Eric Sunshine
2019-02-21 10:50 ` Duy Nguyen
2019-02-21 13:50 ` Michal Suchánek
2019-02-21 17:07 ` Phillip Wood [this message]
2019-02-21 17:12 ` Eric Sunshine
2019-02-21 17:27 ` Phillip Wood
2019-03-04 13:30 ` Michal Suchánek
2019-02-21 17:33 ` Michal Suchánek
2019-02-22 9:32 ` Duy Nguyen
2019-02-22 10:20 ` Phillip Wood
2019-02-22 9:26 ` Duy Nguyen
2019-02-20 16:16 ` [PATCH v3 1/2] worktree: fix worktree add race Michal Suchanek
2019-02-20 16:34 ` Eric Sunshine
2019-02-20 17:29 ` Michal Suchánek
2019-03-08 9:20 ` Duy Nguyen
2019-03-08 9:37 ` Eric Sunshine
2019-03-11 1:55 ` Junio C Hamano
2019-02-20 16:16 ` [PATCH v3 2/2] setup: don't fail if commondir reference is deleted Michal Suchanek
2019-02-20 16:55 ` Eric Sunshine
2019-02-20 17:16 ` Michal Suchánek
2019-02-20 18:35 ` Eric Sunshine
2019-02-21 9:27 ` Eric Sunshine
2019-02-21 11:13 ` Michal Suchánek
2019-02-21 11:19 ` Michal Suchánek
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