From: David Howells <email@example.com> To: Miklos Szeredi <firstname.lastname@example.org> Cc: email@example.com, Al Viro <firstname.lastname@example.org>, Kernel Mailing List <email@example.com>, Linux-Fsdevel <firstname.lastname@example.org>, "email@example.com" <firstname.lastname@example.org> Subject: Re: Can ovl_drop_write() be called earlier in ovl_dentry_open() Date: Mon, 01 Jun 2015 16:53:49 +0100 [thread overview] Message-ID: <email@example.com> (raw) In-Reply-To: <CAJfpegsaZvTuSu3WBO8jABA1bA4VJuNEK30dCdNQGrZe68CqSg@mail.gmail.com> Miklos Szeredi <firstname.lastname@example.org> wrote: > >> Hmm, that could result in a race where remount r/o of upper fs comes > >> in between copy-up and vfs_open() so copy-up succeeds but the actual > >> open fails. It's harmless, though, and not very likely. So I guess > >> your patch is OK. > > > > That race is there anyway if there's no copy up, right? > > No. The race I'm talking about is that with your patch it's possible > that the file will be copied up, but open will return -EROFS. Ah, I see what you're getting at. > Without your patch, that is not possible since holding write counter > for the mnt over both the copy-up and the open ensures that the > filesystem cannot become read-only in the middle. > > So your patch changes behavior, but the new behavior is acceptable, > because there's no major change in semantics (it should only be > detectable by the increased disk usage in the rare case of the failed > open). Okay. David
prev parent reply other threads:[~2015-06-01 15:53 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-06-01 13:52 David Howells 2015-06-01 14:21 ` [PATCH] overlay: Call ovl_drop_write() " David Howells 2015-06-01 14:22 ` Can ovl_drop_write() be called " Miklos Szeredi 2015-06-01 15:45 ` David Howells 2015-06-01 15:51 ` Miklos Szeredi 2015-06-01 15:53 ` David Howells [this message]
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