Date: Wed, 3 Feb 2021 21:44:11 +0200 From: Konstantin Belousov <kostikbel@gmail.com> To: Ka Ho Ng <khng300@gmail.com> Cc: freebsd-hackers@freebsd.org Subject: Re: About upgrading vnode lock in VOP Message-ID: <YBr9C1ODM2N9qe3s@kib.kiev.ua> In-Reply-To: <CANnchUY6VsOW7gJRFm8MgiNZ0DV0fBHo6o=A8pdara5CHYUedg@mail.gmail.com> References: <CANnchUY6VsOW7gJRFm8MgiNZ0DV0fBHo6o=A8pdara5CHYUedg@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Wed, Feb 03, 2021 at 10:43:10PM +0800, Ka Ho Ng wrote: > Hi all, > > Is it generally okay if an VOP upgrades the vnode lock from shared > lock to exclusive lock in case it is held as shared lock? The reason > behind is, the VOP would possibly extend the file size. It is up to VOP. As a note, you generally cannot upgrade from shared to exclusive without dropping the lock. This opens a possibility for the vnode to be reclaimed, which means that VOP can no longer safely operate on the vnode. If the scope is not just a VOP call from top of VFS, then again it might be not safe to continue the operation.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?YBr9C1ODM2N9qe3s>