Re: Understanding locking for buf
- Reply: Konstantin Belousov : "Re: Understanding locking for buf"
- In reply to: Konstantin Belousov : "Re: Understanding locking for buf"
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Date: Mon, 20 Mar 2023 10:25:30 UTC
On 16.03.23 12:24, Konstantin Belousov wrote: >> Is the following correct? >> The aforementioned accesses by 100033 in g_vfs_done() are no violations with >> respect to the locking rule because from a global perspective the buf is >> locked. It is the only concurrent access at that moment. > I would formulate it differently: > No other thread might legitimately get access to the buffer using > either bread() or getblk() until current io operation finishes. > The io operation is handled in two contexts: top-level, where a thread > used getblk() as usual to claim buffer ownership, and completion > thread context (geom up thread). The completion code legitimately > manipulates the buffer, because the top-level code expects that after > the buffer strategy routine is called, effectively moving the ownership > to the geom up thread. Thx. But the top-level thread, using getblk(), legitimately releases the lock. Am I right? - Alex -- Technische Universität Dortmund Computer Science XII - System Software Group Alexander Lochmann PGP key: 0xBC3EF6FD Otto-Hahn-Str. 16 phone: +49.231.7556141 D-44227 Dortmund fax: +49.231.7556116 https://sys.cs.tu-dortmund.de/al