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Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: References: <2318298.1711551844@warthog.procyon.org.uk> <2506007.1711562145@warthog.procyon.org.uk> To: Matthew Wilcox Cc: dhowells@redhat.com, Miklos Szeredi , Trond Myklebust , Christoph Hellwig , Andrew Morton , Alexander Viro , Christian Brauner , Jeff Layton , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, netfs@lists.linux.dev, v9fs@lists.linux.dev, linux-afs@lists.infradead.org, ceph-devel@vger.kernel.org, linux-cifs@vger.kernel.org, linux-nfs@vger.kernel.org, devel@lists.orangefs.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH v2] mm, netfs: Provide a means of invalidation without using launder_folio MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <2541307.1711571866.1@warthog.procyon.org.uk> Date: Wed, 27 Mar 2024 20:37:46 +0000 Message-ID: <2541308.1711571866@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.8 X-Rspamd-Queue-Id: CCC5F12000B X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: 79h8ajssw8oksgxxocp9itdkozu8undm X-HE-Tag: 1711571880-993162 X-HE-Meta: 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 mdEuGuD/ 3MCIgQsu5rS45eDb0FVni0hORYh0CEC3mSkGvhaSYXv4gMHMG+jCYAQT8N7ZYLgzgMh5kS0g7IUPQ91hnCcRk3Rd9kDU1ADKLq3lmyTCzZMp30YCuDMf8QSrgWRsmx9bBreXjt+2Gi4T/fByMz4zoENnuhofKIFkkaRfHW31pypJAlS356rfFgkUjd29A+TrE0H2PdKv2ZaNkAxJjhVY8mFEvoxTmgA4QHB1UD2f2VUaYFPLT8/vQg7z9iBaiGYIMA6e3i4PxMvcEerPim5tbiyqAexOqKamk6+cJ X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Matthew Wilcox wrote: > > + /* Prevent new folios from being added to the inode. */ > > + filemap_invalidate_lock(mapping); > > I'm kind of surprised that the callers wouldn't want to hold that lock > over a call to this function. I guess you're working on the callers, > so you'd know better than I would, but I would have used lockdep to > assert that invalidate_lock was held. I'm not sure. None of the places that look like they'd be calling this currently take that lock (though possibly they should). Also, should I provide it with explicit range, I wonder? > > + if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root))) > > + unmap_mapping_pages(mapping, 0, ULONG_MAX, false); > > Is this optimisation worth it? Perhaps not. David