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b=HdGmA/T8Yh36xJUAh9kQ4QRKg7xEAQSuwUEa0iQfBV+TmOCP9i2ysDi55lCEigAVt iMT8PDu6Rsb3s5qii2+KygzOb/oCQ9TYhW7beSNZoJsCyQepfzdtxrVNl6qdJpDfM9 ENot3D+ATZi+xZnx9fTxI67SE5FeCahLHb/4spD+As4ZJA9cprBz+57uYMwVLGHLxo dUoQEOj3B16cNb7kuh8ze8i6nhjOtYUO6nOlEpyjUfRbKUX24e7uigjhU/IF3uPzzV 3e6/jprnSqfIlqBk7V1r9K0s6hbEbuvieS7jIy8VvBS7T/S/8Pa9u5ZtLGfGibQ3us f9XfJxph4bz1g== Date: Tue, 20 Feb 2024 10:51:26 +0100 From: Christian Brauner To: Linux regressions mailing list Cc: David Howells , Christian Brauner , Eric Van Hensbergen , Dominique Martinet , Jeff Layton , Matthew Wilcox , netfs@lists.linux.dev, linux-afs@lists.infradead.org, linux-cifs@vger.kernel.org, linux-nfs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs@lists.linux.dev, linux-erofs@lists.ozlabs.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux_oss@crudebyte.com Subject: Re: [PATCH 2/2] netfs: Fix missing zero-length check in unbuffered write Message-ID: <20240220-autoteile-enthoben-a9a16739b2b9@brauner> References: <20240129094924.1221977-1-dhowells@redhat.com> <20240129094924.1221977-3-dhowells@redhat.com> <960e015a-ec2e-42c2-bd9e-4aa47ab4ef2a@leemhuis.info> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <960e015a-ec2e-42c2-bd9e-4aa47ab4ef2a@leemhuis.info> X-Rspamd-Queue-Id: BA8E71A0019 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: zn9sqcc594zo8t3mby6t99i167oyebcb X-HE-Tag: 1708422693-511997 X-HE-Meta: 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 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: On Mon, Feb 19, 2024 at 09:38:33AM +0100, Linux regression tracking (Thorsten Leemhuis) wrote: > On 29.01.24 10:49, David Howells wrote: > > Fix netfs_unbuffered_write_iter() to return immediately if > > generic_write_checks() returns 0, indicating there's nothing to write. > > Note that netfs_file_write_iter() already does this. > > > > Also, whilst we're at it, put in checks for the size being zero before we > > even take the locks. Note that generic_write_checks() can still reduce the > > size to zero, so we still need that check. > > > > Without this, a warning similar to the following is logged to dmesg: > > > > netfs: Zero-sized write [R=1b6da] > > > > and the syscall fails with EIO, e.g.: > > > > /sbin/ldconfig.real: Writing of cache extension data failed: Input/output error > > > > This can be reproduced on 9p by: > > > > xfs_io -f -c 'pwrite 0 0' /xfstest.test/foo > > > > Fixes: 153a9961b551 ("netfs: Implement unbuffered/DIO write support") > > Reported-by: Eric Van Hensbergen > > Link: https://lore.kernel.org/r/ZbQUU6QKmIftKsmo@FV7GG9FTHL/ > > David, thx for fixing Eric's regression, which I'm tracking. > > Christian, just wondering: that patch afaics is sitting in vfs.netfs for > about three weeks now -- is that intentional or did it maybe fell > through the cracks somehow? I've moved it to vfs.fixes now and will send later this week. Thanks for the reminder!