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Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells To: torvalds@linux-foundation.org cc: dhowells@redhat.com, Andrew W Elble , Jeff Layton , "Matthew Wilcox (Oracle)" , Al Viro , ceph-devel@vger.kernel.org, linux-afs@lists.infradead.org, linux-cachefs@redhat.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [GIT PULL] netfs, afs: Fix write_begin/end MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <2842347.1624308062.1@warthog.procyon.org.uk> Content-Transfer-Encoding: quoted-printable Date: Mon, 21 Jun 2021 21:41:02 +0100 Message-ID: <2842348.1624308062@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Linus, Could you pull this please? It includes patches to fix netfs_write_begin(= ) and afs_write_end() in the following ways: (1) In netfs_write_begin(), extract the decision about whether to skip a page out to its own helper and have that clear around the region to b= e written, but not clear that region. This requires the filesystem to patch it up afterwards if the hole doesn't get completely filled. (2) Use offset_in_thp() in (1) rather than manually calculating the offse= t into the page. (3) Due to (1), afs_write_end() now needs to handle short data write into the page by generic_perform_write(). I've adopted an analogous approach to ceph of just returning 0 in this case and letting the caller go round again. It also adds a note that (in the future) the len parameter may extend beyond the page allocated. This is because the page allocation is deferre= d to write_begin() and that gets to decide what size of THP to allocate. Thanks, David Link: https://lore.kernel.org/r/20210613233345.113565-1-jlayton@kernel.org= / Link: https://lore.kernel.org/r/162367681795.460125.11729955608839747375.s= tgit@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/162391823192.1173366.9740514875196345746.s= tgit@warthog.procyon.org.uk/ # v2 Link: https://lore.kernel.org/r/162429000639.2770648.6368710175435880749.s= tgit@warthog.procyon.org.uk/ # v3 Changes =3D=3D=3D=3D=3D=3D=3D ver #3: - Drop the bits that make afs take account of len exceeding the end of the page in afs_write_begin/end(). ver #2: - Removed a var that's no longer used (spotted by the kernel test robot= ) - Removed a forgotten "noinline". ver #1: - Prefixed the Jeff's new helper with "netfs_". - Don't call zero_user_segments() for a full-page write. - Altered the beyond-last-page check to avoid a DIV. - Removed redundant zero-length-file check. - Added patches to fix afs. --- The following changes since commit 009c9aa5be652675a06d5211e1640e02bbb1c33= d: Linux 5.13-rc6 (2021-06-13 14:43:10 -0700) are available in the Git repository at: git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git tags= /netfs-fixes-20210621 for you to fetch changes up to 827a746f405d25f79560c7868474aec5aee174e1: netfs: fix test for whether we can skip read when writing beyond EOF (20= 21-06-21 21:24:07 +0100) ---------------------------------------------------------------- netfslib fixes ---------------------------------------------------------------- David Howells (1): afs: Fix afs_write_end() to handle short writes Jeff Layton (1): netfs: fix test for whether we can skip read when writing beyond EOF fs/afs/write.c | 11 +++++++++-- fs/netfs/read_helper.c | 49 ++++++++++++++++++++++++++++++++++++---------= ---- 2 files changed, 45 insertions(+), 15 deletions(-)