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[2003:dc:6f2b:4400:230:64ff:fe74:809]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-43cf21e9e24sm31410655f8f.10.2026.03.31.22.31.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 31 Mar 2026 22:31:22 -0700 (PDT) From: Max Kellermann To: idryomov@gmail.com, amarkuze@redhat.com, ceph-devel@vger.kernel.org, dhowells@redhat.com, pc@manguebit.org, netfs@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Max Kellermann Subject: [PATCH] ceph: support RWF_DONTCACHE Date: Wed, 1 Apr 2026 07:31:09 +0200 Message-ID: <20260401053109.1861724-1-max.kellermann@ionos.com> X-Mailer: git-send-email 2.47.3 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Similar to commit 902893e39076 ("NFS: Enable use of the RWF_DONTCACHE flag on the NFS client"). The Ceph client now supports RWF_DONTCACHE for buffered file IO, but it needs preserve the IOCB_DONTCACHE state through netfs_write_begin(). Unlike NFS, Ceph does not need to defer drop-behind until after a separate COMMIT step. Ceph's buffered writeback completes when the OSD write completes, so the existing folio_end_writeback() handling is sufficient. This patch changes netfs because Ceph does not get its write_begin folio directly. ceph_write_begin() is a wrapper around netfs_write_begin(), and that helper was calling __filemap_get_folio(FGP_WRITEBEGIN, ...) without access to the kiocb. As a result, the per-IO IOCB_DONTCACHE flag was lost before folio allocation. Fix this by passing the kiocb into netfs_write_begin() and switching it to write_begin_get_folio(iocb, ...), so IOCB_DONTCACHE is translated into FGP_DONTCACHE when appropriate. Then set FOP_DONTCACHE on ceph_file_fops so the VFS will accept RWF_DONTCACHE for files on Ceph. Signed-off-by: Max Kellermann --- fs/ceph/addr.c | 3 ++- fs/ceph/file.c | 1 + fs/netfs/buffered_read.c | 6 +++--- include/linux/netfs.h | 3 ++- 4 files changed, 8 insertions(+), 5 deletions(-) diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c index 2090fc78529c..b4ea3ba8211e 100644 --- a/fs/ceph/addr.c +++ b/fs/ceph/addr.c @@ -1865,7 +1865,8 @@ static int ceph_write_begin(const struct kiocb *iocb, struct ceph_inode_info *ci =3D ceph_inode(inode); int r; =20 - r =3D netfs_write_begin(&ci->netfs, file, inode->i_mapping, pos, len, fol= iop, NULL); + r =3D netfs_write_begin(iocb, &ci->netfs, file, inode->i_mapping, pos, + len, foliop, NULL); if (r < 0) return r; =20 diff --git a/fs/ceph/file.c b/fs/ceph/file.c index 5e7c73a29aa3..341589ef32cd 100644 --- a/fs/ceph/file.c +++ b/fs/ceph/file.c @@ -3191,4 +3191,5 @@ const struct file_operations ceph_file_fops =3D { .compat_ioctl =3D compat_ptr_ioctl, .fallocate =3D ceph_fallocate, .copy_file_range =3D ceph_copy_file_range, + .fop_flags =3D FOP_DONTCACHE, }; diff --git a/fs/netfs/buffered_read.c b/fs/netfs/buffered_read.c index a8c0d86118c5..6ec7c2459d8a 100644 --- a/fs/netfs/buffered_read.c +++ b/fs/netfs/buffered_read.c @@ -589,6 +589,7 @@ static bool netfs_skip_folio_read(struct folio *folio, = loff_t pos, size_t len, =20 /** * netfs_write_begin - Helper to prepare for writing [DEPRECATED] + * @iocb: The kiocb describing the write request * @ctx: The netfs context * @file: The file to read from * @mapping: The mapping to read from @@ -620,7 +621,7 @@ static bool netfs_skip_folio_read(struct folio *folio, = loff_t pos, size_t len, * Note that this should be considered deprecated and netfs_perform_write() * used instead. */ -int netfs_write_begin(struct netfs_inode *ctx, +int netfs_write_begin(const struct kiocb *iocb, struct netfs_inode *ctx, struct file *file, struct address_space *mapping, loff_t pos, unsigned int len, struct folio **_folio, void **_fsdata) @@ -631,8 +632,7 @@ int netfs_write_begin(struct netfs_inode *ctx, int ret; =20 retry: - folio =3D __filemap_get_folio(mapping, index, FGP_WRITEBEGIN, - mapping_gfp_mask(mapping)); + folio =3D write_begin_get_folio(iocb, mapping, index, len); if (IS_ERR(folio)) return PTR_ERR(folio); =20 diff --git a/include/linux/netfs.h b/include/linux/netfs.h index ba17ac5bf356..d58c614e32fd 100644 --- a/include/linux/netfs.h +++ b/include/linux/netfs.h @@ -414,7 +414,8 @@ int netfs_writeback_single(struct address_space *mappin= g, struct readahead_control; void netfs_readahead(struct readahead_control *); int netfs_read_folio(struct file *, struct folio *); -int netfs_write_begin(struct netfs_inode *, struct file *, +int netfs_write_begin(const struct kiocb *iocb, + struct netfs_inode *ctx, struct file *file, struct address_space *, loff_t pos, unsigned int len, struct folio **, void **fsdata); int netfs_writepages(struct address_space *mapping, --=20 2.47.3