{"id":2230308,"url":"http://patchwork.ozlabs.org/api/1.1/patches/2230308/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-ext4/patch/177747214787.4107473.16073984189804321726.stgit@frogsfrogsfrogs/","project":{"id":8,"url":"http://patchwork.ozlabs.org/api/1.1/projects/8/?format=json","name":"Linux ext4 filesystem development","link_name":"linux-ext4","list_id":"linux-ext4.vger.kernel.org","list_email":"linux-ext4@vger.kernel.org","web_url":null,"scm_url":null,"webscm_url":null},"msgid":"<177747214787.4107473.16073984189804321726.stgit@frogsfrogsfrogs>","date":"2026-04-29T14:56:16","name":"[14/19] fuse2fs: configure block device block size","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"35aa67bba567c935d807c69e0ec0c365d2341db3","submitter":{"id":77032,"url":"http://patchwork.ozlabs.org/api/1.1/people/77032/?format=json","name":"Darrick J. Wong","email":"djwong@kernel.org"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/linux-ext4/patch/177747214787.4107473.16073984189804321726.stgit@frogsfrogsfrogs/mbox/","series":[{"id":502087,"url":"http://patchwork.ozlabs.org/api/1.1/series/502087/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-ext4/list/?series=502087","date":"2026-04-29T14:53:09","name":"[01/19] fuse2fs: implement bare minimum iomap for file mapping reporting","version":1,"mbox":"http://patchwork.ozlabs.org/series/502087/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2230308/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2230308/checks/","tags":{},"headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linux-ext4@vger.kernel.org"],"Delivered-To":["patchwork-incoming@legolas.ozlabs.org","patchwork-incoming@ozlabs.org"],"Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256\n header.s=k20201202 header.b=QasxMH05;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=ozlabs.org\n (client-ip=2404:9400:2221:ea00::3; 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arc=none smtp.client-ip=10.30.226.201"],"DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org;\n\ts=k20201202; t=1777474577;\n\tbh=Gp4tKHLmNcgnhXdR79ayHiGMEIzy1dTJzbSE3IvNSHc=;\n\th=Date:Subject:From:To:Cc:In-Reply-To:References:From;\n\tb=QasxMH05kEEkSWxzrIDxObwckTSuQL4loFrXdkbVZ8mEbeWIlTa1HGTvPwKHJfJms\n\t MuLVyL959IlBmrueptdFXuwmxShPayQL7UuQ8j0mZ1yVCWW3vcm5WIBdKcsT4whFAq\n\t H0djGTFqBWHK0CIxjLMtaCN7yRosqXVZ/xhx0vHFIFSK+eIKbbWoXmN7mJMSqmK5vS\n\t fhh5MJwH4sVvoBZPKwSDFiLYIgaWqDVwfGhD4ifFFEM85CAdAaYHb55cQtZq4g6Zpq\n\t S7dZz5byrSl4WEO1FqI3v/xK8VB5M43gAzdUueDUXomY77iOTzTG3peeeGxSvyHwbk\n\t mVr3UX6A+zrjA==","Date":"Wed, 29 Apr 2026 07:56:16 -0700","Subject":"[PATCH 14/19] fuse2fs: configure block device block size","From":"\"Darrick J. Wong\" ","To":"tytso@mit.edu","Cc":"bernd@bsbernd.com, miklos@szeredi.hu, linux-ext4@vger.kernel.org,\n neal@gompa.dev, linux-fsdevel@vger.kernel.org, fuse-devel@lists.linux.dev,\n joannelkoong@gmail.com","Message-ID":"<177747214787.4107473.16073984189804321726.stgit@frogsfrogsfrogs>","In-Reply-To":"<177747214459.4107473.9520724883867588970.stgit@frogsfrogsfrogs>","References":"<177747214459.4107473.9520724883867588970.stgit@frogsfrogsfrogs>","Precedence":"bulk","X-Mailing-List":"linux-ext4@vger.kernel.org","List-Id":"","List-Subscribe":"","List-Unsubscribe":"","MIME-Version":"1.0","Content-Type":"text/plain; charset=\"utf-8\"","Content-Transfer-Encoding":"7bit","X-Spam-Status":"No, score=-1.2 required=5.0 tests=ARC_SIGNED,ARC_VALID,\n\tDKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DMARC_PASS,\n\tMAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=disabled\n\tversion=4.0.1","X-Spam-Checker-Version":"SpamAssassin 4.0.1 (2024-03-25) on gandalf.ozlabs.org"},"content":"From: Darrick J. Wong \n\nSet the blocksize of the block device to the filesystem blocksize.\nThis prevents the bdev pagecache from caching file data blocks that\niomap will read and write directly. Cache duplication is dangerous.\n\nSigned-off-by: \"Darrick J. Wong\" \n---\n fuse4fs/fuse4fs.c | 43 +++++++++++++++++++++++++++++++++++++++++++\n misc/fuse2fs.c | 43 +++++++++++++++++++++++++++++++++++++++++++\n 2 files changed, 86 insertions(+)","diff":"diff --git a/fuse4fs/fuse4fs.c b/fuse4fs/fuse4fs.c\nindex f9c905c0805d9e..e92a85da0115ca 100644\n--- a/fuse4fs/fuse4fs.c\n+++ b/fuse4fs/fuse4fs.c\n@@ -6891,6 +6891,45 @@ static off_t fuse4fs_max_size(struct fuse4fs *ff, off_t upper_limit)\n \treturn res;\n }\n \n+/*\n+ * Set the block device's blocksize to the fs blocksize.\n+ *\n+ * This is required to avoid creating uptodate bdev pagecache that aliases file\n+ * data blocks because iomap reads and writes directly to file data blocks.\n+ */\n+static int fuse4fs_set_bdev_blocksize(struct fuse4fs *ff, int fd)\n+{\n+\tint blocksize = ff->fs->blocksize;\n+\tint set_error;\n+\tint ret;\n+\n+\tret = ioctl(fd, BLKBSZSET, &blocksize);\n+\tif (!ret)\n+\t\treturn 0;\n+\n+\t/*\n+\t * Save the original errno so we can report that if the block device\n+\t * blocksize isn't set in an agreeable way.\n+\t */\n+\tset_error = errno;\n+\n+\tret = ioctl(fd, BLKBSZGET, &blocksize);\n+\tif (ret)\n+\t\tgoto out_bad;\n+\n+\t/* Pretend that BLKBSZSET rejected our proposed block size */\n+\tif (blocksize > ff->fs->blocksize) {\n+\t\tset_error = EINVAL;\n+\t\tgoto out_bad;\n+\t}\n+\n+\treturn 0;\n+out_bad:\n+\terr_printf(ff, \"%s: cannot set blocksize %u: %s\\n\", __func__,\n+\t\t blocksize, strerror(set_error));\n+\treturn -EIO;\n+}\n+\n static int fuse4fs_iomap_config_devices(struct fuse4fs *ff)\n {\n \terrcode_t err;\n@@ -6901,6 +6940,10 @@ static int fuse4fs_iomap_config_devices(struct fuse4fs *ff)\n \tif (err)\n \t\treturn translate_error(ff->fs, 0, err);\n \n+\tret = fuse4fs_set_bdev_blocksize(ff, fd);\n+\tif (ret)\n+\t\treturn ret;\n+\n \tret = fuse_lowlevel_iomap_device_add(ff->fuse, fd, 0);\n \tif (ret < 0) {\n \t\tdbg_printf(ff, \"%s: cannot register iomap dev fd=%d, err=%d\\n\",\ndiff --git a/misc/fuse2fs.c b/misc/fuse2fs.c\nindex c6472a1c45506f..c922c7fb45d311 100644\n--- a/misc/fuse2fs.c\n+++ b/misc/fuse2fs.c\n@@ -6211,6 +6211,45 @@ static off_t fuse2fs_max_size(struct fuse2fs *ff, off_t upper_limit)\n \treturn res;\n }\n \n+/*\n+ * Set the block device's blocksize to the fs blocksize.\n+ *\n+ * This is required to avoid creating uptodate bdev pagecache that aliases file\n+ * data blocks because iomap reads and writes directly to file data blocks.\n+ */\n+static int fuse2fs_set_bdev_blocksize(struct fuse2fs *ff, int fd)\n+{\n+\tint blocksize = ff->fs->blocksize;\n+\tint set_error;\n+\tint ret;\n+\n+\tret = ioctl(fd, BLKBSZSET, &blocksize);\n+\tif (!ret)\n+\t\treturn 0;\n+\n+\t/*\n+\t * Save the original errno so we can report that if the block device\n+\t * blocksize isn't set in an agreeable way.\n+\t */\n+\tset_error = errno;\n+\n+\tret = ioctl(fd, BLKBSZGET, &blocksize);\n+\tif (ret)\n+\t\tgoto out_bad;\n+\n+\t/* Pretend that BLKBSZSET rejected our proposed block size */\n+\tif (blocksize > ff->fs->blocksize) {\n+\t\tset_error = EINVAL;\n+\t\tgoto out_bad;\n+\t}\n+\n+\treturn 0;\n+out_bad:\n+\terr_printf(ff, \"%s: cannot set blocksize %u: %s\\n\", __func__,\n+\t\t blocksize, strerror(set_error));\n+\treturn -EIO;\n+}\n+\n static int fuse2fs_iomap_config_devices(struct fuse2fs *ff)\n {\n \terrcode_t err;\n@@ -6221,6 +6260,10 @@ static int fuse2fs_iomap_config_devices(struct fuse2fs *ff)\n \tif (err)\n \t\treturn translate_error(ff->fs, 0, err);\n \n+\tret = fuse2fs_set_bdev_blocksize(ff, fd);\n+\tif (ret)\n+\t\treturn ret;\n+\n \tret = fuse_fs_iomap_device_add(fd, 0);\n \tif (ret < 0) {\n \t\tdbg_printf(ff, \"%s: cannot register iomap dev fd=%d, err=%d\\n\",\n","prefixes":["14/19"]}