From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 00D3B350288; Wed, 3 Dec 2025 16:20:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764778846; cv=none; b=fGmQOts+gSrCM3feQQQAw0fEVYzKEa0nmKy6pbnGL2P1rBLRV7sRSytQzRa9/WxEOFMT3aeTE50OP8YX6/mQw7NlVvF9krynpdRp8ENgtMg83B1qBCd3dIzL92h+SkjgPhHcvMfcEavlQtOdYzCYhyZ8ZZiLVLFclYElxPPTdSo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764778846; c=relaxed/simple; bh=5PdWTP3GpQIOk/VCe9fqQ18WCXUqCww4BqQQAv71qM4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=IcgFHpCrt7L5061hbESVunMdBj5In0s4Xd8G1W2Y5E0gWkBavwvcyM/4nH7fFD0+2jSoW2STQcoIGZiIRW10AlXcGqeeAviTuTNqvjdji3VBrBhmu9u3/Vt9RW1OA7yi0aIbC7BWkLIScpzb2dyH1r5bmcawBDbvmVhxkdfG/kM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=oBkVmx2f; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="oBkVmx2f" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EC8A9C4CEF5; Wed, 3 Dec 2025 16:20:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1764778845; bh=5PdWTP3GpQIOk/VCe9fqQ18WCXUqCww4BqQQAv71qM4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=oBkVmx2f5TS9Pox2kO6+AyIUxwumengZ5Fsu+rDlsV5i2WSnoATvL8mHrbjfzeggn Fc9ojGGbbBee7s8736jFCgRrWll20gHwM8Nu3+q15H4lD+x13CwCgIfyjrMwGgFc+u gtp5DC3ZMy1tQrn7r7e1q4A+hhHXJPxbGWdZzG9k= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Christoph Hellwig , Damien Le Moal , Miklos Szeredi , "Darrick J. Wong" , Al Viro , Andreas Gruenbacher , Anna Schumaker , Chao Yu , Christian Brauner , Hannes Reinecke , Ilya Dryomov , Jaegeuk Kim , Jens Axboe , Johannes Thumshirn , Matthew Wilcox , Miklos Szeredi , Theodore Tso , Trond Myklebust , Xiubo Li , Andrew Morton , Mahmoud Adam Subject: [PATCH 6.1 078/568] fs: factor out a direct_write_fallback helper Date: Wed, 3 Dec 2025 16:21:20 +0100 Message-ID: <20251203152443.576503016@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20251203152440.645416925@linuxfoundation.org> References: <20251203152440.645416925@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Christoph Hellwig commit 44fff0fa08ec5a6d9d5fb05443a36d854d0ece4d upstream. Add a helper dealing with handling the syncing of a buffered write fallback for direct I/O. Link: https://lkml.kernel.org/r/20230601145904.1385409-10-hch@lst.de Signed-off-by: Christoph Hellwig Reviewed-by: Damien Le Moal Reviewed-by: Miklos Szeredi Reviewed-by: Darrick J. Wong Cc: Al Viro Cc: Andreas Gruenbacher Cc: Anna Schumaker Cc: Chao Yu Cc: Christian Brauner Cc: Hannes Reinecke Cc: Ilya Dryomov Cc: Jaegeuk Kim Cc: Jens Axboe Cc: Johannes Thumshirn Cc: Matthew Wilcox Cc: Miklos Szeredi Cc: Theodore Ts'o Cc: Trond Myklebust Cc: Xiubo Li Signed-off-by: Andrew Morton [backing_dev_info still being used here. do small changes to the patch to keep the out label. Which means replacing all returns to goto out.] Signed-off-by: Mahmoud Adam Signed-off-by: Greg Kroah-Hartman --- fs/libfs.c | 41 +++++++++++++++++++++++++++++++++++ include/linux/fs.h | 2 + mm/filemap.c | 61 ++++++++++++----------------------------------------- 3 files changed, 57 insertions(+), 47 deletions(-) --- a/fs/libfs.c +++ b/fs/libfs.c @@ -1582,3 +1582,44 @@ bool inode_maybe_inc_iversion(struct ino return true; } EXPORT_SYMBOL(inode_maybe_inc_iversion); + +ssize_t direct_write_fallback(struct kiocb *iocb, struct iov_iter *iter, + ssize_t direct_written, ssize_t buffered_written) +{ + struct address_space *mapping = iocb->ki_filp->f_mapping; + loff_t pos = iocb->ki_pos - buffered_written; + loff_t end = iocb->ki_pos - 1; + int err; + + /* + * If the buffered write fallback returned an error, we want to return + * the number of bytes which were written by direct I/O, or the error + * code if that was zero. + * + * Note that this differs from normal direct-io semantics, which will + * return -EFOO even if some bytes were written. + */ + if (unlikely(buffered_written < 0)) { + if (direct_written) + return direct_written; + return buffered_written; + } + + /* + * We need to ensure that the page cache pages are written to disk and + * invalidated to preserve the expected O_DIRECT semantics. + */ + err = filemap_write_and_wait_range(mapping, pos, end); + if (err < 0) { + /* + * We don't know how much we wrote, so just return the number of + * bytes which were direct-written + */ + if (direct_written) + return direct_written; + return err; + } + invalidate_mapping_pages(mapping, pos >> PAGE_SHIFT, end >> PAGE_SHIFT); + return direct_written + buffered_written; +} +EXPORT_SYMBOL_GPL(direct_write_fallback); --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -3278,6 +3278,8 @@ extern ssize_t __generic_file_write_iter extern ssize_t generic_file_write_iter(struct kiocb *, struct iov_iter *); extern ssize_t generic_file_direct_write(struct kiocb *, struct iov_iter *); ssize_t generic_perform_write(struct kiocb *, struct iov_iter *); +ssize_t direct_write_fallback(struct kiocb *iocb, struct iov_iter *iter, + ssize_t direct_written, ssize_t buffered_written); ssize_t vfs_iter_read(struct file *file, struct iov_iter *iter, loff_t *ppos, rwf_t flags); --- a/mm/filemap.c +++ b/mm/filemap.c @@ -3923,25 +3923,21 @@ ssize_t __generic_file_write_iter(struct { struct file *file = iocb->ki_filp; struct address_space *mapping = file->f_mapping; - struct inode *inode = mapping->host; - ssize_t written = 0; - ssize_t err; - ssize_t status; + struct inode *inode = mapping->host; + ssize_t ret; /* We can write back this queue in page reclaim */ current->backing_dev_info = inode_to_bdi(inode); - err = file_remove_privs(file); - if (err) + ret = file_remove_privs(file); + if (ret) goto out; - err = file_update_time(file); - if (err) + ret = file_update_time(file); + if (ret) goto out; if (iocb->ki_flags & IOCB_DIRECT) { - loff_t pos, endbyte; - - written = generic_file_direct_write(iocb, from); + ret = generic_file_direct_write(iocb, from); /* * If the write stopped short of completing, fall back to * buffered writes. Some filesystems do this for writes to @@ -3949,46 +3945,17 @@ ssize_t __generic_file_write_iter(struct * not succeed (even if it did, DAX does not handle dirty * page-cache pages correctly). */ - if (written < 0 || !iov_iter_count(from) || IS_DAX(inode)) - goto out; - - pos = iocb->ki_pos; - status = generic_perform_write(iocb, from); - /* - * If generic_perform_write() returned a synchronous error - * then we want to return the number of bytes which were - * direct-written, or the error code if that was zero. Note - * that this differs from normal direct-io semantics, which - * will return -EFOO even if some bytes were written. - */ - if (unlikely(status < 0)) { - err = status; + if (ret < 0 || !iov_iter_count(from) || IS_DAX(inode)) goto out; - } - /* - * We need to ensure that the page cache pages are written to - * disk and invalidated to preserve the expected O_DIRECT - * semantics. - */ - endbyte = pos + status - 1; - err = filemap_write_and_wait_range(mapping, pos, endbyte); - if (err == 0) { - written += status; - invalidate_mapping_pages(mapping, - pos >> PAGE_SHIFT, - endbyte >> PAGE_SHIFT); - } else { - /* - * We don't know how much we wrote, so just return - * the number of bytes which were direct-written - */ - } - } else { - written = generic_perform_write(iocb, from); + ret = direct_write_fallback(iocb, from, ret, + generic_perform_write(iocb, from)); + goto out; } + + ret = generic_perform_write(iocb, from); out: current->backing_dev_info = NULL; - return written ? written : err; + return ret; } EXPORT_SYMBOL(__generic_file_write_iter);