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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 Ts'o" , Trond Myklebust , Xiubo Li , Andrew Morton , "Jeff Layton" , Andreas Dilger , Christoph Hellwig , Ryusuke Konishi , Luis Chamberlain , , , , , , , , , , Subject: [PATCH 6.1 4/8] fs: factor out a direct_write_fallback helper Date: Tue, 21 Oct 2025 09:03:39 +0200 Message-ID: <20251021070353.96705-6-mngyadam@amazon.de> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20251021070353.96705-2-mngyadam@amazon.de> References: <20251021070353.96705-2-mngyadam@amazon.de> MIME-Version: 1.0 X-Originating-IP: [10.253.107.175] X-ClientProxiedBy: EX19D038UWB002.ant.amazon.com (10.13.139.185) To EX19D013EUB004.ant.amazon.com (10.252.51.92) Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Queue-Id: 8A92E10000F X-Rspamd-Server: rspam03 X-Stat-Signature: cc9tzku5ey1d39wf43uuqdnwqrbsxqud X-HE-Tag: 1761030671-690509 X-HE-Meta: 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 KJXc81Lf 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 BfnAjnS5 DBNBJqeLSyrpg51vU8yBrA== 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: 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 --- fs/libfs.c | 41 +++++++++++++++++++++++++++++++ include/linux/fs.h | 2 ++ mm/filemap.c | 61 +++++++++++----------------------------------- 3 files changed, 57 insertions(+), 47 deletions(-) diff --git a/fs/libfs.c b/fs/libfs.c index cbd42d76fbd018..a5bbe8e31d6616 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -1582,3 +1582,44 @@ bool inode_maybe_inc_iversion(struct inode *inode, bool force) 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); diff --git a/include/linux/fs.h b/include/linux/fs.h index 4e8a3e4f894c0f..02c83cd07d4f20 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -3278,6 +3278,8 @@ extern ssize_t __generic_file_write_iter(struct kiocb *, struct iov_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); diff --git a/mm/filemap.c b/mm/filemap.c index e2045266d2f2c9..b77f534dfad35a 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -3923,25 +3923,21 @@ ssize_t __generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from) { 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 kiocb *iocb, struct iov_iter *from) * 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)) + if (ret < 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; - 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); -- 2.47.3 Amazon Web Services Development Center Germany GmbH Tamara-Danz-Str. 13 10243 Berlin Geschaeftsfuehrung: Christian Schlaeger Eingetragen am Amtsgericht Charlottenburg unter HRB 257764 B Sitz: Berlin Ust-ID: DE 365 538 597