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See http://www.infradead.org/rpr.html X-Headers-End: 1q4jmC-008Sat-8p Subject: [f2fs-dev] [PATCH 09/12] fs: factor out a direct_write_fallback helper X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Darrick J. Wong" , linux-mm@kvack.org, Andreas Gruenbacher , Miklos Szeredi , cluster-devel@redhat.com, Ilya Dryomov , linux-ext4@vger.kernel.org, Miklos Szeredi , linux-nfs@vger.kernel.org, linux-block@vger.kernel.org, Damien Le Moal , Alexander Viro , Jaegeuk Kim , ceph-devel@vger.kernel.org, Xiubo Li , Trond Myklebust , Jens Axboe , Christian Brauner , Theodore Ts'o , linux-f2fs-devel@lists.sourceforge.net, linux-xfs@vger.kernel.org, Anna Schumaker , linux-fsdevel@vger.kernel.org, Andrew Morton Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net Add a helper dealing with handling the syncing of a buffered write fallback for direct I/O. Signed-off-by: Christoph Hellwig Reviewed-by: Damien Le Moal Reviewed-by: Miklos Szeredi Reviewed-by: Darrick J. Wong --- fs/libfs.c | 41 ++++++++++++++++++++++++++++ include/linux/fs.h | 2 ++ mm/filemap.c | 66 +++++++++++----------------------------------- 3 files changed, 58 insertions(+), 51 deletions(-) diff --git a/fs/libfs.c b/fs/libfs.c index 89cf614a327158..5b851315eeed03 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -1613,3 +1613,44 @@ u64 inode_query_iversion(struct inode *inode) return cur >> I_VERSION_QUERIED_SHIFT; } EXPORT_SYMBOL(inode_query_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 91021b4e1f6f48..6af25137543824 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2738,6 +2738,8 @@ 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 ddb6f8aa86d6ca..137508da5525b6 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -4006,23 +4006,19 @@ 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; - err = file_remove_privs(file); - if (err) - goto out; + ret = file_remove_privs(file); + if (ret) + return ret; - err = file_update_time(file); - if (err) - goto out; + ret = file_update_time(file); + if (ret) + return ret; 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 @@ -4030,45 +4026,13 @@ 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)) - 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); + if (ret < 0 || !iov_iter_count(from) || IS_DAX(inode)) + return ret; + return direct_write_fallback(iocb, from, ret, + generic_perform_write(iocb, from)); } -out: - return written ? written : err; + + return generic_perform_write(iocb, from); } EXPORT_SYMBOL(__generic_file_write_iter);