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See http://www.infradead.org/rpr.html X-Headers-End: 1pqp5W-0003VG-6L Subject: [f2fs-dev] [PATCH 09/17] 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: linux-block@vger.kernel.org, linux-nfs@vger.kernel.org, cluster-devel@redhat.com, linux-xfs@vger.kernel.org, Miklos Szeredi , "Darrick J. Wong" , linux-kernel@vger.kernel.org, Matthew Wilcox , linux-f2fs-devel@lists.sourceforge.net, David Howells , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Andrew Morton , linux-ext4@vger.kernel.org, ceph-devel@vger.kernel.org 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 --- fs/libfs.c | 36 ++++++++++++++++++++++++++++ include/linux/fs.h | 2 ++ mm/filemap.c | 59 ++++++++++------------------------------------ 3 files changed, 50 insertions(+), 47 deletions(-) diff --git a/fs/libfs.c b/fs/libfs.c index 4eda519c30022f..a530d36e0d1a3d 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -1618,3 +1618,39 @@ 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, end; + 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)) + 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. + */ + end = pos + buffered_written - 1; + 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 + */ + 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 b8ca376e606255..337afdb5024dcb 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2719,6 +2719,8 @@ 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 8c5196cf93a454..bb769746f78b08 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -4009,25 +4009,21 @@ 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 @@ -4035,46 +4031,15 @@ 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 - */ - } + if (ret >= 0 && iov_iter_count(from) && !IS_DAX(inode)) + ret = direct_write_fallback(iocb, from, ret, + generic_perform_write(iocb, from)); } else { - written = generic_perform_write(iocb, from); + ret = generic_perform_write(iocb, from); } out: current->backing_dev_info = NULL; - return written ? written : err; + return ret; } EXPORT_SYMBOL(__generic_file_write_iter);