ceph: Implement writev/pwritev for sync operation.

For writev/pwritev sync-operatoin, ceph only do the first iov.

I divided the write-sync-operation into two functions. One for
direct-write, other for none-direct-sync-write. This is because for
none-direct-sync-write we can merge iovs to one. But for direct-write,
we can't merge iovs.
Signed-off-by: Jianpeng Ma <majianpeng@gmail.com>
Reviewed-by: Yan, Zheng <zheng.z.yan@intel.com>
Signed-off-by: Sage Weil <sage@inktank.com>

fs/ceph/file.c

@@ -489,83 +489,79 @@ static void ceph_sync_write_unsafe(struct ceph_osd_request *req, bool unsafe)
 	}
 }
 
+
 /*
- * Synchronous write, straight from __user pointer or user pages (if
- * O_DIRECT).
+ * Synchronous write, straight from __user pointer or user pages.
  *
  * If write spans object boundary, just do multiple writes.  (For a
  * correct atomic write, we should e.g. take write locks on all
  * objects, rollback on failure, etc.)
  */
-static ssize_t ceph_sync_write(struct file *file, const char __user *data,
-			       size_t left, loff_t pos, loff_t *ppos)
+static ssize_t
+ceph_sync_direct_write(struct kiocb *iocb, const struct iovec *iov,
+		       unsigned long nr_segs, size_t count)
 {
+	struct file *file = iocb->ki_filp;
 	struct inode *inode = file_inode(file);
 	struct ceph_inode_info *ci = ceph_inode(inode);
 	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
 	struct ceph_snap_context *snapc;
 	struct ceph_vino vino;
 	struct ceph_osd_request *req;
-	int num_ops = 1;
 	struct page **pages;
 	int num_pages;
-	u64 len;
 	int written = 0;
 	int flags;
 	int check_caps = 0;
-	int page_align, io_align;
-	unsigned long buf_align;
+	int page_align;
 	int ret;
 	struct timespec mtime = CURRENT_TIME;
-	bool own_pages = false;
+	loff_t pos = iocb->ki_pos;
+	struct iov_iter i;
 
 	if (ceph_snap(file_inode(file)) != CEPH_NOSNAP)
 		return -EROFS;
 
-	dout("sync_write on file %p %lld~%u %s\n", file, pos,
-	     (unsigned)left, (file->f_flags & O_DIRECT) ? "O_DIRECT" : "");
+	dout("sync_direct_write on file %p %lld~%u\n", file, pos,
+	     (unsigned)count);
 
-	ret = filemap_write_and_wait_range(inode->i_mapping, pos, pos + left);
+	ret = filemap_write_and_wait_range(inode->i_mapping, pos, pos + count);
 	if (ret < 0)
 		return ret;
 
 	ret = invalidate_inode_pages2_range(inode->i_mapping,
 					    pos >> PAGE_CACHE_SHIFT,
-					    (pos + left) >> PAGE_CACHE_SHIFT);
+					    (pos + count) >> PAGE_CACHE_SHIFT);
 	if (ret < 0)
 		dout("invalidate_inode_pages2_range returned %d\n", ret);
 
 	flags = CEPH_OSD_FLAG_ORDERSNAP |
 		CEPH_OSD_FLAG_ONDISK |
 		CEPH_OSD_FLAG_WRITE;
-	if ((file->f_flags & (O_SYNC|O_DIRECT)) == 0)
-		flags |= CEPH_OSD_FLAG_ACK;
-	else
-		num_ops++;	/* Also include a 'startsync' command. */
 
-	/*
-	 * we may need to do multiple writes here if we span an object
-	 * boundary.  this isn't atomic, unfortunately.  :(
-	 */
-more:
-	io_align = pos & ~PAGE_MASK;
-	buf_align = (unsigned long)data & ~PAGE_MASK;
-	len = left;
+	iov_iter_init(&i, iov, nr_segs, count, 0);
+
+	while (iov_iter_count(&i) > 0) {
+		void __user *data = i.iov->iov_base + i.iov_offset;
+		u64 len = i.iov->iov_len - i.iov_offset;
+
+		page_align = (unsigned long)data & ~PAGE_MASK;
 
 		snapc = ci->i_snap_realm->cached_context;
 		vino = ceph_vino(inode);
 		req = ceph_osdc_new_request(&fsc->client->osdc, &ci->i_layout,
-				    vino, pos, &len, num_ops,
+					    vino, pos, &len,
+					    2,/*include a 'startsync' command*/
 					    CEPH_OSD_OP_WRITE, flags, snapc,
-				    ci->i_truncate_seq, ci->i_truncate_size,
+					    ci->i_truncate_seq,
+					    ci->i_truncate_size,
 					    false);
-	if (IS_ERR(req))
-		return PTR_ERR(req);
+		if (IS_ERR(req)) {
+			ret = PTR_ERR(req);
+			goto out;
+		}
 
-	/* write from beginning of first page, regardless of io alignment */
-	page_align = file->f_flags & O_DIRECT ? buf_align : io_align;
 		num_pages = calc_pages_for(page_align, len);
-	if (file->f_flags & O_DIRECT) {
 		pages = ceph_get_direct_page_vector(data, num_pages, false);
 		if (IS_ERR(pages)) {
 			ret = PTR_ERR(pages);
@@ -578,27 +574,146 @@ static ssize_t ceph_sync_write(struct file *file, const char __user *data,
 		 */
 		truncate_inode_pages_range(inode->i_mapping, pos,
 				   (pos+len) | (PAGE_CACHE_SIZE-1));
-	} else {
+		osd_req_op_extent_osd_data_pages(req, 0, pages, len, page_align,
+						false, false);
+
+		/* BUG_ON(vino.snap != CEPH_NOSNAP); */
+		ceph_osdc_build_request(req, pos, snapc, vino.snap, &mtime);
+
+		ret = ceph_osdc_start_request(&fsc->client->osdc, req, false);
+		if (!ret)
+			ret = ceph_osdc_wait_request(&fsc->client->osdc, req);
+
+		ceph_put_page_vector(pages, num_pages, false);
+
+out:
+		ceph_osdc_put_request(req);
+		if (ret == 0) {
+			pos += len;
+			written += len;
+			iov_iter_advance(&i, (size_t)len);
+
+			if (pos > i_size_read(inode)) {
+				check_caps = ceph_inode_set_size(inode, pos);
+				if (check_caps)
+					ceph_check_caps(ceph_inode(inode),
+							CHECK_CAPS_AUTHONLY,
+							NULL);
+			}
+		} else
+			break;
+	}
+
+	if (ret != -EOLDSNAPC && written > 0) {
+		iocb->ki_pos = pos;
+		ret = written;
+	}
+	return ret;
+}
+
+
+/*
+ * Synchronous write, straight from __user pointer or user pages.
+ *
+ * If write spans object boundary, just do multiple writes.  (For a
+ * correct atomic write, we should e.g. take write locks on all
+ * objects, rollback on failure, etc.)
+ */
+static ssize_t ceph_sync_write(struct kiocb *iocb, const struct iovec *iov,
+			       unsigned long nr_segs, size_t count)
+{
+	struct file *file = iocb->ki_filp;
+	struct inode *inode = file_inode(file);
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
+	struct ceph_snap_context *snapc;
+	struct ceph_vino vino;
+	struct ceph_osd_request *req;
+	struct page **pages;
+	u64 len;
+	int num_pages;
+	int written = 0;
+	int flags;
+	int check_caps = 0;
+	int ret;
+	struct timespec mtime = CURRENT_TIME;
+	loff_t pos = iocb->ki_pos;
+	struct iov_iter i;
+
+	if (ceph_snap(file_inode(file)) != CEPH_NOSNAP)
+		return -EROFS;
+
+	dout("sync_write on file %p %lld~%u\n", file, pos, (unsigned)count);
+
+	ret = filemap_write_and_wait_range(inode->i_mapping, pos, pos + count);
+	if (ret < 0)
+		return ret;
+
+	ret = invalidate_inode_pages2_range(inode->i_mapping,
+					    pos >> PAGE_CACHE_SHIFT,
+					    (pos + count) >> PAGE_CACHE_SHIFT);
+	if (ret < 0)
+		dout("invalidate_inode_pages2_range returned %d\n", ret);
+
+	flags = CEPH_OSD_FLAG_ORDERSNAP |
+		CEPH_OSD_FLAG_ONDISK |
+		CEPH_OSD_FLAG_WRITE |
+		CEPH_OSD_FLAG_ACK;
+
+	iov_iter_init(&i, iov, nr_segs, count, 0);
+
+	while ((len = iov_iter_count(&i)) > 0) {
+		size_t left;
+		int n;
+
+		snapc = ci->i_snap_realm->cached_context;
+		vino = ceph_vino(inode);
+		req = ceph_osdc_new_request(&fsc->client->osdc, &ci->i_layout,
+					    vino, pos, &len, 1,
+					    CEPH_OSD_OP_WRITE, flags, snapc,
+					    ci->i_truncate_seq,
+					    ci->i_truncate_size,
+					    false);
+		if (IS_ERR(req)) {
+			ret = PTR_ERR(req);
+			goto out;
+		}
+
+		/*
+		 * write from beginning of first page,
+		 * regardless of io alignment
+		 */
+		num_pages = (len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+
 		pages = ceph_alloc_page_vector(num_pages, GFP_NOFS);
 		if (IS_ERR(pages)) {
 			ret = PTR_ERR(pages);
 			goto out;
 		}
-		ret = ceph_copy_user_to_page_vector(pages, data, pos, len);
+
+		left = len;
+		for (n = 0; n < num_pages; n++) {
+			size_t plen = min(left, PAGE_SIZE);
+			ret = iov_iter_copy_from_user(pages[n], &i, 0, plen);
+			if (ret != plen) {
+				ret = -EFAULT;
+				break;
+			}
+			left -= ret;
+			iov_iter_advance(&i, ret);
+		}
+
 		if (ret < 0) {
 			ceph_release_page_vector(pages, num_pages);
 			goto out;
 		}
 
-		if ((file->f_flags & O_SYNC) == 0) {
 		/* get a second commit callback */
 		req->r_unsafe_callback = ceph_sync_write_unsafe;
 		req->r_inode = inode;
-			own_pages = true;
-		}
-	}
-	osd_req_op_extent_osd_data_pages(req, 0, pages, len, page_align,
-					false, own_pages);
+
+		osd_req_op_extent_osd_data_pages(req, 0, pages, len, 0,
+						false, true);
 
 		/* BUG_ON(vino.snap != CEPH_NOSNAP); */
 		ceph_osdc_build_request(req, pos, snapc, vino.snap, &mtime);
@@ -607,30 +722,26 @@ static ssize_t ceph_sync_write(struct file *file, const char __user *data,
 		if (!ret)
 			ret = ceph_osdc_wait_request(&fsc->client->osdc, req);
 
-	if (file->f_flags & O_DIRECT)
-		ceph_put_page_vector(pages, num_pages, false);
-	else if (file->f_flags & O_SYNC)
-		ceph_release_page_vector(pages, num_pages);
-
 out:
 		ceph_osdc_put_request(req);
 		if (ret == 0) {
 			pos += len;
 			written += len;
-		left -= len;
-		data += len;
-		if (left)
-			goto more;
 
-		ret = written;
-		*ppos = pos;
-		if (pos > i_size_read(inode))
+			if (pos > i_size_read(inode)) {
 				check_caps = ceph_inode_set_size(inode, pos);
 				if (check_caps)
-			ceph_check_caps(ceph_inode(inode), CHECK_CAPS_AUTHONLY,
+					ceph_check_caps(ceph_inode(inode),
+							CHECK_CAPS_AUTHONLY,
 							NULL);
-	} else if (ret != -EOLDSNAPC && written > 0) {
+			}
+		} else
+			break;
+	}
+
+	if (ret != -EOLDSNAPC && written > 0) {
 		ret = written;
+		iocb->ki_pos = pos;
 	}
 	return ret;
 }
@@ -772,11 +883,13 @@ static ssize_t ceph_aio_write(struct kiocb *iocb, const struct iovec *iov,
 	     inode, ceph_vinop(inode), pos, count, ceph_cap_string(got));
 
 	if ((got & (CEPH_CAP_FILE_BUFFER|CEPH_CAP_FILE_LAZYIO)) == 0 ||
-	    (iocb->ki_filp->f_flags & O_DIRECT) ||
-	    (fi->flags & CEPH_F_SYNC)) {
+	    (file->f_flags & O_DIRECT) || (fi->flags & CEPH_F_SYNC)) {
 		mutex_unlock(&inode->i_mutex);
-		written = ceph_sync_write(file, iov->iov_base, count,
-					  pos, &iocb->ki_pos);
+		if (file->f_flags & O_DIRECT)
+			written = ceph_sync_direct_write(iocb, iov,
+							 nr_segs, count);
+		else
+			written = ceph_sync_write(iocb, iov, nr_segs, count);
 		if (written == -EOLDSNAPC) {
 			dout("aio_write %p %llx.%llx %llu~%u"
 				"got EOLDSNAPC, retrying\n",