ceph: make page alignment explicit in osd interface

We used to infer alignment of IOs within a page based on the file offset,
which assumed they matched. This broke with direct IO that was not aligned
to pages (e.g., 512-byte aligned IO). We were also trusting the alignment
specified in the OSD reply, which could have been adjusted by the server.

Explicitly specify the page alignment when setting up OSD IO requests.

Signed-off-by: Sage Weil <[e-mail]>

fs/ceph/addr.c

···
 	err = ceph_osdc_readpages(osdc, ceph_vino(inode), &ci->i_layout,
 				  page->index << PAGE_CACHE_SHIFT, &len,
 				  ci->i_truncate_seq, ci->i_truncate_size,
-				  &page, 1);
+				  &page, 1, 0);
 	if (err == -ENOENT)
 		err = 0;
 	if (err < 0) {
···
 	rc = ceph_osdc_readpages(osdc, ceph_vino(inode), &ci->i_layout,
 				 offset, &len,
 				 ci->i_truncate_seq, ci->i_truncate_size,
-				 pages, nr_pages);
+				 pages, nr_pages, 0);
 	if (rc == -ENOENT)
 		rc = 0;
 	if (rc < 0)
···
 					    snapc, do_sync,
 					    ci->i_truncate_seq,
 					    ci->i_truncate_size,
-					    &inode->i_mtime, true, 1);
+					    &inode->i_mtime, true, 1, 0);
 				max_pages = req->r_num_pages;
 
 				alloc_page_vec(fsc, req);

fs/ceph/file.c

···
 static int striped_read(struct inode *inode,
 			u64 off, u64 len,
 			struct page **pages, int num_pages,
-			int *checkeof)
+			int *checkeof, bool align_to_pages)
 {
 	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
 	struct ceph_inode_info *ci = ceph_inode(inode);
 	u64 pos, this_len;
+	int io_align, page_align;
 	int page_off = off & ~PAGE_CACHE_MASK; /* first byte's offset in page */
 	int left, pages_left;
 	int read;
···
 	page_pos = pages;
 	pages_left = num_pages;
 	read = 0;
+	io_align = off & ~PAGE_MASK;
 
 more:
+	if (align_to_pages)
+		page_align = (pos - io_align) & ~PAGE_MASK;
+	else
+		page_align = pos & ~PAGE_MASK;
 	this_len = left;
 	ret = ceph_osdc_readpages(&fsc->client->osdc, ceph_vino(inode),
 				  &ci->i_layout, pos, &this_len,
 				  ci->i_truncate_seq,
 				  ci->i_truncate_size,
-				  page_pos, pages_left);
+				  page_pos, pages_left, page_align);
 	hit_stripe = this_len < left;
 	was_short = ret >= 0 && ret < this_len;
 	if (ret == -ENOENT)
···
 	if (ret < 0)
 		goto done;
 
-	ret = striped_read(inode, off, len, pages, num_pages, checkeof);
+	ret = striped_read(inode, off, len, pages, num_pages, checkeof,
+			   file->f_flags & O_DIRECT);
 
 	if (ret >= 0 && (file->f_flags & O_DIRECT) == 0)
 		ret = ceph_copy_page_vector_to_user(pages, data, off, ret);
···
 	int flags;
 	int do_sync = 0;
 	int check_caps = 0;
+	int page_align, io_align;
 	int ret;
 	struct timespec mtime = CURRENT_TIME;
 
···
 		pos = i_size_read(inode);
 	else
 		pos = *offset;
+
+	io_align = pos & ~PAGE_MASK;
 
 	ret = filemap_write_and_wait_range(inode->i_mapping, pos, pos + left);
 	if (ret < 0)
···
 	 */
 more:
 	len = left;
+	if (file->f_flags & O_DIRECT)
+		/* write from beginning of first page, regardless of
+		   io alignment */
+		page_align = (pos - io_align) & ~PAGE_MASK;
+	else
+		page_align = pos & ~PAGE_MASK;
 	req = ceph_osdc_new_request(&fsc->client->osdc, &ci->i_layout,
 				    ceph_vino(inode), pos, &len,
 				    CEPH_OSD_OP_WRITE, flags,
 				    ci->i_snap_realm->cached_context,
 				    do_sync,
 				    ci->i_truncate_seq, ci->i_truncate_size,
-				    &mtime, false, 2);
+				    &mtime, false, 2, page_align);
 	if (!req)
 		return -ENOMEM;
 
 	num_pages = calc_pages_for(pos, len);
 
 	if (file->f_flags & O_DIRECT) {
-		pages = ceph_get_direct_page_vector(data, num_pages, pos, len);
+		pages = ceph_get_direct_page_vector(data, num_pages);
 		if (IS_ERR(pages)) {
 			ret = PTR_ERR(pages);
 			goto out;

fs/ceph/inode.c

···
 		return 0;
 	}
 
-	dout("do_getattr inode %p mask %s\n", inode, ceph_cap_string(mask));
+	dout("do_getattr inode %p mask %s mode 0%o\n", inode, ceph_cap_string(mask), inode->i_mode);
 	if (ceph_caps_issued_mask(ceph_inode(inode), mask, 1))
 		return 0;
 

include/linux/ceph/osd_client.h

···
 	struct ceph_file_layout r_file_layout;
 	struct ceph_snap_context *r_snapc;    /* snap context for writes */
 	unsigned          r_num_pages;        /* size of page array (follows) */
+	unsigned          r_page_alignment;   /* io offset in first page */
 	struct page     **r_pages;            /* pages for data payload */
 	int               r_pages_from_pool;
 	int               r_own_pages;        /* if true, i own page list */
···
 				      int do_sync, u32 truncate_seq,
 				      u64 truncate_size,
 				      struct timespec *mtime,
-				      bool use_mempool, int num_reply);
+				      bool use_mempool, int num_reply,
+				      int page_align);
 
 static inline void ceph_osdc_get_request(struct ceph_osd_request *req)
 {
···
 			       struct ceph_file_layout *layout,
 			       u64 off, u64 *plen,
 			       u32 truncate_seq, u64 truncate_size,
-			       struct page **pages, int nr_pages);
+			       struct page **pages, int nr_pages,
+			       int page_align);
 
 extern int ceph_osdc_writepages(struct ceph_osd_client *osdc,
 				struct ceph_vino vino,

net/ceph/osd_client.c

···
 		op->extent.length = objlen;
 	}
 	req->r_num_pages = calc_pages_for(off, *plen);
+	req->r_page_alignment = off & ~PAGE_MASK;
 	if (op->op == CEPH_OSD_OP_WRITE)
 		op->payload_len = *plen;
 
···
 					       u32 truncate_seq,
 					       u64 truncate_size,
 					       struct timespec *mtime,
-					       bool use_mempool, int num_reply)
+					       bool use_mempool, int num_reply,
+					       int page_align)
 {
 	struct ceph_osd_req_op ops[3];
 	struct ceph_osd_request *req;
···
 	/* calculate max write size */
 	calc_layout(osdc, vino, layout, off, plen, req, ops);
 	req->r_file_layout = *layout;  /* keep a copy */
+
+	/* in case it differs from natural alignment that calc_layout
+	   filled in for us */
+	req->r_page_alignment = page_align;
 
 	ceph_osdc_build_request(req, off, plen, ops,
 				snapc,
···
 			struct ceph_vino vino, struct ceph_file_layout *layout,
 			u64 off, u64 *plen,
 			u32 truncate_seq, u64 truncate_size,
-			struct page **pages, int num_pages)
+			struct page **pages, int num_pages, int page_align)
 {
 	struct ceph_osd_request *req;
 	int rc = 0;
···
 	req = ceph_osdc_new_request(osdc, layout, vino, off, plen,
 				    CEPH_OSD_OP_READ, CEPH_OSD_FLAG_READ,
 				    NULL, 0, truncate_seq, truncate_size, NULL,
-				    false, 1);
+				    false, 1, page_align);
 	if (!req)
 		return -ENOMEM;
 
 	/* it may be a short read due to an object boundary */
 	req->r_pages = pages;
 
-	dout("readpages  final extent is %llu~%llu (%d pages)\n",
-	     off, *plen, req->r_num_pages);
+	dout("readpages  final extent is %llu~%llu (%d pages align %d)\n",
+	     off, *plen, req->r_num_pages, page_align);
 
 	rc = ceph_osdc_start_request(osdc, req, false);
 	if (!rc)
···
 {
 	struct ceph_osd_request *req;
 	int rc = 0;
+	int page_align = off & ~PAGE_MASK;
 
 	BUG_ON(vino.snap != CEPH_NOSNAP);
 	req = ceph_osdc_new_request(osdc, layout, vino, off, &len,
···
 					    CEPH_OSD_FLAG_WRITE,
 				    snapc, do_sync,
 				    truncate_seq, truncate_size, mtime,
-				    nofail, 1);
+				    nofail, 1, page_align);
 	if (!req)
 		return -ENOMEM;
 
···
 	m = ceph_msg_get(req->r_reply);
 
 	if (data_len > 0) {
-		unsigned data_off = le16_to_cpu(hdr->data_off);
-		int want = calc_pages_for(data_off & ~PAGE_MASK, data_len);
+		int want = calc_pages_for(req->r_page_alignment, data_len);
 
 		if (unlikely(req->r_num_pages < want)) {
 			pr_warning("tid %lld reply %d > expected %d pages\n",