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 <sage@newdream.net>

1 files changed, 5 insertions, 2 deletions

diff --git a/include/linux/ceph/osd_client.h b/include/linux/ceph/osd_client.h
index 6c91fb032c39..a1af29648fb5 100644
--- a/include/linux/ceph/osd_client.h
+++ b/include/linux/ceph/osd_client.h
@@ -79,6 +79,7 @@ struct ceph_osd_request {
         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 */
@@ -194,7 +195,8 @@ extern struct ceph_osd_request *ceph_osdc_new_request(struct ceph_osd_client *,
                                       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)
 {
@@ -218,7 +220,8 @@ extern int ceph_osdc_readpages(struct ceph_osd_client *osdc,
                                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,