[SCSI] st: fix mdata->page_order handling

dio transfer always resets mdata->page_order to zero. It breaks
high-order pages previously allocated for non-dio transfer.

This patches adds reserved_page_order to st_buffer structure to save
page order for non-dio transfer.

http://bugzilla.kernel.org/show_bug.cgi?id=14563

When enlarge_buffer() allocates 524288 from 0, st uses six-order page
allocation. So mdata->page_order is 6 and frp_seg is 2.

After that, if st uses dio, sgl_map_user_pages() sets
mdata->page_order to 0 for st_do_scsi(). After that, when we call
normalize_buffer(), it frees only free frp_seg * PAGE_SIZE (2 * 4096)
though we should free frp_seg * PAGE_SIZE << 6 (2 * 4096 << 6). So we
see buffer_size is set to 516096 (524288 - 8192).

Reported-by: Joachim Breuer <linux-kernel@jmbreuer.net>
Tested-by: Joachim Breuer <linux-kernel@jmbreuer.net>
Acked-by: Kai Makisara <kai.makisara@kolumbus.fi>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: stable@kernel.org
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

2 files changed, 13 insertions, 11 deletions

diff --git a/drivers/scsi/st.c b/drivers/scsi/st.c
index ad59abb47722..d04ea9a6f673 100644
--- a/drivers/scsi/st.c
+++ b/drivers/scsi/st.c
@@ -552,13 +552,15 @@ st_do_scsi(struct st_request * SRpnt, struct scsi_tape * STp, unsigned char *cmd
         SRpnt->waiting = waiting;
 
         if (STp->buffer->do_dio) {
+                mdata->page_order = 0;
                 mdata->nr_entries = STp->buffer->sg_segs;
                 mdata->pages = STp->buffer->mapped_pages;
         } else {
+                mdata->page_order = STp->buffer->reserved_page_order;
                 mdata->nr_entries =
                         DIV_ROUND_UP(bytes, PAGE_SIZE << mdata->page_order);
-                STp->buffer->map_data.pages = STp->buffer->reserved_pages;
-                STp->buffer->map_data.offset = 0;
+                mdata->pages = STp->buffer->reserved_pages;
+                mdata->offset = 0;
         }
 
         memcpy(SRpnt->cmd, cmd, sizeof(SRpnt->cmd));
@@ -3719,7 +3721,7 @@ static int enlarge_buffer(struct st_buffer * STbuffer, int new_size, int need_dm
                 priority |= __GFP_ZERO;
 
         if (STbuffer->frp_segs) {
-                order = STbuffer->map_data.page_order;
+                order = STbuffer->reserved_page_order;
                 b_size = PAGE_SIZE << order;
         } else {
                 for (b_size = PAGE_SIZE, order = 0;
@@ -3752,7 +3754,7 @@ static int enlarge_buffer(struct st_buffer * STbuffer, int new_size, int need_dm
                 segs++;
         }
         STbuffer->b_data = page_address(STbuffer->reserved_pages[0]);
-        STbuffer->map_data.page_order = order;
+        STbuffer->reserved_page_order = order;
 
         return 1;
 }
@@ -3765,7 +3767,7 @@ static void clear_buffer(struct st_buffer * st_bp)
 
         for (i=0; i < st_bp->frp_segs; i++)
                 memset(page_address(st_bp->reserved_pages[i]), 0,
-                       PAGE_SIZE << st_bp->map_data.page_order);
+                       PAGE_SIZE << st_bp->reserved_page_order);
         st_bp->cleared = 1;
 }
 
@@ -3773,7 +3775,7 @@ static void clear_buffer(struct st_buffer * st_bp)
 /* Release the extra buffer */
 static void normalize_buffer(struct st_buffer * STbuffer)
 {
-        int i, order = STbuffer->map_data.page_order;
+        int i, order = STbuffer->reserved_page_order;
 
         for (i = 0; i < STbuffer->frp_segs; i++) {
                 __free_pages(STbuffer->reserved_pages[i], order);
@@ -3781,7 +3783,7 @@ static void normalize_buffer(struct st_buffer * STbuffer)
         }
         STbuffer->frp_segs = 0;
         STbuffer->sg_segs = 0;
-        STbuffer->map_data.page_order = 0;
+        STbuffer->reserved_page_order = 0;
         STbuffer->map_data.offset = 0;
 }
 
@@ -3791,7 +3793,7 @@ static void normalize_buffer(struct st_buffer * STbuffer)
 static int append_to_buffer(const char __user *ubp, struct st_buffer * st_bp, int do_count)
 {
         int i, cnt, res, offset;
-        int length = PAGE_SIZE << st_bp->map_data.page_order;
+        int length = PAGE_SIZE << st_bp->reserved_page_order;
 
         for (i = 0, offset = st_bp->buffer_bytes;
              i < st_bp->frp_segs && offset >= length; i++)
@@ -3823,7 +3825,7 @@ static int append_to_buffer(const char __user *ubp, struct st_buffer * st_bp, in
 static int from_buffer(struct st_buffer * st_bp, char __user *ubp, int do_count)
 {
         int i, cnt, res, offset;
-        int length = PAGE_SIZE << st_bp->map_data.page_order;
+        int length = PAGE_SIZE << st_bp->reserved_page_order;
 
         for (i = 0, offset = st_bp->read_pointer;
              i < st_bp->frp_segs && offset >= length; i++)
@@ -3856,7 +3858,7 @@ static void move_buffer_data(struct st_buffer * st_bp, int offset)
 {
         int src_seg, dst_seg, src_offset = 0, dst_offset;
         int count, total;
-        int length = PAGE_SIZE << st_bp->map_data.page_order;
+        int length = PAGE_SIZE << st_bp->reserved_page_order;
 
         if (offset == 0)
                 return;
@@ -4578,7 +4580,6 @@ static int sgl_map_user_pages(struct st_buffer *STbp,
         }
 
         mdata->offset = uaddr & ~PAGE_MASK;
-        mdata->page_order = 0;
         STbp->mapped_pages = pages;
 
         return nr_pages;
diff --git a/drivers/scsi/st.h b/drivers/scsi/st.h
index 544dc6b1f548..f91a67c6d968 100644
--- a/drivers/scsi/st.h
+++ b/drivers/scsi/st.h
@@ -46,6 +46,7 @@ struct st_buffer {
         struct st_request *last_SRpnt;
         struct st_cmdstatus cmdstat;
         struct page **reserved_pages;
+        int reserved_page_order;
         struct page **mapped_pages;
         struct rq_map_data map_data;
         unsigned char *b_data;