[SCSI] st: kill struct st_buff_fragment

This removes struct st_buff_fragment and use reserved_pages array to
store fragment buffer.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: Kai Makisara <Kai.Makisara@kolumbus.fi>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

2 files changed, 43 insertions, 42 deletions

diff --git a/drivers/scsi/st.c b/drivers/scsi/st.c
index ce1fd3ab243b..1cfd217f8904 100644
--- a/drivers/scsi/st.c
+++ b/drivers/scsi/st.c
@@ -3753,8 +3753,9 @@ static struct st_buffer *
         else
                 priority = GFP_KERNEL;
 
-        i = sizeof(struct st_buffer) + (max_sg - 1) * sizeof(struct scatterlist) +
-                max_sg * sizeof(struct st_buf_fragment);
+        i = sizeof(struct st_buffer) +
+                (max_sg - 1) * sizeof(struct scatterlist);
+
         tb = kzalloc(i, priority);
         if (!tb) {
                 printk(KERN_NOTICE "st: Can't allocate new tape buffer.\n");
@@ -3762,7 +3763,6 @@ static struct st_buffer *
         }
         tb->frp_segs = tb->orig_frp_segs = 0;
         tb->use_sg = max_sg;
-        tb->frp = (struct st_buf_fragment *)(&(tb->sg[0]) + max_sg);
 
         tb->dma = need_dma;
         tb->buffer_size = got;
@@ -3799,9 +3799,12 @@ static int enlarge_buffer(struct st_buffer * STbuffer, int new_size, int need_dm
         if (need_dma)
                 priority |= GFP_DMA;
 
+        if (STbuffer->cleared)
+                priority |= __GFP_ZERO;
+
         if (STbuffer->frp_segs) {
-                b_size = STbuffer->frp[0].length;
-                order = get_order(b_size);
+                order = STbuffer->map_data.page_order;
+                b_size = PAGE_SIZE << order;
         } else {
                 for (b_size = PAGE_SIZE, order = 0;
                      order <= 6 && b_size < new_size; order++, b_size *= 2)
@@ -3810,22 +3813,22 @@ static int enlarge_buffer(struct st_buffer * STbuffer, int new_size, int need_dm
 
         for (segs = STbuffer->frp_segs, got = STbuffer->buffer_size;
              segs < max_segs && got < new_size;) {
-                STbuffer->frp[segs].page = alloc_pages(priority, order);
-                if (STbuffer->frp[segs].page == NULL) {
+                struct page *page;
+
+                page = alloc_pages(priority, order);
+                if (!page) {
                         DEB(STbuffer->buffer_size = got);
                         normalize_buffer(STbuffer);
                         return 0;
                 }
-                STbuffer->frp[segs].length = b_size;
+
                 STbuffer->frp_segs += 1;
                 got += b_size;
                 STbuffer->buffer_size = got;
-                if (STbuffer->cleared)
-                        memset(page_address(STbuffer->frp[segs].page), 0, b_size);
-                STbuffer->reserved_pages[segs] = STbuffer->frp[segs].page;
+                STbuffer->reserved_pages[segs] = page;
                 segs++;
         }
-        STbuffer->b_data = page_address(STbuffer->frp[0].page);
+        STbuffer->b_data = page_address(STbuffer->reserved_pages[0]);
         STbuffer->map_data.page_order = order;
 
         return 1;
@@ -3838,7 +3841,8 @@ static void clear_buffer(struct st_buffer * st_bp)
         int i;
 
         for (i=0; i < st_bp->frp_segs; i++)
-                memset(page_address(st_bp->frp[i].page), 0, st_bp->frp[i].length);
+                memset(page_address(st_bp->reserved_pages[i]), 0,
+                       PAGE_SIZE << st_bp->map_data.page_order);
         st_bp->cleared = 1;
 }
 
@@ -3846,12 +3850,11 @@ static void clear_buffer(struct st_buffer * st_bp)
 /* Release the extra buffer */
 static void normalize_buffer(struct st_buffer * STbuffer)
 {
-        int i, order;
+        int i, order = STbuffer->map_data.page_order;
 
         for (i = STbuffer->orig_frp_segs; i < STbuffer->frp_segs; i++) {
-                order = get_order(STbuffer->frp[i].length);
-                __free_pages(STbuffer->frp[i].page, order);
-                STbuffer->buffer_size -= STbuffer->frp[i].length;
+                __free_pages(STbuffer->reserved_pages[i], order);
+                STbuffer->buffer_size -= (PAGE_SIZE << order);
         }
         STbuffer->frp_segs = STbuffer->orig_frp_segs;
         STbuffer->frp_sg_current = 0;
@@ -3866,18 +3869,19 @@ 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;
 
         for (i = 0, offset = st_bp->buffer_bytes;
-             i < st_bp->frp_segs && offset >= st_bp->frp[i].length; i++)
-                offset -= st_bp->frp[i].length;
+             i < st_bp->frp_segs && offset >= length; i++)
+                offset -= length;
         if (i == st_bp->frp_segs) {     /* Should never happen */
                 printk(KERN_WARNING "st: append_to_buffer offset overflow.\n");
                 return (-EIO);
         }
         for (; i < st_bp->frp_segs && do_count > 0; i++) {
-                cnt = st_bp->frp[i].length - offset < do_count ?
-                    st_bp->frp[i].length - offset : do_count;
-                res = copy_from_user(page_address(st_bp->frp[i].page) + offset, ubp, cnt);
+                struct page *page = st_bp->reserved_pages[i];
+                cnt = length - offset < do_count ? length - offset : do_count;
+                res = copy_from_user(page_address(page) + offset, ubp, cnt);
                 if (res)
                         return (-EFAULT);
                 do_count -= cnt;
@@ -3897,18 +3901,19 @@ 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;
 
         for (i = 0, offset = st_bp->read_pointer;
-             i < st_bp->frp_segs && offset >= st_bp->frp[i].length; i++)
-                offset -= st_bp->frp[i].length;
+             i < st_bp->frp_segs && offset >= length; i++)
+                offset -= length;
         if (i == st_bp->frp_segs) {     /* Should never happen */
                 printk(KERN_WARNING "st: from_buffer offset overflow.\n");
                 return (-EIO);
         }
         for (; i < st_bp->frp_segs && do_count > 0; i++) {
-                cnt = st_bp->frp[i].length - offset < do_count ?
-                    st_bp->frp[i].length - offset : do_count;
-                res = copy_to_user(ubp, page_address(st_bp->frp[i].page) + offset, cnt);
+                struct page *page = st_bp->reserved_pages[i];
+                cnt = length - offset < do_count ? length - offset : do_count;
+                res = copy_to_user(ubp, page_address(page) + offset, cnt);
                 if (res)
                         return (-EFAULT);
                 do_count -= cnt;
@@ -3929,6 +3934,7 @@ 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;
 
         if (offset == 0)
                 return;
@@ -3936,24 +3942,26 @@ static void move_buffer_data(struct st_buffer * st_bp, int offset)
         total=st_bp->buffer_bytes - offset;
         for (src_seg=0; src_seg < st_bp->frp_segs; src_seg++) {
                 src_offset = offset;
-                if (src_offset < st_bp->frp[src_seg].length)
+                if (src_offset < length)
                         break;
-                offset -= st_bp->frp[src_seg].length;
+                offset -= length;
         }
 
         st_bp->buffer_bytes = st_bp->read_pointer = total;
         for (dst_seg=dst_offset=0; total > 0; ) {
-                count = min(st_bp->frp[dst_seg].length - dst_offset,
-                            st_bp->frp[src_seg].length - src_offset);
-                memmove(page_address(st_bp->frp[dst_seg].page) + dst_offset,
-                        page_address(st_bp->frp[src_seg].page) + src_offset, count);
+                struct page *dpage = st_bp->reserved_pages[dst_seg];
+                struct page *spage = st_bp->reserved_pages[src_seg];
+
+                count = min(length - dst_offset, length - src_offset);
+                memmove(page_address(dpage) + dst_offset,
+                        page_address(spage) + src_offset, count);
                 src_offset += count;
-                if (src_offset >= st_bp->frp[src_seg].length) {
+                if (src_offset >= length) {
                         src_seg++;
                         src_offset = 0;
                 }
                 dst_offset += count;
-                if (dst_offset >= st_bp->frp[dst_seg].length) {
+                if (dst_offset >= length) {
                         dst_seg++;
                         dst_offset = 0;
                 }
diff --git a/drivers/scsi/st.h b/drivers/scsi/st.h
index d80926f9c6e3..cc46f18762b7 100644
--- a/drivers/scsi/st.h
+++ b/drivers/scsi/st.h
@@ -54,16 +54,9 @@ struct st_buffer {
         unsigned short orig_frp_segs;   /* number of segments allocated at first try */
         unsigned short frp_segs;        /* number of buffer segments */
         unsigned int frp_sg_current;    /* driver buffer length currently in s/g list */
-        struct st_buf_fragment *frp;    /* the allocated buffer fragment list */
         struct scatterlist sg[1];       /* MUST BE last item */
 };
 
-/* The tape buffer fragment descriptor */
-struct st_buf_fragment {
-        struct page *page;
-        unsigned int length;
-};
-
 /* The tape mode definition */
 struct st_modedef {
         unsigned char defined;