[XFS] Only use refcounted pages for I/O

Many block drivers (aoe, iscsi) really want refcountable pages in bios,
which is what almost everyone send down. XFS unfortunately has a few
places where it sends down buffers that may come from kmalloc, which
breaks them.

Fix the places that use kmalloc()d buffers.

SGI-PV: 964546
SGI-Modid: xfs-linux-melb:xfs-kern:28562a

Signed-Off-By: Christoph Hellwig <hch@infradead.org>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>

2 files changed, 22 insertions, 29 deletions

diff --git a/fs/xfs/linux-2.6/xfs_buf.c b/fs/xfs/linux-2.6/xfs_buf.c
index fe4f66a5af14..208daf58b826 100644
--- a/fs/xfs/linux-2.6/xfs_buf.c
+++ b/fs/xfs/linux-2.6/xfs_buf.c
@@ -314,7 +314,7 @@ xfs_buf_free(
 
         ASSERT(list_empty(&bp->b_hash_list));
 
-        if (bp->b_flags & _XBF_PAGE_CACHE) {
+        if (bp->b_flags & (_XBF_PAGE_CACHE|_XBF_PAGES)) {
                 uint            i;
 
                 if ((bp->b_flags & XBF_MAPPED) && (bp->b_page_count > 1))
@@ -323,18 +323,11 @@ xfs_buf_free(
                 for (i = 0; i < bp->b_page_count; i++) {
                         struct page     *page = bp->b_pages[i];
 
-                        ASSERT(!PagePrivate(page));
+                        if (bp->b_flags & _XBF_PAGE_CACHE)
+                                ASSERT(!PagePrivate(page));
                         page_cache_release(page);
                 }
                 _xfs_buf_free_pages(bp);
-        } else if (bp->b_flags & _XBF_KMEM_ALLOC) {
-                 /*
-                  * XXX(hch): bp->b_count_desired might be incorrect (see
-                  * xfs_buf_associate_memory for details), but fortunately
-                  * the Linux version of kmem_free ignores the len argument..
-                  */
-                kmem_free(bp->b_addr, bp->b_count_desired);
-                _xfs_buf_free_pages(bp);
         }
 
         xfs_buf_deallocate(bp);
@@ -764,41 +757,41 @@ xfs_buf_get_noaddr(
         size_t                  len,
         xfs_buftarg_t           *target)
 {
-        size_t                  malloc_len = len;
+        unsigned long           page_count = PAGE_ALIGN(len) >> PAGE_SHIFT;
+        int                     error, i;
         xfs_buf_t               *bp;
-        void                    *data;
-        int                     error;
 
         bp = xfs_buf_allocate(0);
         if (unlikely(bp == NULL))
                 goto fail;
         _xfs_buf_initialize(bp, target, 0, len, 0);
 
- try_again:
-        data = kmem_alloc(malloc_len, KM_SLEEP | KM_MAYFAIL | KM_LARGE);
-        if (unlikely(data == NULL))
+        error = _xfs_buf_get_pages(bp, page_count, 0);
+        if (error)
                 goto fail_free_buf;
 
-        /* check whether alignment matches.. */
-        if ((__psunsigned_t)data !=
-            ((__psunsigned_t)data & ~target->bt_smask)) {
-                /* .. else double the size and try again */
-                kmem_free(data, malloc_len);
-                malloc_len <<= 1;
-                goto try_again;
+        for (i = 0; i < page_count; i++) {
+                bp->b_pages[i] = alloc_page(GFP_KERNEL);
+                if (!bp->b_pages[i])
+                        goto fail_free_mem;
         }
+        bp->b_flags |= _XBF_PAGES;
 
-        error = xfs_buf_associate_memory(bp, data, len);
-        if (error)
+        error = _xfs_buf_map_pages(bp, XBF_MAPPED);
+        if (unlikely(error)) {
+                printk(KERN_WARNING "%s: failed to map pages\n",
+                                __FUNCTION__);
                 goto fail_free_mem;
-        bp->b_flags |= _XBF_KMEM_ALLOC;
+        }
 
         xfs_buf_unlock(bp);
 
-        XB_TRACE(bp, "no_daddr", data);
+        XB_TRACE(bp, "no_daddr", len);
         return bp;
+
  fail_free_mem:
-        kmem_free(data, malloc_len);
+        while (--i >= 0)
+                __free_page(bp->b_pages[i]);
  fail_free_buf:
         xfs_buf_free(bp);
  fail:
diff --git a/fs/xfs/linux-2.6/xfs_buf.h b/fs/xfs/linux-2.6/xfs_buf.h
index b6241f6201a5..b5908a34b15d 100644
--- a/fs/xfs/linux-2.6/xfs_buf.h
+++ b/fs/xfs/linux-2.6/xfs_buf.h
@@ -63,7 +63,7 @@ typedef enum {
 
         /* flags used only internally */
         _XBF_PAGE_CACHE = (1 << 17),/* backed by pagecache                 */
-        _XBF_KMEM_ALLOC = (1 << 18),/* backed by kmem_alloc()              */
+        _XBF_PAGES = (1 << 18),     /* backed by refcounted pages          */
         _XBF_RUN_QUEUES = (1 << 19),/* run block device task queue         */
         _XBF_DELWRI_Q = (1 << 21),   /* buffer on delwri queue             */
 } xfs_buf_flags_t;