2 files changed, 84 insertions, 297 deletions

diff --git a/fs/xfs/linux-2.6/xfs_buf.c b/fs/xfs/linux-2.6/xfs_buf.c
index a5a260fab824..d45b2cdee6c4 100644
--- a/fs/xfs/linux-2.6/xfs_buf.c
+++ b/fs/xfs/linux-2.6/xfs_buf.c
@@ -94,75 +94,6 @@ xfs_buf_vmap_len(
 }
 
 /*
- *      Page Region interfaces.
- *
- *      For pages in filesystems where the blocksize is smaller than the
- *      pagesize, we use the page->private field (long) to hold a bitmap
- *      of uptodate regions within the page.
- *
- *      Each such region is "bytes per page / bits per long" bytes long.
- *
- *      NBPPR == number-of-bytes-per-page-region
- *      BTOPR == bytes-to-page-region (rounded up)
- *      BTOPRT == bytes-to-page-region-truncated (rounded down)
- */
-#if (BITS_PER_LONG == 32)
-#define PRSHIFT         (PAGE_CACHE_SHIFT - 5)  /* (32 == 1<<5) */
-#elif (BITS_PER_LONG == 64)
-#define PRSHIFT         (PAGE_CACHE_SHIFT - 6)  /* (64 == 1<<6) */
-#else
-#error BITS_PER_LONG must be 32 or 64
-#endif
-#define NBPPR           (PAGE_CACHE_SIZE/BITS_PER_LONG)
-#define BTOPR(b)        (((unsigned int)(b) + (NBPPR - 1)) >> PRSHIFT)
-#define BTOPRT(b)       (((unsigned int)(b) >> PRSHIFT))
-
-STATIC unsigned long
-page_region_mask(
-        size_t          offset,
-        size_t          length)
-{
-        unsigned long   mask;
-        int             first, final;
-
-        first = BTOPR(offset);
-        final = BTOPRT(offset + length - 1);
-        first = min(first, final);
-
-        mask = ~0UL;
-        mask <<= BITS_PER_LONG - (final - first);
-        mask >>= BITS_PER_LONG - (final);
-
-        ASSERT(offset + length <= PAGE_CACHE_SIZE);
-        ASSERT((final - first) < BITS_PER_LONG && (final - first) >= 0);
-
-        return mask;
-}
-
-STATIC void
-set_page_region(
-        struct page     *page,
-        size_t          offset,
-        size_t          length)
-{
-        set_page_private(page,
-                page_private(page) | page_region_mask(offset, length));
-        if (page_private(page) == ~0UL)
-                SetPageUptodate(page);
-}
-
-STATIC int
-test_page_region(
-        struct page     *page,
-        size_t          offset,
-        size_t          length)
-{
-        unsigned long   mask = page_region_mask(offset, length);
-
-        return (mask && (page_private(page) & mask) == mask);
-}
-
-/*
  * xfs_buf_lru_add - add a buffer to the LRU.
  *
  * The LRU takes a new reference to the buffer so that it will only be freed
@@ -332,7 +263,7 @@ xfs_buf_free(
 
         ASSERT(list_empty(&bp->b_lru));
 
-        if (bp->b_flags & (_XBF_PAGE_CACHE|_XBF_PAGES)) {
+        if (bp->b_flags & _XBF_PAGES) {
                 uint            i;
 
                 if (xfs_buf_is_vmapped(bp))
@@ -342,25 +273,22 @@ xfs_buf_free(
                 for (i = 0; i < bp->b_page_count; i++) {
                         struct page     *page = bp->b_pages[i];
 
-                        if (bp->b_flags & _XBF_PAGE_CACHE)
-                                ASSERT(!PagePrivate(page));
-                        page_cache_release(page);
+                        __free_page(page);
                 }
-        }
+        } else if (bp->b_flags & _XBF_KMEM)
+                kmem_free(bp->b_addr);
         _xfs_buf_free_pages(bp);
         xfs_buf_deallocate(bp);
 }
 
 /*
- *      Finds all pages for buffer in question and builds it's page list.
+ * Allocates all the pages for buffer in question and builds it's page list.
  */
 STATIC int
-_xfs_buf_lookup_pages(
+xfs_buf_allocate_memory(
         xfs_buf_t               *bp,
         uint                    flags)
 {
-        struct address_space    *mapping = bp->b_target->bt_mapping;
-        size_t                  blocksize = bp->b_target->bt_bsize;
         size_t                  size = bp->b_count_desired;
         size_t                  nbytes, offset;
         gfp_t                   gfp_mask = xb_to_gfp(flags);
@@ -369,29 +297,55 @@ _xfs_buf_lookup_pages(
         xfs_off_t               end;
         int                     error;
 
+        /*
+         * for buffers that are contained within a single page, just allocate
+         * the memory from the heap - there's no need for the complexity of
+         * page arrays to keep allocation down to order 0.
+         */
+        if (bp->b_buffer_length < PAGE_SIZE) {
+                bp->b_addr = kmem_alloc(bp->b_buffer_length, xb_to_km(flags));
+                if (!bp->b_addr) {
+                        /* low memory - use alloc_page loop instead */
+                        goto use_alloc_page;
+                }
+
+                if (((unsigned long)(bp->b_addr + bp->b_buffer_length - 1) &
+                                                                PAGE_MASK) !=
+                    ((unsigned long)bp->b_addr & PAGE_MASK)) {
+                        /* b_addr spans two pages - use alloc_page instead */
+                        kmem_free(bp->b_addr);
+                        bp->b_addr = NULL;
+                        goto use_alloc_page;
+                }
+                bp->b_offset = offset_in_page(bp->b_addr);
+                bp->b_pages = bp->b_page_array;
+                bp->b_pages[0] = virt_to_page(bp->b_addr);
+                bp->b_page_count = 1;
+                bp->b_flags |= XBF_MAPPED | _XBF_KMEM;
+                return 0;
+        }
+
+use_alloc_page:
         end = bp->b_file_offset + bp->b_buffer_length;
         page_count = xfs_buf_btoc(end) - xfs_buf_btoct(bp->b_file_offset);
-
         error = _xfs_buf_get_pages(bp, page_count, flags);
         if (unlikely(error))
                 return error;
-        bp->b_flags |= _XBF_PAGE_CACHE;
 
         offset = bp->b_offset;
-        first = bp->b_file_offset >> PAGE_CACHE_SHIFT;
+        first = bp->b_file_offset >> PAGE_SHIFT;
+        bp->b_flags |= _XBF_PAGES;
 
         for (i = 0; i < bp->b_page_count; i++) {
                 struct page     *page;
                 uint            retries = 0;
-
-              retry:
-                page = find_or_create_page(mapping, first + i, gfp_mask);
+retry:
+                page = alloc_page(gfp_mask);
                 if (unlikely(page == NULL)) {
                         if (flags & XBF_READ_AHEAD) {
                                 bp->b_page_count = i;
-                                for (i = 0; i < bp->b_page_count; i++)
-                                        unlock_page(bp->b_pages[i]);
-                                return -ENOMEM;
+                                error = ENOMEM;
+                                goto out_free_pages;