2.6.24-git18

 fs

diff --git a/fs/buffer.c b/fs/buffer.c
index 7249e01..826baf4 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1798,7 +1798,7 @@ void page_zero_new_buffers(struct page *page, unsigned from, unsigned to)
                start = max(from, block_start);
                size = min(to, block_end) - start;
 
-               zero_user_page(page, start, size, KM_USER0);
+               zero_user(page, start, size);
                set_buffer_uptodate(bh);
             }
 
@@ -1861,19 +1861,10 @@ static int __block_prepare_write(struct inode *inode, struct page *page,
                mark_buffer_dirty(bh);
                continue;
             }
-            if (block_end > to || block_start < from) {
-               void *kaddr;
-
-               kaddr = kmap_atomic(page, KM_USER0);
-               if (block_end > to)
-                  memset(kaddr+to, 0,
-                     block_end-to);
-               if (block_start < from)
-                  memset(kaddr+block_start,
-                     0, from-block_start);
-               flush_dcache_page(page);
-               kunmap_atomic(kaddr, KM_USER0);
-            }
+            if (block_end > to || block_start < from)
+               zero_user_segments(page,
+                  to, block_end,
+                  block_start, from);
             continue;
          }
       }
@@ -2104,8 +2095,7 @@ int block_read_full_page(struct page *page, get_block_t *get_block)
                SetPageError(page);
          }
          if (!buffer_mapped(bh)) {
-            zero_user_page(page, i * blocksize, blocksize,
-                  KM_USER0);
+            zero_user(page, i * blocksize, blocksize);
             if (!err)
                set_buffer_uptodate(bh);
             continue;
@@ -2218,7 +2208,7 @@ int cont_expand_zero(struct file *file, struct address_space *mapping,
                   &page, &fsdata);
       if (err)
          goto out;
-      zero_user_page(page, zerofrom, len, KM_USER0);
+      zero_user(page, zerofrom, len);
       err = pagecache_write_end(file, mapping, curpos, len, len,
                   page, fsdata);
       if (err < 0)
@@ -2245,7 +2235,7 @@ int cont_expand_zero(struct file *file, struct address_space *mapping,
                   &page, &fsdata);
       if (err)
          goto out;
-      zero_user_page(page, zerofrom, len, KM_USER0);
+      zero_user(page, zerofrom, len);
       err = pagecache_write_end(file, mapping, curpos, len, len,
                   page, fsdata);
       if (err < 0)
@@ -2422,7 +2412,6 @@ int nobh_write_begin(struct file *file, struct address_space *mapping,
    unsigned block_in_page;
    unsigned block_start, block_end;
    sector_t block_in_file;
-   char *kaddr;
    int nr_reads = 0;
    int ret = 0;
    int is_mapped_to_disk = 1;
@@ -2493,13 +2482,8 @@ int nobh_write_begin(struct file *file, struct address_space *mapping,
          continue;
       }
       if (buffer_new(bh) || !buffer_mapped(bh)) {
-         kaddr = kmap_atomic(page, KM_USER0);
-         if (block_start < from)
-            memset(kaddr+block_start, 0, from-block_start);
-         if (block_end > to)
-            memset(kaddr + to, 0, block_end - to);
-         flush_dcache_page(page);
-         kunmap_atomic(kaddr, KM_USER0);
+         zero_user_segments(page, block_start, from,
+                     to, block_end);
          continue;
       }
       if (buffer_uptodate(bh))
@@ -2636,7 +2620,7 @@ int nobh_writepage(struct page *page, get_block_t *get_block,
     * the  page size, the remaining memory is zeroed when mapped, and
     * writes to that region are not written out to the file."
     */
-   zero_user_page(page, offset, PAGE_CACHE_SIZE - offset, KM_USER0);
+   zero_user_segment(page, offset, PAGE_CACHE_SIZE);
 out:
    ret = mpage_writepage(page, get_block, wbc);
    if (ret == -EAGAIN)
@@ -2709,7 +2693,7 @@ has_buffers:
       if (page_has_buffers(page))
          goto has_buffers;
    }
-   zero_user_page(page, offset, length, KM_USER0);
+   zero_user(page, offset, length);
    set_page_dirty(page);
    err = 0;
 
@@ -2785,7 +2769,7 @@ int block_truncate_page(struct address_space *mapping,
          goto unlock;
    }
 
-   zero_user_page(page, offset, length, KM_USER0);
+   zero_user(page, offset, length);
    mark_buffer_dirty(bh);
    err = 0;
 
@@ -2831,7 +2815,7 @@ int block_write_full_page(struct page *page, get_block_t *get_block,
     * the  page size, the remaining memory is zeroed when mapped, and
     * writes to that region are not written out to the file."
     */
-   zero_user_page(page, offset, PAGE_CACHE_SIZE - offset, KM_USER0);
+   zero_user_segment(page, offset, PAGE_CACHE_SIZE);
    return __block_write_full_page(inode, page, get_block, wbc);
 }
 
@@ -3169,7 +3153,7 @@ static void recalc_bh_state(void)
    
 struct buffer_head *alloc_buffer_head(gfp_t gfp_flags)
 {
-   struct buffer_head *ret = kmem_cache_zalloc(bh_cachep,
+   struct buffer_head *ret = kmem_cache_alloc(bh_cachep,
             set_migrateflags(gfp_flags, __GFP_RECLAIMABLE));
    if (ret) {
       INIT_LIST_HEAD(&ret->b_assoc_buffers);
@@ -3213,12 +3197,68 @@ static int buffer_cpu_notify(struct notifier_block *self,
    return NOTIFY_OK;
 }
 
+/**
+ * bh_uptodate_or_lock: Test whether the buffer is uptodate
+ * @bh: struct buffer_head
+ *
+ * Return true if the buffer is up-to-date and false,
+ * with the buffer locked, if not.
+ */
+int bh_uptodate_or_lock(struct buffer_head *bh)
+{
+   if (!buffer_uptodate(bh)) {
+      lock_buffer(bh);
+      if (!buffer_uptodate(bh))
+         return 0;
+      unlock_buffer(bh);
+   }
+   return 1;
+}
+EXPORT_SYMBOL(bh_uptodate_or_lock);
+
+/**
+ * bh_submit_read: Submit a locked buffer for reading
+ * @bh: struct buffer_head
+ *
+ * Returns zero on success and -EIO on error.
+ */
+int bh_submit_read(struct buffer_head *bh)
+{
+   BUG_ON(!buffer_locked(bh));
+
+   if (buffer_uptodate(bh)) {
+      unlock_buffer(bh);
+      return 0;
+   }
+
+   get_bh(bh);
+   bh->b_end_io = end_buffer_read_sync;
+   submit_bh(READ, bh);
+   wait_on_buffer(bh);
+   if (buffer_uptodate(bh))
+      return 0;
+   return -EIO;
+}
+EXPORT_SYMBOL(bh_submit_read);
+
+static void
+init_buffer_head(struct kmem_cache *cachep, void *data)
+{
+   struct buffer_head *bh = data;
+
+   memset(bh, 0, sizeof(*bh));
+   INIT_LIST_HEAD(&bh->b_assoc_buffers);
+}
+
 void __init buffer_init(void)
 {
    int nrpages;
 
-   bh_cachep = KMEM_CACHE(buffer_head,
-         SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD);
+   bh_cachep = kmem_cache_create("buffer_head",
+         sizeof(struct buffer_head), 0,
+            (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
+            SLAB_MEM_SPREAD),
+            init_buffer_head);
 
    /*
     * Limit the bh occupancy to 10% of ZONE_NORMAL