Merge branch 'master' into upstream

[pandora-kernel.git] / mm / filemap.c

diff --git a/mm/filemap.c b/mm/filemap.c
index 8332c77..d1060b8 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -327,7 +327,7 @@ EXPORT_SYMBOL(sync_page_range);
  * @pos:       beginning offset in pages to write
  * @count:     number of bytes to write
  *
- * Note: Holding i_mutex across sync_page_range_nolock is not a good idea
+ * Note: Holding i_mutex across sync_page_range_nolock() is not a good idea
  * as it forces O_SYNC writers to different parts of the same file
  * to be serialised right until io completion.
  */
@@ -605,26 +605,6 @@ struct page * find_get_page(struct address_space *mapping, unsigned long offset)
 }
 EXPORT_SYMBOL(find_get_page);
 
-/**
- * find_trylock_page - find and lock a page
- * @mapping: the address_space to search
- * @offset: the page index
- *
- * Same as find_get_page(), but trylock it instead of incrementing the count.
- */
-struct page *find_trylock_page(struct address_space *mapping, unsigned long offset)
-{
-       struct page *page;
-
-       read_lock_irq(&mapping->tree_lock);
-       page = radix_tree_lookup(&mapping->page_tree, offset);
-       if (page && TestSetPageLocked(page))
-               page = NULL;
-       read_unlock_irq(&mapping->tree_lock);
-       return page;
-}
-EXPORT_SYMBOL(find_trylock_page);
-
 /**
  * find_lock_page - locate, pin and lock a pagecache page
  * @mapping: the address_space to search
@@ -804,7 +784,7 @@ unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
  * @mapping: target address_space
  * @index: the page index
  *
- * Same as grab_cache_page, but do not wait if the page is unavailable.
+ * Same as grab_cache_page(), but do not wait if the page is unavailable.
  * This is intended for speculative data generators, where the data can
  * be regenerated if the page couldn't be grabbed.  This routine should
  * be safe to call while holding the lock for another page.
@@ -2099,21 +2079,27 @@ generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
                /* Limit the size of the copy to the caller's write size */
                bytes = min(bytes, count);
 
-               /*
-                * Limit the size of the copy to that of the current segment,
-                * because fault_in_pages_readable() doesn't know how to walk
-                * segments.
-                */
-               bytes = min(bytes, cur_iov->iov_len - iov_base);
-
-               /*
-                * Bring in the user page that we will copy from _first_.
-                * Otherwise there's a nasty deadlock on copying from the
-                * same page as we're writing to, without it being marked
-                * up-to-date.
+               /* We only need to worry about prefaulting when writes are from
+                * user-space.  NFSd uses vfs_writev with several non-aligned
+                * segments in the vector, and limiting to one segment a time is
+                * a noticeable performance for re-write
                 */
-               fault_in_pages_readable(buf, bytes);
+               if (!segment_eq(get_fs(), KERNEL_DS)) {
+                       /*
+                        * Limit the size of the copy to that of the current
+                        * segment, because fault_in_pages_readable() doesn't
+                        * know how to walk segments.
+                        */
+                       bytes = min(bytes, cur_iov->iov_len - iov_base);
 
+                       /*
+                        * Bring in the user page that we will copy from
+                        * _first_.  Otherwise there's a nasty deadlock on
+                        * copying from the same page as we're writing to,
+                        * without it being marked up-to-date.
+                        */
+                       fault_in_pages_readable(buf, bytes);
+               }
                page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec);
                if (!page) {
                        status = -ENOMEM;