mm: document tree_lock->zone.lock lockorder

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

diff --git a/mm/filemap.c b/mm/filemap.c
index ec25ba1..4fb1546 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -63,6 +63,7 @@ generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
  *    ->private_lock           (__free_pte->__set_page_dirty_buffers)
  *      ->swap_lock            (exclusive_swap_page, others)
  *        ->mapping->tree_lock
+ *          ->zone.lock
  *
  *  ->i_mutex
  *    ->i_mmap_lock            (truncate->unmap_mapping_range)
@@ -1684,6 +1685,7 @@ size_t iov_iter_copy_from_user_atomic(struct page *page,
 
        return copied;
 }
+EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
 
 /*
  * This has the same sideeffects and return value as
@@ -1710,6 +1712,7 @@ size_t iov_iter_copy_from_user(struct page *page,
        kunmap(page);
        return copied;
 }
+EXPORT_SYMBOL(iov_iter_copy_from_user);
 
 static void __iov_iter_advance_iov(struct iov_iter *i, size_t bytes)
 {
@@ -1741,6 +1744,7 @@ void iov_iter_advance(struct iov_iter *i, size_t bytes)
        __iov_iter_advance_iov(i, bytes);
        i->count -= bytes;
 }
+EXPORT_SYMBOL(iov_iter_advance);
 
 /*
  * Fault in the first iovec of the given iov_iter, to a maximum length
@@ -1757,6 +1761,7 @@ int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
        bytes = min(bytes, i->iov->iov_len - i->iov_offset);
        return fault_in_pages_readable(buf, bytes);
 }
+EXPORT_SYMBOL(iov_iter_fault_in_readable);
 
 /*
  * Return the count of just the current iov_iter segment.
@@ -1769,6 +1774,7 @@ size_t iov_iter_single_seg_count(struct iov_iter *i)
        else
                return min(i->count, iov->iov_len - i->iov_offset);
 }
+EXPORT_SYMBOL(iov_iter_single_seg_count);
 
 /*
  * Performs necessary checks before doing a write
@@ -1893,13 +1899,10 @@ again:
 
                ret = aops->prepare_write(file, page, offset, offset+len);
                if (ret) {
-                       if (ret != AOP_TRUNCATED_PAGE)
-                               unlock_page(page);
+                       unlock_page(page);
                        page_cache_release(page);
                        if (pos + len > inode->i_size)
                                vmtruncate(inode, inode->i_size);
-                       if (ret == AOP_TRUNCATED_PAGE)
-                               goto again;
                }
                return ret;
        }
@@ -1926,7 +1929,6 @@ int pagecache_write_end(struct file *file, struct address_space *mapping,
                unlock_page(page);
                mark_page_accessed(page);
                page_cache_release(page);
-               BUG_ON(ret == AOP_TRUNCATED_PAGE); /* can't deal with */
 
                if (ret < 0) {
                        if (pos + len > inode->i_size)
@@ -2061,7 +2063,7 @@ static ssize_t generic_perform_write_2copy(struct file *file,
                 * cannot take a pagefault with the destination page locked.
                 * So pin the source page to copy it.
                 */
-               if (!PageUptodate(page)) {
+               if (!PageUptodate(page) && !segment_eq(get_fs(), KERNEL_DS)) {
                        unlock_page(page);
 
                        src_page = alloc_page(GFP_KERNEL);
@@ -2137,7 +2139,7 @@ static ssize_t generic_perform_write_2copy(struct file *file,
                flush_dcache_page(page);
 
                status = a_ops->commit_write(file, page, offset, offset+bytes);
-               if (unlikely(status < 0 || status == AOP_TRUNCATED_PAGE))
+               if (unlikely(status < 0))
                        goto fs_write_aop_error;
                if (unlikely(status > 0)) /* filesystem did partial write */
                        copied = min_t(size_t, copied, status);
@@ -2157,8 +2159,7 @@ static ssize_t generic_perform_write_2copy(struct file *file,
                continue;
 
 fs_write_aop_error:
-               if (status != AOP_TRUNCATED_PAGE)
-                       unlock_page(page);
+               unlock_page(page);
                page_cache_release(page);
                if (src_page)
                        page_cache_release(src_page);
@@ -2170,10 +2171,7 @@ fs_write_aop_error:
                 */
                if (pos + bytes > inode->i_size)
                        vmtruncate(inode, inode->i_size);
-               if (status == AOP_TRUNCATED_PAGE)
-                       continue;
-               else
-                       break;
+               break;
        } while (iov_iter_count(i));
 
        return written ? written : status;
@@ -2186,6 +2184,13 @@ static ssize_t generic_perform_write(struct file *file,
        const struct address_space_operations *a_ops = mapping->a_ops;
        long status = 0;
        ssize_t written = 0;
+       unsigned int flags = 0;
+
+       /*
+        * Copies from kernel address space cannot fail (NFSD is a big user).
+        */
+       if (segment_eq(get_fs(), KERNEL_DS))
+               flags |= AOP_FLAG_UNINTERRUPTIBLE;
 
        do {
                struct page *page;
@@ -2217,7 +2222,7 @@ again:
                        break;
                }
 
-               status = a_ops->write_begin(file, mapping, pos, bytes, 0,
+               status = a_ops->write_begin(file, mapping, pos, bytes, flags,
                                                &page, &fsdata);
                if (unlikely(status))
                        break;