[PATCH] BLOCK: Make it possible to disable the block layer [try #6]

[net-next-2.6.git] / mm / filemap.c

diff --git a/mm/filemap.c b/mm/filemap.c
index afcdc72b5e906658475a8ff47b5e3dcd389c0188..c4fe97f5ace0851d3023d1305d8de5c7ad2b1dd5 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1471,7 +1471,7 @@ outside_data_content:
         * accessible..
         */
        if (area->vm_mm == current->mm)
-               return NULL;
+               return NOPAGE_SIGBUS;
        /* Fall through to the non-read-ahead case */
 no_cached_page:
        /*
@@ -1496,7 +1496,7 @@ no_cached_page:
         */
        if (error == -ENOMEM)
                return NOPAGE_OOM;
-       return NULL;
+       return NOPAGE_SIGBUS;
 
 page_not_uptodate:
        if (!did_readaround) {
@@ -1565,7 +1565,7 @@ page_not_uptodate:
         */
        shrink_readahead_size_eio(file, ra);
        page_cache_release(page);
-       return NULL;
+       return NOPAGE_SIGBUS;
 }
 EXPORT_SYMBOL(filemap_nopage);
 
@@ -2020,6 +2020,7 @@ inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, i
                if (unlikely(*pos + *count > inode->i_sb->s_maxbytes))
                        *count = inode->i_sb->s_maxbytes - *pos;
        } else {
+#ifdef CONFIG_BLOCK
                loff_t isize;
                if (bdev_read_only(I_BDEV(inode)))
                        return -EPERM;
@@ -2031,6 +2032,9 @@ inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, i
 
                if (*pos + *count > isize)
                        *count = isize - *pos;
+#else
+               return -EPERM;
+#endif
        }
        return 0;
 }
@@ -2491,3 +2495,33 @@ generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
        }
        return retval;
 }
+
+/**
+ * try_to_release_page() - release old fs-specific metadata on a page
+ *
+ * @page: the page which the kernel is trying to free
+ * @gfp_mask: memory allocation flags (and I/O mode)
+ *
+ * The address_space is to try to release any data against the page
+ * (presumably at page->private).  If the release was successful, return `1'.
+ * Otherwise return zero.
+ *
+ * The @gfp_mask argument specifies whether I/O may be performed to release
+ * this page (__GFP_IO), and whether the call may block (__GFP_WAIT).
+ *
+ * NOTE: @gfp_mask may go away, and this function may become non-blocking.
+ */
+int try_to_release_page(struct page *page, gfp_t gfp_mask)
+{
+       struct address_space * const mapping = page->mapping;
+
+       BUG_ON(!PageLocked(page));
+       if (PageWriteback(page))
+               return 0;
+
+       if (mapping && mapping->a_ops->releasepage)
+               return mapping->a_ops->releasepage(page, gfp_mask);
+       return try_to_free_buffers(page);
+}
+
+EXPORT_SYMBOL(try_to_release_page);