1 files changed, 111 insertions, 0 deletions
diff --git a/mm/fadvise.c b/mm/fadvise.c
new file mode 100644
index 000000000000..57264d74b8bf
--- /dev/null
+++ b/mm/fadvise.c
@@ -0,0 +1,111 @@
+/*
+ * mm/fadvise.c
+ *
+ * Copyright (C) 2002, Linus Torvalds
+ *
+ * 11Jan2003	akpm@digeo.com
+ *		Initial version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+#include <linux/backing-dev.h>
+#include <linux/pagevec.h>
+#include <linux/fadvise.h>
+#include <linux/syscalls.h>
+
+#include <asm/unistd.h>
+
+/*
+ * POSIX_FADV_WILLNEED could set PG_Referenced, and POSIX_FADV_NOREUSE could
+ * deactivate the pages and clear PG_Referenced.
+ */
+asmlinkage long sys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice)
+{
+	struct file *file = fget(fd);
+	struct address_space *mapping;
+	struct backing_dev_info *bdi;
+	loff_t endbyte;
+	pgoff_t start_index;
+	pgoff_t end_index;
+	unsigned long nrpages;
+	int ret = 0;
+
+	if (!file)
+		return -EBADF;
+
+	mapping = file->f_mapping;
+	if (!mapping || len < 0) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	/* Careful about overflows. Len == 0 means "as much as possible" */
+	endbyte = offset + len;
+	if (!len || endbyte < len)
+		endbyte = -1;
+
+	bdi = mapping->backing_dev_info;
+
+	switch (advice) {
+	case POSIX_FADV_NORMAL:
+		file->f_ra.ra_pages = bdi->ra_pages;
+		break;
+	case POSIX_FADV_RANDOM:
+		file->f_ra.ra_pages = 0;
+		break;
+	case POSIX_FADV_SEQUENTIAL:
+		file->f_ra.ra_pages = bdi->ra_pages * 2;
+		break;
+	case POSIX_FADV_WILLNEED:
+	case POSIX_FADV_NOREUSE:
+		if (!mapping->a_ops->readpage) {
+			ret = -EINVAL;
+			break;
+		}
+
+		/* First and last PARTIAL page! */
+		start_index = offset >> PAGE_CACHE_SHIFT;
+		end_index = (endbyte-1) >> PAGE_CACHE_SHIFT;
+
+		/* Careful about overflow on the "+1" */
+		nrpages = end_index - start_index + 1;
+		if (!nrpages)
+			nrpages = ~0UL;
+		
+		ret = force_page_cache_readahead(mapping, file,
+				start_index,
+				max_sane_readahead(nrpages));
+		if (ret > 0)
+			ret = 0;
+		break;
+	case POSIX_FADV_DONTNEED:
+		if (!bdi_write_congested(mapping->backing_dev_info))
+			filemap_flush(mapping);
+
+		/* First and last FULL page! */
+		start_index = (offset + (PAGE_CACHE_SIZE-1)) >> PAGE_CACHE_SHIFT;
+		end_index = (endbyte >> PAGE_CACHE_SHIFT);
+
+		if (end_index > start_index)
+			invalidate_mapping_pages(mapping, start_index, end_index-1);
+		break;
+	default:
+		ret = -EINVAL;
+	}
+out:
+	fput(file);
+	return ret;
+}
+
+#ifdef __ARCH_WANT_SYS_FADVISE64
+
+asmlinkage long sys_fadvise64(int fd, loff_t offset, size_t len, int advice)
+{
+	return sys_fadvise64_64(fd, offset, len, advice);
+}
+
+#endif