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-rw-r--r--mm/fadvise.c111
1 files changed, 111 insertions, 0 deletions
diff --git a/mm/fadvise.c b/mm/fadvise.c
new file mode 100644
index 0000000..57264d7
--- /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
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