Skip to contentSkip to conversation

add page_offset to mm.h

PATCH New Christoph Hellwig 1 participant 1 message Jan 19, 2005

Subsystems (2)
NFS client Page cache
lore
Share & tools
lore

Christoph Hellwig

author
#0 lore raw

PATCH 1/1 add page_offset to mm.h

To convert page->index to a byte index you need to cast it to loff_t first so it's a 64bit value. There have been quite a few places that got it wrong in the kernel. To make it easier a nice little helper would be nice, and in fact the NFS code already has it. Let's move it to pagemap.h so everyone can use it.

include/linux/nfs_fs.h +0 -6
@@ -254,12 +254,6 @@
 	return NFS_FLAGS(inode) & NFS_INO_ADVISE_RDPLUS;
 }
 
-static inline
-loff_t page_offset(struct page *page)
-{
-	return ((loff_t)page->index) << PAGE_CACHE_SHIFT;
-}
-
 /**
  * nfs_save_change_attribute - Returns the inode attribute change cookie
  * @inode - pointer to inode
include/linux/pagemap.h +8 -0
@@ -143,6 +143,14 @@
 	return ret;
 }
 
+/*
+ * Return byte-offset into filesystem object for page.
+ */
+static inline loff_t page_offset(struct page *page)
+{
+	return ((loff_t)page->index) << PAGE_CACHE_SHIFT;
+}
+
 static inline pgoff_t linear_page_index(struct vm_area_struct *vma,
 					unsigned long address)
 {