Merge tag 'v2.6.37' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6

[mv-sheeva.git] / Documentation / filesystems / vfs.txt

diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index ed7e5efc06d8fe33dc54a2122a059fdbec874092..20899e095e7e6879580b53aa9aa0282fb4b5ce63 100644 (file)
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -534,6 +534,7 @@ struct address_space_operations {
        sector_t (*bmap)(struct address_space *, sector_t);
        int (*invalidatepage) (struct page *, unsigned long);
        int (*releasepage) (struct page *, int);
+       void (*freepage)(struct page *);
        ssize_t (*direct_IO)(int, struct kiocb *, const struct iovec *iov,
                        loff_t offset, unsigned long nr_segs);
        struct page* (*get_xip_page)(struct address_space *, sector_t,
@@ -660,11 +661,10 @@ struct address_space_operations {
   releasepage: releasepage is called on PagePrivate pages to indicate
         that the page should be freed if possible.  ->releasepage
         should remove any private data from the page and clear the
-        PagePrivate flag.  It may also remove the page from the
-        address_space.  If this fails for some reason, it may indicate
-        failure with a 0 return value.
-       This is used in two distinct though related cases.  The first
-        is when the VM finds a clean page with no active users and
+        PagePrivate flag. If releasepage() fails for some reason, it must
+       indicate failure with a 0 return value.
+       releasepage() is used in two distinct though related cases.  The
+       first is when the VM finds a clean page with no active users and
         wants to make it a free page.  If ->releasepage succeeds, the
         page will be removed from the address_space and become free.
 
@@ -679,6 +679,12 @@ struct address_space_operations {
         need to ensure this.  Possibly it can clear the PageUptodate
         bit if it cannot free private data yet.
 
+  freepage: freepage is called once the page is no longer visible in
+        the page cache in order to allow the cleanup of any private
+       data. Since it may be called by the memory reclaimer, it
+       should not assume that the original address_space mapping still
+       exists, and it should not block.
+
   direct_IO: called by the generic read/write routines to perform
         direct_IO - that is IO requests which bypass the page cache
         and transfer data directly between the storage and the