From 6072d13c429373c5d63b69dadbbef40a9b035552 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Wed, 1 Dec 2010 13:35:19 -0500 Subject: Call the filesystem back whenever a page is removed from the page cache NFS needs to be able to release objects that are stored in the page cache once the page itself is no longer visible from the page cache. This patch adds a callback to the address space operations that allows filesystems to perform page cleanups once the page has been removed from the page cache. Original patch by: Linus Torvalds [trondmy: cover the cases of invalidate_inode_pages2() and truncate_inode_pages()] Signed-off-by: Trond Myklebust --- Documentation/filesystems/vfs.txt | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'Documentation/filesystems/vfs.txt') diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt index ed7e5efc06d8..3b14a557eca6 100644 --- 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, @@ -679,6 +680,12 @@ 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 -- cgit v1.2.3 From 4fe65cab844e6d3d7d310e66a501d5e7242ecb54 Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Thu, 2 Dec 2010 14:31:19 -0800 Subject: Documentation/filesystems/vfs.txt: fix ->repeasepage() description ->releasepage() does not remove the page from the mapping. Acked-by: Neil Brown Cc: Trond Myklebust Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/filesystems/vfs.txt | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) (limited to 'Documentation/filesystems/vfs.txt') diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt index ed7e5efc06d8..55c28b79d8dc 100644 --- a/Documentation/filesystems/vfs.txt +++ b/Documentation/filesystems/vfs.txt @@ -660,11 +660,10 @@ 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. -- cgit v1.2.3