Migrate a page with buffers without requiring writeback
This introduces a new address space operation migrate_page() that
may be used by a filesystem to implement its own version of page migration.
A version is provided that migrates buffers attached to pages. Some
filesystems (ext2, ext3, xfs) are modified to utilize this feature.
The swapper address space operation are modified so that a regular
migrate_pages() will occur for anonymous pages without writeback
(migrate_pages forces every anonymous page to have a swap entry).
Signed-off-by: Mike Kravetz <[email protected]>
Signed-off-by: Christoph Lameter <[email protected]>
Index: linux-2.6.14-rc5-mm1/include/linux/fs.h
===================================================================
--- linux-2.6.14-rc5-mm1.orig/include/linux/fs.h 2005-10-31 14:11:15.000000000 -0800
+++ linux-2.6.14-rc5-mm1/include/linux/fs.h 2005-11-04 11:50:29.000000000 -0800
@@ -327,6 +327,8 @@ struct address_space_operations {
loff_t offset, unsigned long nr_segs);
struct page* (*get_xip_page)(struct address_space *, sector_t,
int);
+ /* migrate the contents of a page to the specified target */
+ int (*migrate_page) (struct page *, struct page *);
};
struct backing_dev_info;
Index: linux-2.6.14-rc5-mm1/mm/swap_state.c
===================================================================
--- linux-2.6.14-rc5-mm1.orig/mm/swap_state.c 2005-10-31 14:11:17.000000000 -0800
+++ linux-2.6.14-rc5-mm1/mm/swap_state.c 2005-11-04 11:50:29.000000000 -0800
@@ -26,6 +26,7 @@ static struct address_space_operations s
.writepage = swap_writepage,
.sync_page = block_sync_page,
.set_page_dirty = __set_page_dirty_nobuffers,
+ .migrate_page = migrate_page,
};
static struct backing_dev_info swap_backing_dev_info = {
Index: linux-2.6.14-rc5-mm1/fs/xfs/linux-2.6/xfs_aops.c
===================================================================
--- linux-2.6.14-rc5-mm1.orig/fs/xfs/linux-2.6/xfs_aops.c 2005-10-19 23:23:05.000000000 -0700
+++ linux-2.6.14-rc5-mm1/fs/xfs/linux-2.6/xfs_aops.c 2005-11-04 11:50:29.000000000 -0800
@@ -1356,4 +1356,5 @@ struct address_space_operations linvfs_a
.commit_write = generic_commit_write,
.bmap = linvfs_bmap,
.direct_IO = linvfs_direct_IO,
+ .migrate_page = buffer_migrate_page,
};
Index: linux-2.6.14-rc5-mm1/fs/buffer.c
===================================================================
--- linux-2.6.14-rc5-mm1.orig/fs/buffer.c 2005-10-31 14:11:00.000000000 -0800
+++ linux-2.6.14-rc5-mm1/fs/buffer.c 2005-11-04 14:43:55.000000000 -0800
@@ -3024,6 +3024,73 @@ asmlinkage long sys_bdflush(int func, lo
}
/*
+ * Migration function for pages with buffers. This function can only be used
+ * if the underlying filesystem guarantees that no other references to "page"
+ * exist.
+ */
+int buffer_migrate_page(struct page *newpage, struct page *page)
+{
+#ifdef CONFIG_MIGRATION
+ struct address_space *mapping = page->mapping;
+ struct buffer_head *bh, *head;
+
+ if (!mapping)
+ return -EAGAIN;
+
+ if (!page_has_buffers(page))
+ return migrate_page(newpage, page);
+
+ head = page_buffers(page);
+
+ /*
+ * Remove the mapping so the page can be migrated.
+ */
+ if (migrate_page_remove_references(newpage, page, 3))
+ return -EAGAIN;
+
+ spin_lock(&mapping->private_lock);
+
+ bh = head;
+ do {
+ get_bh(bh);
+ lock_buffer(bh);
+ bh = bh->b_this_page;
+
+ } while (bh != head);
+
+ ClearPagePrivate(page);
+ set_page_private(newpage, page_private(page));
+ set_page_private(page, 0);
+ put_page(page);
+ get_page(newpage);
+
+ bh = head;
+ do {
+ set_bh_page(bh, newpage, bh_offset(bh));
+ bh = bh->b_this_page;
+
+ } while (bh != head);
+
+ SetPagePrivate(newpage);
+ spin_unlock(&mapping->private_lock);
+
+ migrate_page_copy(newpage, page);
+
+ spin_lock(&mapping->private_lock);
+ bh = head;
+ do {
+ unlock_buffer(bh);
+ put_bh(bh);
+ bh = bh->b_this_page;
+
+ } while (bh != head);
+ spin_unlock(&mapping->private_lock);
+
+#endif
+ return 0;
+}
+
+/*
* Buffer-head allocation
*/
static kmem_cache_t *bh_cachep;
Index: linux-2.6.14-rc5-mm1/fs/ext3/inode.c
===================================================================
--- linux-2.6.14-rc5-mm1.orig/fs/ext3/inode.c 2005-10-31 14:11:03.000000000 -0800
+++ linux-2.6.14-rc5-mm1/fs/ext3/inode.c 2005-11-04 11:50:29.000000000 -0800
@@ -1557,6 +1557,7 @@ static struct address_space_operations e
.invalidatepage = ext3_invalidatepage,
.releasepage = ext3_releasepage,
.direct_IO = ext3_direct_IO,
+ .migrate_page = buffer_migrate_page,
};
static struct address_space_operations ext3_writeback_aops = {
@@ -1570,6 +1571,7 @@ static struct address_space_operations e
.invalidatepage = ext3_invalidatepage,
.releasepage = ext3_releasepage,
.direct_IO = ext3_direct_IO,
+ .migrate_page = buffer_migrate_page,
};
static struct address_space_operations ext3_journalled_aops = {
Index: linux-2.6.14-rc5-mm1/fs/ext2/inode.c
===================================================================
--- linux-2.6.14-rc5-mm1.orig/fs/ext2/inode.c 2005-10-31 14:11:03.000000000 -0800
+++ linux-2.6.14-rc5-mm1/fs/ext2/inode.c 2005-11-04 11:50:29.000000000 -0800
@@ -706,6 +706,7 @@ struct address_space_operations ext2_aop
.bmap = ext2_bmap,
.direct_IO = ext2_direct_IO,
.writepages = ext2_writepages,
+ .migrate_page = buffer_migrate_page,
};
struct address_space_operations ext2_aops_xip = {
@@ -723,6 +724,7 @@ struct address_space_operations ext2_nob
.bmap = ext2_bmap,
.direct_IO = ext2_direct_IO,
.writepages = ext2_writepages,
+ .migrate_page = buffer_migrate_page,
};
/*
Index: linux-2.6.14-rc5-mm1/fs/xfs/linux-2.6/xfs_buf.c
===================================================================
--- linux-2.6.14-rc5-mm1.orig/fs/xfs/linux-2.6/xfs_buf.c 2005-10-31 14:10:52.000000000 -0800
+++ linux-2.6.14-rc5-mm1/fs/xfs/linux-2.6/xfs_buf.c 2005-11-04 11:50:29.000000000 -0800
@@ -1633,6 +1633,7 @@ xfs_mapping_buftarg(
struct address_space *mapping;
static struct address_space_operations mapping_aops = {
.sync_page = block_sync_page,
+ .migrate_page = fail_migrate_page,
};
inode = new_inode(bdev->bd_inode->i_sb);
Index: linux-2.6.14-rc5-mm1/include/linux/buffer_head.h
===================================================================
--- linux-2.6.14-rc5-mm1.orig/include/linux/buffer_head.h 2005-10-31 14:10:59.000000000 -0800
+++ linux-2.6.14-rc5-mm1/include/linux/buffer_head.h 2005-11-04 11:50:29.000000000 -0800
@@ -210,6 +210,7 @@ int nobh_truncate_page(struct address_sp
int nobh_writepage(struct page *page, get_block_t *get_block,
struct writeback_control *wbc);
+int buffer_migrate_page(struct page *, struct page *);
/*
* inline definitions
Index: linux-2.6.14-rc5-mm1/mm/vmscan.c
===================================================================
--- linux-2.6.14-rc5-mm1.orig/mm/vmscan.c 2005-11-04 10:24:57.000000000 -0800
+++ linux-2.6.14-rc5-mm1/mm/vmscan.c 2005-11-04 11:50:29.000000000 -0800
@@ -572,6 +572,15 @@ keep:
return reclaimed;
}
+/*
+ * Non migratable page
+ */
+int fail_migrate_page(struct page *newpage, struct page *page)
+{
+ return -EIO;
+}
+
+
#ifdef CONFIG_MIGRATION
/*
* swapout a single page
@@ -885,6 +894,11 @@ redo:
*/
mapping = page_mapping(page);
+ if (mapping->a_ops->migrate_page) {
+ rc = mapping->a_ops->migrate_page(newpage, page);
+ goto unlock_both;
+ }
+
/*
* Trigger writeout if page is dirty
*/
Index: linux-2.6.14-rc5-mm1/include/linux/swap.h
===================================================================
--- linux-2.6.14-rc5-mm1.orig/include/linux/swap.h 2005-11-04 10:24:09.000000000 -0800
+++ linux-2.6.14-rc5-mm1/include/linux/swap.h 2005-11-04 11:50:29.000000000 -0800
@@ -185,6 +185,7 @@ extern int migrate_pages(struct list_hea
extern int migrate_page(struct page *, struct page *);
extern int migrate_page_remove_references(struct page *, struct page *, int);
extern void migrate_page_copy(struct page *, struct page *);
+extern int fail_migrate_page(struct page *, struct page *);
#endif
#ifdef CONFIG_MMU
-
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