nilfs2: add routines to roll back state of DAT file
This adds optional function to metadata files which makes a copy of
bmap, page caches, and b-tree node cache, and rolls back to the copy
as needed.
This enhancement is intended to displace gcdat inode that provides a
similar function in a different way.
In this patch, nilfs_shadow_map structure is added to store a copy of
the foregoing states. nilfs_mdt_setup_shadow_map relates this
structure to a metadata file. And, nilfs_mdt_save_to_shadow_map() and
nilfs_mdt_restore_from_shadow_map() provides save and restore
functions respectively. Finally, nilfs_mdt_clear_shadow_map() clears
states of nilfs_shadow_map.
The copy of b-tree node cache and page cache is made by duplicating
only dirty pages into corresponding caches in nilfs_shadow_map. Their
restoration is done by clearing dirty pages from original caches and
by copying dirty pages back from nilfs_shadow_map.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
diff --git a/fs/nilfs2/btnode.c b/fs/nilfs2/btnode.c
index f78ab10..5115814 100644
--- a/fs/nilfs2/btnode.c
+++ b/fs/nilfs2/btnode.c
@@ -37,15 +37,7 @@
void nilfs_btnode_cache_init_once(struct address_space *btnc)
{
- memset(btnc, 0, sizeof(*btnc));
- INIT_RADIX_TREE(&btnc->page_tree, GFP_ATOMIC);
- spin_lock_init(&btnc->tree_lock);
- INIT_LIST_HEAD(&btnc->private_list);
- spin_lock_init(&btnc->private_lock);
-
- spin_lock_init(&btnc->i_mmap_lock);
- INIT_RAW_PRIO_TREE_ROOT(&btnc->i_mmap);
- INIT_LIST_HEAD(&btnc->i_mmap_nonlinear);
+ nilfs_mapping_init_once(btnc);
}
static const struct address_space_operations def_btnode_aops = {
@@ -55,12 +47,7 @@
void nilfs_btnode_cache_init(struct address_space *btnc,
struct backing_dev_info *bdi)
{
- btnc->host = NULL; /* can safely set to host inode ? */
- btnc->flags = 0;
- mapping_set_gfp_mask(btnc, GFP_NOFS);
- btnc->assoc_mapping = NULL;
- btnc->backing_dev_info = bdi;
- btnc->a_ops = &def_btnode_aops;
+ nilfs_mapping_init(btnc, bdi, &def_btnode_aops);
}
void nilfs_btnode_cache_clear(struct address_space *btnc)