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..5115814c 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)
diff --git a/fs/nilfs2/mdt.c b/fs/nilfs2/mdt.c
index 73e5da3..00664686 100644
--- a/fs/nilfs2/mdt.c
+++ b/fs/nilfs2/mdt.c
@@ -398,16 +398,22 @@
static int
nilfs_mdt_write_page(struct page *page, struct writeback_control *wbc)
{
- struct inode *inode = container_of(page->mapping,
- struct inode, i_data);
- struct super_block *sb = inode->i_sb;
- struct the_nilfs *nilfs = NILFS_MDT(inode)->mi_nilfs;
+ struct inode *inode;
+ struct super_block *sb;
+ struct the_nilfs *nilfs;
struct nilfs_sb_info *writer = NULL;
int err = 0;
redirty_page_for_writepage(wbc, page);
unlock_page(page);
+ inode = page->mapping->host;
+ if (!inode)
+ return 0;
+
+ sb = inode->i_sb;
+ nilfs = NILFS_MDT(inode)->mi_nilfs;
+
if (page->mapping->assoc_mapping)
return 0; /* Do not request flush for shadow page cache */
if (!sb) {
@@ -567,6 +573,96 @@
&NILFS_I(orig)->i_btnode_cache;
}
+static const struct address_space_operations shadow_map_aops = {
+ .sync_page = block_sync_page,
+};
+
+/**
+ * nilfs_mdt_setup_shadow_map - setup shadow map and bind it to metadata file
+ * @inode: inode of the metadata file
+ * @shadow: shadow mapping
+ */
+int nilfs_mdt_setup_shadow_map(struct inode *inode,
+ struct nilfs_shadow_map *shadow)
+{
+ struct nilfs_mdt_info *mi = NILFS_MDT(inode);
+ struct backing_dev_info *bdi = NILFS_I_NILFS(inode)->ns_bdi;
+
+ INIT_LIST_HEAD(&shadow->frozen_buffers);
+ nilfs_mapping_init_once(&shadow->frozen_data);
+ nilfs_mapping_init(&shadow->frozen_data, bdi, &shadow_map_aops);
+ nilfs_mapping_init_once(&shadow->frozen_btnodes);
+ nilfs_mapping_init(&shadow->frozen_btnodes, bdi, &shadow_map_aops);
+ mi->mi_shadow = shadow;
+ return 0;
+}
+
+/**
+ * nilfs_mdt_save_to_shadow_map - copy bmap and dirty pages to shadow map
+ * @inode: inode of the metadata file
+ */
+int nilfs_mdt_save_to_shadow_map(struct inode *inode)
+{
+ struct nilfs_mdt_info *mi = NILFS_MDT(inode);
+ struct nilfs_inode_info *ii = NILFS_I(inode);
+ struct nilfs_shadow_map *shadow = mi->mi_shadow;
+ int ret;
+
+ ret = nilfs_copy_dirty_pages(&shadow->frozen_data, inode->i_mapping);
+ if (ret)
+ goto out;
+
+ ret = nilfs_copy_dirty_pages(&shadow->frozen_btnodes,
+ &ii->i_btnode_cache);
+ if (ret)
+ goto out;
+
+ nilfs_bmap_save(ii->i_bmap, &shadow->bmap_store);
+ out:
+ return ret;
+}
+
+/**
+ * nilfs_mdt_restore_from_shadow_map - restore dirty pages and bmap state
+ * @inode: inode of the metadata file
+ */
+void nilfs_mdt_restore_from_shadow_map(struct inode *inode)
+{
+ struct nilfs_mdt_info *mi = NILFS_MDT(inode);
+ struct nilfs_inode_info *ii = NILFS_I(inode);
+ struct nilfs_shadow_map *shadow = mi->mi_shadow;
+
+ down_write(&mi->mi_sem);
+
+ if (mi->mi_palloc_cache)
+ nilfs_palloc_clear_cache(inode);
+
+ nilfs_clear_dirty_pages(inode->i_mapping);
+ nilfs_copy_back_pages(inode->i_mapping, &shadow->frozen_data);
+
+ nilfs_clear_dirty_pages(&ii->i_btnode_cache);
+ nilfs_copy_back_pages(&ii->i_btnode_cache, &shadow->frozen_btnodes);
+
+ nilfs_bmap_restore(ii->i_bmap, &shadow->bmap_store);
+
+ up_write(&mi->mi_sem);
+}
+
+/**
+ * nilfs_mdt_clear_shadow_map - truncate pages in shadow map caches
+ * @inode: inode of the metadata file
+ */
+void nilfs_mdt_clear_shadow_map(struct inode *inode)
+{
+ struct nilfs_mdt_info *mi = NILFS_MDT(inode);
+ struct nilfs_shadow_map *shadow = mi->mi_shadow;
+
+ down_write(&mi->mi_sem);
+ truncate_inode_pages(&shadow->frozen_data, 0);
+ truncate_inode_pages(&shadow->frozen_btnodes, 0);
+ up_write(&mi->mi_sem);
+}
+
static void nilfs_mdt_clear(struct inode *inode)
{
struct nilfs_inode_info *ii = NILFS_I(inode);
diff --git a/fs/nilfs2/mdt.h b/fs/nilfs2/mdt.h
index f445602..e7f0d15 100644
--- a/fs/nilfs2/mdt.h
+++ b/fs/nilfs2/mdt.h
@@ -28,6 +28,13 @@
#include "nilfs.h"
#include "page.h"
+struct nilfs_shadow_map {
+ struct nilfs_bmap_store bmap_store;
+ struct address_space frozen_data;
+ struct address_space frozen_btnodes;
+ struct list_head frozen_buffers;
+};
+
/**
* struct nilfs_mdt_info - on-memory private data of meta data files
* @mi_nilfs: back pointer to the_nilfs struct
@@ -37,6 +44,7 @@
* @mi_first_entry_offset: offset to the first entry
* @mi_entries_per_block: number of entries in a block
* @mi_palloc_cache: persistent object allocator cache
+ * @mi_shadow: shadow of bmap and page caches
* @mi_blocks_per_group: number of blocks in a group
* @mi_blocks_per_desc_block: number of blocks per descriptor block
*/
@@ -48,6 +56,7 @@
unsigned mi_first_entry_offset;
unsigned long mi_entries_per_block;
struct nilfs_palloc_cache *mi_palloc_cache;
+ struct nilfs_shadow_map *mi_shadow;
unsigned long mi_blocks_per_group;
unsigned long mi_blocks_per_desc_block;
};
@@ -86,6 +95,11 @@
void nilfs_mdt_set_entry_size(struct inode *, unsigned, unsigned);
void nilfs_mdt_set_shadow(struct inode *, struct inode *);
+int nilfs_mdt_setup_shadow_map(struct inode *inode,
+ struct nilfs_shadow_map *shadow);
+int nilfs_mdt_save_to_shadow_map(struct inode *inode);
+void nilfs_mdt_restore_from_shadow_map(struct inode *inode);
+void nilfs_mdt_clear_shadow_map(struct inode *inode);
#define nilfs_mdt_mark_buffer_dirty(bh) nilfs_mark_buffer_dirty(bh)
diff --git a/fs/nilfs2/page.c b/fs/nilfs2/page.c
index aab11db..6384ac1 100644
--- a/fs/nilfs2/page.c
+++ b/fs/nilfs2/page.c
@@ -513,6 +513,31 @@
}
return nc;
}
+
+void nilfs_mapping_init_once(struct address_space *mapping)
+{
+ memset(mapping, 0, sizeof(*mapping));
+ INIT_RADIX_TREE(&mapping->page_tree, GFP_ATOMIC);
+ spin_lock_init(&mapping->tree_lock);
+ INIT_LIST_HEAD(&mapping->private_list);
+ spin_lock_init(&mapping->private_lock);
+
+ spin_lock_init(&mapping->i_mmap_lock);
+ INIT_RAW_PRIO_TREE_ROOT(&mapping->i_mmap);
+ INIT_LIST_HEAD(&mapping->i_mmap_nonlinear);
+}
+
+void nilfs_mapping_init(struct address_space *mapping,
+ struct backing_dev_info *bdi,
+ const struct address_space_operations *aops)
+{
+ mapping->host = NULL;
+ mapping->flags = 0;
+ mapping_set_gfp_mask(mapping, GFP_NOFS);
+ mapping->assoc_mapping = NULL;
+ mapping->backing_dev_info = bdi;
+ mapping->a_ops = aops;
+}
/*
* NILFS2 needs clear_page_dirty() in the following two cases:
diff --git a/fs/nilfs2/page.h b/fs/nilfs2/page.h
index f53d8da..6ec4f49 100644
--- a/fs/nilfs2/page.h
+++ b/fs/nilfs2/page.h
@@ -59,6 +59,10 @@
int nilfs_copy_dirty_pages(struct address_space *, struct address_space *);
void nilfs_copy_back_pages(struct address_space *, struct address_space *);
void nilfs_clear_dirty_pages(struct address_space *);
+void nilfs_mapping_init_once(struct address_space *mapping);
+void nilfs_mapping_init(struct address_space *mapping,
+ struct backing_dev_info *bdi,
+ const struct address_space_operations *aops);
unsigned nilfs_page_count_clean_buffers(struct page *, unsigned, unsigned);
#define NILFS_PAGE_BUG(page, m, a...) \