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>
This commit is contained in:
Ryusuke Konishi 2010-09-06 12:05:43 +09:00
parent a8070dd365
commit ebdfed4dc5
5 changed files with 145 additions and 19 deletions

View file

@ -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 @@ static const struct address_space_operations def_btnode_aops = {
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)

View file

@ -398,16 +398,22 @@ int nilfs_mdt_fetch_dirty(struct inode *inode)
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 @@ void nilfs_mdt_set_shadow(struct inode *orig, struct inode *shadow)
&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);

View file

@ -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 @@ struct nilfs_mdt_info {
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_destroy(struct inode *);
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)

View file

@ -513,6 +513,31 @@ unsigned nilfs_page_count_clean_buffers(struct page *page,
}
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:

View file

@ -59,6 +59,10 @@ void nilfs_free_private_page(struct page *);
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...) \