From ebdfed4dc59d177cf26013a0c9b8ee9652e9a140 Mon Sep 17 00:00:00 2001 From: Ryusuke Konishi Date: Mon, 6 Sep 2010 12:05:43 +0900 Subject: 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 --- fs/nilfs2/mdt.c | 104 +++++++++++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 100 insertions(+), 4 deletions(-) (limited to 'fs/nilfs2/mdt.c') diff --git a/fs/nilfs2/mdt.c b/fs/nilfs2/mdt.c index 73e5da3b097e..0066468609da 100644 --- a/fs/nilfs2/mdt.c +++ b/fs/nilfs2/mdt.c @@ -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); -- cgit v1.2.3-58-ga151