f2fs: add recovery routines for roll-forward

This adds roll-forward routines to recover fsynced data.

- F2FS uses basically roll-back model with checkpointing.

- In order to implement fsync(), there are two approaches as follows.

1. A roll-back model with checkpointing at every fsync()
 : This is a naive method, but suffers from very low performance.

2. A roll-forward model
 : F2FS adopts this model where all the fsynced data should be recovered, which
   were written after checkpointing was done. In order to figure out the data,
   F2FS keeps a "fsync" mark in direct node blocks. In addition, F2FS remains
   the location of next node block in each direct node block for reconstructing
   the chain of node blocks during the recovery.

- In order to enhance the performance, F2FS keeps a "dentry" mark also in direct
  node blocks. If this is set during the recovery, F2FS replays adding a dentry.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c
new file mode 100644 (file)
index 0000000..7a43df0
--- /dev/null
+++ b/fs/f2fs/recovery.c
@@ -0,0 +1,375 @@
+/**
+ * fs/f2fs/recovery.c
+ *
+ * Copyright (c) 2012 Samsung Electronics Co., Ltd.
+ *             http://www.samsung.com/
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/fs.h>
+#include <linux/f2fs_fs.h>
+#include "f2fs.h"
+#include "node.h"
+#include "segment.h"
+
+static struct kmem_cache *fsync_entry_slab;
+
+bool space_for_roll_forward(struct f2fs_sb_info *sbi)
+{
+       if (sbi->last_valid_block_count + sbi->alloc_valid_block_count
+                       > sbi->user_block_count)
+               return false;
+       return true;
+}
+
+static struct fsync_inode_entry *get_fsync_inode(struct list_head *head,
+                                                               nid_t ino)
+{
+       struct list_head *this;
+       struct fsync_inode_entry *entry;
+
+       list_for_each(this, head) {
+               entry = list_entry(this, struct fsync_inode_entry, list);
+               if (entry->inode->i_ino == ino)
+                       return entry;
+       }
+       return NULL;
+}
+
+static int recover_dentry(struct page *ipage, struct inode *inode)
+{
+       struct f2fs_node *raw_node = (struct f2fs_node *)kmap(ipage);
+       struct f2fs_inode *raw_inode = &(raw_node->i);
+       struct dentry dent, parent;
+       struct f2fs_dir_entry *de;
+       struct page *page;
+       struct inode *dir;
+       int err = 0;
+
+       if (!is_dent_dnode(ipage))
+               goto out;
+
+       dir = f2fs_iget(inode->i_sb, le32_to_cpu(raw_inode->i_pino));
+       if (IS_ERR(dir)) {
+               err = -EINVAL;
+               goto out;
+       }
+
+       parent.d_inode = dir;
+       dent.d_parent = &parent;
+       dent.d_name.len = le32_to_cpu(raw_inode->i_namelen);
+       dent.d_name.name = raw_inode->i_name;
+
+       de = f2fs_find_entry(dir, &dent.d_name, &page);
+       if (de) {
+               kunmap(page);
+               f2fs_put_page(page, 0);
+       } else {
+               f2fs_add_link(&dent, inode);
+       }
+       iput(dir);
+out:
+       kunmap(ipage);
+       return err;
+}
+
+static int recover_inode(struct inode *inode, struct page *node_page)
+{
+       void *kaddr = page_address(node_page);
+       struct f2fs_node *raw_node = (struct f2fs_node *)kaddr;
+       struct f2fs_inode *raw_inode = &(raw_node->i);
+
+       inode->i_mode = le32_to_cpu(raw_inode->i_mode);
+       i_size_write(inode, le64_to_cpu(raw_inode->i_size));
+       inode->i_atime.tv_sec = le64_to_cpu(raw_inode->i_mtime);
+       inode->i_ctime.tv_sec = le64_to_cpu(raw_inode->i_ctime);
+       inode->i_mtime.tv_sec = le64_to_cpu(raw_inode->i_mtime);
+       inode->i_atime.tv_nsec = le32_to_cpu(raw_inode->i_mtime_nsec);
+       inode->i_ctime.tv_nsec = le32_to_cpu(raw_inode->i_ctime_nsec);
+       inode->i_mtime.tv_nsec = le32_to_cpu(raw_inode->i_mtime_nsec);
+
+       return recover_dentry(node_page, inode);
+}
+
+static int find_fsync_dnodes(struct f2fs_sb_info *sbi, struct list_head *head)
+{
+       unsigned long long cp_ver = le64_to_cpu(sbi->ckpt->checkpoint_ver);
+       struct curseg_info *curseg;
+       struct page *page;
+       block_t blkaddr;
+       int err = 0;
+
+       /* get node pages in the current segment */
+       curseg = CURSEG_I(sbi, CURSEG_WARM_NODE);
+       blkaddr = START_BLOCK(sbi, curseg->segno) + curseg->next_blkoff;
+
+       /* read node page */
+       page = alloc_page(GFP_F2FS_ZERO);
+       if (IS_ERR(page))
+               return PTR_ERR(page);
+       lock_page(page);
+
+       while (1) {
+               struct fsync_inode_entry *entry;
+
+               if (f2fs_readpage(sbi, page, blkaddr, READ_SYNC))
+                       goto out;
+
+               if (cp_ver != cpver_of_node(page))
+                       goto out;
+
+               if (!is_fsync_dnode(page))
+                       goto next;
+
+               entry = get_fsync_inode(head, ino_of_node(page));
+               if (entry) {
+                       entry->blkaddr = blkaddr;
+                       if (IS_INODE(page) && is_dent_dnode(page))
+                               set_inode_flag(F2FS_I(entry->inode),
+                                                       FI_INC_LINK);
+               } else {
+                       if (IS_INODE(page) && is_dent_dnode(page)) {
+                               if (recover_inode_page(sbi, page)) {
+                                       err = -ENOMEM;
+                                       goto out;
+                               }
+                       }
+
+                       /* add this fsync inode to the list */
+                       entry = kmem_cache_alloc(fsync_entry_slab, GFP_NOFS);
+                       if (!entry) {
+                               err = -ENOMEM;
+                               goto out;
+                       }
+
+                       INIT_LIST_HEAD(&entry->list);
+                       list_add_tail(&entry->list, head);
+
+                       entry->inode = f2fs_iget(sbi->sb, ino_of_node(page));
+                       if (IS_ERR(entry->inode)) {
+                               err = PTR_ERR(entry->inode);
+                               goto out;
+                       }
+                       entry->blkaddr = blkaddr;
+               }
+               if (IS_INODE(page)) {
+                       err = recover_inode(entry->inode, page);
+                       if (err)
+                               goto out;
+               }
+next:
+               /* check next segment */
+               blkaddr = next_blkaddr_of_node(page);
+               ClearPageUptodate(page);
+       }
+out:
+       unlock_page(page);
+       __free_pages(page, 0);
+       return err;
+}
+
+static void destroy_fsync_dnodes(struct f2fs_sb_info *sbi,
+                                       struct list_head *head)
+{
+       struct list_head *this;
+       struct fsync_inode_entry *entry;
+       list_for_each(this, head) {
+               entry = list_entry(this, struct fsync_inode_entry, list);
+               iput(entry->inode);
+               list_del(&entry->list);
+               kmem_cache_free(fsync_entry_slab, entry);
+       }
+}
+
+static void check_index_in_prev_nodes(struct f2fs_sb_info *sbi,
+                                               block_t blkaddr)
+{
+       struct seg_entry *sentry;
+       unsigned int segno = GET_SEGNO(sbi, blkaddr);
+       unsigned short blkoff = GET_SEGOFF_FROM_SEG0(sbi, blkaddr) &
+                                       (sbi->blocks_per_seg - 1);
+       struct f2fs_summary sum;
+       nid_t ino;
+       void *kaddr;
+       struct inode *inode;
+       struct page *node_page;
+       block_t bidx;
+       int i;
+
+       sentry = get_seg_entry(sbi, segno);
+       if (!f2fs_test_bit(blkoff, sentry->cur_valid_map))
+               return;
+
+       /* Get the previous summary */
+       for (i = CURSEG_WARM_DATA; i <= CURSEG_COLD_DATA; i++) {
+               struct curseg_info *curseg = CURSEG_I(sbi, i);
+               if (curseg->segno == segno) {
+                       sum = curseg->sum_blk->entries[blkoff];
+                       break;
+               }
+       }
+       if (i > CURSEG_COLD_DATA) {
+               struct page *sum_page = get_sum_page(sbi, segno);
+               struct f2fs_summary_block *sum_node;
+               kaddr = page_address(sum_page);
+               sum_node = (struct f2fs_summary_block *)kaddr;
+               sum = sum_node->entries[blkoff];
+               f2fs_put_page(sum_page, 1);
+       }
+
+       /* Get the node page */
+       node_page = get_node_page(sbi, le32_to_cpu(sum.nid));
+       bidx = start_bidx_of_node(ofs_of_node(node_page)) +
+                               le16_to_cpu(sum.ofs_in_node);
+       ino = ino_of_node(node_page);
+       f2fs_put_page(node_page, 1);
+
+       /* Deallocate previous index in the node page */
+       inode = f2fs_iget_nowait(sbi->sb, ino);
+       truncate_hole(inode, bidx, bidx + 1);
+       iput(inode);
+}
+
+static void do_recover_data(struct f2fs_sb_info *sbi, struct inode *inode,
+                                       struct page *page, block_t blkaddr)
+{
+       unsigned int start, end;
+       struct dnode_of_data dn;
+       struct f2fs_summary sum;
+       struct node_info ni;
+
+       start = start_bidx_of_node(ofs_of_node(page));
+       if (IS_INODE(page))
+               end = start + ADDRS_PER_INODE;
+       else
+               end = start + ADDRS_PER_BLOCK;
+
+       set_new_dnode(&dn, inode, NULL, NULL, 0);
+       if (get_dnode_of_data(&dn, start, 0))
+               return;
+
+       wait_on_page_writeback(dn.node_page);
+
+       get_node_info(sbi, dn.nid, &ni);
+       BUG_ON(ni.ino != ino_of_node(page));
+       BUG_ON(ofs_of_node(dn.node_page) != ofs_of_node(page));
+
+       for (; start < end; start++) {
+               block_t src, dest;
+
+               src = datablock_addr(dn.node_page, dn.ofs_in_node);
+               dest = datablock_addr(page, dn.ofs_in_node);
+
+               if (src != dest && dest != NEW_ADDR && dest != NULL_ADDR) {
+                       if (src == NULL_ADDR) {
+                               int err = reserve_new_block(&dn);
+                               /* We should not get -ENOSPC */
+                               BUG_ON(err);
+                       }
+
+                       /* Check the previous node page having this index */
+                       check_index_in_prev_nodes(sbi, dest);
+
+                       set_summary(&sum, dn.nid, dn.ofs_in_node, ni.version);
+
+                       /* write dummy data page */
+                       recover_data_page(sbi, NULL, &sum, src, dest);
+                       update_extent_cache(dest, &dn);
+               }
+               dn.ofs_in_node++;
+       }
+
+       /* write node page in place */
+       set_summary(&sum, dn.nid, 0, 0);
+       if (IS_INODE(dn.node_page))
+               sync_inode_page(&dn);
+
+       copy_node_footer(dn.node_page, page);
+       fill_node_footer(dn.node_page, dn.nid, ni.ino,
+                                       ofs_of_node(page), false);
+       set_page_dirty(dn.node_page);
+
+       recover_node_page(sbi, dn.node_page, &sum, &ni, blkaddr);
+       f2fs_put_dnode(&dn);
+}
+
+static void recover_data(struct f2fs_sb_info *sbi,
+                               struct list_head *head, int type)
+{
+       unsigned long long cp_ver = le64_to_cpu(sbi->ckpt->checkpoint_ver);
+       struct curseg_info *curseg;
+       struct page *page;
+       block_t blkaddr;
+
+       /* get node pages in the current segment */
+       curseg = CURSEG_I(sbi, type);
+       blkaddr = NEXT_FREE_BLKADDR(sbi, curseg);
+
+       /* read node page */
+       page = alloc_page(GFP_NOFS | __GFP_ZERO);
+       if (IS_ERR(page))
+               return;
+       lock_page(page);
+
+       while (1) {
+               struct fsync_inode_entry *entry;
+
+               if (f2fs_readpage(sbi, page, blkaddr, READ_SYNC))
+                       goto out;
+
+               if (cp_ver != cpver_of_node(page))
+                       goto out;
+
+               entry = get_fsync_inode(head, ino_of_node(page));
+               if (!entry)
+                       goto next;
+
+               do_recover_data(sbi, entry->inode, page, blkaddr);
+
+               if (entry->blkaddr == blkaddr) {
+                       iput(entry->inode);
+                       list_del(&entry->list);
+                       kmem_cache_free(fsync_entry_slab, entry);
+               }
+next:
+               /* check next segment */
+               blkaddr = next_blkaddr_of_node(page);
+               ClearPageUptodate(page);
+       }
+out:
+       unlock_page(page);
+       __free_pages(page, 0);
+
+       allocate_new_segments(sbi);
+}
+
+void recover_fsync_data(struct f2fs_sb_info *sbi)
+{
+       struct list_head inode_list;
+
+       fsync_entry_slab = f2fs_kmem_cache_create("f2fs_fsync_inode_entry",
+                       sizeof(struct fsync_inode_entry), NULL);
+       if (unlikely(!fsync_entry_slab))
+               return;
+
+       INIT_LIST_HEAD(&inode_list);
+
+       /* step #1: find fsynced inode numbers */
+       if (find_fsync_dnodes(sbi, &inode_list))
+               goto out;
+
+       if (list_empty(&inode_list))
+               goto out;
+
+       /* step #2: recover data */
+       sbi->por_doing = 1;
+       recover_data(sbi, &inode_list, CURSEG_WARM_NODE);
+       sbi->por_doing = 0;
+       BUG_ON(!list_empty(&inode_list));
+out:
+       destroy_fsync_dnodes(sbi, &inode_list);
+       kmem_cache_destroy(fsync_entry_slab);
+       write_checkpoint(sbi, false, false);
+}