From: Andiry Xu <jix...@cs.ucsd.edu>

NOVA appends link change entries to atomically update link count and ctime.
This occurs in link, unlink and rmdir.

Signed-off-by: Andiry Xu <jix...@cs.ucsd.edu>
---
 fs/nova/log.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 fs/nova/log.h |  3 +++
 2 files changed, 55 insertions(+)

diff --git a/fs/nova/log.c b/fs/nova/log.c
index f85b63e..4638ccf 100644
--- a/fs/nova/log.c
+++ b/fs/nova/log.c
@@ -51,6 +51,25 @@ static void nova_update_setattr_entry(struct inode *inode,
        nova_persist_entry(entry);
 }
 
+static void nova_update_link_change_entry(struct inode *inode,
+       struct nova_link_change_entry *entry,
+       struct nova_log_entry_info *entry_info)
+{
+       struct nova_inode_info *si = NOVA_I(inode);
+       struct nova_inode_info_header *sih = &si->header;
+
+       entry->entry_type       = LINK_CHANGE;
+       entry->epoch_id         = cpu_to_le64(entry_info->epoch_id);
+       entry->trans_id         = cpu_to_le64(entry_info->trans_id);
+       entry->invalid          = 0;
+       entry->links            = cpu_to_le16(inode->i_nlink);
+       entry->ctime            = cpu_to_le32(inode->i_ctime.tv_sec);
+       entry->flags            = cpu_to_le32(sih->i_flags);
+       entry->generation       = cpu_to_le32(inode->i_generation);
+
+       nova_persist_entry(entry);
+}
+
 static int nova_update_write_entry(struct super_block *sb,
        struct nova_file_write_entry *entry,
        struct nova_log_entry_info *entry_info)
@@ -150,6 +169,7 @@ static int nova_update_log_entry(struct super_block *sb, 
struct inode *inode,
                nova_update_setattr_entry(inode, entry, entry_info);
                break;
        case LINK_CHANGE:
+               nova_update_link_change_entry(inode, entry, entry_info);
                break;
        default:
                break;
@@ -230,6 +250,38 @@ static int nova_append_setattr_entry(struct super_block 
*sb,
        return ret;
 }
 
+/* Returns new tail after append */
+int nova_append_link_change_entry(struct super_block *sb,
+       struct nova_inode *pi, struct inode *inode,
+       struct nova_inode_update *update, u64 *old_linkc, u64 epoch_id)
+{
+       struct nova_inode_info *si = NOVA_I(inode);
+       struct nova_inode_info_header *sih = &si->header;
+       struct nova_log_entry_info entry_info;
+       int ret = 0;
+       timing_t append_time;
+
+       NOVA_START_TIMING(append_link_change_t, append_time);
+
+       entry_info.type = LINK_CHANGE;
+       entry_info.update = update;
+       entry_info.epoch_id = epoch_id;
+       entry_info.trans_id = sih->trans_id;
+
+       ret = nova_append_log_entry(sb, pi, inode, sih, &entry_info);
+       if (ret) {
+               nova_err(sb, "%s failed\n", __func__);
+               goto out;
+       }
+
+       *old_linkc = sih->last_link_change;
+       sih->last_link_change = entry_info.curr_p;
+       sih->trans_id++;
+out:
+       NOVA_END_TIMING(append_link_change_t, append_time);
+       return ret;
+}
+
 /*
  * Append a nova_file_write_entry to the current nova_inode_log_page.
  * blocknr and start_blk are pgoff.
diff --git a/fs/nova/log.h b/fs/nova/log.h
index db7a72e..f36f4a3 100644
--- a/fs/nova/log.h
+++ b/fs/nova/log.h
@@ -364,6 +364,9 @@ static inline int is_dir_init_entry(struct super_block *sb,
 }
 
 
+int nova_append_link_change_entry(struct super_block *sb,
+       struct nova_inode *pi, struct inode *inode,
+       struct nova_inode_update *update, u64 *old_linkc, u64 epoch_id);
 int nova_append_file_write_entry(struct super_block *sb, struct nova_inode *pi,
        struct inode *inode, struct nova_file_write_item *item,
        struct nova_inode_update *update);
-- 
2.7.4

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