Hi Jaegeuk, Huang,

> -----Original Message-----
> From: Jaegeuk Kim [mailto:jaeg...@kernel.org]
> Sent: Thursday, September 18, 2014 1:51 PM
> To: linux-kernel@vger.kernel.org; linux-fsde...@vger.kernel.org;
> linux-f2fs-de...@lists.sourceforge.net
> Cc: Jaegeuk Kim; Huang Ying
> Subject: [f2fs-dev] [PATCH 2/3] f2fs: fix conditions to remain recovery 
> information in
> f2fs_sync_file
> 
> This patch revisited whole the recovery information during the f2fs_sync_file.
> 
> In this patch, there are three information to make a decision.
> 
> a) IS_CHECKPOINTED,   /* is it checkpointed before? */
> b) HAS_FSYNCED_INODE, /* is the inode fsynced before? */
> c) HAS_LAST_FSYNC,    /* has the latest node fsync mark? */
> 
> And, the scenarios for our rule are based on:
> 
> [Term] F: fsync_mark, D: dentry_mark
> 
> 1. inode(x) | CP | inode(x) | dnode(F)
> 2. inode(x) | CP | inode(F) | dnode(F)
> 3. inode(x) | CP | dnode(F) | inode(x) | inode(F)
> 4. inode(x) | CP | dnode(F) | inode(F)
> 5. CP | inode(x) | dnode(F) | inode(DF)
> 6. CP | inode(DF) | dnode(F)
> 7. CP | dnode(F) | inode(DF)
> 8. CP | dnode(F) | inode(x) | inode(DF)

No sure, do we missed these cases:
inode(x) | CP | inode(F) | dnode(x) -> write inode(F)
CP | inode(DF) | dnode(x) -> write inode(F)

In these cases we will write another inode with fsync flag because our last
dnode is written out to disk by bdi-flusher (HAS_LAST_FSYNC is not marked). But
this appended inode is not useful.

AFAIK, HAS_LAST_FSYNC(AKA fsync_done) is introduced in commit 479f40c44ae3
("f2fs: skip unnecessary node writes during fsync") to avoid writting multiple
unneeded inode page by multiple redundant fsync calls. But for now, its role can
be taken by HAS_FSYNCED_INODE.
So, can we remove this flag to simplify our logic of fsync flow?

Then in fsync flow, the rule can be:
If CPed before, there must be a inode(F) written in warm node chain;
If not CPed before, there must be a inode(DF) written in warm node chain.

Thanks,
Yu

> 
> For example, #3, the three conditions should be changed as follows.
> 
>    inode(x) | CP | dnode(F) | inode(x) | inode(F)
> a)    x       o      o          o          o
> b)    x       x      x          x          o
> c)    x       o      o          x          o
> 
> If f2fs_sync_file stops   ------^,
>  it should write inode(F)    --------------^
> 
> So, the need_inode_block_update should return true, since
>  c) get_nat_flag(e, HAS_LAST_FSYNC), is false.
> 
> For example, #8,
>       CP | alloc | dnode(F) | inode(x) | inode(DF)
> a)    o      x        x          x          x
> b)    x               x          x          o
> c)    o               o          x          o
> 
> If f2fs_sync_file stops   -------^,
>  it should write inode(DF)    --------------^
> 
> Note that, the roll-forward policy should follow this rule, which means,
> if there are any missing blocks, we doesn't need to recover that inode.
> 
> Signed-off-by: Huang Ying <ying.hu...@intel.com>
> Signed-off-by: Jaegeuk Kim <jaeg...@kernel.org>
> ---
>  fs/f2fs/data.c |  3 ---
>  fs/f2fs/f2fs.h |  6 +++---
>  fs/f2fs/file.c | 10 ++++++----
>  fs/f2fs/node.c | 56 +++++++++++++++++++++++++++++++++++---------------------
>  fs/f2fs/node.h | 21 ++++++++++++---------
>  5 files changed, 56 insertions(+), 40 deletions(-)
> 
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index 0e37658..fdc3dbe 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -1089,9 +1089,6 @@ static ssize_t f2fs_direct_IO(int rw, struct kiocb 
> *iocb,
>       if (check_direct_IO(inode, rw, iter, offset))
>               return 0;
> 
> -     /* clear fsync mark to recover these blocks */
> -     fsync_mark_clear(F2FS_I_SB(inode), inode->i_ino);
> -
>       trace_f2fs_direct_IO_enter(inode, offset, count, rw);
> 
>       err = blockdev_direct_IO(rw, iocb, inode, iter, offset, get_data_block);
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 9fc1bcd..fd44083 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -1224,9 +1224,9 @@ struct dnode_of_data;
>  struct node_info;
> 
>  bool available_free_memory(struct f2fs_sb_info *, int);
> -int is_checkpointed_node(struct f2fs_sb_info *, nid_t);
> -bool fsync_mark_done(struct f2fs_sb_info *, nid_t);
> -void fsync_mark_clear(struct f2fs_sb_info *, nid_t);
> +bool is_checkpointed_node(struct f2fs_sb_info *, nid_t);
> +bool has_fsynced_inode(struct f2fs_sb_info *, nid_t);
> +bool need_inode_block_update(struct f2fs_sb_info *, nid_t);
>  void get_node_info(struct f2fs_sb_info *, nid_t, struct node_info *);
>  int get_dnode_of_data(struct dnode_of_data *, pgoff_t, int);
>  int truncate_inode_blocks(struct inode *, pgoff_t);
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index af06e22..3035c79 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -207,15 +207,17 @@ int f2fs_sync_file(struct file *file, loff_t start, 
> loff_t end, int
> datasync)
>                       up_write(&fi->i_sem);
>               }
>       } else {
> -             /* if there is no written node page, write its inode page */
> -             while (!sync_node_pages(sbi, ino, &wbc)) {
> -                     if (fsync_mark_done(sbi, ino))
> -                             goto out;
> +sync_nodes:
> +             sync_node_pages(sbi, ino, &wbc);
> +
> +             if (need_inode_block_update(sbi, ino)) {
>                       mark_inode_dirty_sync(inode);
>                       ret = f2fs_write_inode(inode, NULL);
>                       if (ret)
>                               goto out;
> +                     goto sync_nodes;
>               }
> +
>               ret = wait_on_node_pages_writeback(sbi, ino);
>               if (ret)
>                       goto out;
> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> index d19d6b1..7a2d9c9 100644
> --- a/fs/f2fs/node.c
> +++ b/fs/f2fs/node.c
> @@ -123,44 +123,48 @@ static void __del_from_nat_cache(struct f2fs_nm_info 
> *nm_i, struct
> nat_entry *e)
>       kmem_cache_free(nat_entry_slab, e);
>  }
> 
> -int is_checkpointed_node(struct f2fs_sb_info *sbi, nid_t nid)
> +bool is_checkpointed_node(struct f2fs_sb_info *sbi, nid_t nid)
>  {
>       struct f2fs_nm_info *nm_i = NM_I(sbi);
>       struct nat_entry *e;
> -     int is_cp = 1;
> +     bool is_cp = true;
> 
>       read_lock(&nm_i->nat_tree_lock);
>       e = __lookup_nat_cache(nm_i, nid);
>       if (e && !get_nat_flag(e, IS_CHECKPOINTED))
> -             is_cp = 0;
> +             is_cp = false;
>       read_unlock(&nm_i->nat_tree_lock);
>       return is_cp;
>  }
> 
> -bool fsync_mark_done(struct f2fs_sb_info *sbi, nid_t nid)
> +bool has_fsynced_inode(struct f2fs_sb_info *sbi, nid_t ino)
>  {
>       struct f2fs_nm_info *nm_i = NM_I(sbi);
>       struct nat_entry *e;
> -     bool fsync_done = false;
> +     bool fsynced = false;
> 
>       read_lock(&nm_i->nat_tree_lock);
> -     e = __lookup_nat_cache(nm_i, nid);
> -     if (e)
> -             fsync_done = get_nat_flag(e, HAS_FSYNC_MARK);
> +     e = __lookup_nat_cache(nm_i, ino);
> +     if (e && get_nat_flag(e, HAS_FSYNCED_INODE))
> +             fsynced = true;
>       read_unlock(&nm_i->nat_tree_lock);
> -     return fsync_done;
> +     return fsynced;
>  }
> 
> -void fsync_mark_clear(struct f2fs_sb_info *sbi, nid_t nid)
> +bool need_inode_block_update(struct f2fs_sb_info *sbi, nid_t ino)
>  {
>       struct f2fs_nm_info *nm_i = NM_I(sbi);
>       struct nat_entry *e;
> +     bool need_update = true;
> 
> -     write_lock(&nm_i->nat_tree_lock);
> -     e = __lookup_nat_cache(nm_i, nid);
> -     if (e)
> -             set_nat_flag(e, HAS_FSYNC_MARK, false);
> -     write_unlock(&nm_i->nat_tree_lock);
> +     read_lock(&nm_i->nat_tree_lock);
> +     e = __lookup_nat_cache(nm_i, ino);
> +     if (e && get_nat_flag(e, HAS_LAST_FSYNC) &&
> +                     (get_nat_flag(e, IS_CHECKPOINTED) ||
> +                      get_nat_flag(e, HAS_FSYNCED_INODE)))
> +             need_update = false;
> +     read_unlock(&nm_i->nat_tree_lock);
> +     return need_update;
>  }
> 
>  static struct nat_entry *grab_nat_entry(struct f2fs_nm_info *nm_i, nid_t nid)
> @@ -176,7 +180,7 @@ static struct nat_entry *grab_nat_entry(struct 
> f2fs_nm_info *nm_i, nid_t
> nid)
>       }
>       memset(new, 0, sizeof(struct nat_entry));
>       nat_set_nid(new, nid);
> -     set_nat_flag(new, IS_CHECKPOINTED, true);
> +     nat_reset_flag(new);
>       list_add_tail(&new->list, &nm_i->nat_entries);
>       nm_i->nat_cnt++;
>       return new;
> @@ -244,12 +248,17 @@ retry:
> 
>       /* change address */
>       nat_set_blkaddr(e, new_blkaddr);
> +     if (new_blkaddr == NEW_ADDR || new_blkaddr == NULL_ADDR)
> +             set_nat_flag(e, IS_CHECKPOINTED, false);
>       __set_nat_cache_dirty(nm_i, e);
> 
>       /* update fsync_mark if its inode nat entry is still alive */
>       e = __lookup_nat_cache(nm_i, ni->ino);
> -     if (e)
> -             set_nat_flag(e, HAS_FSYNC_MARK, fsync_done);
> +     if (e) {
> +             if (fsync_done && ni->nid == ni->ino)
> +                     set_nat_flag(e, HAS_FSYNCED_INODE, true);
> +             set_nat_flag(e, HAS_LAST_FSYNC, fsync_done);
> +     }
>       write_unlock(&nm_i->nat_tree_lock);
>  }
> 
> @@ -1121,10 +1130,14 @@ continue_unlock:
> 
>                       /* called by fsync() */
>                       if (ino && IS_DNODE(page)) {
> -                             int mark = !is_checkpointed_node(sbi, ino);
>                               set_fsync_mark(page, 1);
> -                             if (IS_INODE(page))
> -                                     set_dentry_mark(page, mark);
> +                             if (IS_INODE(page)) {
> +                                     if (!is_checkpointed_node(sbi, ino) &&
> +                                             !has_fsynced_inode(sbi, ino))
> +                                             set_dentry_mark(page, 1);
> +                                     else
> +                                             set_dentry_mark(page, 0);
> +                             }
>                               nwritten++;
>                       } else {
>                               set_fsync_mark(page, 0);
> @@ -1912,6 +1925,7 @@ void flush_nat_entries(struct f2fs_sb_info *sbi)
>                               write_unlock(&nm_i->nat_tree_lock);
>                       } else {
>                               write_lock(&nm_i->nat_tree_lock);
> +                             nat_reset_flag(ne);
>                               __clear_nat_cache_dirty(nm_i, ne);
>                               write_unlock(&nm_i->nat_tree_lock);
>                       }
> diff --git a/fs/f2fs/node.h b/fs/f2fs/node.h
> index 3043778..b8ba63c 100644
> --- a/fs/f2fs/node.h
> +++ b/fs/f2fs/node.h
> @@ -41,7 +41,8 @@ struct node_info {
> 
>  enum {
>       IS_CHECKPOINTED,        /* is it checkpointed before? */
> -     HAS_FSYNC_MARK,         /* has the latest node fsync mark? */
> +     HAS_FSYNCED_INODE,      /* is the inode fsynced before? */
> +     HAS_LAST_FSYNC,         /* has the latest node fsync mark? */
>  };
> 
>  struct nat_entry {
> @@ -60,15 +61,9 @@ struct nat_entry {
>  #define nat_set_version(nat, v)              (nat->ni.version = v)
> 
>  #define __set_nat_cache_dirty(nm_i, ne)                                      
> \
> -     do {                                                            \
> -             set_nat_flag(ne, IS_CHECKPOINTED, false);               \
> -             list_move_tail(&ne->list, &nm_i->dirty_nat_entries);    \
> -     } while (0)
> +             list_move_tail(&ne->list, &nm_i->dirty_nat_entries);
>  #define __clear_nat_cache_dirty(nm_i, ne)                            \
> -     do {                                                            \
> -             set_nat_flag(ne, IS_CHECKPOINTED, true);                \
> -             list_move_tail(&ne->list, &nm_i->nat_entries);          \
> -     } while (0)
> +             list_move_tail(&ne->list, &nm_i->nat_entries);
>  #define inc_node_version(version)    (++version)
> 
>  static inline void set_nat_flag(struct nat_entry *ne,
> @@ -87,6 +82,14 @@ static inline bool get_nat_flag(struct nat_entry *ne, 
> unsigned int type)
>       return ne->flag & mask;
>  }
> 
> +static inline void nat_reset_flag(struct nat_entry *ne)
> +{
> +     /* these states can be set only after checkpoint was done */
> +     set_nat_flag(ne, IS_CHECKPOINTED, true);
> +     set_nat_flag(ne, HAS_FSYNCED_INODE, false);
> +     set_nat_flag(ne, HAS_LAST_FSYNC, true);
> +}
> +
>  static inline void node_info_from_raw_nat(struct node_info *ni,
>                                               struct f2fs_nat_entry *raw_ne)
>  {
> --
> 1.8.5.2 (Apple Git-48)
> 
> 
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