RE: [f2fs-dev] [PATCH 2/3] f2fs: fix conditions to remain recovery information in f2fs_sync_file

From: Chao Yu
Date: Tue Sep 23 2014 - 04:52:01 EST

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> -----Original Message-----
> From: Jaegeuk Kim [mailto:jaegeuk@xxxxxxxxxx]
> Sent: Tuesday, September 23, 2014 12:53 PM
> To: Chao Yu
> Cc: 'Huang Ying'; linux-kernel@xxxxxxxxxxxxxxx; linux-fsdevel@xxxxxxxxxxxxxxx;
> linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx
> Subject: Re: [f2fs-dev] [PATCH 2/3] f2fs: fix conditions to remain recovery information in
> f2fs_sync_file
>
> On Mon, Sep 22, 2014 at 05:20:19PM +0800, Chao Yu wrote:
> > > -----Original Message-----
> > > From: Huang Ying [mailto:ying.huang@xxxxxxxxx]
> > > Sent: Monday, September 22, 2014 3:39 PM
> > > To: Chao Yu
> > > Cc: 'Jaegeuk Kim'; linux-kernel@xxxxxxxxxxxxxxx; linux-fsdevel@xxxxxxxxxxxxxxx;
> > > linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx
> > > Subject: Re: [f2fs-dev] [PATCH 2/3] f2fs: fix conditions to remain recovery information
> in
> > > f2fs_sync_file
> > >
> > > On Mon, 2014-09-22 at 15:24 +0800, Chao Yu wrote:
> > > > Hi Jaegeuk, Huang,
> > > >
> > > > > -----Original Message-----
> > > > > From: Jaegeuk Kim [mailto:jaegeuk@xxxxxxxxxx]
> > > > > Sent: Thursday, September 18, 2014 1:51 PM
> > > > > To: linux-kernel@xxxxxxxxxxxxxxx; linux-fsdevel@xxxxxxxxxxxxxxx;
> > > > > linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx
> > > > > 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;
> > >
> > > How about
> > >
> > > inode(x) | CP | dnode(F)
> >
> > Oh, I missed this one, thanks for remindering that.
> >
> > There is another case:
> > inode(x) | CP | dnode(F) | dnode(x) -> write inode(F)
> > It seems we will append another unneeded inode(F) in this patch also due to
> > no HAS_LAST_FSYNC in nat entry cache of inode.
>
> As the current rule for roll-forward recovery, we need inode(F) to find the
> latest mark. This can also be used to distinguish fsynced inode from writebacked
> inodes.

Got it now, thanks for your explanation!

>
> >
> > >
> > > > If not CPed before, there must be a inode(DF) written in warm node chain.
> > >
> > > For example below:
> > >
> > > 1) checkpoint
> > > 2) create "a", change "a"
> > > 3) fsync "a"
> > > 4) open "a", change "a"
> > >
> > > Do we want recovery to stop at dnode(F) in step 3) or stop at dnode(x)
> > > produced by step 4)?
> >
> > To my understanding, we will recover all info related to fsynced nodes in warm
> > node chain. So will produce to step 4 if changed nodes in step 4 are flushed to
> > device.

To Huang,
My mistaken for the wrong explanation due to my misunderstanding about the recover
code, sorry about that!

>
> Current rule should stop at 3) fsync "a". It won't recover 4)'s inode, since it
> was just writebacked.
>
> If we'd like to recover whole the inode and its data, we should traverse all the
> recovery paths from the sketch.

I am missing some codes when traverse the recover flow.
You're right, and thanks for correcting me.

Regards,
Yu

>
> Thanks,
>
> >
> > Thanks,
> > Yu
> > >
> > > Best Regards,
> > > Huang, Ying
> > >
> > > > >
> > > > > 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.huang@xxxxxxxxx>
> > > > > Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
> > > > > ---
> > > > > 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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> > > > > Manually upgrade your production database.
> > > > > When you want reliability, choose Perforce
> > > > > Perforce version control. Predictably reliable.
> > > > > http://pubads.g.doubleclick.net/gampad/clk?id=157508191&iu=/4140/ostg.clktrk
> > > > > _______________________________________________
> > > > > Linux-f2fs-devel mailing list
> > > > > Linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx
> > > > > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
> > > >

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