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Message-ID: <1410507288.7276.8.camel@yhuang-dev> Date: Fri, 12 Sep 2014 15:34:48 +0800 From: Huang Ying <ying.huang@...el.com> To: Jaegeuk Kim <jaegeuk@...nel.org> Cc: huang ying <huang.ying.caritas@...il.com>, Changman Lee <cm224.lee@...sung.com>, linux-f2fs-devel@...ts.sourceforge.net, LKML <linux-kernel@...r.kernel.org> Subject: Re: [PATCH] f2fs: Fix recover when nid of non-inode dnode < nid of inode On Thu, 2014-09-11 at 22:13 -0700, Jaegeuk Kim wrote: > On Thu, Sep 11, 2014 at 08:25:17PM +0800, Huang Ying wrote: > > > > On Wed, 2014-09-10 at 22:37 -0700, Jaegeuk Kim wrote: > > > On Wed, Sep 10, 2014 at 07:08:32PM +0800, huang ying wrote: > > > > On Wed, Sep 10, 2014 at 3:21 PM, Jaegeuk Kim <jaegeuk@...nel.org> wrote: > > > > > > > > > On Tue, Sep 09, 2014 at 07:31:49PM +0800, huang ying wrote: > > > > > > On Tue, Sep 9, 2014 at 3:09 PM, Jaegeuk Kim <jaegeuk@...nel.org> wrote: > > > > > > > > > > > > > Hi, > > > > > > > > > > > > > > On Tue, Sep 09, 2014 at 01:39:30PM +0800, Huang Ying wrote: > > > > > > > > On Mon, 2014-09-08 at 22:23 -0700, Jaegeuk Kim wrote: > > > > > > > > > Hi Huang, > > > > > > > > > > > > > > > > > > On Mon, Sep 08, 2014 at 07:38:26PM +0800, Huang Ying wrote: > > > > > > > > > > For fsync, if the nid of a non-inode dnode < nid of inode and the > > > > > > > > > > inode is not checkpointed. The non-inode dnode may be written > > > > > before > > > > > > > > > > inode. So in find_fsync_dnodes, f2fs_iget will fail, cause the > > > > > > > > > > recovery fail. > > > > > > > > > > > > > > > > > > > > Usually, inode will be allocated before non-inode dnode, so the > > > > > nid > > > > > > > of > > > > > > > > > > inode < nid of non-inode dnode. But it is possible for the > > > > > reverse. > > > > > > > > > > For example, because of alloc_nid_failed. > > > > > > > > > > > > > > > > > > > > This is fixed via ignoring non-inode dnode before inode dnode in > > > > > > > > > > find_fsync_dnodes. > > > > > > > > > > > > > > > > > > > > The patch was tested via allocating nid reversely via a debugging > > > > > > > > > > patch, that is, from big number to small number. > > > > > > > > > > > > > > > > > > > > Signed-off-by: Huang, Ying <ying.huang@...el.com> > > > > > > > > > > --- > > > > > > > > > > fs/f2fs/recovery.c | 7 ++++--- > > > > > > > > > > 1 file changed, 4 insertions(+), 3 deletions(-) > > > > > > > > > > > > > > > > > > > > --- a/fs/f2fs/recovery.c > > > > > > > > > > +++ b/fs/f2fs/recovery.c > > > > > > > > > > @@ -172,8 +172,8 @@ static int find_fsync_dnodes(struct f2fs > > > > > > > > > > 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 this is not inode block, we should add this inode to recover its > > > > > > > data blocks. > > > > > > > > > > > > > > > > Is it possible that there is only non-inode dnode but no inode when > > > > > > > > find_fsync_dnodes checking dnodes? Per my understanding, any > > > > > changes to > > > > > > > > file will cause inode page dirty (for example, mtime changed), so > > > > > that > > > > > > > > we will write inode block. Is it right? If so, the solution in this > > > > > > > > patch should work too. > > > > > > > > > > > > > > Your description says that f2fs_iget will fail, which causes the > > > > > recovery > > > > > > > fail. > > > > > > > So, I thought it would be better to handle the f2fs_iget failure > > > > > directly. > > > > > > > > > > > > > > > > > > > Yes. That is another way to fix the issue. > > > > > > > > > > > > > > > > > > > In addition, we cannot guarantee the write order of dnode and inode. > > > > > > > For exmaple, > > > > > > > 1. the inode is written by flusher or kswapd, then, > > > > > > > 2. f2fs_sync_file writes its dnode. > > > > > > > > > > > > > > In that case, we can get only non-inode dnode in the node chain, since > > > > > the > > > > > > > inode > > > > > > > has not fsync_mark. > > > > > > > > > > > > > > > > > > > I think your solution is better here, but does not fix all scenarios. If > > > > > > the inode is checkpointed, the file can be recovered, although the inode > > > > > > information may be not up to date. But if the inode is not checkpointed, > > > > > > f2fs_iget will fail too and recover will fail. > > > > > > > > > > Ok, let me consider your scenarios. > > > > > > > > > > Term: F: fsync_mark, D: dentry_mark > > > > > > > > > > 1. inode(x) | CP | inode(x) | dnode(F) > > > > > -> Lose the latest inode(x). Need to fix. > > > > > > > > > > 2. inode(x) | CP | dnode(F) | inode(x) > > > > > -> Impossible, but recover latest dnode(F) > > > > > > > > > > 3. CP | inode(x) | dnode(F) > > > > > -> Need to write inode(DF) in f2fs_sync_file. > > > > > > > > > > 4. CP | dnode(F) | inode(DF) > > > > > -> If f2fs_iget fails, then goto next. > > > > > > > > > > 5. CP | dnode(F) | inode(x) > > > > > -> If f2fs_iget fails, then goto next. But, this is an impossible > > > > > scenario. > > > > > Drop this dnode(F). > > > > > > > > > > Indeed, there were some missing scenarios. > > > > > > > > > > So, how about this patch? > > > > > > > > > > From 552dc68c5f07a335d7b55c197bab531efb135521 Mon Sep 17 00:00:00 2001 > > > > > From: Jaegeuk Kim <jaegeuk@...nel.org> > > > > > Date: Wed, 10 Sep 2014 00:16:34 -0700 > > > > > Subject: [PATCH] f2fs: fix roll-forward missing scenarios > > > > > > > > > > We can summarize the roll forward recovery scenarios as follows. > > > > > > > > > > [Term] F: fsync_mark, D: dentry_mark > > > > > > > > > > 1. inode(x) | CP | inode(x) | dnode(F) > > > > > -> Update the latest inode(x). > > > > > > > > > > 2. inode(x) | CP | inode(F) | dnode(F) > > > > > -> No problem. > > > > > > > > > > 3. inode(x) | CP | dnode(F) | inode(x) > > > > > -> Impossible, but recover latest dnode(F) > > > > > > > > > > > > > I think this is possible. If f2fs_sync_file runs concurrently with > > > > writeback. f2fs_sync_file written dnode(F), then writeback written inode(x). > > > > > > If the inode(x) was written, f2fs_sync_file will do write the inode again with > > > fsync_mark. So, dnode(F) | inode(x) | inode(F) should be shown. > > > > > > In f2fs_sync_file, > > > ... > > > while (!sync_node_pages(sbi, ino, &wbc)) { > > > if (fsync_mark_done(sbi, ino)) > > > goto out; > > > mark_inode_dirty_sync(inode); > > > ret = f2fs_write_inode(inode, NULL); > > > if (ret) > > > goto out; > > > } > > > ... > > > > Is the following situation possible? > > > > f2fs_sync_file <writeback> > > sync_node_pages f2fs_write_node_pages > > write dnode(F) sync_node_pages > > write inode(x) /* clear PAGECACHE_TAG_DIRTY */ > > > > > > That is, f2fs_sync_file run parallel with <writeback>. The > > sync_node_pages above will return 1, because dnode(F) is written. > > inode(x) is written by <writeback> path. And because > > PAGECACHE_TAG_DIRTY is cleared, it is possible that sync_node_pages > > called by f2fs_sync_file does not write inode(F). > > I think Chao's comment would work. > How about this patch? > > From 32fe5ff49d2c78d3be4cf3638cc64ae71cf44549 Mon Sep 17 00:00:00 2001 > From: Jaegeuk Kim <jaegeuk@...nel.org> > Date: Wed, 10 Sep 2014 00:16:34 -0700 > Subject: [PATCH] f2fs: fix roll-forward missing scenarios > > We can summarize the roll forward recovery scenarios as follows. > > [Term] F: fsync_mark, D: dentry_mark > > 1. inode(x) | CP | inode(x) | dnode(F) > -> Update the latest inode(x). > > 2. inode(x) | CP | inode(F) | dnode(F) > -> No problem. > > 3. inode(x) | CP | dnode(F) | inode(x) > -> Recover to the latest dnode(F), and drop the last inode(x) > > 4. inode(x) | CP | dnode(F) | inode(F) > -> No problem. > > 5. CP | inode(x) | dnode(F) > -> The inode(DF) was missing. Should drop this dnode(F). > > 6. CP | inode(DF) | dnode(F) > -> No problem. > > 7. CP | dnode(F) | inode(DF) > -> If f2fs_iget fails, then goto next to find inode(DF). > > 8. CP | dnode(F) | inode(x) > -> If f2fs_iget fails, then goto next to find inode(DF). > But it will fail due to no inode(DF). > > So, this patch adds some missing points such as #1, #5, #7, and #8. > > Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org> > --- > fs/f2fs/file.c | 20 ++++++++++++---- > fs/f2fs/node.c | 11 ++++++++- > fs/f2fs/recovery.c | 70 +++++++++++++++++++++++++++++++++++++++++++++--------- > 3 files changed, 85 insertions(+), 16 deletions(-) > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c > index e7681c3..70f5d4b 100644 > --- a/fs/f2fs/file.c > +++ b/fs/f2fs/file.c > @@ -206,15 +206,27 @@ 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); > + > + /* > + * inode(x) | CP | inode(x) | dnode(F) > + * -> ok Is it acceptable that we turn this to: inode(x) | CPU | inode (x) | dnode (F) | inode(F) > + * inode(x) | CP | dnode(F) | inode(x) > + * -> inode(x) | CP | dnode(F) | inode(x) | inode(F) > + * CP | inode(x) | dnode(F) > + * -> CP | inode(x) | dnode(F) | inode(DF) > + * CP | dnode(F) | inode(x) > + * -> CP | dnode(F) | inode(x) | inode(DF) > + */ > + if (!fsync_mark_done(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 b32eb56..653aa71 100644 > --- a/fs/f2fs/node.c > +++ b/fs/f2fs/node.c > @@ -248,8 +248,17 @@ retry: > > /* update fsync_mark if its inode nat entry is still alive */ > e = __lookup_nat_cache(nm_i, ni->ino); > - if (e) > + if (e) { > + /* > + * CP | inode(x) | dnode(F) > + * -> CP | inode(x) | dnode(F) | inode(DF) > + */ > + if (!e->checkpointed && !e->fsync_done && > + ni->ino != ni->nid && fsync_done) > + goto skip; > e->fsync_done = fsync_done; > + } > +skip: > write_unlock(&nm_i->nat_tree_lock); > } I don't understand why we need so complex logic? Why not just let e->fsync_done reflect just latest is_fsync_dnode(page)? It appears that in f2fs_sync_file, what we need is just whether inode page has fsync mark or not. Best Regards, Huang, Ying > diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c > index 6c5a74a..3736728 100644 > --- a/fs/f2fs/recovery.c > +++ b/fs/f2fs/recovery.c > @@ -14,6 +14,36 @@ > #include "node.h" > #include "segment.h" > > +/* > + * Roll forward recovery scenarios. > + * > + * [Term] F: fsync_mark, D: dentry_mark > + * > + * 1. inode(x) | CP | inode(x) | dnode(F) > + * -> Update the latest inode(x). > + * > + * 2. inode(x) | CP | inode(F) | dnode(F) > + * -> No problem. > + * > + * 3. inode(x) | CP | dnode(F) | inode(x) > + * -> Recover to the latest dnode(F), and drop the last inode(x) > + * > + * 4. inode(x) | CP | dnode(F) | inode(F) > + * -> No problem. > + * > + * 5. CP | inode(x) | dnode(F) > + * -> The inode(DF) was missing. Should drop this dnode(F). > + * > + * 6. CP | inode(DF) | dnode(F) > + * -> No problem. > + * > + * 7. CP | dnode(F) | inode(DF) > + * -> If f2fs_iget fails, then goto next to find inode(DF). > + * > + * 8. CP | dnode(F) | inode(x) > + * -> If f2fs_iget fails, then goto next to find inode(DF). > + * But it will fail due to no inode(DF). > + */ > static struct kmem_cache *fsync_entry_slab; > > bool space_for_roll_forward(struct f2fs_sb_info *sbi) > @@ -110,27 +140,32 @@ out: > return err; > } > > -static int recover_inode(struct inode *inode, struct page *node_page) > +static void __recover_inode(struct inode *inode, struct page *page) > { > - struct f2fs_inode *raw_inode = F2FS_INODE(node_page); > + struct f2fs_inode *raw = F2FS_INODE(page); > + > + inode->i_mode = le16_to_cpu(raw->i_mode); > + i_size_write(inode, le64_to_cpu(raw->i_size)); > + inode->i_atime.tv_sec = le64_to_cpu(raw->i_mtime); > + inode->i_ctime.tv_sec = le64_to_cpu(raw->i_ctime); > + inode->i_mtime.tv_sec = le64_to_cpu(raw->i_mtime); > + inode->i_atime.tv_nsec = le32_to_cpu(raw->i_mtime_nsec); > + inode->i_ctime.tv_nsec = le32_to_cpu(raw->i_ctime_nsec); > + inode->i_mtime.tv_nsec = le32_to_cpu(raw->i_mtime_nsec); > +} > > +static int recover_inode(struct inode *inode, struct page *node_page) > +{ > if (!IS_INODE(node_page)) > return 0; > > - inode->i_mode = le16_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); > + __recover_inode(inode, node_page); > > if (is_dent_dnode(node_page)) > return recover_dentry(node_page, inode); > > f2fs_msg(inode->i_sb, KERN_NOTICE, "recover_inode: ino = %x, name = %s", > - ino_of_node(node_page), raw_inode->i_name); > + ino_of_node(node_page), F2FS_INODE(node_page)->i_name); > return 0; > } > > @@ -186,10 +221,16 @@ static int find_fsync_dnodes(struct f2fs_sb_info *sbi, struct list_head *head) > break; > } > > + /* > + * CP | dnode(F) | inode(DF) > + * For this case, we should not give up now. > + */ > entry->inode = f2fs_iget(sbi->sb, ino_of_node(page)); > if (IS_ERR(entry->inode)) { > err = PTR_ERR(entry->inode); > kmem_cache_free(fsync_entry_slab, entry); > + if (err == -ENOENT) > + goto next; > break; > } > list_add_tail(&entry->list, head); > @@ -416,6 +457,13 @@ static int recover_data(struct f2fs_sb_info *sbi, > entry = get_fsync_inode(head, ino_of_node(page)); > if (!entry) > goto next; > + /* > + * inode(x) | CP | inode(x) | dnode(F) > + * In this case, we can lose the latest inode(x). > + * So, call __recover_inode for the inode update. > + */ > + if (IS_INODE(page)) > + __recover_inode(entry->inode, page); > > err = do_recover_data(sbi, entry->inode, page, blkaddr); > if (err) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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