Hi Jaegeuk, > -----Original Message----- > From: Jaegeuk Kim [mailto:jaegeuk@xxxxxxxxxx] > Sent: Tuesday, January 26, 2016 3:18 AM > To: Chao Yu > Cc: linux-kernel@xxxxxxxxxxxxxxx; linux-fsdevel@xxxxxxxxxxxxxxx; > linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx > Subject: Re: [f2fs-dev] [PATCH 1/2] f2fs: avoid multiple node page writes due to inline_data > > Hi Chao, > > On Mon, Jan 25, 2016 at 05:42:40PM +0800, Chao Yu wrote: > > Hi Jaegeuk, > > > > > -----Original Message----- > > > From: Jaegeuk Kim [mailto:jaegeuk@xxxxxxxxxx] > > > Sent: Sunday, January 24, 2016 4:16 AM > > > To: linux-kernel@xxxxxxxxxxxxxxx; linux-fsdevel@xxxxxxxxxxxxxxx; > > > linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx > > > Cc: Jaegeuk Kim > > > Subject: [f2fs-dev] [PATCH 1/2] f2fs: avoid multiple node page writes due to inline_data > > > > > > The sceanrio is: > > > 1. create fully node blocks > > > 2. flush node blocks > > > 3. write inline_data for all the node blocks again > > > 4. flush node blocks redundantly > > > > > > Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx> > > > --- > > > fs/f2fs/data.c | 14 +++++++++++--- > > > 1 file changed, 11 insertions(+), 3 deletions(-) > > > > > > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c > > > index 8d0d9ec..011456e 100644 > > > --- a/fs/f2fs/data.c > > > +++ b/fs/f2fs/data.c > > > @@ -1622,14 +1622,22 @@ static int f2fs_write_end(struct file *file, > > > > > > trace_f2fs_write_end(inode, pos, len, copied); > > > > > > - set_page_dirty(page); > > > - > > > if (pos + copied > i_size_read(inode)) { > > > i_size_write(inode, pos + copied); > > > mark_inode_dirty(inode); > > > - update_inode_page(inode); > > > } > > > > > > + if (f2fs_has_inline_data(inode) && > > > + is_inode_flag_set(F2FS_I(inode), FI_DATA_EXIST)) { > > > + int err = f2fs_write_inline_data(inode, page); > > > > Oh, I'm sure this can fix that issue, but IMO: > > a) this implementation has side-effect, it triggers inline data copying > > between data page and node page whenever user write inline datas, so if > > user updates inline data frequently, write-through approach would cause > > memory copy overhead. > > Agreed. > > > b) inline storm should be a rare case, as we didn't get any report about > > problem for long time until Dave's, and write_end is a hot path, I think > > it's better to be cautious to change our inline data cache policy for > > fixing a rare issue in hot path. > > > > What about delaying the merge operation? like: > > 1) as I proposed before, merging inline page into inode page when > > detecting free_sections <= (node_secs + 2 * dent_secs + inline_secs). > > 2) merge inline page into inode page before writeback inode page in > > sync_node_pages. > > Okay, I'm thinking more general way where we can get rid of every inlien_data > write when we flush node pages. I encountered deadlock issue, could you have a look at it? ====================================================== [ INFO: possible circular locking dependency detected ] 4.5.0-rc1 #45 Tainted: G O ------------------------------------------------------- fstrim/15301 is trying to acquire lock: (sb_internal#2){++++..}, at: [<ffffffff81216fca>] __sb_start_write+0xda/0xf0 but task is already holding lock: (&sbi->cp_rwsem){++++..}, at: [<ffffffffa07d06d2>] block_operations+0x82/0x130 [f2fs] which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&sbi->cp_rwsem){++++..}: [<ffffffff810bf827>] lock_acquire+0xb7/0x130 [<ffffffff817de829>] down_read+0x39/0x50 [<ffffffffa07c27af>] f2fs_evict_inode+0x26f/0x370 [f2fs] [<ffffffff812326cd>] evict+0xdd/0x1d0 [<ffffffff8123323f>] iput+0x19f/0x250 [<ffffffff81224d9d>] do_unlinkat+0x20d/0x310 [<ffffffff81224ee2>] SyS_unlinkat+0x22/0x40 [<ffffffff817e0957>] entry_SYSCALL_64_fastpath+0x12/0x6f -> #0 (sb_internal#2){++++..}: [<ffffffff810bf32b>] __lock_acquire+0x132b/0x1770 [<ffffffff810bf827>] lock_acquire+0xb7/0x130 [<ffffffff810b8fac>] percpu_down_read+0x3c/0x80 [<ffffffff81216fca>] __sb_start_write+0xda/0xf0 [<ffffffffa07c2761>] f2fs_evict_inode+0x221/0x370 [f2fs] [<ffffffff812326cd>] evict+0xdd/0x1d0 [<ffffffff8123323f>] iput+0x19f/0x250 [<ffffffffa07dd4d3>] sync_node_pages+0x703/0x900 [f2fs] [<ffffffffa07d075a>] block_operations+0x10a/0x130 [f2fs] [<ffffffffa07d13e4>] write_checkpoint+0xc4/0xb80 [f2fs] [<ffffffffa07e0af2>] f2fs_trim_fs+0x122/0x1d0 [f2fs] [<ffffffffa07c07da>] f2fs_ioctl+0x7fa/0x9d0 [f2fs] [<ffffffff81228448>] vfs_ioctl+0x18/0x40 [<ffffffff81228b96>] do_vfs_ioctl+0x96/0x680 [<ffffffff81229212>] SyS_ioctl+0x92/0xa0 [<ffffffff817e0957>] entry_SYSCALL_64_fastpath+0x12/0x6f other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&sbi->cp_rwsem); lock(sb_internal#2); lock(&sbi->cp_rwsem); lock(sb_internal#2); *** DEADLOCK *** Thanks, > > I've been testing this patch. > > From ebddf607c64da691fef08cf68a8ecadafd5d896b Mon Sep 17 00:00:00 2001 > From: Jaegeuk Kim <jaegeuk@xxxxxxxxxx> > Date: Mon, 25 Jan 2016 05:57:05 -0800 > Subject: [PATCH] f2fs: avoid multiple node page writes due to inline_data > > The sceanrio is: > 1. create fully node blocks > 2. flush node blocks > 3. write inline_data for all the node blocks again > 4. flush node blocks redundantly > > So, this patch tries to flush inline_data when flushing node blocks. > > Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx> > --- > fs/f2fs/data.c | 1 + > fs/f2fs/inline.c | 2 ++ > fs/f2fs/node.c | 35 +++++++++++++++++++++++++++++++++++ > fs/f2fs/node.h | 15 +++++++++++++++ > 4 files changed, 53 insertions(+) > > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c > index 6925c10..9043ecf 100644 > --- a/fs/f2fs/data.c > +++ b/fs/f2fs/data.c > @@ -1464,6 +1464,7 @@ restart: > if (pos + len <= MAX_INLINE_DATA) { > read_inline_data(page, ipage); > set_inode_flag(F2FS_I(inode), FI_DATA_EXIST); > + set_inline_node(ipage); > sync_inode_page(&dn); > } else { > err = f2fs_convert_inline_page(&dn, page); > diff --git a/fs/f2fs/inline.c b/fs/f2fs/inline.c > index 8df13e5..fc4d298 100644 > --- a/fs/f2fs/inline.c > +++ b/fs/f2fs/inline.c > @@ -159,6 +159,7 @@ no_update: > > /* clear inline data and flag after data writeback */ > truncate_inline_inode(dn->inode_page, 0); > + clear_inline_node(dn->inode_page); > clear_out: > stat_dec_inline_inode(dn->inode); > f2fs_clear_inline_inode(dn->inode); > @@ -233,6 +234,7 @@ int f2fs_write_inline_data(struct inode *inode, struct page *page) > set_inode_flag(F2FS_I(inode), FI_DATA_EXIST); > > sync_inode_page(&dn); > + clear_inline_node(dn.inode_page); > f2fs_put_dnode(&dn); > return 0; > } > diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c > index 23b800d..1c5023e 100644 > --- a/fs/f2fs/node.c > +++ b/fs/f2fs/node.c > @@ -1154,6 +1154,33 @@ void sync_inode_page(struct dnode_of_data *dn) > dn->node_changed = ret ? true: false; > } > > +static void flush_inline_data(struct f2fs_sb_info *sbi, nid_t ino) > +{ > + struct inode *inode; > + struct page *page; > + > + inode = ilookup(sbi->sb, ino); > + if (!inode) > + return; > + > + page = find_lock_page(inode->i_mapping, 0); > + if (!page) > + goto iput_out; > + > + if (!PageDirty(page)) > + goto put_page_out; > + > + if (!clear_page_dirty_for_io(page)) > + goto put_page_out; > + > + if (!f2fs_write_inline_data(inode, page)) > + inode_dec_dirty_pages(inode); > +put_page_out: > + f2fs_put_page(page, 1); > +iput_out: > + iput(inode); > +} > + > int sync_node_pages(struct f2fs_sb_info *sbi, nid_t ino, > struct writeback_control *wbc) > { > @@ -1221,6 +1248,14 @@ continue_unlock: > goto continue_unlock; > } > > + /* flush inline_data */ > + if (!ino && is_inline_node(page)) { > + clear_inline_node(page); > + unlock_page(page); > + flush_inline_data(sbi, ino_of_node(page)); > + continue; > + } > + > if (!clear_page_dirty_for_io(page)) > goto continue_unlock; > > diff --git a/fs/f2fs/node.h b/fs/f2fs/node.h > index 23bd992..1f4f9d4 100644 > --- a/fs/f2fs/node.h > +++ b/fs/f2fs/node.h > @@ -379,6 +379,21 @@ static inline int is_node(struct page *page, int type) > #define is_fsync_dnode(page) is_node(page, FSYNC_BIT_SHIFT) > #define is_dent_dnode(page) is_node(page, DENT_BIT_SHIFT) > > +static inline int is_inline_node(struct page *page) > +{ > + return PageChecked(page); > +} > + > +static inline void set_inline_node(struct page *page) > +{ > + SetPageChecked(page); > +} > + > +static inline void clear_inline_node(struct page *page) > +{ > + ClearPageChecked(page); > +} > + > static inline void set_cold_node(struct inode *inode, struct page *page) > { > struct f2fs_node *rn = F2FS_NODE(page); > -- > 2.6.3 > -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
