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Message-ID: <CAK896s4EgEPU4FyyXczW79uFhVDido-Cwc=X-6jJ3kz2LXwBqw@mail.gmail.com>
Date: Sat, 8 Jan 2022 10:09:06 +0800
From: Xin Yin <yinxin.x@...edance.com>
To: harshad shirwadkar <harshadshirwadkar@...il.com>
Cc: "Theodore Y. Ts'o" <tytso@....edu>,
Andreas Dilger <adilger.kernel@...ger.ca>,
Ext4 Developers List <linux-ext4@...r.kernel.org>,
linux-kernel@...r.kernel.org
Subject: Re: [External] Re: [PATCH 1/2] ext4: prevent used blocks from being
allocated during fast commit replay
On Sat, Jan 8, 2022 at 4:26 AM harshad shirwadkar
<harshadshirwadkar@...il.com> wrote:
>
> On Wed, Jan 5, 2022 at 6:45 PM Xin Yin <yinxin.x@...edance.com> wrote:
> >
> > during fast commit replay procedure, we clear inode blocks bitmap in
> > ext4_ext_clear_bb(), this may cause ext4_mb_new_blocks_simple() allocate
> > blocks still in use.
> >
> > make ext4_fc_record_regions() also record physical disk regions used by
> > inodes during replay procedure. Then ext4_mb_new_blocks_simple() can
> > excludes these blocks in use.
> >
> > Signed-off-by: Xin Yin <yinxin.x@...edance.com>
> > ---
> > fs/ext4/ext4.h | 2 ++
> > fs/ext4/extents.c | 4 ++++
> > fs/ext4/fast_commit.c | 11 ++++++++---
> > 3 files changed, 14 insertions(+), 3 deletions(-)
> >
> > diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> > index 82fa51d6f145..7b0686758691 100644
> > --- a/fs/ext4/ext4.h
> > +++ b/fs/ext4/ext4.h
> > @@ -2932,6 +2932,8 @@ bool ext4_fc_replay_check_excluded(struct super_block *sb, ext4_fsblk_t block);
> > void ext4_fc_replay_cleanup(struct super_block *sb);
> > int ext4_fc_commit(journal_t *journal, tid_t commit_tid);
> > int __init ext4_fc_init_dentry_cache(void);
> > +int ext4_fc_record_regions(struct super_block *sb, int ino,
> > + ext4_lblk_t lblk, ext4_fsblk_t pblk, int len, int replay);
> >
> > /* mballoc.c */
> > extern const struct seq_operations ext4_mb_seq_groups_ops;
> > diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> > index c3e76a5de661..9b6c76629c93 100644
> > --- a/fs/ext4/extents.c
> > +++ b/fs/ext4/extents.c
> > @@ -6096,11 +6096,15 @@ int ext4_ext_clear_bb(struct inode *inode)
> >
> > ext4_mb_mark_bb(inode->i_sb,
> > path[j].p_block, 1, 0);
> > + ext4_fc_record_regions(inode->i_sb, inode->i_ino,
> > + 0, path[j].p_block, 1, 1);
> > }
> > ext4_ext_drop_refs(path);
> > kfree(path);
> > }
> > ext4_mb_mark_bb(inode->i_sb, map.m_pblk, map.m_len, 0);
> > + ext4_fc_record_regions(inode->i_sb, inode->i_ino,
> > + map.m_lblk, map.m_pblk, map.m_len, 1);
> > }
> > cur = cur + map.m_len;
> > }
> > diff --git a/fs/ext4/fast_commit.c b/fs/ext4/fast_commit.c
> > index 23d13983a281..f0cd20f5fe5e 100644
> > --- a/fs/ext4/fast_commit.c
> > +++ b/fs/ext4/fast_commit.c
> > @@ -1567,13 +1567,15 @@ static int ext4_fc_replay_create(struct super_block *sb, struct ext4_fc_tl *tl,
> > * Record physical disk regions which are in use as per fast commit area. Our
> > * simple replay phase allocator excludes these regions from allocation.
> > */
> > -static int ext4_fc_record_regions(struct super_block *sb, int ino,
> > - ext4_lblk_t lblk, ext4_fsblk_t pblk, int len)
> > +int ext4_fc_record_regions(struct super_block *sb, int ino,
> > + ext4_lblk_t lblk, ext4_fsblk_t pblk, int len, int replay)
> Can you explain a bit why this replay parameter is needed here? This
> function simply reallocs the regions array if it doesn't have enough
> space. I am not sure why we need to change that behavior.
ext4_fc_record_regions() originally only used during scan phase, and
set fc_regions_valid = fc_regions_use when getting a TAIL tag. Now we
also use it during the replay phase, and need to update
fc_regions_valid in this case, because ext4_fc_replay_check_excluded()
uses fc_regions_valid for regions checking.
Please correct me if I'm wrong.
> > {
> > struct ext4_fc_replay_state *state;
> > struct ext4_fc_alloc_region *region;
> >
> > state = &EXT4_SB(sb)->s_fc_replay_state;
> > + if (replay && state->fc_regions_used != state->fc_regions_valid)
> > + state->fc_regions_used = state->fc_regions_valid;
> > if (state->fc_regions_used == state->fc_regions_size) {
> > state->fc_regions_size +=
> > EXT4_FC_REPLAY_REALLOC_INCREMENT;
> > @@ -1591,6 +1593,9 @@ static int ext4_fc_record_regions(struct super_block *sb, int ino,
> > region->pblk = pblk;
> > region->len = len;
> >
> > + if (replay)
> > + state->fc_regions_valid++;
> > +
> > return 0;
> > }
> >
> > @@ -1938,7 +1943,7 @@ static int ext4_fc_replay_scan(journal_t *journal,
> > ret = ext4_fc_record_regions(sb,
> > le32_to_cpu(ext.fc_ino),
> > le32_to_cpu(ex->ee_block), ext4_ext_pblock(ex),
> > - ext4_ext_get_actual_len(ex));
> > + ext4_ext_get_actual_len(ex), 0);
> > if (ret < 0)
> > break;
> > ret = JBD2_FC_REPLAY_CONTINUE;
> > --
> > 2.20.1
> >
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