Messages in this thread | | | Subject | Re: [f2fs-dev] [PATCH v3] f2fs: add a rw_sem to cover quota flag changes | From | Chao Yu <> | Date | Tue, 11 Jun 2019 15:46:04 +0800 |
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On 2019/6/5 2:36, Jaegeuk Kim wrote: > Two paths to update quota and f2fs_lock_op: > > 1. > - lock_op > | - quota_update > `- unlock_op > > 2. > - quota_update > - lock_op > `- unlock_op > > But, we need to make a transaction on quota_update + lock_op in #2 case. > So, this patch introduces: > 1. lock_op > 2. down_write > 3. check __need_flush > 4. up_write > 5. if there is dirty quota entries, flush them > 6. otherwise, good to go > > Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> > --- > > v3 from v2: > - refactor to fix quota corruption issue > : it seems that the previous scenario is not real and no deadlock case was > encountered.
- f2fs_dquot_commit - down_read(&sbi->quota_sem) - block_operation - f2fs_lock_all - need_flush_quota - down_write(&sbi->quota_sem) - f2fs_quota_write - f2fs_lock_op
Why can't this happen?
Once more question, should we hold quota_sem during checkpoint to avoid further quota update? f2fs_lock_op can do this job as well?
Thanks,
> > fs/f2fs/checkpoint.c | 41 +++++++++++++++++++---------------------- > fs/f2fs/f2fs.h | 1 + > fs/f2fs/super.c | 26 +++++++++++++++++++++----- > 3 files changed, 41 insertions(+), 27 deletions(-) > > diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c > index 89825261d474..43f65f0962e5 100644 > --- a/fs/f2fs/checkpoint.c > +++ b/fs/f2fs/checkpoint.c > @@ -1131,17 +1131,24 @@ static void __prepare_cp_block(struct f2fs_sb_info *sbi) > > static bool __need_flush_quota(struct f2fs_sb_info *sbi) > { > + bool ret = false; > + > if (!is_journalled_quota(sbi)) > return false; > - if (is_sbi_flag_set(sbi, SBI_QUOTA_SKIP_FLUSH)) > - return false; > - if (is_sbi_flag_set(sbi, SBI_QUOTA_NEED_REPAIR)) > - return false; > - if (is_sbi_flag_set(sbi, SBI_QUOTA_NEED_FLUSH)) > - return true; > - if (get_pages(sbi, F2FS_DIRTY_QDATA)) > - return true; > - return false; > + > + down_write(&sbi->quota_sem); > + if (is_sbi_flag_set(sbi, SBI_QUOTA_SKIP_FLUSH)) { > + ret = false; > + } else if (is_sbi_flag_set(sbi, SBI_QUOTA_NEED_REPAIR)) { > + ret = false; > + } else if (is_sbi_flag_set(sbi, SBI_QUOTA_NEED_FLUSH)) { > + clear_sbi_flag(sbi, SBI_QUOTA_NEED_FLUSH); > + ret = true; > + } else if (get_pages(sbi, F2FS_DIRTY_QDATA)) { > + ret = true; > + } > + up_write(&sbi->quota_sem); > + return ret; > } > > /* > @@ -1160,26 +1167,22 @@ static int block_operations(struct f2fs_sb_info *sbi) > blk_start_plug(&plug); > > retry_flush_quotas: > + f2fs_lock_all(sbi); > if (__need_flush_quota(sbi)) { > int locked; > > if (++cnt > DEFAULT_RETRY_QUOTA_FLUSH_COUNT) { > set_sbi_flag(sbi, SBI_QUOTA_SKIP_FLUSH); > - f2fs_lock_all(sbi); > + set_sbi_flag(sbi, SBI_QUOTA_NEED_FLUSH); > goto retry_flush_dents; > } > - clear_sbi_flag(sbi, SBI_QUOTA_NEED_FLUSH); > + f2fs_unlock_all(sbi); > > /* only failed during mount/umount/freeze/quotactl */ > locked = down_read_trylock(&sbi->sb->s_umount); > f2fs_quota_sync(sbi->sb, -1); > if (locked) > up_read(&sbi->sb->s_umount); > - } > - > - f2fs_lock_all(sbi); > - if (__need_flush_quota(sbi)) { > - f2fs_unlock_all(sbi); > cond_resched(); > goto retry_flush_quotas; > } > @@ -1201,12 +1204,6 @@ static int block_operations(struct f2fs_sb_info *sbi) > */ > down_write(&sbi->node_change); > > - if (__need_flush_quota(sbi)) { > - up_write(&sbi->node_change); > - f2fs_unlock_all(sbi); > - goto retry_flush_quotas; > - } > - > if (get_pages(sbi, F2FS_DIRTY_IMETA)) { > up_write(&sbi->node_change); > f2fs_unlock_all(sbi); > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h > index 9674a85154b2..9bd2bf0f559b 100644 > --- a/fs/f2fs/f2fs.h > +++ b/fs/f2fs/f2fs.h > @@ -1253,6 +1253,7 @@ struct f2fs_sb_info { > block_t unusable_block_count; /* # of blocks saved by last cp */ > > unsigned int nquota_files; /* # of quota sysfile */ > + struct rw_semaphore quota_sem; /* blocking cp for flags */ > > /* # of pages, see count_type */ > atomic_t nr_pages[NR_COUNT_TYPE]; > diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c > index 15d7e30bfc72..5a318399a2fa 100644 > --- a/fs/f2fs/super.c > +++ b/fs/f2fs/super.c > @@ -1964,6 +1964,7 @@ int f2fs_quota_sync(struct super_block *sb, int type) > int cnt; > int ret; > > + down_read(&sbi->quota_sem); > ret = dquot_writeback_dquots(sb, type); > if (ret) > goto out; > @@ -2001,6 +2002,7 @@ int f2fs_quota_sync(struct super_block *sb, int type) > out: > if (ret) > set_sbi_flag(F2FS_SB(sb), SBI_QUOTA_NEED_REPAIR); > + up_read(&sbi->quota_sem); > return ret; > } > > @@ -2094,32 +2096,40 @@ static void f2fs_truncate_quota_inode_pages(struct super_block *sb) > > static int f2fs_dquot_commit(struct dquot *dquot) > { > + struct f2fs_sb_info *sbi = F2FS_SB(dquot->dq_sb); > int ret; > > + down_read(&sbi->quota_sem); > ret = dquot_commit(dquot); > if (ret < 0) > - set_sbi_flag(F2FS_SB(dquot->dq_sb), SBI_QUOTA_NEED_REPAIR); > + set_sbi_flag(sbi, SBI_QUOTA_NEED_REPAIR); > + up_read(&sbi->quota_sem); > return ret; > } > > static int f2fs_dquot_acquire(struct dquot *dquot) > { > + struct f2fs_sb_info *sbi = F2FS_SB(dquot->dq_sb); > int ret; > > + down_read(&sbi->quota_sem); > ret = dquot_acquire(dquot); > if (ret < 0) > - set_sbi_flag(F2FS_SB(dquot->dq_sb), SBI_QUOTA_NEED_REPAIR); > - > + set_sbi_flag(sbi, SBI_QUOTA_NEED_REPAIR); > + up_read(&sbi->quota_sem); > return ret; > } > > static int f2fs_dquot_release(struct dquot *dquot) > { > + struct f2fs_sb_info *sbi = F2FS_SB(dquot->dq_sb); > int ret; > > + down_read(&sbi->quota_sem); > ret = dquot_release(dquot); > if (ret < 0) > - set_sbi_flag(F2FS_SB(dquot->dq_sb), SBI_QUOTA_NEED_REPAIR); > + set_sbi_flag(sbi, SBI_QUOTA_NEED_REPAIR); > + up_read(&sbi->quota_sem); > return ret; > } > > @@ -2129,22 +2139,27 @@ static int f2fs_dquot_mark_dquot_dirty(struct dquot *dquot) > struct f2fs_sb_info *sbi = F2FS_SB(sb); > int ret; > > + down_read(&sbi->quota_sem); > ret = dquot_mark_dquot_dirty(dquot); > > /* if we are using journalled quota */ > if (is_journalled_quota(sbi)) > set_sbi_flag(sbi, SBI_QUOTA_NEED_FLUSH); > > + up_read(&sbi->quota_sem); > return ret; > } > > static int f2fs_dquot_commit_info(struct super_block *sb, int type) > { > + struct f2fs_sb_info *sbi = F2FS_SB(sb); > int ret; > > + down_read(&sbi->quota_sem); > ret = dquot_commit_info(sb, type); > if (ret < 0) > - set_sbi_flag(F2FS_SB(sb), SBI_QUOTA_NEED_REPAIR); > + set_sbi_flag(sbi, SBI_QUOTA_NEED_REPAIR); > + up_read(&sbi->quota_sem); > return ret; > } > > @@ -3253,6 +3268,7 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent) > } > > init_rwsem(&sbi->cp_rwsem); > + init_rwsem(&sbi->quota_sem); > init_waitqueue_head(&sbi->cp_wait); > init_sb_info(sbi); > >
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