Messages in this thread | | | Date | Wed, 19 Jun 2019 10:26:51 -0700 | From | Jaegeuk Kim <> | Subject | Re: [f2fs-dev] [PATCH v3] f2fs: add a rw_sem to cover quota flag changes |
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On 06/18, Chao Yu wrote: > On 2019/6/14 10:46, Jaegeuk Kim wrote: > > On 06/11, Chao Yu wrote: > >> 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? > > > > I couldn't find write_dquot() call to make this happen, and f2fs_lock_op was not > > - f2fs_dquot_commit > - dquot_commit > ->commit_dqblk (v2_write_dquot) > - qtree_write_dquot > ->quota_write (f2fs_quota_write) > - f2fs_lock_op > > Do you mean there is no such way that calling f2fs_lock_op() from > f2fs_quota_write()? So that deadlock condition is not existing?
I mean write_dquot->f2fs_dquot_commit and block_operation seems not racing together.
> > Thanks, > > > enough to cover quota updates. Current stress & power-cut tests are running for > > several days without problem with this patch. > > > >> > >> 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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