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Message-ID: <20180926194932.GA44119@jaegeuk-macbookpro.roam.corp.google.com>
Date: Wed, 26 Sep 2018 12:49:32 -0700
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: Chao Yu <yuchao0@...wei.com>
Cc: linux-kernel@...r.kernel.org,
linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH 2/2 v2] f2fs: avoid f2fs_bug_on if
f2fs_get_meta_page_nofail got EIO
On 09/26, Chao Yu wrote:
> On 2018/9/26 9:10, Chao Yu wrote:
> > On 2018/9/26 8:18, Jaegeuk Kim wrote:
> >> On 09/21, Chao Yu wrote:
> >>> On 2018/9/21 5:46, Jaegeuk Kim wrote:
> >>>> On 09/20, Chao Yu wrote:
> >>>>> On 2018/9/19 1:56, Jaegeuk Kim wrote:
> >>>>>> This patch avoids BUG_ON when f2fs_get_meta_page_nofail got EIO during
> >>>>>> xfstests/generic/475.
> >>>>>>
> >>>>>> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
> >>>>>> ---
> >>>>>> Change log from v1:
> >>>>>> - propagate errno
> >>>>>> - drop sum_pages
> >>>>>>
> >>>>>> fs/f2fs/checkpoint.c | 10 +++++-----
> >>>>>> fs/f2fs/f2fs.h | 2 +-
> >>>>>> fs/f2fs/gc.c | 9 +++++++++
> >>>>>> fs/f2fs/node.c | 32 ++++++++++++++++++++++++--------
> >>>>>> fs/f2fs/recovery.c | 2 ++
> >>>>>> fs/f2fs/segment.c | 3 +++
> >>>>>> 6 files changed, 44 insertions(+), 14 deletions(-)
> >>>>>>
> >>>>>> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> >>>>>> index 01e0d8f5bbbe..1ddf332ce4b2 100644
> >>>>>> --- a/fs/f2fs/checkpoint.c
> >>>>>> +++ b/fs/f2fs/checkpoint.c
> >>>>>> @@ -119,11 +119,8 @@ struct page *f2fs_get_meta_page_nofail(struct f2fs_sb_info *sbi, pgoff_t index)
> >>>>>> if (PTR_ERR(page) == -EIO &&
> >>>>>> ++count <= DEFAULT_RETRY_IO_COUNT)
> >>>>>> goto retry;
> >>>>>> -
> >>>>>> f2fs_stop_checkpoint(sbi, false);
> >>>>>> - f2fs_bug_on(sbi, 1);
> >>>>>> }
> >>>>>> -
> >>>>>> return page;
> >>>>>> }
> >>>>>>
> >>>>>> @@ -1512,7 +1509,10 @@ int f2fs_write_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> >>>>>> ckpt->checkpoint_ver = cpu_to_le64(++ckpt_ver);
> >>>>>>
> >>>>>> /* write cached NAT/SIT entries to NAT/SIT area */
> >>>>>> - f2fs_flush_nat_entries(sbi, cpc);
> >>>>>> + err = f2fs_flush_nat_entries(sbi, cpc);
> >>>>>> + if (err)
> >>>>>> + goto stop;
> >>>>>
> >>>>> To make sure, if partial NAT pages become dirty, flush them back to device
> >>>>> outside checkpoint() is not harmful, right?
> >>>>
> >>>> I think so.
> >>>
> >>> Oh, one more case, now we use NAT #0, if partial NAT pages were
> >>> writebacked, then we start to use NAT #1, later, in another checkpoint(),
> >>> we update those NAT pages again, we will write them to NAT #0, which is
> >>> belong to last valid checkpoint(), it's may cause corrupted checkpoint in
> >>> scenario of SPO. So it's harmfull, right?
> >>
> >> We already stopped checkpoint anymore, so there'd be no way to proceed another
> >> checkpoint. Am I missing something?
> >
> > You're right, we have called f2fs_stop_checkpoint(), so we are safe now. :)
>
> Can we allow to writeback fs metadata (NAT/SIT/SSA) in prior to checkpoint
> to mitigate IO stress of checkpoint?
What's the point related to this patch?
Anyway, do you mean f2fs_write_meta_pages is not enough?
>
> Maybe below conditions can be consider to trigger writebacking:
> a) dirty count of meta (NAT/SIT/SSA) exceeds threshold
> b) exceed time threshold
>
> Thanks,
>
> >
> > Thanks,
> >
> >>
> >>>
> >>> Thanks,
> >>>
> >>>>
> >>>>>
> >>>>>> +
> >>>>>> f2fs_flush_sit_entries(sbi, cpc);
> >>>>>>
> >>>>>> /* unlock all the fs_lock[] in do_checkpoint() */
> >>>>>> @@ -1521,7 +1521,7 @@ int f2fs_write_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> >>>>>> f2fs_release_discard_addrs(sbi);
> >>>>>> else
> >>>>>> f2fs_clear_prefree_segments(sbi, cpc);
> >>>>>> -
> >>>>>> +stop:
> >>>>>> unblock_operations(sbi);
> >>>>>> stat_inc_cp_count(sbi->stat_info);
> >>>>>>
> >>>>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> >>>>>> index a0c868127a7c..29021dbc8f2a 100644
> >>>>>> --- a/fs/f2fs/f2fs.h
> >>>>>> +++ b/fs/f2fs/f2fs.h
> >>>>>> @@ -2895,7 +2895,7 @@ int f2fs_recover_xattr_data(struct inode *inode, struct page *page);
> >>>>>> int f2fs_recover_inode_page(struct f2fs_sb_info *sbi, struct page *page);
> >>>>>> int f2fs_restore_node_summary(struct f2fs_sb_info *sbi,
> >>>>>> unsigned int segno, struct f2fs_summary_block *sum);
> >>>>>> -void f2fs_flush_nat_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc);
> >>>>>> +int f2fs_flush_nat_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc);
> >>>>>> int f2fs_build_node_manager(struct f2fs_sb_info *sbi);
> >>>>>> void f2fs_destroy_node_manager(struct f2fs_sb_info *sbi);
> >>>>>> int __init f2fs_create_node_manager_caches(void);
> >>>>>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> >>>>>> index 4bcc8a59fdef..c7d14282dbf4 100644
> >>>>>> --- a/fs/f2fs/gc.c
> >>>>>> +++ b/fs/f2fs/gc.c
> >>>>>> @@ -1070,6 +1070,15 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
> >>>>>> /* reference all summary page */
> >>>>>> while (segno < end_segno) {
> >>>>>> sum_page = f2fs_get_sum_page(sbi, segno++);
> >>>>>> + if (IS_ERR(sum_page)) {
> >>>>>> + end_segno = segno - 1;
> >>>>>> + for (segno = start_segno; segno < end_segno; segno++) {
> >>>>>> + sum_page = find_get_page(META_MAPPING(sbi),
> >>>>>> + GET_SUM_BLOCK(sbi, segno));
> >>>>>> + f2fs_put_page(sum_page, 0);
> >>>>>
> >>>>> find_get_page() will add one more reference on page, so we need to call
> >>>>> f2fs_put_page(sum_page, 0) twice.
> >>>>
> >>>> Done.
> >>>>
> >>>>>
> >>>>> Thanks,
> >>>>>
> >>>>>> + }
> >>>>>> + return PTR_ERR(sum_page);
> >>>>>> + }
> >>>>>> unlock_page(sum_page);
> >>>>>> }
> >>>>>>
> >>>>>> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> >>>>>> index fa2381c0bc47..79b6fee354f7 100644
> >>>>>> --- a/fs/f2fs/node.c
> >>>>>> +++ b/fs/f2fs/node.c
> >>>>>> @@ -126,6 +126,8 @@ static struct page *get_next_nat_page(struct f2fs_sb_info *sbi, nid_t nid)
> >>>>>>
> >>>>>> /* get current nat block page with lock */
> >>>>>> src_page = get_current_nat_page(sbi, nid);
> >>>>>> + if (IS_ERR(src_page))
> >>>>>> + return src_page;
> >>>>>> dst_page = f2fs_grab_meta_page(sbi, dst_off);
> >>>>>> f2fs_bug_on(sbi, PageDirty(src_page));
> >>>>>>
> >>>>>> @@ -2265,15 +2267,19 @@ static int __f2fs_build_free_nids(struct f2fs_sb_info *sbi,
> >>>>>> nm_i->nat_block_bitmap)) {
> >>>>>> struct page *page = get_current_nat_page(sbi, nid);
> >>>>>>
> >>>>>> - ret = scan_nat_page(sbi, page, nid);
> >>>>>> - f2fs_put_page(page, 1);
> >>>>>> + if (IS_ERR(page)) {
> >>>>>> + ret = PTR_ERR(page);
> >>>>>> + } else {
> >>>>>> + ret = scan_nat_page(sbi, page, nid);
> >>>>>> + f2fs_put_page(page, 1);
> >>>>>> + }
> >>>>>>
> >>>>>> if (ret) {
> >>>>>> up_read(&nm_i->nat_tree_lock);
> >>>>>> f2fs_bug_on(sbi, !mount);
> >>>>>> f2fs_msg(sbi->sb, KERN_ERR,
> >>>>>> "NAT is corrupt, run fsck to fix it");
> >>>>>> - return -EINVAL;
> >>>>>> + return ret;
> >>>>>> }
> >>>>>> }
> >>>>>>
> >>>>>> @@ -2700,7 +2706,7 @@ static void __update_nat_bits(struct f2fs_sb_info *sbi, nid_t start_nid,
> >>>>>> __clear_bit_le(nat_index, nm_i->full_nat_bits);
> >>>>>> }
> >>>>>>
> >>>>>> -static void __flush_nat_entry_set(struct f2fs_sb_info *sbi,
> >>>>>> +static int __flush_nat_entry_set(struct f2fs_sb_info *sbi,
> >>>>>> struct nat_entry_set *set, struct cp_control *cpc)
> >>>>>> {
> >>>>>> struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_HOT_DATA);
> >>>>>> @@ -2724,6 +2730,9 @@ static void __flush_nat_entry_set(struct f2fs_sb_info *sbi,
> >>>>>> down_write(&curseg->journal_rwsem);
> >>>>>> } else {
> >>>>>> page = get_next_nat_page(sbi, start_nid);
> >>>>>> + if (IS_ERR(page))
> >>>>>> + return PTR_ERR(page);
> >>>>>> +
> >>>>>> nat_blk = page_address(page);
> >>>>>> f2fs_bug_on(sbi, !nat_blk);
> >>>>>> }
> >>>>>> @@ -2769,12 +2778,13 @@ static void __flush_nat_entry_set(struct f2fs_sb_info *sbi,
> >>>>>> radix_tree_delete(&NM_I(sbi)->nat_set_root, set->set);
> >>>>>> kmem_cache_free(nat_entry_set_slab, set);
> >>>>>> }
> >>>>>> + return 0;
> >>>>>> }
> >>>>>>
> >>>>>> /*
> >>>>>> * This function is called during the checkpointing process.
> >>>>>> */
> >>>>>> -void f2fs_flush_nat_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> >>>>>> +int f2fs_flush_nat_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> >>>>>> {
> >>>>>> struct f2fs_nm_info *nm_i = NM_I(sbi);
> >>>>>> struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_HOT_DATA);
> >>>>>> @@ -2784,6 +2794,7 @@ void f2fs_flush_nat_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> >>>>>> unsigned int found;
> >>>>>> nid_t set_idx = 0;
> >>>>>> LIST_HEAD(sets);
> >>>>>> + int err = 0;
> >>>>>>
> >>>>>> /* during unmount, let's flush nat_bits before checking dirty_nat_cnt */
> >>>>>> if (enabled_nat_bits(sbi, cpc)) {
> >>>>>> @@ -2793,7 +2804,7 @@ void f2fs_flush_nat_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> >>>>>> }
> >>>>>>
> >>>>>> if (!nm_i->dirty_nat_cnt)
> >>>>>> - return;
> >>>>>> + return 0;
> >>>>>>
> >>>>>> down_write(&nm_i->nat_tree_lock);
> >>>>>>
> >>>>>> @@ -2816,11 +2827,16 @@ void f2fs_flush_nat_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> >>>>>> }
> >>>>>>
> >>>>>> /* flush dirty nats in nat entry set */
> >>>>>> - list_for_each_entry_safe(set, tmp, &sets, set_list)
> >>>>>> - __flush_nat_entry_set(sbi, set, cpc);
> >>>>>> + list_for_each_entry_safe(set, tmp, &sets, set_list) {
> >>>>>> + err = __flush_nat_entry_set(sbi, set, cpc);
> >>>>>> + if (err)
> >>>>>> + break;
> >>>>>> + }
> >>>>>>
> >>>>>> up_write(&nm_i->nat_tree_lock);
> >>>>>> /* Allow dirty nats by node block allocation in write_begin */
> >>>>>> +
> >>>>>> + return err;
> >>>>>> }
> >>>>>>
> >>>>>> static int __get_nat_bitmaps(struct f2fs_sb_info *sbi)
> >>>>>> diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c
> >>>>>> index 56d34193a74b..ba678efe7cad 100644
> >>>>>> --- a/fs/f2fs/recovery.c
> >>>>>> +++ b/fs/f2fs/recovery.c
> >>>>>> @@ -355,6 +355,8 @@ static int check_index_in_prev_nodes(struct f2fs_sb_info *sbi,
> >>>>>> }
> >>>>>>
> >>>>>> sum_page = f2fs_get_sum_page(sbi, segno);
> >>>>>> + if (IS_ERR(sum_page))
> >>>>>> + return PTR_ERR(sum_page);
> >>>>>> sum_node = (struct f2fs_summary_block *)page_address(sum_page);
> >>>>>> sum = sum_node->entries[blkoff];
> >>>>>> f2fs_put_page(sum_page, 1);
> >>>>>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> >>>>>> index aa96a371aaf8..ab7386a7e9d3 100644
> >>>>>> --- a/fs/f2fs/segment.c
> >>>>>> +++ b/fs/f2fs/segment.c
> >>>>>> @@ -2487,6 +2487,7 @@ static void change_curseg(struct f2fs_sb_info *sbi, int type)
> >>>>>> __next_free_blkoff(sbi, curseg, 0);
> >>>>>>
> >>>>>> sum_page = f2fs_get_sum_page(sbi, new_segno);
> >>>>>> + f2fs_bug_on(sbi, IS_ERR(sum_page));
> >>>>>> sum_node = (struct f2fs_summary_block *)page_address(sum_page);
> >>>>>> memcpy(curseg->sum_blk, sum_node, SUM_ENTRY_SIZE);
> >>>>>> f2fs_put_page(sum_page, 1);
> >>>>>> @@ -3971,6 +3972,8 @@ static int build_sit_entries(struct f2fs_sb_info *sbi)
> >>>>>>
> >>>>>> se = &sit_i->sentries[start];
> >>>>>> page = get_current_sit_page(sbi, start);
> >>>>>> + if (IS_ERR(page))
> >>>>>> + return PTR_ERR(page);
> >>>>>> sit_blk = (struct f2fs_sit_block *)page_address(page);
> >>>>>> sit = sit_blk->entries[SIT_ENTRY_OFFSET(sit_i, start)];
> >>>>>> f2fs_put_page(page, 1);
> >>>>>>
> >>>>
> >>>> .
> >>>>
> >>
> >> .
> >>
> >
> >
> >
> > _______________________________________________
> > Linux-f2fs-devel mailing list
> > Linux-f2fs-devel@...ts.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
> >
> > .
> >
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