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SubjectRe: [PATCH] f2fs: submit cached bio to avoid endless PageWriteback
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Thank you, ;)

On 2018/9/12 8:12, Jaegeuk Kim wrote:
> On 09/12, Chao Yu wrote:
>> Jaegeuk,
>>
>> Could you update dev-test branch? so I can rebase this on yours, there are some
>> pending patches in my tree, I guess it can avoid conflict when you merge this.
>
> Done.
>
>>
>> On 2018/9/12 6:39, Jaegeuk Kim wrote:
>>> On 09/11, Chao Yu wrote:
>>>> When migrating encrypted block from background GC thread, we only add
>>>> them into f2fs inner bio cache, but forget to submit the cached bio, it
>>>> may cause potential deadlock when we are waiting page writebacked, fix
>>>> it.
>>>>
>>>> Signed-off-by: Chao Yu <yuchao0@huawei.com>
>>>> ---
>>>> fs/f2fs/gc.c | 42 +++++++++++++++++++++++++++++-------------
>>>> 1 file changed, 29 insertions(+), 13 deletions(-)
>>>>
>>>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
>>>> index c4ea4009cf05..a2ea0d445345 100644
>>>> --- a/fs/f2fs/gc.c
>>>> +++ b/fs/f2fs/gc.c
>>>> @@ -687,7 +687,7 @@ static int ra_data_block(struct inode *inode, pgoff_t index)
>>>> * Move data block via META_MAPPING while keeping locked data page.
>>>> * This can be used to move blocks, aka LBAs, directly on disk.
>>>> */
>>>> -static void move_data_block(struct inode *inode, block_t bidx,
>>>> +static int move_data_block(struct inode *inode, block_t bidx,
>>>> int gc_type, unsigned int segno, int off)
>>>> {
>>>> struct f2fs_io_info fio = {
>>>> @@ -706,25 +706,29 @@ static void move_data_block(struct inode *inode, block_t bidx,
>>>> struct node_info ni;
>>>> struct page *page, *mpage;
>>>> block_t newaddr;
>>>> - int err;
>>>> + int err = 0;
>>>> bool lfs_mode = test_opt(fio.sbi, LFS);
>>>>
>>>> /* do not read out */
>>>> page = f2fs_grab_cache_page(inode->i_mapping, bidx, false);
>>>> if (!page)
>>>> - return;
>>>> + return -ENOMEM;
>>>>
>>>> - if (!check_valid_map(F2FS_I_SB(inode), segno, off))
>>>> + if (!check_valid_map(F2FS_I_SB(inode), segno, off)) {
>>>> + err = -ENOENT;
>>>> goto out;
>>>> + }
>>>>
>>>> if (f2fs_is_atomic_file(inode)) {
>>>> F2FS_I(inode)->i_gc_failures[GC_FAILURE_ATOMIC]++;
>>>> F2FS_I_SB(inode)->skipped_atomic_files[gc_type]++;
>>>> + err = -EAGAIN;
>>>> goto out;
>>>> }
>>>>
>>>> if (f2fs_is_pinned_file(inode)) {
>>>> f2fs_pin_file_control(inode, true);
>>>> + err = -EAGAIN;
>>>> goto out;
>>>> }
>>>>
>>>> @@ -735,6 +739,7 @@ static void move_data_block(struct inode *inode, block_t bidx,
>>>>
>>>> if (unlikely(dn.data_blkaddr == NULL_ADDR)) {
>>>> ClearPageUptodate(page);
>>>> + err = -ENOENT;
>>>> goto put_out;
>>>> }
>>>>
>>>> @@ -817,6 +822,7 @@ static void move_data_block(struct inode *inode, block_t bidx,
>>>> fio.new_blkaddr = newaddr;
>>>> f2fs_submit_page_write(&fio);
>>>> if (fio.retry) {
>>>> + err = -EAGAIN;
>>>> if (PageWriteback(fio.encrypted_page))
>>>> end_page_writeback(fio.encrypted_page);
>>>> goto put_page_out;
>>>> @@ -840,6 +846,8 @@ static void move_data_block(struct inode *inode, block_t bidx,
>>>> f2fs_put_dnode(&dn);
>>>> out:
>>>> f2fs_put_page(page, 1);
>>>> +
>>>> + return err;
>>>> }
>>>>
>>>> static void move_data_page(struct inode *inode, block_t bidx, int gc_type,
>>>> @@ -919,7 +927,7 @@ static void move_data_page(struct inode *inode, block_t bidx, int gc_type,
>>>> * If the parent node is not valid or the data block address is different,
>>>> * the victim data block is ignored.
>>>> */
>>>> -static void gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
>>>> +static int gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
>>>> struct gc_inode_list *gc_list, unsigned int segno, int gc_type)
>>>> {
>>>> struct super_block *sb = sbi->sb;
>>>> @@ -927,6 +935,7 @@ static void gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
>>>> block_t start_addr;
>>>> int off;
>>>> int phase = 0;
>>>> + int submitted = 0;
>>>>
>>>> start_addr = START_BLOCK(sbi, segno);
>>>>
>>>> @@ -943,7 +952,7 @@ static void gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
>>>>
>>>> /* stop BG_GC if there is not enough free sections. */
>>>> if (gc_type == BG_GC && has_not_enough_free_secs(sbi, 0, 0))
>>>> - return;
>>>> + return submitted;
>>>>
>>>> if (check_valid_map(sbi, segno, off) == 0)
>>>> continue;
>>>> @@ -1015,6 +1024,7 @@ static void gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
>>>> if (inode) {
>>>> struct f2fs_inode_info *fi = F2FS_I(inode);
>>>> bool locked = false;
>>>> + int err;
>>>>
>>>> if (S_ISREG(inode->i_mode)) {
>>>> if (!down_write_trylock(&fi->i_gc_rwsem[READ]))
>>>> @@ -1033,12 +1043,15 @@ static void gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
>>>>
>>>> start_bidx = f2fs_start_bidx_of_node(nofs, inode)
>>>> + ofs_in_node;
>>>> - if (f2fs_post_read_required(inode))
>>>> - move_data_block(inode, start_bidx, gc_type,
>>>> - segno, off);
>>>> - else
>>>> + if (f2fs_post_read_required(inode)) {
>>>> + err = move_data_block(inode, start_bidx,
>>>> + gc_type, segno, off);
>>>> + if (!err)
>>>> + submitted++;
>>>> + } else {
>>>> move_data_page(inode, start_bidx, gc_type,
>>>> segno, off);
>>>> + }
>>>>
>>>> if (locked) {
>>>> up_write(&fi->i_gc_rwsem[WRITE]);
>>>> @@ -1051,6 +1064,8 @@ static void gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
>>>>
>>>> if (++phase < 5)
>>>> goto next_step;
>>>> +
>>>> + return submitted;
>>>> }
>>>>
>>>> static int __get_victim(struct f2fs_sb_info *sbi, unsigned int *victim,
>>>> @@ -1078,6 +1093,7 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
>>>> unsigned char type = IS_DATASEG(get_seg_entry(sbi, segno)->type) ?
>>>> SUM_TYPE_DATA : SUM_TYPE_NODE;
>>>> unsigned int units = 0;
>>>> + int submitted = 0;
>>>>
>>>> /* start segno may point to middle of section, so adjust it */
>>>> if (__is_large_section(sbi))
>>>> @@ -1136,8 +1152,8 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
>>>> if (type == SUM_TYPE_NODE)
>>>> gc_node_segment(sbi, sum->entries, segno, gc_type);
>>>> else
>>>> - gc_data_segment(sbi, sum->entries, gc_list, segno,
>>>> - gc_type);
>>>> + submitted += gc_data_segment(sbi, sum->entries, gc_list,
>>>> + segno, gc_type);
>>>>
>>>> stat_inc_seg_count(sbi, type, gc_type);
>>>>
>>>> @@ -1152,7 +1168,7 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
>>>> f2fs_put_page(sum_page, 0);
>>>> }
>>>>
>>>> - if (gc_type == FG_GC)
>>>> + if (gc_type == FG_GC || submitted)
>>>
>>> Do we need to check submitted for both of node and data? Then, we can remove
>>> FG_GC case?
>>
>> Yup, good idea, let me adjust.
>>
>> Thanks,
>>
>>>
>>>> f2fs_submit_merged_write(sbi,
>>>> (type == SUM_TYPE_NODE) ? NODE : DATA);
>>>>
>>>> --
>>>> 2.18.0.rc1
>
> .
>

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