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SubjectRe: [PATCH] f2fs: submit cached bio to avoid endless PageWriteback
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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.

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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