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SubjectRe: [PATCH v2] f2fs: submit cached bio to avoid endless PageWriteback
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On 2018/9/13 4:03, Jaegeuk Kim wrote:
> On 09/12, 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>
>> ---
>> v2:
>> - cover node path suggested by Jaegeuk.
>>
>> fs/f2fs/f2fs.h | 4 ++-
>> fs/f2fs/gc.c | 72 +++++++++++++++++++++++++++++++++++---------------
>> fs/f2fs/node.c | 14 +++++++---
>> 3 files changed, 65 insertions(+), 25 deletions(-)
>>
>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>> index 8c8ce6b8f45a..da60e283ad1b 100644
>> --- a/fs/f2fs/f2fs.h
>> +++ b/fs/f2fs/f2fs.h
>> @@ -523,6 +523,8 @@ enum {
>> */
>> };
>>
>> +#define WAIT_WRITEBACK 1 /* indicate page is set dirty in GC */
>> +
>> #define DEFAULT_RETRY_IO_COUNT 8 /* maximum retry read IO count */
>>
>> /* maximum retry quota flush count */
>> @@ -2876,7 +2878,7 @@ struct page *f2fs_new_node_page(struct dnode_of_data *dn, unsigned int ofs);
>> void f2fs_ra_node_page(struct f2fs_sb_info *sbi, nid_t nid);
>> struct page *f2fs_get_node_page(struct f2fs_sb_info *sbi, pgoff_t nid);
>> struct page *f2fs_get_node_page_ra(struct page *parent, int start);
>> -void f2fs_move_node_page(struct page *node_page, int gc_type);
>> +int f2fs_move_node_page(struct page *node_page, int gc_type);
>> int f2fs_fsync_node_pages(struct f2fs_sb_info *sbi, struct inode *inode,
>> struct writeback_control *wbc, bool atomic,
>> unsigned int *seq_id);
>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
>> index a4c1a419611d..1ee287b7b94b 100644
>> --- a/fs/f2fs/gc.c
>> +++ b/fs/f2fs/gc.c
>> @@ -461,7 +461,7 @@ static int check_valid_map(struct f2fs_sb_info *sbi,
>> * On validity, copy that node with cold status, otherwise (invalid node)
>> * ignore that.
>> */
>> -static void gc_node_segment(struct f2fs_sb_info *sbi,
>> +static int gc_node_segment(struct f2fs_sb_info *sbi,
>> struct f2fs_summary *sum, unsigned int segno, int gc_type)
>> {
>> struct f2fs_summary *entry;
>> @@ -469,6 +469,7 @@ static void gc_node_segment(struct f2fs_sb_info *sbi,
>> int off;
>> int phase = 0;
>> bool fggc = (gc_type == FG_GC);
>> + int submitted = 0;
>>
>> start_addr = START_BLOCK(sbi, segno);
>>
>> @@ -482,10 +483,11 @@ static void gc_node_segment(struct f2fs_sb_info *sbi,
>> nid_t nid = le32_to_cpu(entry->nid);
>> struct page *node_page;
>> struct node_info ni;
>> + int err;
>>
>> /* 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;
>> @@ -522,7 +524,9 @@ static void gc_node_segment(struct f2fs_sb_info *sbi,
>> continue;
>> }
>>
>> - f2fs_move_node_page(node_page, gc_type);
>> + err = f2fs_move_node_page(node_page, gc_type);
>> + if (!err)
>> + submitted++;
>> stat_inc_node_blk_count(sbi, 1, gc_type);
>> }
>>
>> @@ -531,6 +535,7 @@ static void gc_node_segment(struct f2fs_sb_info *sbi,
>>
>> if (fggc)
>> atomic_dec(&sbi->wb_sync_req[NODE]);
>> + return submitted;
>> }
>>
>> /*
>> @@ -666,7 +671,7 @@ 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 = {
>> @@ -685,25 +690,29 @@ 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;
>> }
>>
>> @@ -714,6 +723,7 @@ 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;
>> }
>>
>> @@ -796,6 +806,7 @@ 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;
>> @@ -819,36 +830,46 @@ 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,
>> +static int move_data_page(struct inode *inode, block_t bidx, int gc_type,
>> unsigned int segno, int off)
>> {
>> struct page *page;
>> + int err = 0;
>>
>> page = f2fs_get_lock_data_page(inode, bidx, true);
>> if (IS_ERR(page))
>> - return;
>> + return PTR_ERR(page);
>>
>> - 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)) {
>> if (gc_type == FG_GC)
>> f2fs_pin_file_control(inode, true);
>> + err = -EAGAIN;
>> goto out;
>> }
>>
>> if (gc_type == BG_GC) {
>> - if (PageWriteback(page))
>> + if (PageWriteback(page)) {
>> + err = -EAGAIN;
>> goto out;
>> + }
>> set_page_dirty(page);
>> set_cold_data(page);
>> +
>> + err = WAIT_WRITEBACK;
>
> Can we just return 0, and check like this?
>
> if (f2fs_post_read_required(inode)) {
> move_data_block(inode, start_bidx, gc_type,
> segno, off);
> } else {
> move_data_page(inode, start_bidx, gc_type,
> err = move_data_page(inode, start_bidx, gc_type,
> segno, off);
>
> if (!err && gc_type == FG_GC)
> submitted++;
> }

Looks better. :)

Thanks,

>
>
>> } else {
>> struct f2fs_io_info fio = {
>> .sbi = F2FS_I_SB(inode),
>> @@ -864,7 +885,6 @@ static void move_data_page(struct inode *inode, block_t bidx, int gc_type,
>> .io_type = FS_GC_DATA_IO,
>> };
>> bool is_dirty = PageDirty(page);
>> - int err;
>>
>> retry:
>> set_page_dirty(page);
>> @@ -889,6 +909,7 @@ static void move_data_page(struct inode *inode, block_t bidx, int gc_type,
>> }
>> out:
>> f2fs_put_page(page, 1);
>> + return err;
>> }
>>
>> /*
>> @@ -898,7 +919,7 @@ 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;
>> @@ -906,6 +927,7 @@ 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);
>>
>> @@ -922,7 +944,7 @@ 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;
>> @@ -994,6 +1016,7 @@ 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]))
>> @@ -1013,12 +1036,15 @@ 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);
>> + err = move_data_block(inode, start_bidx,
>> + gc_type, segno, off);
>> else
>> - move_data_page(inode, start_bidx, gc_type,
>> + err = move_data_page(inode, start_bidx, gc_type,
>> segno, off);
>>
>> + if (!err)
>> + submitted++;
>> +
>> if (locked) {
>> up_write(&fi->i_gc_rwsem[WRITE]);
>> up_write(&fi->i_gc_rwsem[READ]);
>> @@ -1030,6 +1056,8 @@ 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,
>> @@ -1057,6 +1085,7 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
>> int seg_freed = 0;
>> unsigned char type = IS_DATASEG(get_seg_entry(sbi, segno)->type) ?
>> SUM_TYPE_DATA : SUM_TYPE_NODE;
>> + int submitted = 0;
>>
>> /* readahead multi ssa blocks those have contiguous address */
>> if (sbi->segs_per_sec > 1)
>> @@ -1100,10 +1129,11 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
>> * - lock_page(sum_page)
>> */
>> if (type == SUM_TYPE_NODE)
>> - gc_node_segment(sbi, sum->entries, segno, gc_type);
>> - else
>> - gc_data_segment(sbi, sum->entries, gc_list, segno,
>> + submitted += gc_node_segment(sbi, sum->entries, segno,
>> gc_type);
>> + else
>> + submitted += gc_data_segment(sbi, sum->entries, gc_list,
>> + segno, gc_type);
>>
>> stat_inc_seg_count(sbi, type, gc_type);
>>
>> @@ -1114,7 +1144,7 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
>> f2fs_put_page(sum_page, 0);
>> }
>>
>> - if (gc_type == FG_GC)
>> + if (submitted)
>> f2fs_submit_merged_write(sbi,
>> (type == SUM_TYPE_NODE) ? NODE : DATA);
>>
>> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
>> index fa2381c0bc47..5594765f4a71 100644
>> --- a/fs/f2fs/node.c
>> +++ b/fs/f2fs/node.c
>> @@ -1584,8 +1584,10 @@ static int __write_node_page(struct page *page, bool atomic, bool *submitted,
>> return AOP_WRITEPAGE_ACTIVATE;
>> }
>>
>> -void f2fs_move_node_page(struct page *node_page, int gc_type)
>> +int f2fs_move_node_page(struct page *node_page, int gc_type)
>> {
>> + int err = 0;
>> +
>> if (gc_type == FG_GC) {
>> struct writeback_control wbc = {
>> .sync_mode = WB_SYNC_ALL,
>> @@ -1597,22 +1599,28 @@ void f2fs_move_node_page(struct page *node_page, int gc_type)
>> f2fs_wait_on_page_writeback(node_page, NODE, true);
>>
>> f2fs_bug_on(F2FS_P_SB(node_page), PageWriteback(node_page));
>> - if (!clear_page_dirty_for_io(node_page))
>> + if (!clear_page_dirty_for_io(node_page)) {
>> + err = -EAGAIN;
>> goto out_page;
>> + }
>>
>> if (__write_node_page(node_page, false, NULL,
>> - &wbc, false, FS_GC_NODE_IO, NULL))
>> + &wbc, false, FS_GC_NODE_IO, NULL)) {
>> + err = -EAGAIN;
>> unlock_page(node_page);
>> + }
>> goto release_page;
>> } else {
>> /* set page dirty and write it */
>> if (!PageWriteback(node_page))
>> set_page_dirty(node_page);
>> + err = WAIT_WRITEBACK;
>> }
>> out_page:
>> unlock_page(node_page);
>> release_page:
>> f2fs_put_page(node_page, 0);
>> + return err;
>> }
>>
>> static int f2fs_write_node_page(struct page *page,
>> --
>> 2.18.0.rc1

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