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Date: Tue, 11 Sep 2018 17:12:44 -0700
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: Chao Yu <chao@...nel.org>
Cc: Chao Yu <yuchao0@...wei.com>, kassey1216@...il.com,
linux-f2fs-devel@...ts.sourceforge.net,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] f2fs: submit cached bio to avoid endless PageWriteback
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@...wei.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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