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Date: Mon, 17 Sep 2018 18:37:43 -0700
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: Chao Yu <yuchao0@...wei.com>
Cc: Chao Yu <chao@...nel.org>, linux-f2fs-devel@...ts.sourceforge.net,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] f2fs: submit cached bio to avoid endless PageWriteback
On 09/18, Chao Yu wrote:
> On 2018/9/18 9:04, Jaegeuk Kim wrote:
> > On 09/13, Chao Yu wrote:
> >> From: Chao Yu <yuchao0@...wei.com>
> >>
> >> 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>
> >> ---
> >> v3:
> >> clean up codes suggested by Jaegeuk.
> >> fs/f2fs/f2fs.h | 2 +-
> >> fs/f2fs/gc.c | 71 +++++++++++++++++++++++++++++++++++---------------
> >> fs/f2fs/node.c | 13 ++++++---
> >> 3 files changed, 61 insertions(+), 25 deletions(-)
> >>
> >> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> >> index b676b82312e0..917b2ca76aac 100644
> >> --- a/fs/f2fs/f2fs.h
> >> +++ b/fs/f2fs/f2fs.h
> >> @@ -2869,7 +2869,7 @@ 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..f57622cfe058 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 && gc_type == FG_GC)
> >> + 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)
> >
> > We don't need to submit IOs in this case.
>
> Actually, previously, we missed to submit IOs for encrypted block only in
> BGGC, so we fix to submit for this case, all other codes are cleanups. Right?
The move_data_block migrates encrypted blocks all the time with meta page IOs.
I don't know what you're saying about BGGC.
>
> Thanks,
>
> >
> >> {
> >> 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;
> >> @@ -819,34 +830,42 @@ 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);
> >> } else {
> >> @@ -864,7 +883,6 @@ 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 +907,7 @@ static void move_data_page(struct inode *inode, block_t bidx, int gc_type,
> >> }
> >> out:
> >> f2fs_put_page(page, 1);
> >> + return err;
> >> }
> >>
> >> /*
> >> @@ -898,7 +917,7 @@ 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 +925,7 @@ 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 +942,7 @@ 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 +1014,7 @@ 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 +1034,16 @@ 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 && (gc_type == FG_GC ||
> >> + f2fs_post_read_required(inode)))
> >> + submitted++;
> >> +
> >> if (locked) {
> >> up_write(&fi->i_gc_rwsem[WRITE]);
> >> up_write(&fi->i_gc_rwsem[READ]);
> >> @@ -1030,6 +1055,8 @@ 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 +1084,7 @@ 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 +1128,11 @@ 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 +1143,7 @@ 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..214dd6326b4b 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,
> >> @@ -1597,12 +1599,16 @@ 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 */
> >> @@ -1613,6 +1619,7 @@ void f2fs_move_node_page(struct page *node_page, int gc_type)
> >> 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
> >
> > .
> >
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