Messages in this thread | | | Date | Mon, 9 Sep 2019 08:30:11 +0100 | From | Jaegeuk Kim <> | Subject | Re: [f2fs-dev] [PATCH 2/2] f2fs: avoid infinite GC loop due to stale atomic files |
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On 09/09, Chao Yu wrote: > On 2019/9/9 9:25, Jaegeuk Kim wrote: > > If committing atomic pages is failed when doing f2fs_do_sync_file(), we can > > get commited pages but atomic_file being still set like: > > > > - inmem: 0, atomic IO: 4 (Max. 10), volatile IO: 0 (Max. 0) > > > > If GC selects this block, we can get an infinite loop like this: > > > > f2fs_submit_page_bio: dev = (253,7), ino = 2, page_index = 0x2359a8, oldaddr = 0x2359a8, newaddr = 0x2359a8, rw = READ(), type = COLD_DATA > > f2fs_submit_read_bio: dev = (253,7)/(253,7), rw = READ(), DATA, sector = 18533696, size = 4096 > > f2fs_get_victim: dev = (253,7), type = No TYPE, policy = (Foreground GC, LFS-mode, Greedy), victim = 4355, cost = 1, ofs_unit = 1, pre_victim_secno = 4355, prefree = 0, free = 234 > > f2fs_iget: dev = (253,7), ino = 6247, pino = 5845, i_mode = 0x81b0, i_size = 319488, i_nlink = 1, i_blocks = 624, i_advise = 0x2c > > f2fs_submit_page_bio: dev = (253,7), ino = 2, page_index = 0x2359a8, oldaddr = 0x2359a8, newaddr = 0x2359a8, rw = READ(), type = COLD_DATA > > f2fs_submit_read_bio: dev = (253,7)/(253,7), rw = READ(), DATA, sector = 18533696, size = 4096 > > f2fs_get_victim: dev = (253,7), type = No TYPE, policy = (Foreground GC, LFS-mode, Greedy), victim = 4355, cost = 1, ofs_unit = 1, pre_victim_secno = 4355, prefree = 0, free = 234 > > f2fs_iget: dev = (253,7), ino = 6247, pino = 5845, i_mode = 0x81b0, i_size = 319488, i_nlink = 1, i_blocks = 624, i_advise = 0x2c > > > > In that moment, we can observe: > > > > [Before] > > Try to move 5084219 blocks (BG: 384508) > > - data blocks : 4962373 (274483) > > - node blocks : 121846 (110025) > > Skipped : atomic write 4534686 (10) > > > > [After] > > Try to move 5088973 blocks (BG: 384508) > > - data blocks : 4967127 (274483) > > - node blocks : 121846 (110025) > > Skipped : atomic write 4539440 (10) > > > > Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> > > --- > > fs/f2fs/file.c | 10 +++++----- > > 1 file changed, 5 insertions(+), 5 deletions(-) > > > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c > > index 7ae2f3bd8c2f..68b6da734e5f 100644 > > --- a/fs/f2fs/file.c > > +++ b/fs/f2fs/file.c > > @@ -1997,11 +1997,11 @@ static int f2fs_ioc_commit_atomic_write(struct file *filp) > > goto err_out; > > > > ret = f2fs_do_sync_file(filp, 0, LLONG_MAX, 0, true); > > - if (!ret) { > > - clear_inode_flag(inode, FI_ATOMIC_FILE); > > - F2FS_I(inode)->i_gc_failures[GC_FAILURE_ATOMIC] = 0; > > - stat_dec_atomic_write(inode); > > - } > > + > > + /* doesn't need to check error */ > > + clear_inode_flag(inode, FI_ATOMIC_FILE); > > + F2FS_I(inode)->i_gc_failures[GC_FAILURE_ATOMIC] = 0; > > + stat_dec_atomic_write(inode); > > If there are still valid atomic write pages linked in .inmem_pages, it may cause > memory leak when we just clear FI_ATOMIC_FILE flag.
f2fs_commit_inmem_pages() should have flushed them.
> > So my question is why below logic didn't handle such condition well? > > f2fs_gc() > > if (has_not_enough_free_secs(sbi, sec_freed, 0)) { > if (skipped_round <= MAX_SKIP_GC_COUNT || > skipped_round * 2 < round) { > segno = NULL_SEGNO; > goto gc_more; > } > > if (first_skipped < last_skipped && > (last_skipped - first_skipped) > > sbi->skipped_gc_rwsem) { > f2fs_drop_inmem_pages_all(sbi, true);
This is doing nothing, since f2fs_commit_inmem_pages() removed the inode from inmem list.
> segno = NULL_SEGNO; > goto gc_more; > } > if (gc_type == FG_GC && !is_sbi_flag_set(sbi, SBI_CP_DISABLED)) > ret = f2fs_write_checkpoint(sbi, &cpc); > } > > > } else { > > ret = f2fs_do_sync_file(filp, 0, LLONG_MAX, 1, false); > > } > >
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