Messages in this thread | | | Date | Mon, 9 Sep 2019 09:01:08 +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 15:30, Jaegeuk Kim wrote: > > 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. > > Oh, we failed to flush its nodes. > > However we won't clear such info if we failed to flush inmen pages, it looks > inconsistent. > > Any interface needed to drop inmem pages or clear ATOMIC_FILE flag in that two > error path? I'm not very clear how sqlite handle such error.
f2fs_drop_inmem_pages() did that, but not in this case.
> > Thanks, > > > > >> > >> 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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