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Mon, 09 Sep 2019 08:28:11 +0000 Received: from DGGEMS402-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 093C4DC141C1F1E4F691; Mon, 9 Sep 2019 16:28:00 +0800 (CST) Received: from [10.134.22.195] (10.134.22.195) by smtp.huawei.com (10.3.19.202) with Microsoft SMTP Server (TLS) id 14.3.439.0; Mon, 9 Sep 2019 16:27:56 +0800 To: Jaegeuk Kim , References: <20190909012532.20454-1-jaegeuk@kernel.org> <20190909012532.20454-2-jaegeuk@kernel.org> <20190909073011.GA21625@jaegeuk-macbookpro.roam.corp.google.com> <5a473076-14b8-768a-62ac-f686e850d5a6@huawei.com> <20190909080108.GC21625@jaegeuk-macbookpro.roam.corp.google.com> <20190909082112.GA25724@jaegeuk-macbookpro.roam.corp.google.com> From: Chao Yu Message-ID: <2f5b844c-f722-6a80-a4ab-61bdd72b8be4@huawei.com> Date: Mon, 9 Sep 2019 16:27:42 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20190909082112.GA25724@jaegeuk-macbookpro.roam.corp.google.com> Content-Language: en-US X-Originating-IP: [10.134.22.195] X-CFilter-Loop: Reflected X-Headers-End: 1i7F1r-00ErUB-M2 Subject: Re: [f2fs-dev] [PATCH 2/2] f2fs: avoid infinite GC loop due to stale atomic files X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net On 2019/9/9 16:21, Jaegeuk Kim wrote: > On 09/09, Chao Yu wrote: >> On 2019/9/9 16:01, Jaegeuk Kim wrote: >>> 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 >>>>>>> --- >>>>>>> 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. >> >> What I mean is, for any error returned from atomic_commit() interface, should >> userspace application handle it with consistent way, like trigger >> f2fs_drop_inmem_pages(), so we don't need to handle it inside atomic_commit(). > > f2fs_ioc_abort_volatile_write() will be triggered. If userspace can do this, we can get rid of this patch, or am I missing sth? - f2fs_ioc_abort_volatile_write - f2fs_drop_inmem_pages - clear_inode_flag(inode, FI_ATOMIC_FILE); - fi->i_gc_failures[GC_FAILURE_ATOMIC] = 0; - stat_dec_atomic_write(inode); > >> >>> >>>> >>>> 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); >>>>>>> } >>>>>>> >>>>> . >>>>> >>> . >>> > . > _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel