On 2016/9/27 9:39, Jaegeuk Kim wrote:
> On Tue, Sep 27, 2016 at 08:57:41AM +0800, Chao Yu wrote:
>> Hi Jaegeuk,
>>
>> On 2016/9/27 2:33, Jaegeuk Kim wrote:
>>> Hi Chao,
>>>
>>> On Tue, Sep 27, 2016 at 12:09:52AM +0800, Chao Yu wrote:
>>>> From: Chao Yu <yuch...@huawei.com>
>>>>
>>>> In sync_node_pages, we won't check and commit last merged pages in private
>>>> bio cache of f2fs, as these pages were taged as writeback, someone who is
>>>> waiting for writebacking of the page will be blocked until the cache was
>>>> committed by someone else.
>>>>
>>>> We need to commit node type bio cache to avoid potential deadlock or long
>>>> delay of waiting writeback.
>>>>
>>>> Signed-off-by: Chao Yu <yuch...@huawei.com>
>>>> ---
>>>> fs/f2fs/node.c | 11 +++++++++--
>>>> 1 file changed, 9 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
>>>> index 9faddcd..f73f774 100644
>>>> --- a/fs/f2fs/node.c
>>>> +++ b/fs/f2fs/node.c
>>>> @@ -1416,6 +1416,7 @@ int sync_node_pages(struct f2fs_sb_info *sbi, struct
>>>> writeback_control *wbc)
>>>> struct pagevec pvec;
>>>> int step = 0;
>>>> int nwritten = 0;
>>>> + int ret = 0;
>>>>
>>>> pagevec_init(&pvec, 0);
>>>>
>>>> @@ -1436,7 +1437,8 @@ next_step:
>>>>
>>>> if (unlikely(f2fs_cp_error(sbi))) {
>>>> pagevec_release(&pvec);
>>>> - return -EIO;
>>>> + ret = -EIO;
>>>> + goto out;
>>>> }
>>>>
>>>> /*
>>>> @@ -1487,6 +1489,8 @@ continue_unlock:
>>>>
>>>> if (NODE_MAPPING(sbi)->a_ops->writepage(page, wbc))
>>>> unlock_page(page);
>>>> + else
>>>> + nwritten++;
>>>>
>>>> if (--wbc->nr_to_write == 0)
>>>> break;
>>>> @@ -1504,7 +1508,10 @@ continue_unlock:
>>>> step++;
>>>> goto next_step;
>>>> }
>>>> - return nwritten;
>>>> +out:
>>>> + if (nwritten)
>>>> + f2fs_submit_merged_bio(sbi, NODE, WRITE);
>>>
>>> IIRC, we don't need to flush this, since f2fs_submit_merged_bio_cond() would
>>> handle this in f2fs_wait_on_page_writeback().
>>
>> Yes, it covers all the cases in f2fs private codes, but there are still some
>> codes in mm or fs directory, and they didn't use f2fs_wait_on_page_writeback
>> when waiting page writeback. Such as do_writepages && filemap_fdatawait in
>> __writeback_single_inode...
>
> The do_writepages() is okay, which will call f2fs_write_node_pages().
> The __writeback_single_inode() won't do filemap_fdatawait() with WB_SYNC_ALL.
> We don't need to take care of truncation as well.
>
> Any missing one?
Another is: while testing with first version of checkpoint error injection, I
encounter below dump stack:
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
mount D ffff8801c1bf7960 0 97685 97397 0x00080000
ffff8801c1bf7960 ffff8801c1bf7930 ffff880175900000 ffff8801c1bf7980
ffff8801c1bf8000 0000000000000000 7fffffffffffffff ffff88021f7be340
ffffffff817c8880 ffff8801c1bf7978 ffffffff817c80a5 ffff880214f58fc0
Call Trace:
[<ffffffff817c8880>] ? bit_wait+0x50/0x50
[<ffffffff817c80a5>] schedule+0x35/0x80
[<ffffffff817cb152>] schedule_timeout+0x292/0x3d0
[<ffffffff81022ab5>] ? xen_clocksource_get_cycles+0x15/0x20
[<ffffffff810eeb5c>] ? ktime_get+0x3c/0xb0
[<ffffffff817c8880>] ? bit_wait+0x50/0x50
[<ffffffff817c7906>] io_schedule_timeout+0xa6/0x110
[<ffffffff817c889b>] bit_wait_io+0x1b/0x60
[<ffffffff817c84e4>] __wait_on_bit+0x64/0x90
[<ffffffff8117dcd4>] wait_on_page_bit+0xc4/0xd0
[<ffffffff810bc4d0>] ? autoremove_wake_function+0x40/0x40
[<ffffffff81190a29>] truncate_inode_pages_range+0x409/0x840
[<ffffffff811a406d>] ? pcpu_free_area+0x13d/0x1a0
[<ffffffff810bc025>] ? wake_up_bit+0x25/0x30
[<ffffffff81190ecc>] truncate_inode_pages_final+0x4c/0x60
[<ffffffffa025e9e8>] f2fs_evict_inode+0x48/0x390 [f2fs]
[<ffffffff812212f7>] evict+0xc7/0x1a0
[<ffffffff81221f77>] iput+0x197/0x200
[<ffffffffa0268242>] f2fs_fill_super+0xab2/0x1130 [f2fs]
[<ffffffff81209454>] mount_bdev+0x184/0x1c0
[<ffffffffa0267790>] ? f2fs_commit_super+0x100/0x100 [f2fs]
[<ffffffffa02646a5>] f2fs_mount+0x15/0x20 [f2fs]
[<ffffffff81209e19>] mount_fs+0x39/0x160
[<ffffffff81225e47>] vfs_kern_mount+0x67/0x110
[<ffffffff812283bb>] do_mount+0x1bb/0xc80
[<ffffffff81229163>] SyS_mount+0x83/0xd0
[<ffffffff8100391e>] do_syscall_64+0x6e/0x170
[<ffffffff817cc325>] entry_SYSCALL64_slow_path+0x25/0x25
Any thoughts?
>
>>
>> Thanks,
>>
>>>
>>> Thanks,
>>>
>>>> + return ret;
>>>> }
>>>>
>>>> int wait_on_node_pages_writeback(struct f2fs_sb_info *sbi, nid_t ino)
>>>> --
>>>> 2.7.2
>>>
>>> .
>>>
>
> .
>
