Re: Possible issues with fsck of f2fs root

[Chao Yu <yuchao0@huawei.com>]

On 2019/4/17 2:53, Jaegeuk Kim wrote:
> On 04/02, Hagbard Celine wrote:
>> Hi, I lost the root filesystem on my previous install after a few
>> weeks of several power outages last winter. While trying to recover I
>> discovered that it seem fsck was never run properly during boot in the
>> lifetime of that install.
>> After getting the system installed again a while ago, I have been
>> trying to discern why.
>> So far I've found the following two possible issues:
>>
>> ISSUE 1:
>> If I boot with kernel option "ro rootfstype=f2fs
>> rootflags=background_gc=on,heap,disable_ext_identify,discard,user_xattr,inline_xattr,inline_dentry,acl,inline_data,flush_merge,data_flush,extent_cache,whint_mode=fs-based,fsync_mode=strict"
>> I get the following halfway trough boot:
>>
>>  * Checking local filesystems  ...
>> Info: Use default preen mode
>> Info: Mounted device!
>> Info: Check FS only due to RO
>>         Error: Failed to open the device!
>>  * Filesystems couldn't be fixed
>>
>>
>>                      [ !! ] * rc: Aborting!
>>
>> If i from this state try to mount another partition:
>> # mount -o "ro,relatime,lazytime,background_gc=on,discard,heap,user_xattr,inline_xattr,acl,disable_ext_identify,inline_data,inline_dentry,flush_merge,extent_cache,data_flush,mode=adaptive,active_logs=6,whint_mode=fs-based,alloc_mode=default,fsync_mode=strict"
>> /dev/nvme0n1p7 /mnt/f2fstest/
>>
>> I get the same error if I try to run fsck on it:
>> # fsck.f2fs /dev/nvme0n1p7
>> Info: Mounted device!
>> Info: Check FS only due to RO
>>         Error: Failed to open the device!
>>
>> If I on the other had boot with kernel option "rw rootfstype=f2fs
>> rootflags=background_gc=on,heap,disable_ext_identify,discard,user_xattr,inline_xattr,inline_dentry,acl,inline_data,flush_merge,data_flush,extent_cache,whint_mode=fs-based,fsync_mode=strict
>> panic=30 scsi_mod.use_blk_mq=1"
>>
>> The boot does not hang and if I try same test as before, mount test partition:
>> # mount -o "ro,relatime,lazytime,background_gc=on,discard,heap,user_xattr,inline_xattr,acl,disable_ext_identify,inline_data,inline_dentry,flush_merge,extent_cache,data_flush,mode=adaptive,active_logs=6,whint_mode=fs-based,alloc_mode=default,fsync_mode=strict"
>> /dev/nvme0n1p7 /mnt/f2fstest/
>>
>> Run fsck:
>> # fsck.f2fs  -f /dev/nvme0n1p7
>> Info: Force to fix corruption
>> Info: Mounted device!
>> Info: Check FS only due to RO
>> Info: Segments per section = 1
>> Info: Sections per zone = 1
>> Info: sector size = 512
>> Info: total sectors = 134101647 (65479 MB)
>> Info: MKFS version
>>   "Linux version 5.0.5-gentoof2fsfix (root@40o2) (gcc version 8.2.0
>> (Gentoo 8.2.0-r6 p1.7)) #2 SMP PREEMPT Mon Apr 1 17:04:41 +01 2019"
>> Info: FSCK version
>>   from "Linux version 5.0.5-gentoo (root@40o2) (gcc version 8.2.0
>> (Gentoo 8.2.0-r6 p1.7)) #2 SMP PREEMPT Tue Apr 2 07:42:40 +01 2019"
>>     to "Linux version 5.0.5-gentoo (root@40o2) (gcc version 8.2.0
>> (Gentoo 8.2.0-r6 p1.7)) #2 SMP PREEMPT Tue Apr 2 07:42:40 +01 2019"
>> Info: superblock features = 0 :
>> Info: superblock encrypt level = 0, salt = 00000000000000000000000000000000
>> Info: total FS sectors = 134101640 (65479 MB)
>> Info: CKPT version = 70e1454a
>> Info: Checked valid nat_bits in checkpoint
>> Info: checkpoint state = 4c1 :  large_nat_bitmap nat_bits crc unmount
>>
>> [FSCK] Unreachable nat entries                        [Ok..] [0x0]
>> [FSCK] SIT valid block bitmap checking                [Ok..]
>> [FSCK] Hard link checking for regular file            [Ok..] [0x70]
>> [FSCK] valid_block_count matching with CP             [Ok..] [0x1fe244]
>> [FSCK] valid_node_count matcing with CP (de lookup)   [Ok..] [0x6c487]
>> [FSCK] valid_node_count matcing with CP (nat lookup)  [Ok..] [0x6c487]
>> [FSCK] valid_inode_count matched with CP              [Ok..] [0x6c362]
>> [FSCK] free segment_count matched with CP             [Ok..] [0x6c44]
>> [FSCK] next block offset is free                      [Ok..]
>> [FSCK] fixing SIT types
>> [FSCK] other corrupted bugs                           [Ok..]
>>
>> Done.
>>
>> So a system booted with "rw" root can fsck an "ro" filesystem but a
>> system booted with root "ro" can not.
>>
>>
>> ISSUE 2:
>> Referring to the output from the fsck running against a "ro"
>> filesystem, especially this line:
>> Info: Check FS only due to RO
>>
>> As far as i can tell this says that opposed to other filesystems
>> running fsck against a "ro" mounted f2fs partition will never fix any
>> errors.
>> So I tried running fsck against the same partition mounted "rw":
>> # mount -o remount,rw /mnt/f2fstest/
>> # fsck.f2fs  -f /dev/nvme0n1p7
>> Info: Force to fix corruption
>> Info: Mounted device!
>>         Error: Not available on mounted device!
>>
>> I might be misunderstanding something, but all this tells me that
>> unless one make a custom initramfs that runs fsck before root is
>> mounted (something no distributions has, as far as I know), fsck will
>> never fix an f2fs formatted root partition during boot.
>> If this is by design and not a bug/unintended behavior, it should be
>> documented somewhere least more people will experience system crashes
>> like mine.
>>
>> All tests above done with kernel 5.0.5 and f2fs-tools 1.12.0 with
>> "fsck.f2fs: allow to fsck readonly image w/ -f option"-patch by Chao
>> Yu.
> 
> Hi Hagbard,
> 
> It looks like fsck.f2fs failed to open a device as RW on RO disk. Could you
> try this patch?
> 
> Thanks,
> 
>>From 3f18ff744f4d510d8e2f42c5a3b2539651baccc5 Mon Sep 17 00:00:00 2001
> From: Jaegeuk Kim <jaegeuk@kernel.org>
> Date: Tue, 16 Apr 2019 11:46:31 -0700
> Subject: [PATCH] fsck.f2fs: open ro disk if we want to check fs only
> 
> This patch fixes the "open failure" issue on ro disk, reported by Hagbard.
> 
> "
>  If I boot with kernel option "ro rootfstype=f2fs
>  I get the following halfway trough boot:
> 
>   * Checking local filesystems  ...
>  Info: Use default preen mode
>  Info: Mounted device!
>  Info: Check FS only due to RO
>          Error: Failed to open the device!
>   * Filesystems couldn't be fixed
> "
> 
> Reported-by: Hagbard Celine <hagbardcelin@gmail.com>
> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
> ---
>  lib/libf2fs.c | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/lib/libf2fs.c b/lib/libf2fs.c
> index f8f6921..1a0d179 100644
> --- a/lib/libf2fs.c
> +++ b/lib/libf2fs.c
> @@ -818,9 +818,16 @@ int get_device_info(int i)
>  	unsigned char model_inq[6] = {MODELINQUIRY};
>  #endif
>  	struct device_info *dev = c.devices + i;
> +	int rw_flag;
> +
> +	/* Check FS only */
> +	if (c.fix_on == 0 && c.auto_fix == 0)
> +		rw_flag = O_RDONLY;
> +	else
> +		rw_flag = O_RDWR;
>  
>  	if (c.sparse_mode) {
> -		fd = open(dev->path, O_RDWR | O_CREAT | O_BINARY, 0644);
> +		fd = open(dev->path, rw_flag | O_CREAT | O_BINARY, 0644);
>  		if (fd < 0) {
>  			MSG(0, "\tError: Failed to open a sparse file!\n");
>  			return -1;
> @@ -838,9 +845,9 @@ int get_device_info(int i)
>  		}
>  
>  		if (S_ISBLK(stat_buf->st_mode) && !c.force)
> -			fd = open(dev->path, O_RDWR | O_EXCL);
> +			fd = open(dev->path, rw_flag | O_EXCL);
>  		else
> -			fd = open(dev->path, O_RDWR);
> +			fd = open(dev->path, rw_flag);
>  	}
>  	if (fd < 0) {
>  		MSG(0, "\tError: Failed to open the device!\n");

Jaegeuk,

Last merged patch wasn't sent out..., so I just reply on this old one.

		if (S_ISBLK(stat_buf->st_mode) && !c.force) {

Shouldn't be (.. && c.force) ?

			fd = open(dev->path, O_RDWR | O_EXCL);
			if (fd < 0)
				fd = open_check_fs(dev->path, O_EXCL);

It

		} else {
			fd = open(dev->path, O_RDWR);
			if (fd < 0)
				fd = open_check_fs(dev->path, 0);
		}

>