Messages in this thread | | | Subject | Re: [f2fs-dev] [PATCH] Revert "f2fs: give a warning only for readonly partition" | From | Chao Yu <> | Date | Wed, 31 Mar 2021 11:17:46 +0800 |
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On 2021/3/31 9:57, Jaegeuk Kim wrote: > On 03/27, Chao Yu wrote: >> On 2021/3/27 9:52, Chao Yu wrote: >>> On 2021/3/27 1:30, Jaegeuk Kim wrote: >>>> On 03/26, Chao Yu wrote: >>>>> On 2021/3/26 9:19, Jaegeuk Kim wrote: >>>>>> On 03/26, Chao Yu wrote: >>>>>>> On 2021/3/25 9:59, Chao Yu wrote: >>>>>>>> On 2021/3/25 6:44, Jaegeuk Kim wrote: >>>>>>>>> On 03/24, Chao Yu wrote: >>>>>>>>>> On 2021/3/24 12:22, Jaegeuk Kim wrote: >>>>>>>>>>> On 03/24, Chao Yu wrote: >>>>>>>>>>>> On 2021/3/24 2:39, Jaegeuk Kim wrote: >>>>>>>>>>>>> On 03/23, Chao Yu wrote: >>>>>>>>>>>>>> This reverts commit 938a184265d75ea474f1c6fe1da96a5196163789. >>>>>>>>>>>>>> >>>>>>>>>>>>>> Because that commit fails generic/050 testcase which expect failure >>>>>>>>>>>>>> during mount a recoverable readonly partition. >>>>>>>>>>>>> >>>>>>>>>>>>> I think we need to change generic/050, since f2fs can recover this partition, >>>>>>>>>>>> >>>>>>>>>>>> Well, not sure we can change that testcase, since it restricts all generic >>>>>>>>>>>> filesystems behavior. At least, ext4's behavior makes sense to me: >>>>>>>>>>>> >>>>>>>>>>>> journal_dev_ro = bdev_read_only(journal->j_dev); >>>>>>>>>>>> really_read_only = bdev_read_only(sb->s_bdev) | journal_dev_ro; >>>>>>>>>>>> >>>>>>>>>>>> if (journal_dev_ro && !sb_rdonly(sb)) { >>>>>>>>>>>> ext4_msg(sb, KERN_ERR, >>>>>>>>>>>> "journal device read-only, try mounting with '-o ro'"); >>>>>>>>>>>> err = -EROFS; >>>>>>>>>>>> goto err_out; >>>>>>>>>>>> } >>>>>>>>>>>> >>>>>>>>>>>> if (ext4_has_feature_journal_needs_recovery(sb)) { >>>>>>>>>>>> if (sb_rdonly(sb)) { >>>>>>>>>>>> ext4_msg(sb, KERN_INFO, "INFO: recovery " >>>>>>>>>>>> "required on readonly filesystem"); >>>>>>>>>>>> if (really_read_only) { >>>>>>>>>>>> ext4_msg(sb, KERN_ERR, "write access " >>>>>>>>>>>> "unavailable, cannot proceed " >>>>>>>>>>>> "(try mounting with noload)"); >>>>>>>>>>>> err = -EROFS; >>>>>>>>>>>> goto err_out; >>>>>>>>>>>> } >>>>>>>>>>>> ext4_msg(sb, KERN_INFO, "write access will " >>>>>>>>>>>> "be enabled during recovery"); >>>>>>>>>>>> } >>>>>>>>>>>> } >>>>>>>>>>>> >>>>>>>>>>>>> even though using it as readonly. And, valid checkpoint can allow for user to >>>>>>>>>>>>> read all the data without problem. >>>>>>>>>>>> >>>>>>>>>>>>>> if (f2fs_hw_is_readonly(sbi)) { >>>>>>>>>>>> >>>>>>>>>>>> Since device is readonly now, all write to the device will fail, checkpoint can >>>>>>>>>>>> not persist recovered data, after page cache is expired, user can see stale data. >>>>>>>>>>> >>>>>>>>>>> My point is, after mount with ro, there'll be no data write which preserves the >>>>>>>>>>> current status. So, in the next time, we can recover fsync'ed data later, if >>>>>>>>>>> user succeeds to mount as rw. Another point is, with the current checkpoint, we >>>>>>>>>>> should not have any corrupted metadata. So, why not giving a chance to show what >>>>>>>>>>> data remained to user? I think this can be doable only with CoW filesystems. >>>>>>>>>> >>>>>>>>>> I guess we're talking about the different things... >>>>>>>>>> >>>>>>>>>> Let me declare two different readonly status: >>>>>>>>>> >>>>>>>>>> 1. filesystem readonly: file system is mount with ro mount option, and >>>>>>>>>> app from userspace can not modify any thing of filesystem, but filesystem >>>>>>>>>> itself can modify data on device since device may be writable. >>>>>>>>>> >>>>>>>>>> 2. device readonly: device is set to readonly status via 'blockdev --setro' >>>>>>>>>> command, and then filesystem should never issue any write IO to the device. >>>>>>>>>> >>>>>>>>>> So, what I mean is, *when device is readonly*, rather than f2fs mountpoint >>>>>>>>>> is readonly (f2fs_hw_is_readonly() returns true as below code, instead of >>>>>>>>>> f2fs_readonly() returns true), in this condition, we should not issue any >>>>>>>>>> write IO to device anyway, because, AFAIK, write IO will fail due to >>>>>>>>>> bio_check_ro() check. >>>>>>>>> >>>>>>>>> In that case, mount(2) will try readonly, no? >>>>>>>> >>>>>>>> Yes, if device is readonly, mount (2) can not mount/remount device to rw >>>>>>>> mountpoint. >>>>>>> >>>>>>> Any other concern about this patch? >>>>>> >>>>>> Indeed we're talking about different things. :) >>>>>> >>>>>> This case is mount(ro) with device(ro) having some data to recover. >>>>>> My point is why not giving a chance to mount(ro) to show the current data >>>>>> covered by a valid checkpoint. This doesn't change anything in the disk, >>>>> Got your idea. >>>>> >>>>> IMO, it has potential issue in above condition: >>>>> >>>>>>>>>>>> Since device is readonly now, all write to the device will fail, checkpoint can >>>>>>>>>>>> not persist recovered data, after page cache is expired, user can see stale data. >>>>> >>>>> e.g. >>>>> >>>>> Recovery writes one inode and then triggers a checkpoint, all writes fail >>>> >>>> I'm confused. Currently we don't trigger the roll-forward recovery. >>> >>> Oh, my miss, sorry. :-P >>> >>> My point is in this condition we can return error and try to notice user to >>> mount with disable_roll_forward or norecovery option, then at least user can >>> know he should not expect last fsynced data in newly mounted image. >>> >>> Or we can use f2fs_recover_fsync_data() to check whether there is fsynced data, >>> if there is no such data, then let mount() succeed. >> >> Something like this, maybe: >> >> --- >> fs/f2fs/super.c | 17 +++++++++++++---- >> 1 file changed, 13 insertions(+), 4 deletions(-) >> >> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c >> index 954b1fe97d67..5e1a1caf412d 100644 >> --- a/fs/f2fs/super.c >> +++ b/fs/f2fs/super.c >> @@ -3966,10 +3966,19 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent) >> * previous checkpoint was not done by clean system shutdown. >> */ >> if (f2fs_hw_is_readonly(sbi)) { >> - if (!is_set_ckpt_flags(sbi, CP_UMOUNT_FLAG)) >> - f2fs_err(sbi, "Need to recover fsync data, but write access unavailable"); >> - else >> - f2fs_info(sbi, "write access unavailable, skipping recovery"); >> + if (!is_set_ckpt_flags(sbi, CP_UMOUNT_FLAG)) { >> + err = f2fs_recover_fsync_data(sbi, true); > > Can we do like this? > > if (err > 0) { > err = -EROFS; > f2fs_err(sbi, "Need to recover fsync data, but " > "write access unavailable, please try " > "mount w/ disable_roll_forward or norecovery"); > } > if (err < 0) > goto free_meta; > } > f2fs_info(sbi, "write access unavailable, skipping recovery"); > goto reset_checkpoint;
More clear, revised in v2.
Thanks,
> >> + if (!err) >> + goto reset_checkpoint; >> + else if (err < 0) >> + goto free_meta; >> + err = -EROFS; >> + f2fs_err(sbi, "Need to recover fsync data, but " >> + "write access unavailable, please try " >> + "mount w/ disable_roll_forward or norecovery"); >> + goto free_meta; >> + } >> + f2fs_info(sbi, "write access unavailable, skipping recovery"); >> goto reset_checkpoint; >> } >> >> -- >> 2.29.2 >> >> Thanks, >> >>> >>> Thanks, >>> >>>> >>>>> due to device is readonly, once inode cache is reclaimed by vm, user will see >>>>> old inode when reloading it, or even see corrupted fs if partial meta inode's >>>>> cache is expired. >>>>> >>>>> Thoughts? >>>>> >>>>> Thanks, >>>>> >>>>>> and in the next time, it allows mount(rw|ro) with device(rw) to recover >>>>>> the data seamlessly. >>>>>> >>>>>>> >>>>>>> Thanks, >>>>>>> >>>>>>>> >>>>>>>> Thanks, >>>>>>>> >>>>>>>>> >>>>>>>>> # blockdev --setro /dev/vdb >>>>>>>>> # mount -t f2fs /dev/vdb /mnt/test/ >>>>>>>>> mount: /mnt/test: WARNING: source write-protected, mounted read-only. >>>>>>>>> >>>>>>>>>> >>>>>>>>>> if (f2fs_hw_is_readonly(sbi)) { >>>>>>>>>> - if (!is_set_ckpt_flags(sbi, CP_UMOUNT_FLAG)) { >>>>>>>>>> - err = -EROFS; >>>>>>>>>> + if (!is_set_ckpt_flags(sbi, CP_UMOUNT_FLAG)) >>>>>>>>>> f2fs_err(sbi, "Need to recover fsync data, but write access unavailable"); >>>>>>>>>> - goto free_meta; >>>>>>>>>> - } >>>>>>>>>> - f2fs_info(sbi, "write access unavailable, skipping recovery"); >>>>>>>>>> + else >>>>>>>>>> + f2fs_info(sbi, "write access unavailable, skipping recovery"); >>>>>>>>>> goto reset_checkpoint; >>>>>>>>>> } >>>>>>>>>> >>>>>>>>>> For the case of filesystem is readonly and device is writable, it's fine >>>>>>>>>> to do recovery in order to let user to see fsynced data. >>>>>>>>>> >>>>>>>>>> Thanks, >>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> Am I missing something? >>>>>>>>>>>> >>>>>>>>>>>> Thanks, >>>>>>>>>>>> >>>>>>>>>>>>> >>>>>>>>>>>>>> >>>>>>>>>>>>>> Fixes: 938a184265d7 ("f2fs: give a warning only for readonly partition") >>>>>>>>>>>>>> Signed-off-by: Chao Yu <yuchao0@huawei.com> >>>>>>>>>>>>>> --- >>>>>>>>>>>>>> fs/f2fs/super.c | 8 +++++--- >>>>>>>>>>>>>> 1 file changed, 5 insertions(+), 3 deletions(-) >>>>>>>>>>>>>> >>>>>>>>>>>>>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c >>>>>>>>>>>>>> index b48281642e98..2b78ee11f093 100644 >>>>>>>>>>>>>> --- a/fs/f2fs/super.c >>>>>>>>>>>>>> +++ b/fs/f2fs/super.c >>>>>>>>>>>>>> @@ -3952,10 +3952,12 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent) >>>>>>>>>>>>>> * previous checkpoint was not done by clean system shutdown. >>>>>>>>>>>>>> */ >>>>>>>>>>>>>> if (f2fs_hw_is_readonly(sbi)) { >>>>>>>>>>>>>> - if (!is_set_ckpt_flags(sbi, CP_UMOUNT_FLAG)) >>>>>>>>>>>>>> + if (!is_set_ckpt_flags(sbi, CP_UMOUNT_FLAG)) { >>>>>>>>>>>>>> + err = -EROFS; >>>>>>>>>>>>>> f2fs_err(sbi, "Need to recover fsync data, but write access unavailable"); >>>>>>>>>>>>>> - else >>>>>>>>>>>>>> - f2fs_info(sbi, "write access unavailable, skipping recovery"); >>>>>>>>>>>>>> + goto free_meta; >>>>>>>>>>>>>> + } >>>>>>>>>>>>>> + f2fs_info(sbi, "write access unavailable, skipping recovery"); >>>>>>>>>>>>>> goto reset_checkpoint; >>>>>>>>>>>>>> } >>>>>>>>>>>>>> -- >>>>>>>>>>>>>> 2.29.2 >>>>>>>>>>>>> . >>>>>>>>>>>>> >>>>>>>>>>> . >>>>>>>>>>> >>>>>>>>> . >>>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> _______________________________________________ >>>>>>>> Linux-f2fs-devel mailing list >>>>>>>> Linux-f2fs-devel@lists.sourceforge.net >>>>>>>> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel >>>>>>>> . >>>>>>>> >>>>>> . >>>>>> >>>> . >>>> >>> >>> >>> _______________________________________________ >>> Linux-f2fs-devel mailing list >>> Linux-f2fs-devel@lists.sourceforge.net >>> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel >>> . >>> > . >
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