Messages in this thread | | | Date | Wed, 24 Mar 2021 15:44:58 -0700 | From | Jaegeuk Kim <> | Subject | Re: [PATCH] Revert "f2fs: give a warning only for readonly partition" |
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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?
# 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 > > > > . > > > > > > . > >
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