Re: [PATCH] f2fs: fix to check readonly condition correctly

[Chao Yu]

On 2023/4/4 1:59, Jaegeuk Kim wrote:
> On 04/02, Chao Yu wrote:
> > This patch does below changes:
> >
> > - If f2fs enables readonly feature or device is readonly, allow to
> > mount readonly mode only
> > - Introduce f2fs_dev_is_readonly() to indicate whether image or device
> > is readonly
> > - remove unnecessary f2fs_hw_is_readonly() in f2fs_write_checkpoint()
> > and f2fs_convert_inline_inode()
> > - enable FLUSH_MERGE only if f2fs is mounted as rw and image/device
> > is writable
>
> What is the problem to solve here?

With below case, it can mount multi-device image w/ rw option, however
one of secondary device is set as ro, later update will cause panic, so
I introduced f2fs_dev_is_readonly(), and check multi-devices rw status
in parse_options() w/ it in order to avoid such inconsistent mount status.

mkfs.f2fs -c /dev/zram1 /dev/zram0 -f
blockdev --setro /dev/zram1
mount -t f2fs /dev/zram0 /mnt/f2fs/
mount: /mnt/f2fs: WARNING: source write-protected, mounted read-only.
mount -t f2fs -o remount,rw /mnt/f2fs/
dd if=/dev/zero  of=/mnt/f2fs/file bs=1M count=8192

kernel BUG at fs/f2fs/inline.c:258!
RIP: 0010:f2fs_write_inline_data+0x23e/0x2d0 [f2fs]
Call Trace:
 f2fs_write_single_data_page+0x26b/0x9f0 [f2fs]
 f2fs_write_cache_pages+0x389/0xa60 [f2fs]
 __f2fs_write_data_pages+0x26b/0x2d0 [f2fs]
 f2fs_write_data_pages+0x2e/0x40 [f2fs]
 do_writepages+0xd3/0x1b0
 __writeback_single_inode+0x5b/0x420
 writeback_sb_inodes+0x236/0x5a0
 __writeback_inodes_wb+0x56/0xf0
 wb_writeback+0x2a3/0x490
 wb_do_writeback+0x2b2/0x330
 wb_workfn+0x6a/0x260
 process_one_work+0x270/0x5e0
 worker_thread+0x52/0x3e0
 kthread+0xf4/0x120
 ret_from_fork+0x29/0x50

Thanks,

> > Signed-off-by: Chao Yu <chao@xxxxxxxxxx>
> > ---
> >   fs/f2fs/checkpoint.c |  2 +-
> >   fs/f2fs/f2fs.h       | 10 +++++-----
> >   fs/f2fs/inline.c     |  3 +--
> >   fs/f2fs/super.c      | 13 +++++++------
> >   4 files changed, 14 insertions(+), 14 deletions(-)
> >
> > diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> > index 8e1db5752fff..1eef597ed393 100644
> > --- a/fs/f2fs/checkpoint.c
> > +++ b/fs/f2fs/checkpoint.c
> > @@ -1604,7 +1604,7 @@ int f2fs_write_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> >   	unsigned long long ckpt_ver;
> >   	int err = 0;
> >   
> > -	if (f2fs_readonly(sbi->sb) || f2fs_hw_is_readonly(sbi))
> > +	if (f2fs_readonly(sbi->sb))
> >   		return -EROFS;
> >   
> >   	if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED))) {
> > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> > index 2d4a7ef62537..7de95133478a 100644
> > --- a/fs/f2fs/f2fs.h
> > +++ b/fs/f2fs/f2fs.h
> > @@ -4446,6 +4446,11 @@ static inline bool f2fs_hw_is_readonly(struct f2fs_sb_info *sbi)
> >   	return false;
> >   }
> >   
> > +static inline bool f2fs_dev_is_readonly(struct f2fs_sb_info *sbi)
> > +{
> > +	return f2fs_sb_has_readonly(sbi) || f2fs_hw_is_readonly(sbi);
> > +}
> > +
> >   static inline bool f2fs_lfs_mode(struct f2fs_sb_info *sbi)
> >   {
> >   	return F2FS_OPTION(sbi).fs_mode == FS_MODE_LFS;
> > @@ -4546,11 +4551,6 @@ static inline void f2fs_handle_page_eio(struct f2fs_sb_info *sbi, pgoff_t ofs,
> >   	}
> >   }
> >   
> > -static inline bool f2fs_is_readonly(struct f2fs_sb_info *sbi)
> > -{
> > -	return f2fs_sb_has_readonly(sbi) || f2fs_readonly(sbi->sb);
> > -}
> > -
> >   #define EFSBADCRC	EBADMSG		/* Bad CRC detected */
> >   #define EFSCORRUPTED	EUCLEAN		/* Filesystem is corrupted */
> >   
> > diff --git a/fs/f2fs/inline.c b/fs/f2fs/inline.c
> > index 72269e7efd26..2c36f2dc2317 100644
> > --- a/fs/f2fs/inline.c
> > +++ b/fs/f2fs/inline.c
> > @@ -203,8 +203,7 @@ int f2fs_convert_inline_inode(struct inode *inode)
> >   	struct page *ipage, *page;
> >   	int err = 0;
> >   
> > -	if (!f2fs_has_inline_data(inode) ||
> > -			f2fs_hw_is_readonly(sbi) || f2fs_readonly(sbi->sb))
> > +	if (!f2fs_has_inline_data(inode) || f2fs_readonly(sbi->sb))
> >   		return 0;
> >   
> >   	err = f2fs_dquot_initialize(inode);
> > diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> > index d016f398fcad..db7649010c12 100644
> > --- a/fs/f2fs/super.c
> > +++ b/fs/f2fs/super.c
> > @@ -1382,15 +1382,16 @@ static int parse_options(struct super_block *sb, char *options, bool is_remount)
> >   		return -EINVAL;
> >   	}
> >   
> > -	if (f2fs_is_readonly(sbi) && test_opt(sbi, FLUSH_MERGE)) {
> > +	if (f2fs_dev_is_readonly(sbi) && !f2fs_readonly(sbi->sb)) {
> > +		f2fs_err(sbi, "Allow to mount readonly mode only");
> > +		return -EROFS;
> > +	}
> > +
> > +	if (f2fs_readonly(sbi->sb) && test_opt(sbi, FLUSH_MERGE)) {
> >   		f2fs_err(sbi, "FLUSH_MERGE not compatible with readonly mode");
> >   		return -EINVAL;
> >   	}
> >   
> > -	if (f2fs_sb_has_readonly(sbi) && !f2fs_readonly(sbi->sb)) {
> > -		f2fs_err(sbi, "Allow to mount readonly mode only");
> > -		return -EROFS;
> > -	}
> >   	return 0;
> >   }
> >   
> > @@ -2122,7 +2123,7 @@ static void default_options(struct f2fs_sb_info *sbi)
> >   	set_opt(sbi, MERGE_CHECKPOINT);
> >   	F2FS_OPTION(sbi).unusable_cap = 0;
> >   	sbi->sb->s_flags |= SB_LAZYTIME;
> > -	if (!f2fs_is_readonly(sbi))
> > +	if (!f2fs_readonly(sbi->sb) && !f2fs_dev_is_readonly(sbi))
> >   		set_opt(sbi, FLUSH_MERGE);
> >   	if (f2fs_hw_support_discard(sbi) || f2fs_hw_should_discard(sbi))
> >   		set_opt(sbi, DISCARD);
> > --
> > 2.36.1