linux-kernel - Re: [f2fs-dev] [PATCH] Revert "f2fs: remove unreachable lazytime mount option parsing"

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Message-ID: <Zz5ILj2H-F8iBSHV@google.com>
Date: Wed, 20 Nov 2024 20:35:58 +0000
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: Chao Yu <chao@...nel.org>
Cc: Eric Sandeen <sandeen@...hat.com>, Daniel Rosenberg <drosen@...gle.com>,
	stable@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH] Revert "f2fs: remove unreachable lazytime
 mount option parsing"

On 11/20, Chao Yu wrote:
> On 2024/11/20 4:48, Jaegeuk Kim wrote:
> > On 11/19, Chao Yu wrote:
> > > On 2024/11/13 5:39, Jaegeuk Kim via Linux-f2fs-devel wrote:
> > > > Hi Eric,
> > > > 
> > > > Could you please check this revert as it breaks the mount()?
> > > > It seems F2FS needs to implement new mount support.
> > > 
> > > Hi all,
> > > 
> > > Actually, if we want to enable lazytime option, we can use mount
> > > syscall as:
> > > 
> > > mount("/dev/vdb", "/mnt/test", "f2fs", MS_LAZYTIME, NULL);
> > > 
> > > or use shell script as:
> > > 
> > > mount -t f2fs -o lazytime /dev/vdb /mnt/test
> > > 
> > > IIUC, the reason why mount command can handle lazytime is, after
> > > 8c7f073aaeaa ("libmount: add support for MS_LAZYTIME"), mount command
> > > supports to map "lazytime" to MS_LAZYTIME, and use MS_LAZYTIME in
> > > parameter @mountflags of mount(2).
> > > 
> > > So, it looks we have alternative way to enable/disable lazytime feature
> > > after removing Opt_{no,}lazytime parsing in f2fs, do we really need this
> > > revert patch?
> > 
> > This is a regression of the below command. I don't think offering others are
> > feasible.
> > 
> > mount("/dev/vdb", "/mnt/test", "f2fs", 0, "lazytime");
> 
> Alright, there are other options were removed along w/ removal of
> related feature. e.g.
> 
> 1. io_bits=%u by commit 87161a2b0aed ("f2fs: deprecate io_bits")
> 2. whint_mode=%s by commit 930e2607638d ("f2fs: remove obsolete whint_mode")
> 
> Do we need to add these options handling back, and print "xxx options were
> deprecated" as we did in ("f2fs: kill heap-based allocation"), in order to
> avoid mount(......, "io_bits=%u" or "whint_mode=%s") command regression?

These are different from the generic lazytime option, and I haven't got any
complaint on this removal.

> 
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index 867b147eb957..329f317e6f09 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -733,10 +733,8 @@ static int parse_options(struct super_block *sb, char *options, bool is_remount)
>  			clear_opt(sbi, DISCARD);
>  			break;
>  		case Opt_noheap:
> -			set_opt(sbi, NOHEAP);
> -			break;
>  		case Opt_heap:
> -			clear_opt(sbi, NOHEAP);
> +			f2fs_warn(sbi, "heap/no_heap options were deprecated");
>  			break;
> 
> Thanks,
> 
> > 
> > > 
> > > Thanks,
> > > 
> > > > 
> > > > Thanks,
> > > > 
> > > > On 11/12, Jaegeuk Kim wrote:
> > > > > This reverts commit 54f43a10fa257ad4af02a1d157fefef6ebcfa7dc.
> > > > > 
> > > > > The above commit broke the lazytime mount, given
> > > > > 
> > > > > mount("/dev/vdb", "/mnt/test", "f2fs", 0, "lazytime");
> > > > > 
> > > > > CC: stable@...r.kernel.org # 6.11+
> > > > > Signed-off-by: Daniel Rosenberg <drosen@...gle.com>
> > > > > Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
> > > > > ---
> > > > >    fs/f2fs/super.c | 10 ++++++++++
> > > > >    1 file changed, 10 insertions(+)
> > > > > 
> > > > > diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> > > > > index 49519439b770..35c4394e4fc6 100644
> > > > > --- a/fs/f2fs/super.c
> > > > > +++ b/fs/f2fs/super.c
> > > > > @@ -150,6 +150,8 @@ enum {
> > > > >    	Opt_mode,
> > > > >    	Opt_fault_injection,
> > > > >    	Opt_fault_type,
> > > > > +	Opt_lazytime,
> > > > > +	Opt_nolazytime,
> > > > >    	Opt_quota,
> > > > >    	Opt_noquota,
> > > > >    	Opt_usrquota,
> > > > > @@ -226,6 +228,8 @@ static match_table_t f2fs_tokens = {
> > > > >    	{Opt_mode, "mode=%s"},
> > > > >    	{Opt_fault_injection, "fault_injection=%u"},
> > > > >    	{Opt_fault_type, "fault_type=%u"},
> > > > > +	{Opt_lazytime, "lazytime"},
> > > > > +	{Opt_nolazytime, "nolazytime"},
> > > > >    	{Opt_quota, "quota"},
> > > > >    	{Opt_noquota, "noquota"},
> > > > >    	{Opt_usrquota, "usrquota"},
> > > > > @@ -922,6 +926,12 @@ static int parse_options(struct super_block *sb, char *options, bool is_remount)
> > > > >    			f2fs_info(sbi, "fault_type options not supported");
> > > > >    			break;
> > > > >    #endif
> > > > > +		case Opt_lazytime:
> > > > > +			sb->s_flags |= SB_LAZYTIME;
> > > > > +			break;
> > > > > +		case Opt_nolazytime:
> > > > > +			sb->s_flags &= ~SB_LAZYTIME;
> > > > > +			break;
> > > > >    #ifdef CONFIG_QUOTA
> > > > >    		case Opt_quota:
> > > > >    		case Opt_usrquota:
> > > > > -- 
> > > > > 2.47.0.277.g8800431eea-goog
> > > > 
> > > > 
> > > > _______________________________________________
> > > > Linux-f2fs-devel mailing list
> > > > Linux-f2fs-devel@...ts.sourceforge.net
> > > > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel