[PATCH 1/2] exfat: call sync_filesystem for read-only remount

[PATCH 1/2] exfat: call sync_filesystem for read-only remount

[Hyunchul Lee]

We need to commit dirty metadata and pages to disk
before remounting exfat as read-only.

This fixes a failure in xfstests generic/452

Signed-off-by: Hyunchul Lee <hyc.lee@gmail.com>
---
 fs/exfat/super.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/fs/exfat/super.c b/fs/exfat/super.c
index e650e65536f8..61c6cf240c19 100644
--- a/fs/exfat/super.c
+++ b/fs/exfat/super.c
@@ -693,10 +693,29 @@ static void exfat_free(struct fs_context *fc)
 	}
 }
 
+static int exfat_reconfigure(struct fs_context *fc)
+{
+	struct super_block *sb = fc->root->d_sb;
+	int ret;
+	bool new_rdonly;
+
+	new_rdonly = fc->sb_flags & SB_RDONLY;
+	if (new_rdonly != sb_rdonly(sb)) {
+		if (new_rdonly) {
+			/* volume flag will be updated in exfat_sync_fs */
+			ret = sync_filesystem(sb);
+			if (ret < 0)
+				return ret;
+		}
+	}
+	return 0;
+}
+
 static const struct fs_context_operations exfat_context_ops = {
 	.parse_param	= exfat_parse_param,
 	.get_tree	= exfat_get_tree,
 	.free		= exfat_free,
+	.reconfigure	= exfat_reconfigure,
 };
 
 static int exfat_init_fs_context(struct fs_context *fc)
-- 
2.17.1

[PATCH 2/2] exfat: allow to change some mount options for remount

[Hyunchul Lee]

Allow to change permission masks, allow_utime,
errors. But ignore other options.

Signed-off-by: Hyunchul Lee <hyc.lee@gmail.com>
---
 fs/exfat/super.c | 40 +++++++++++++++++++++++++++++-----------
 1 file changed, 29 insertions(+), 11 deletions(-)

diff --git a/fs/exfat/super.c b/fs/exfat/super.c
index 61c6cf240c19..3c1d47289ba2 100644
--- a/fs/exfat/super.c
+++ b/fs/exfat/super.c
@@ -696,9 +696,13 @@ static void exfat_free(struct fs_context *fc)
 static int exfat_reconfigure(struct fs_context *fc)
 {
 	struct super_block *sb = fc->root->d_sb;
+	struct exfat_sb_info *sbi = EXFAT_SB(sb);
+	struct exfat_mount_options *new_opts;
 	int ret;
 	bool new_rdonly;
 
+	new_opts = &((struct exfat_sb_info *)fc->s_fs_info)->options;
+
 	new_rdonly = fc->sb_flags & SB_RDONLY;
 	if (new_rdonly != sb_rdonly(sb)) {
 		if (new_rdonly) {
@@ -708,6 +712,12 @@ static int exfat_reconfigure(struct fs_context *fc)
 				return ret;
 		}
 	}
+
+	/* allow to change these options but ignore others */
+	sbi->options.fs_fmask = new_opts->fs_fmask;
+	sbi->options.fs_dmask = new_opts->fs_dmask;
+	sbi->options.allow_utime = new_opts->allow_utime;
+	sbi->options.errors = new_opts->errors;
 	return 0;
 }
 
@@ -726,17 +736,25 @@ static int exfat_init_fs_context(struct fs_context *fc)
 	if (!sbi)
 		return -ENOMEM;
 
-	mutex_init(&sbi->s_lock);
-	ratelimit_state_init(&sbi->ratelimit, DEFAULT_RATELIMIT_INTERVAL,
-			DEFAULT_RATELIMIT_BURST);
-
-	sbi->options.fs_uid = current_uid();
-	sbi->options.fs_gid = current_gid();
-	sbi->options.fs_fmask = current->fs->umask;
-	sbi->options.fs_dmask = current->fs->umask;
-	sbi->options.allow_utime = -1;
-	sbi->options.iocharset = exfat_default_iocharset;
-	sbi->options.errors = EXFAT_ERRORS_RO;
+	if (fc->root) {
+		/* reconfiguration */
+		memcpy(&sbi->options, &EXFAT_SB(fc->root->d_sb)->options,
+			sizeof(struct exfat_mount_options));
+		sbi->options.iocharset = exfat_default_iocharset;
+	} else {
+		mutex_init(&sbi->s_lock);
+		ratelimit_state_init(&sbi->ratelimit,
+				DEFAULT_RATELIMIT_INTERVAL,
+				DEFAULT_RATELIMIT_BURST);
+
+		sbi->options.fs_uid = current_uid();
+		sbi->options.fs_gid = current_gid();
+		sbi->options.fs_fmask = current->fs->umask;
+		sbi->options.fs_dmask = current->fs->umask;
+		sbi->options.allow_utime = -1;
+		sbi->options.iocharset = exfat_default_iocharset;
+		sbi->options.errors = EXFAT_ERRORS_RO;
+	}
 
 	fc->s_fs_info = sbi;
 	fc->ops = &exfat_context_ops;
-- 
2.17.1

RE: [PATCH 1/2] exfat: call sync_filesystem for read-only remount

[Namjae Jeon]

Hi Hyunchul,
> We need to commit dirty metadata and pages to disk before remounting exfat as read-only.
> 
> This fixes a failure in xfstests generic/452
Could you please elaborate more the reason why generic/452 in xfstests failed ?
> 
> Signed-off-by: Hyunchul Lee <hyc.lee@gmail.com>
> ---
>  fs/exfat/super.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/fs/exfat/super.c b/fs/exfat/super.c index e650e65536f8..61c6cf240c19 100644
> --- a/fs/exfat/super.c
> +++ b/fs/exfat/super.c
> @@ -693,10 +693,29 @@ static void exfat_free(struct fs_context *fc)
>  	}
>  }
> 
> +static int exfat_reconfigure(struct fs_context *fc) {
> +	struct super_block *sb = fc->root->d_sb;
> +	int ret;
int ret = 0;
> +	bool new_rdonly;
> +
> +	new_rdonly = fc->sb_flags & SB_RDONLY;
> +	if (new_rdonly != sb_rdonly(sb)) {
If you modify it like this, would not we need new_rdonly?
        if (fc->sb_flags & SB_RDONLY && !sb_rdonly(sb))

> +		if (new_rdonly) {
> +			/* volume flag will be updated in exfat_sync_fs */
> +			ret = sync_filesystem(sb);
> +			if (ret < 0)
> +				return ret;
I think that this ret check can be removed by using return ret; below ?
> +		}
> +	}
> +	return 0;
return ret;
> +}
> +
>  static const struct fs_context_operations exfat_context_ops = {
>  	.parse_param	= exfat_parse_param,
>  	.get_tree	= exfat_get_tree,
>  	.free		= exfat_free,
> +	.reconfigure	= exfat_reconfigure,
>  };
> 
>  static int exfat_init_fs_context(struct fs_context *fc)
> --
> 2.17.1

RE: [PATCH 2/2] exfat: allow to change some mount options for remount

[Namjae Jeon]

> Allow to change permission masks, allow_utime, errors. But ignore other options.
> 
> Signed-off-by: Hyunchul Lee <hyc.lee@gmail.com>
> ---
>  fs/exfat/super.c | 40 +++++++++++++++++++++++++++++-----------
>  1 file changed, 29 insertions(+), 11 deletions(-)
> 
> diff --git a/fs/exfat/super.c b/fs/exfat/super.c index 61c6cf240c19..3c1d47289ba2 100644
> --- a/fs/exfat/super.c
> +++ b/fs/exfat/super.c
> @@ -696,9 +696,13 @@ static void exfat_free(struct fs_context *fc)  static int
> exfat_reconfigure(struct fs_context *fc)  {
>  	struct super_block *sb = fc->root->d_sb;
> +	struct exfat_sb_info *sbi = EXFAT_SB(sb);
> +	struct exfat_mount_options *new_opts;
>  	int ret;
>  	bool new_rdonly;
> 
> +	new_opts = &((struct exfat_sb_info *)fc->s_fs_info)->options;
> +
>  	new_rdonly = fc->sb_flags & SB_RDONLY;
>  	if (new_rdonly != sb_rdonly(sb)) {
>  		if (new_rdonly) {
> @@ -708,6 +712,12 @@ static int exfat_reconfigure(struct fs_context *fc)
>  				return ret;
>  		}
>  	}
> +
> +	/* allow to change these options but ignore others */
> +	sbi->options.fs_fmask = new_opts->fs_fmask;
> +	sbi->options.fs_dmask = new_opts->fs_dmask;
> +	sbi->options.allow_utime = new_opts->allow_utime;
> +	sbi->options.errors = new_opts->errors;
Is there any reason why you allow a few options on remount ?
>  	return 0;
>  }
> 
> @@ -726,17 +736,25 @@ static int exfat_init_fs_context(struct fs_context *fc)
>  	if (!sbi)
>  		return -ENOMEM;
> 
> -	mutex_init(&sbi->s_lock);
> -	ratelimit_state_init(&sbi->ratelimit, DEFAULT_RATELIMIT_INTERVAL,
> -			DEFAULT_RATELIMIT_BURST);
> -
> -	sbi->options.fs_uid = current_uid();
> -	sbi->options.fs_gid = current_gid();
> -	sbi->options.fs_fmask = current->fs->umask;
> -	sbi->options.fs_dmask = current->fs->umask;
> -	sbi->options.allow_utime = -1;
> -	sbi->options.iocharset = exfat_default_iocharset;
> -	sbi->options.errors = EXFAT_ERRORS_RO;
> +	if (fc->root) {
> +		/* reconfiguration */
> +		memcpy(&sbi->options, &EXFAT_SB(fc->root->d_sb)->options,
> +			sizeof(struct exfat_mount_options));
> +		sbi->options.iocharset = exfat_default_iocharset;
> +	} else {
> +		mutex_init(&sbi->s_lock);
> +		ratelimit_state_init(&sbi->ratelimit,
> +				DEFAULT_RATELIMIT_INTERVAL,
> +				DEFAULT_RATELIMIT_BURST);
> +
> +		sbi->options.fs_uid = current_uid();
> +		sbi->options.fs_gid = current_gid();
> +		sbi->options.fs_fmask = current->fs->umask;
> +		sbi->options.fs_dmask = current->fs->umask;
> +		sbi->options.allow_utime = -1;
> +		sbi->options.iocharset = exfat_default_iocharset;
> +		sbi->options.errors = EXFAT_ERRORS_RO;
> +	}
> 
>  	fc->s_fs_info = sbi;
>  	fc->ops = &exfat_context_ops;
> --
> 2.17.1

Re: [PATCH 1/2] exfat: call sync_filesystem for read-only remount

[Hyunchul Lee]

Hi Namjae,

2020년 6월 15일 (월) 오전 9:14, Namjae Jeon <namjae.jeon@samsung.com>님이 작성:
>
> Hi Hyunchul,
> > We need to commit dirty metadata and pages to disk before remounting exfat as read-only.
> >
> > This fixes a failure in xfstests generic/452
> Could you please elaborate more the reason why generic/452 in xfstests failed ?

xfstests generic/452 does the following.
cp /bin/ls <exfat>/
mount -o remount,ro <exfat>

the <exfat>/ls file is corrupted, because while exfat is remounted as read-only,
exfat doesn't have a chance to commit metadata and vfs invalidates page
caches in a block device.

I will put this explanation in a commit message.

> >
> > Signed-off-by: Hyunchul Lee <hyc.lee@gmail.com>
> > ---
> >  fs/exfat/super.c | 19 +++++++++++++++++++
> >  1 file changed, 19 insertions(+)
> >
> > diff --git a/fs/exfat/super.c b/fs/exfat/super.c index e650e65536f8..61c6cf240c19 100644
> > --- a/fs/exfat/super.c
> > +++ b/fs/exfat/super.c
> > @@ -693,10 +693,29 @@ static void exfat_free(struct fs_context *fc)
> >       }
> >  }
> >
> > +static int exfat_reconfigure(struct fs_context *fc) {
> > +     struct super_block *sb = fc->root->d_sb;
> > +     int ret;
> int ret = 0;
> > +     bool new_rdonly;
> > +
> > +     new_rdonly = fc->sb_flags & SB_RDONLY;
> > +     if (new_rdonly != sb_rdonly(sb)) {
> If you modify it like this, would not we need new_rdonly?
>         if (fc->sb_flags & SB_RDONLY && !sb_rdonly(sb))
>
This condition means that mount options are changed from "rw" to "ro",
or "ro" to "rw".

> > +             if (new_rdonly) {

And this condition means these options are changed from "rw" to "ro".
It seems better to change two conditions to the one you suggested, or
remove those. because sync_filesystem returns 0 when the filesystem is
mounted as read-only.

> > +                     /* volume flag will be updated in exfat_sync_fs */
> > +                     ret = sync_filesystem(sb);
> > +                     if (ret < 0)
> > +                             return ret;
> I think that this ret check can be removed by using return ret; below ?

Okay, I will apply this.
Thank you for your comments!


> > +             }
> > +     }
> > +     return 0;
> return ret;
> > +}
> > +
> >  static const struct fs_context_operations exfat_context_ops = {
> >       .parse_param    = exfat_parse_param,
> >       .get_tree       = exfat_get_tree,
> >       .free           = exfat_free,
> > +     .reconfigure    = exfat_reconfigure,
> >  };
> >
> >  static int exfat_init_fs_context(struct fs_context *fc)
> > --
> > 2.17.1
>
>

Re: [PATCH 2/2] exfat: allow to change some mount options for remount

[Hyunchul Lee]

2020년 6월 15일 (월) 오전 9:18, Namjae Jeon <namjae.jeon@samsung.com>님이 작성:
>
> > Allow to change permission masks, allow_utime, errors. But ignore other options.
> >
> > Signed-off-by: Hyunchul Lee <hyc.lee@gmail.com>
> > ---
> >  fs/exfat/super.c | 40 +++++++++++++++++++++++++++++-----------
> >  1 file changed, 29 insertions(+), 11 deletions(-)
> >
> > diff --git a/fs/exfat/super.c b/fs/exfat/super.c index 61c6cf240c19..3c1d47289ba2 100644
> > --- a/fs/exfat/super.c
> > +++ b/fs/exfat/super.c
> > @@ -696,9 +696,13 @@ static void exfat_free(struct fs_context *fc)  static int
> > exfat_reconfigure(struct fs_context *fc)  {
> >       struct super_block *sb = fc->root->d_sb;
> > +     struct exfat_sb_info *sbi = EXFAT_SB(sb);
> > +     struct exfat_mount_options *new_opts;
> >       int ret;
> >       bool new_rdonly;
> >
> > +     new_opts = &((struct exfat_sb_info *)fc->s_fs_info)->options;
> > +
> >       new_rdonly = fc->sb_flags & SB_RDONLY;
> >       if (new_rdonly != sb_rdonly(sb)) {
> >               if (new_rdonly) {
> > @@ -708,6 +712,12 @@ static int exfat_reconfigure(struct fs_context *fc)
> >                               return ret;
> >               }
> >       }
> > +
> > +     /* allow to change these options but ignore others */
> > +     sbi->options.fs_fmask = new_opts->fs_fmask;
> > +     sbi->options.fs_dmask = new_opts->fs_dmask;
> > +     sbi->options.allow_utime = new_opts->allow_utime;
> > +     sbi->options.errors = new_opts->errors;
> Is there any reason why you allow a few options on remount ?

while exfat is remounted, inodes are not reclaimed. So I think
changing fs_uid, fs_gid, or time_offset is not impossible.
And I am not sure changing the iocharset is safe.

I am curious about your opinion.

Thanks.


> >       return 0;
> >  }
> >
> > @@ -726,17 +736,25 @@ static int exfat_init_fs_context(struct fs_context *fc)
> >       if (!sbi)
> >               return -ENOMEM;
> >
> > -     mutex_init(&sbi->s_lock);
> > -     ratelimit_state_init(&sbi->ratelimit, DEFAULT_RATELIMIT_INTERVAL,
> > -                     DEFAULT_RATELIMIT_BURST);
> > -
> > -     sbi->options.fs_uid = current_uid();
> > -     sbi->options.fs_gid = current_gid();
> > -     sbi->options.fs_fmask = current->fs->umask;
> > -     sbi->options.fs_dmask = current->fs->umask;
> > -     sbi->options.allow_utime = -1;
> > -     sbi->options.iocharset = exfat_default_iocharset;
> > -     sbi->options.errors = EXFAT_ERRORS_RO;
> > +     if (fc->root) {
> > +             /* reconfiguration */
> > +             memcpy(&sbi->options, &EXFAT_SB(fc->root->d_sb)->options,
> > +                     sizeof(struct exfat_mount_options));
> > +             sbi->options.iocharset = exfat_default_iocharset;
> > +     } else {
> > +             mutex_init(&sbi->s_lock);
> > +             ratelimit_state_init(&sbi->ratelimit,
> > +                             DEFAULT_RATELIMIT_INTERVAL,
> > +                             DEFAULT_RATELIMIT_BURST);
> > +
> > +             sbi->options.fs_uid = current_uid();
> > +             sbi->options.fs_gid = current_gid();
> > +             sbi->options.fs_fmask = current->fs->umask;
> > +             sbi->options.fs_dmask = current->fs->umask;
> > +             sbi->options.allow_utime = -1;
> > +             sbi->options.iocharset = exfat_default_iocharset;
> > +             sbi->options.errors = EXFAT_ERRORS_RO;
> > +     }
> >
> >       fc->s_fs_info = sbi;
> >       fc->ops = &exfat_context_ops;
> > --
> > 2.17.1
>
>

RE: [PATCH 1/2] exfat: call sync_filesystem for read-only remount

[Namjae Jeon]

> Hi Namjae,
> 
> 2020년 6월 15일 (월) 오전 9:14, Namjae Jeon <namjae.jeon@samsung.com>님이 작성:
> >
> > Hi Hyunchul,
> > > We need to commit dirty metadata and pages to disk before remounting exfat as read-only.
> > >
> > > This fixes a failure in xfstests generic/452
> > Could you please elaborate more the reason why generic/452 in xfstests failed ?
> 
> xfstests generic/452 does the following.
> cp /bin/ls <exfat>/
> mount -o remount,ro <exfat>
> 
> the <exfat>/ls file is corrupted, because while exfat is remounted as read-only, exfat doesn't have a
> chance to commit metadata and vfs invalidates page caches in a block device.
Got it.
> 
> I will put this explanation in a commit message.
Good.
> 
> > >
> > > Signed-off-by: Hyunchul Lee <hyc.lee@gmail.com>
> > > ---
> > >  fs/exfat/super.c | 19 +++++++++++++++++++
> > >  1 file changed, 19 insertions(+)
> > >
> > > diff --git a/fs/exfat/super.c b/fs/exfat/super.c index
> > > e650e65536f8..61c6cf240c19 100644
> > > --- a/fs/exfat/super.c
> > > +++ b/fs/exfat/super.c
> > > @@ -693,10 +693,29 @@ static void exfat_free(struct fs_context *fc)
> > >       }
> > >  }
> > >
> > > +static int exfat_reconfigure(struct fs_context *fc) {
> > > +     struct super_block *sb = fc->root->d_sb;
> > > +     int ret;
> > int ret = 0;
> > > +     bool new_rdonly;
> > > +
> > > +     new_rdonly = fc->sb_flags & SB_RDONLY;
> > > +     if (new_rdonly != sb_rdonly(sb)) {
> > If you modify it like this, would not we need new_rdonly?
> >         if (fc->sb_flags & SB_RDONLY && !sb_rdonly(sb))
> >
> This condition means that mount options are changed from "rw" to "ro", or "ro" to "rw".
> 
> > > +             if (new_rdonly) {
> 
> And this condition means these options are changed from "rw" to "ro".
> It seems better to change two conditions to the one you suggested, or remove those. because
> sync_filesystem returns 0 when the filesystem is mounted as read-only.
The latter would be fine.
> 
> > > +                     /* volume flag will be updated in exfat_sync_fs */
> > > +                     ret = sync_filesystem(sb);
> > > +                     if (ret < 0)
> > > +                             return ret;
> > I think that this ret check can be removed by using return ret; below ?
> 
> Okay, I will apply this.
> Thank you for your comments!
Thanks for your patch!
> 
> 
> > > +             }
> > > +     }
> > > +     return 0;
> > return ret;
> > > +}
> > > +
> > >  static const struct fs_context_operations exfat_context_ops = {
> > >       .parse_param    = exfat_parse_param,
> > >       .get_tree       = exfat_get_tree,
> > >       .free           = exfat_free,
> > > +     .reconfigure    = exfat_reconfigure,
> > >  };
> > >
> > >  static int exfat_init_fs_context(struct fs_context *fc)
> > > --
> > > 2.17.1
> >
> >