[PATCH v2 1/6] fs: enhance and rename shutdown() callback to remove_bdev()

[PATCH v2 1/6] fs: enhance and rename shutdown() callback to remove_bdev()

[Qu Wenruo]

Currently all the filesystems implementing the
super_opearations::shutdown() call back can not afford losing a device.

Thus fs_bdev_mark_dead() will just call the shutdown() callback for the
involved filesystem.

But it will no longer be the case, with multi-device filesystems like
btrfs and bcachefs the filesystem can handle certain device loss without
shutting down the whole filesystem.

To allow those multi-device filesystems to be integrated to use
fs_holder_ops:

- Rename shutdown() call back to remove_bdev()
  To better describe when the call back is called.

- Add a new @bdev parameter to remove_bdev() callback
  To allow the fs to determine which device is missing, and do the
  proper handling when needed.

For the existing shutdown callback users, the change is minimal.

They only need to follow the rename and the new parameter list.
Since the behavior is still to shutdown the fs, they shouldn't change
their function names.

This has a good side effect that, a single line like
".remove_bdev = ext4_shutdown," will easily show the fs behavior and
indicate the fs will shutdown when a device went missing.

Btrfs is going to implement the callback soon, which will either
shutdown the fs or continue read-write operations.

Cc: linux-fsdevel@vger.kernel.org
Cc: linux-ext4@vger.kernel.org
Cc: linux-f2fs-devel@lists.sourceforge.net
Cc: ntfs3@lists.linux.dev
Cc: linux-xfs@vger.kernel.org
Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 fs/exfat/super.c   | 4 ++--
 fs/ext4/super.c    | 4 ++--
 fs/f2fs/super.c    | 4 ++--
 fs/ntfs3/super.c   | 4 ++--
 fs/super.c         | 4 ++--
 fs/xfs/xfs_super.c | 5 +++--
 include/linux/fs.h | 7 ++++++-
 7 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/fs/exfat/super.c b/fs/exfat/super.c
index 7ed858937d45..5773026be84c 100644
--- a/fs/exfat/super.c
+++ b/fs/exfat/super.c
@@ -172,7 +172,7 @@ int exfat_force_shutdown(struct super_block *sb, u32 flags)
 	return 0;
 }
 
-static void exfat_shutdown(struct super_block *sb)
+static void exfat_shutdown(struct super_block *sb, struct block_device *bdev)
 {
 	exfat_force_shutdown(sb, EXFAT_GOING_DOWN_NOSYNC);
 }
@@ -202,7 +202,7 @@ static const struct super_operations exfat_sops = {
 	.put_super	= exfat_put_super,
 	.statfs		= exfat_statfs,
 	.show_options	= exfat_show_options,
-	.shutdown	= exfat_shutdown,
+	.remove_bdev	= exfat_shutdown,
 };
 
 enum {
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index c7d39da7e733..8724f89d20d8 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1456,7 +1456,7 @@ static void ext4_destroy_inode(struct inode *inode)
 			 EXT4_I(inode)->i_reserved_data_blocks);
 }
 
-static void ext4_shutdown(struct super_block *sb)
+static void ext4_shutdown(struct super_block *sb, struct block_device *bdev)
 {
        ext4_force_shutdown(sb, EXT4_GOING_FLAGS_NOLOGFLUSH);
 }
@@ -1620,7 +1620,7 @@ static const struct super_operations ext4_sops = {
 	.unfreeze_fs	= ext4_unfreeze,
 	.statfs		= ext4_statfs,
 	.show_options	= ext4_show_options,
-	.shutdown	= ext4_shutdown,
+	.remove_bdev	= ext4_shutdown,
 #ifdef CONFIG_QUOTA
 	.quota_read	= ext4_quota_read,
 	.quota_write	= ext4_quota_write,
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index bbf1dad6843f..51c60b429a31 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -2640,7 +2640,7 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
 	return err;
 }
 
-static void f2fs_shutdown(struct super_block *sb)
+static void f2fs_shutdown(struct super_block *sb, struct block_device *bdev)
 {
 	f2fs_do_shutdown(F2FS_SB(sb), F2FS_GOING_DOWN_NOSYNC, false, false);
 }
@@ -3264,7 +3264,7 @@ static const struct super_operations f2fs_sops = {
 	.unfreeze_fs	= f2fs_unfreeze,
 	.statfs		= f2fs_statfs,
 	.remount_fs	= f2fs_remount,
-	.shutdown	= f2fs_shutdown,
+	.remove_bdev	= f2fs_shutdown,
 };
 
 #ifdef CONFIG_FS_ENCRYPTION
diff --git a/fs/ntfs3/super.c b/fs/ntfs3/super.c
index 920a1ab47b63..5e422543b851 100644
--- a/fs/ntfs3/super.c
+++ b/fs/ntfs3/super.c
@@ -764,7 +764,7 @@ static int ntfs_show_options(struct seq_file *m, struct dentry *root)
 /*
  * ntfs_shutdown - super_operations::shutdown
  */
-static void ntfs_shutdown(struct super_block *sb)
+static void ntfs_shutdown(struct super_block *sb, struct block_device *bdev)
 {
 	set_bit(NTFS_FLAGS_SHUTDOWN_BIT, &ntfs_sb(sb)->flags);
 }
@@ -821,7 +821,7 @@ static const struct super_operations ntfs_sops = {
 	.put_super = ntfs_put_super,
 	.statfs = ntfs_statfs,
 	.show_options = ntfs_show_options,
-	.shutdown = ntfs_shutdown,
+	.remove_bdev = ntfs_shutdown,
 	.sync_fs = ntfs_sync_fs,
 	.write_inode = ntfs3_write_inode,
 };
diff --git a/fs/super.c b/fs/super.c
index 80418ca8e215..c972efb38f6a 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -1463,8 +1463,8 @@ static void fs_bdev_mark_dead(struct block_device *bdev, bool surprise)
 		sync_filesystem(sb);
 	shrink_dcache_sb(sb);
 	evict_inodes(sb);
-	if (sb->s_op->shutdown)
-		sb->s_op->shutdown(sb);
+	if (sb->s_op->remove_bdev)
+		sb->s_op->remove_bdev(sb, bdev);
 
 	super_unlock_shared(sb);
 }
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 0bc4b5489078..e47d427f4416 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -1277,7 +1277,8 @@ xfs_fs_free_cached_objects(
 
 static void
 xfs_fs_shutdown(
-	struct super_block	*sb)
+	struct super_block	*sb,
+	struct block_device	*bdev)
 {
 	xfs_force_shutdown(XFS_M(sb), SHUTDOWN_DEVICE_REMOVED);
 }
@@ -1308,7 +1309,7 @@ static const struct super_operations xfs_super_operations = {
 	.show_options		= xfs_fs_show_options,
 	.nr_cached_objects	= xfs_fs_nr_cached_objects,
 	.free_cached_objects	= xfs_fs_free_cached_objects,
-	.shutdown		= xfs_fs_shutdown,
+	.remove_bdev		= xfs_fs_shutdown,
 	.show_stats		= xfs_fs_show_stats,
 };
 
diff --git a/include/linux/fs.h b/include/linux/fs.h
index b085f161ed22..b08af63d2d4f 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2367,7 +2367,12 @@ struct super_operations {
 				  struct shrink_control *);
 	long (*free_cached_objects)(struct super_block *,
 				    struct shrink_control *);
-	void (*shutdown)(struct super_block *sb);
+	/*
+	 * Called when block device @bdev belonging to @sb is removed.
+	 *
+	 * If the fs can't afford the device loss, it should be shutdown.
+	 */
+	void (*remove_bdev)(struct super_block *sb, struct block_device *bdev);
 };
 
 /*
-- 
2.50.0

Re: [PATCH v2 1/6] fs: enhance and rename shutdown() callback to remove_bdev()

[Darrick J. Wong]

On Tue, Jul 01, 2025 at 03:02:34PM +0930, Qu Wenruo wrote:
> Currently all the filesystems implementing the
> super_opearations::shutdown() call back can not afford losing a device.
> 
> Thus fs_bdev_mark_dead() will just call the shutdown() callback for the
> involved filesystem.
> 
> But it will no longer be the case, with multi-device filesystems like
> btrfs and bcachefs the filesystem can handle certain device loss without
> shutting down the whole filesystem.
> 
> To allow those multi-device filesystems to be integrated to use
> fs_holder_ops:
> 
> - Rename shutdown() call back to remove_bdev()
>   To better describe when the call back is called.
> 
> - Add a new @bdev parameter to remove_bdev() callback
>   To allow the fs to determine which device is missing, and do the
>   proper handling when needed.
> 
> For the existing shutdown callback users, the change is minimal.
> 
> They only need to follow the rename and the new parameter list.
> Since the behavior is still to shutdown the fs, they shouldn't change
> their function names.
> 
> This has a good side effect that, a single line like
> ".remove_bdev = ext4_shutdown," will easily show the fs behavior and
> indicate the fs will shutdown when a device went missing.
> 
> Btrfs is going to implement the callback soon, which will either
> shutdown the fs or continue read-write operations.

Hrmm, this could be useful for xfs rt devices, if we could some day
reattach a resurrected bdev to a still-running filesystem....

Looks good to me,
Acked-by: "Darrick J. Wong" <djwong@kernel.org>

--D


> Cc: linux-fsdevel@vger.kernel.org
> Cc: linux-ext4@vger.kernel.org
> Cc: linux-f2fs-devel@lists.sourceforge.net
> Cc: ntfs3@lists.linux.dev
> Cc: linux-xfs@vger.kernel.org
> Signed-off-by: Qu Wenruo <wqu@suse.com>
> ---
>  fs/exfat/super.c   | 4 ++--
>  fs/ext4/super.c    | 4 ++--
>  fs/f2fs/super.c    | 4 ++--
>  fs/ntfs3/super.c   | 4 ++--
>  fs/super.c         | 4 ++--
>  fs/xfs/xfs_super.c | 5 +++--
>  include/linux/fs.h | 7 ++++++-
>  7 files changed, 19 insertions(+), 13 deletions(-)
> 
> diff --git a/fs/exfat/super.c b/fs/exfat/super.c
> index 7ed858937d45..5773026be84c 100644
> --- a/fs/exfat/super.c
> +++ b/fs/exfat/super.c
> @@ -172,7 +172,7 @@ int exfat_force_shutdown(struct super_block *sb, u32 flags)
>  	return 0;
>  }
>  
> -static void exfat_shutdown(struct super_block *sb)
> +static void exfat_shutdown(struct super_block *sb, struct block_device *bdev)
>  {
>  	exfat_force_shutdown(sb, EXFAT_GOING_DOWN_NOSYNC);
>  }
> @@ -202,7 +202,7 @@ static const struct super_operations exfat_sops = {
>  	.put_super	= exfat_put_super,
>  	.statfs		= exfat_statfs,
>  	.show_options	= exfat_show_options,
> -	.shutdown	= exfat_shutdown,
> +	.remove_bdev	= exfat_shutdown,
>  };
>  
>  enum {
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index c7d39da7e733..8724f89d20d8 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -1456,7 +1456,7 @@ static void ext4_destroy_inode(struct inode *inode)
>  			 EXT4_I(inode)->i_reserved_data_blocks);
>  }
>  
> -static void ext4_shutdown(struct super_block *sb)
> +static void ext4_shutdown(struct super_block *sb, struct block_device *bdev)
>  {
>         ext4_force_shutdown(sb, EXT4_GOING_FLAGS_NOLOGFLUSH);
>  }
> @@ -1620,7 +1620,7 @@ static const struct super_operations ext4_sops = {
>  	.unfreeze_fs	= ext4_unfreeze,
>  	.statfs		= ext4_statfs,
>  	.show_options	= ext4_show_options,
> -	.shutdown	= ext4_shutdown,
> +	.remove_bdev	= ext4_shutdown,
>  #ifdef CONFIG_QUOTA
>  	.quota_read	= ext4_quota_read,
>  	.quota_write	= ext4_quota_write,
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index bbf1dad6843f..51c60b429a31 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -2640,7 +2640,7 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
>  	return err;
>  }
>  
> -static void f2fs_shutdown(struct super_block *sb)
> +static void f2fs_shutdown(struct super_block *sb, struct block_device *bdev)
>  {
>  	f2fs_do_shutdown(F2FS_SB(sb), F2FS_GOING_DOWN_NOSYNC, false, false);
>  }
> @@ -3264,7 +3264,7 @@ static const struct super_operations f2fs_sops = {
>  	.unfreeze_fs	= f2fs_unfreeze,
>  	.statfs		= f2fs_statfs,
>  	.remount_fs	= f2fs_remount,
> -	.shutdown	= f2fs_shutdown,
> +	.remove_bdev	= f2fs_shutdown,
>  };
>  
>  #ifdef CONFIG_FS_ENCRYPTION
> diff --git a/fs/ntfs3/super.c b/fs/ntfs3/super.c
> index 920a1ab47b63..5e422543b851 100644
> --- a/fs/ntfs3/super.c
> +++ b/fs/ntfs3/super.c
> @@ -764,7 +764,7 @@ static int ntfs_show_options(struct seq_file *m, struct dentry *root)
>  /*
>   * ntfs_shutdown - super_operations::shutdown
>   */
> -static void ntfs_shutdown(struct super_block *sb)
> +static void ntfs_shutdown(struct super_block *sb, struct block_device *bdev)
>  {
>  	set_bit(NTFS_FLAGS_SHUTDOWN_BIT, &ntfs_sb(sb)->flags);
>  }
> @@ -821,7 +821,7 @@ static const struct super_operations ntfs_sops = {
>  	.put_super = ntfs_put_super,
>  	.statfs = ntfs_statfs,
>  	.show_options = ntfs_show_options,
> -	.shutdown = ntfs_shutdown,
> +	.remove_bdev = ntfs_shutdown,
>  	.sync_fs = ntfs_sync_fs,
>  	.write_inode = ntfs3_write_inode,
>  };
> diff --git a/fs/super.c b/fs/super.c
> index 80418ca8e215..c972efb38f6a 100644
> --- a/fs/super.c
> +++ b/fs/super.c
> @@ -1463,8 +1463,8 @@ static void fs_bdev_mark_dead(struct block_device *bdev, bool surprise)
>  		sync_filesystem(sb);
>  	shrink_dcache_sb(sb);
>  	evict_inodes(sb);
> -	if (sb->s_op->shutdown)
> -		sb->s_op->shutdown(sb);
> +	if (sb->s_op->remove_bdev)
> +		sb->s_op->remove_bdev(sb, bdev);
>  
>  	super_unlock_shared(sb);
>  }
> diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> index 0bc4b5489078..e47d427f4416 100644
> --- a/fs/xfs/xfs_super.c
> +++ b/fs/xfs/xfs_super.c
> @@ -1277,7 +1277,8 @@ xfs_fs_free_cached_objects(
>  
>  static void
>  xfs_fs_shutdown(
> -	struct super_block	*sb)
> +	struct super_block	*sb,
> +	struct block_device	*bdev)
>  {
>  	xfs_force_shutdown(XFS_M(sb), SHUTDOWN_DEVICE_REMOVED);
>  }
> @@ -1308,7 +1309,7 @@ static const struct super_operations xfs_super_operations = {
>  	.show_options		= xfs_fs_show_options,
>  	.nr_cached_objects	= xfs_fs_nr_cached_objects,
>  	.free_cached_objects	= xfs_fs_free_cached_objects,
> -	.shutdown		= xfs_fs_shutdown,
> +	.remove_bdev		= xfs_fs_shutdown,
>  	.show_stats		= xfs_fs_show_stats,
>  };
>  
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index b085f161ed22..b08af63d2d4f 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -2367,7 +2367,12 @@ struct super_operations {
>  				  struct shrink_control *);
>  	long (*free_cached_objects)(struct super_block *,
>  				    struct shrink_control *);
> -	void (*shutdown)(struct super_block *sb);
> +	/*
> +	 * Called when block device @bdev belonging to @sb is removed.
> +	 *
> +	 * If the fs can't afford the device loss, it should be shutdown.
> +	 */
> +	void (*remove_bdev)(struct super_block *sb, struct block_device *bdev);
>  };
>  
>  /*
> -- 
> 2.50.0
> 
> 

Re: [PATCH v2 1/6] fs: enhance and rename shutdown() callback to remove_bdev()

[Christoph Hellwig]

On Tue, Jul 01, 2025 at 03:02:34PM +0930, Qu Wenruo wrote:
> To allow those multi-device filesystems to be integrated to use
> fs_holder_ops:
> 
> - Rename shutdown() call back to remove_bdev()
>   To better describe when the call back is called.

What is renamed back here?

> -static void exfat_shutdown(struct super_block *sb)
> +static void exfat_shutdown(struct super_block *sb, struct block_device *bdev)
>  {
>  	exfat_force_shutdown(sb, EXFAT_GOING_DOWN_NOSYNC);
>  }
> @@ -202,7 +202,7 @@ static const struct super_operations exfat_sops = {
>  	.put_super	= exfat_put_super,
>  	.statfs		= exfat_statfs,
>  	.show_options	= exfat_show_options,
> -	.shutdown	= exfat_shutdown,
> +	.remove_bdev	= exfat_shutdown,

Please also rename the function so that they match the method name.

Re: [PATCH v2 1/6] fs: enhance and rename shutdown() callback to remove_bdev()

[Qu Wenruo]

在 2025/7/1 15:44, Christoph Hellwig 写道:
> On Tue, Jul 01, 2025 at 03:02:34PM +0930, Qu Wenruo wrote:
>> To allow those multi-device filesystems to be integrated to use
>> fs_holder_ops:
>>
>> - Rename shutdown() call back to remove_bdev()
>>    To better describe when the call back is called.
> 
> What is renamed back here?

Rename the old shutdown to remove_bdev().

> 
>> -static void exfat_shutdown(struct super_block *sb)
>> +static void exfat_shutdown(struct super_block *sb, struct block_device *bdev)
>>   {
>>   	exfat_force_shutdown(sb, EXFAT_GOING_DOWN_NOSYNC);
>>   }
>> @@ -202,7 +202,7 @@ static const struct super_operations exfat_sops = {
>>   	.put_super	= exfat_put_super,
>>   	.statfs		= exfat_statfs,
>>   	.show_options	= exfat_show_options,
>> -	.shutdown	= exfat_shutdown,
>> +	.remove_bdev	= exfat_shutdown,
> 
> Please also rename the function so that they match the method name.

I prefer not, and it is intentionally left as is.

This give us a very clear view what a fs is expected to do.

If a fs can only shutdown when losing any device, a read won't need to 
dig into the details, just looking at that line will tell us what is the 
behavior.

Thanks,
Qu

Re: [PATCH v2 1/6] fs: enhance and rename shutdown() callback to remove_bdev()

[Christoph Hellwig]

On Tue, Jul 01, 2025 at 04:05:03PM +0930, Qu Wenruo wrote:
> > Please also rename the function so that they match the method name.
> 
> I prefer not, and it is intentionally left as is.
> 
> This give us a very clear view what a fs is expected to do.

No.  Mismatching method are an insane pest that makes refactoring
or even just reading the code painful as hell.

Nacked-by: Christoph Hellwig <hch@lst.de>

without that.

Re: [PATCH v2 1/6] fs: enhance and rename shutdown() callback to remove_bdev()

[Christian Brauner]

On Tue, Jul 01, 2025 at 04:05:03PM +0930, Qu Wenruo wrote:
> 
> 
> 在 2025/7/1 15:44, Christoph Hellwig 写道:
> > On Tue, Jul 01, 2025 at 03:02:34PM +0930, Qu Wenruo wrote:
> > > To allow those multi-device filesystems to be integrated to use
> > > fs_holder_ops:
> > > 
> > > - Rename shutdown() call back to remove_bdev()
> > >    To better describe when the call back is called.
> > 
> > What is renamed back here?
> 
> Rename the old shutdown to remove_bdev().
> 
> > 
> > > -static void exfat_shutdown(struct super_block *sb)
> > > +static void exfat_shutdown(struct super_block *sb, struct block_device *bdev)
> > >   {
> > >   	exfat_force_shutdown(sb, EXFAT_GOING_DOWN_NOSYNC);
> > >   }
> > > @@ -202,7 +202,7 @@ static const struct super_operations exfat_sops = {
> > >   	.put_super	= exfat_put_super,
> > >   	.statfs		= exfat_statfs,
> > >   	.show_options	= exfat_show_options,
> > > -	.shutdown	= exfat_shutdown,
> > > +	.remove_bdev	= exfat_shutdown,
> > 
> > Please also rename the function so that they match the method name.
> 
> I prefer not, and it is intentionally left as is.
> 
> This give us a very clear view what a fs is expected to do.

Qu, would you please rename the individual functions?

The NAK later just because of this is unnecessary. I will say clearly
that I will ignore gratuitous NAKs that are premised on large scale
rewrites that are out of scope for the problem.

Here the requested rework has an acceptable scope though and we can
sidestep the whole problem and solve it so everyone's happy.

Re: [PATCH v2 1/6] fs: enhance and rename shutdown() callback to remove_bdev()

[Qu Wenruo]

在 2025/7/1 18:11, Christian Brauner 写道:
> On Tue, Jul 01, 2025 at 04:05:03PM +0930, Qu Wenruo wrote:
>>
>>
>> 在 2025/7/1 15:44, Christoph Hellwig 写道:
>>> On Tue, Jul 01, 2025 at 03:02:34PM +0930, Qu Wenruo wrote:
>>>> To allow those multi-device filesystems to be integrated to use
>>>> fs_holder_ops:
>>>>
>>>> - Rename shutdown() call back to remove_bdev()
>>>>     To better describe when the call back is called.
>>>
>>> What is renamed back here?
>>
>> Rename the old shutdown to remove_bdev().
>>
>>>
>>>> -static void exfat_shutdown(struct super_block *sb)
>>>> +static void exfat_shutdown(struct super_block *sb, struct block_device *bdev)
>>>>    {
>>>>    	exfat_force_shutdown(sb, EXFAT_GOING_DOWN_NOSYNC);
>>>>    }
>>>> @@ -202,7 +202,7 @@ static const struct super_operations exfat_sops = {
>>>>    	.put_super	= exfat_put_super,
>>>>    	.statfs		= exfat_statfs,
>>>>    	.show_options	= exfat_show_options,
>>>> -	.shutdown	= exfat_shutdown,
>>>> +	.remove_bdev	= exfat_shutdown,
>>>
>>> Please also rename the function so that they match the method name.
>>
>> I prefer not, and it is intentionally left as is.
>>
>> This give us a very clear view what a fs is expected to do.
> 
> Qu, would you please rename the individual functions?

Sure. I'll keep the fs' function names consistent with the callback names.

Especially there are already quite some maintainers wanting a consistent 
pattern here.

Thanks,
Qu

> 
> The NAK later just because of this is unnecessary. I will say clearly
> that I will ignore gratuitous NAKs that are premised on large scale
> rewrites that are out of scope for the problem.
> 
> Here the requested rework has an acceptable scope though and we can
> sidestep the whole problem and solve it so everyone's happy.
> 

Re: [PATCH v2 1/6] fs: enhance and rename shutdown() callback to remove_bdev()

[Jan Kara]

On Tue 01-07-25 15:02:34, Qu Wenruo wrote:
> Currently all the filesystems implementing the
> super_opearations::shutdown() call back can not afford losing a device.
> 
> Thus fs_bdev_mark_dead() will just call the shutdown() callback for the
> involved filesystem.
> 
> But it will no longer be the case, with multi-device filesystems like
> btrfs and bcachefs the filesystem can handle certain device loss without
> shutting down the whole filesystem.
> 
> To allow those multi-device filesystems to be integrated to use
> fs_holder_ops:
> 
> - Rename shutdown() call back to remove_bdev()
>   To better describe when the call back is called.
> 
> - Add a new @bdev parameter to remove_bdev() callback
>   To allow the fs to determine which device is missing, and do the
>   proper handling when needed.
> 
> For the existing shutdown callback users, the change is minimal.
> 
> They only need to follow the rename and the new parameter list.
> Since the behavior is still to shutdown the fs, they shouldn't change
> their function names.
> 
> This has a good side effect that, a single line like
> ".remove_bdev = ext4_shutdown," will easily show the fs behavior and
> indicate the fs will shutdown when a device went missing.
> 
> Btrfs is going to implement the callback soon, which will either
> shutdown the fs or continue read-write operations.
> 
> Cc: linux-fsdevel@vger.kernel.org
> Cc: linux-ext4@vger.kernel.org
> Cc: linux-f2fs-devel@lists.sourceforge.net
> Cc: ntfs3@lists.linux.dev
> Cc: linux-xfs@vger.kernel.org
> Signed-off-by: Qu Wenruo <wqu@suse.com>

So I don't feel as strongly as Christoph about individual filesystem method
names but I tend to agree that over long term and large codebase
mismatching hook & implementation names does more harm than good (it just
creates these WTH is this moments couple years down the road when you
already forget about the original motivation). So I'd prefer they are named
like ext4_remove_bdev() etc. Otherwise the patch looks good!

								Honza

> ---
>  fs/exfat/super.c   | 4 ++--
>  fs/ext4/super.c    | 4 ++--
>  fs/f2fs/super.c    | 4 ++--
>  fs/ntfs3/super.c   | 4 ++--
>  fs/super.c         | 4 ++--
>  fs/xfs/xfs_super.c | 5 +++--
>  include/linux/fs.h | 7 ++++++-
>  7 files changed, 19 insertions(+), 13 deletions(-)
> 
> diff --git a/fs/exfat/super.c b/fs/exfat/super.c
> index 7ed858937d45..5773026be84c 100644
> --- a/fs/exfat/super.c
> +++ b/fs/exfat/super.c
> @@ -172,7 +172,7 @@ int exfat_force_shutdown(struct super_block *sb, u32 flags)
>  	return 0;
>  }
>  
> -static void exfat_shutdown(struct super_block *sb)
> +static void exfat_shutdown(struct super_block *sb, struct block_device *bdev)
>  {
>  	exfat_force_shutdown(sb, EXFAT_GOING_DOWN_NOSYNC);
>  }
> @@ -202,7 +202,7 @@ static const struct super_operations exfat_sops = {
>  	.put_super	= exfat_put_super,
>  	.statfs		= exfat_statfs,
>  	.show_options	= exfat_show_options,
> -	.shutdown	= exfat_shutdown,
> +	.remove_bdev	= exfat_shutdown,
>  };
>  
>  enum {
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index c7d39da7e733..8724f89d20d8 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -1456,7 +1456,7 @@ static void ext4_destroy_inode(struct inode *inode)
>  			 EXT4_I(inode)->i_reserved_data_blocks);
>  }
>  
> -static void ext4_shutdown(struct super_block *sb)
> +static void ext4_shutdown(struct super_block *sb, struct block_device *bdev)
>  {
>         ext4_force_shutdown(sb, EXT4_GOING_FLAGS_NOLOGFLUSH);
>  }
> @@ -1620,7 +1620,7 @@ static const struct super_operations ext4_sops = {
>  	.unfreeze_fs	= ext4_unfreeze,
>  	.statfs		= ext4_statfs,
>  	.show_options	= ext4_show_options,
> -	.shutdown	= ext4_shutdown,
> +	.remove_bdev	= ext4_shutdown,
>  #ifdef CONFIG_QUOTA
>  	.quota_read	= ext4_quota_read,
>  	.quota_write	= ext4_quota_write,
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index bbf1dad6843f..51c60b429a31 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -2640,7 +2640,7 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
>  	return err;
>  }
>  
> -static void f2fs_shutdown(struct super_block *sb)
> +static void f2fs_shutdown(struct super_block *sb, struct block_device *bdev)
>  {
>  	f2fs_do_shutdown(F2FS_SB(sb), F2FS_GOING_DOWN_NOSYNC, false, false);
>  }
> @@ -3264,7 +3264,7 @@ static const struct super_operations f2fs_sops = {
>  	.unfreeze_fs	= f2fs_unfreeze,
>  	.statfs		= f2fs_statfs,
>  	.remount_fs	= f2fs_remount,
> -	.shutdown	= f2fs_shutdown,
> +	.remove_bdev	= f2fs_shutdown,
>  };
>  
>  #ifdef CONFIG_FS_ENCRYPTION
> diff --git a/fs/ntfs3/super.c b/fs/ntfs3/super.c
> index 920a1ab47b63..5e422543b851 100644
> --- a/fs/ntfs3/super.c
> +++ b/fs/ntfs3/super.c
> @@ -764,7 +764,7 @@ static int ntfs_show_options(struct seq_file *m, struct dentry *root)
>  /*
>   * ntfs_shutdown - super_operations::shutdown
>   */
> -static void ntfs_shutdown(struct super_block *sb)
> +static void ntfs_shutdown(struct super_block *sb, struct block_device *bdev)
>  {
>  	set_bit(NTFS_FLAGS_SHUTDOWN_BIT, &ntfs_sb(sb)->flags);
>  }
> @@ -821,7 +821,7 @@ static const struct super_operations ntfs_sops = {
>  	.put_super = ntfs_put_super,
>  	.statfs = ntfs_statfs,
>  	.show_options = ntfs_show_options,
> -	.shutdown = ntfs_shutdown,
> +	.remove_bdev = ntfs_shutdown,
>  	.sync_fs = ntfs_sync_fs,
>  	.write_inode = ntfs3_write_inode,
>  };
> diff --git a/fs/super.c b/fs/super.c
> index 80418ca8e215..c972efb38f6a 100644
> --- a/fs/super.c
> +++ b/fs/super.c
> @@ -1463,8 +1463,8 @@ static void fs_bdev_mark_dead(struct block_device *bdev, bool surprise)
>  		sync_filesystem(sb);
>  	shrink_dcache_sb(sb);
>  	evict_inodes(sb);
> -	if (sb->s_op->shutdown)
> -		sb->s_op->shutdown(sb);
> +	if (sb->s_op->remove_bdev)
> +		sb->s_op->remove_bdev(sb, bdev);
>  
>  	super_unlock_shared(sb);
>  }
> diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> index 0bc4b5489078..e47d427f4416 100644
> --- a/fs/xfs/xfs_super.c
> +++ b/fs/xfs/xfs_super.c
> @@ -1277,7 +1277,8 @@ xfs_fs_free_cached_objects(
>  
>  static void
>  xfs_fs_shutdown(
> -	struct super_block	*sb)
> +	struct super_block	*sb,
> +	struct block_device	*bdev)
>  {
>  	xfs_force_shutdown(XFS_M(sb), SHUTDOWN_DEVICE_REMOVED);
>  }
> @@ -1308,7 +1309,7 @@ static const struct super_operations xfs_super_operations = {
>  	.show_options		= xfs_fs_show_options,
>  	.nr_cached_objects	= xfs_fs_nr_cached_objects,
>  	.free_cached_objects	= xfs_fs_free_cached_objects,
> -	.shutdown		= xfs_fs_shutdown,
> +	.remove_bdev		= xfs_fs_shutdown,
>  	.show_stats		= xfs_fs_show_stats,
>  };
>  
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index b085f161ed22..b08af63d2d4f 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -2367,7 +2367,12 @@ struct super_operations {
>  				  struct shrink_control *);
>  	long (*free_cached_objects)(struct super_block *,
>  				    struct shrink_control *);
> -	void (*shutdown)(struct super_block *sb);
> +	/*
> +	 * Called when block device @bdev belonging to @sb is removed.
> +	 *
> +	 * If the fs can't afford the device loss, it should be shutdown.
> +	 */
> +	void (*remove_bdev)(struct super_block *sb, struct block_device *bdev);
>  };
>  
>  /*
> -- 
> 2.50.0
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR