On Fri, Aug 04, 2023 at 05:29:37PM +0200, Christian Brauner wrote:
> On Fri, Aug 04, 2023 at 04:49:23PM +0200, Christian Brauner wrote:
> > On Fri, Aug 04, 2023 at 04:43:43PM +0200, Christoph Hellwig wrote:
> > > On Fri, Aug 04, 2023 at 04:36:49PM +0200, Christian Brauner wrote:
> > > > FFS
> > >
> > > Good spot, this explains the missing dropping of s_umount.
> > >
> > > But I don't think it's doing the right thing for MTD mount romfs,
> > > we'll need something like this:
> >
> > I'll fold a fix into Jan's patch.
>
> Folding:
Btw, we really need to think about reworking how super block freeing
works. The calling conventions of ->kill_sb are really horrible right
now:
- every instance of ->kill_sb is supposed to call generic_shutdown_super,
but the instances can do work before and after it
- we have a few generic helpers wrapping generic_shutdown_super, but
they aren't easily combinable for file systems using say MTD and
block backends.
Pair that with ->put_super also called from generic_shutdown_super
I think we have a major mess.
Here is my rough and not very well thought out idea (having a lot of
backlog and beeing on the way to a family celebreation):
1) make ->kill_sb optional and default to generic_shutdown_super if
not provided
2) add a new ->free_fs_info method that is called at the end of
generic_shutdown_super to free sb->s_fs_info
(maybe thing if we should also call this on a failed mount
for fc_fs_info, but I'm not quite sure about that) and then
migrate everything that just frees resources over to that
3) figure out what work really needs to be before
generic_shutdown_super, and if there is something add a new
method for it
4) if we added the new method in 3 figure out if it can also
take over the job from ->put_super
5) PROFIT!!! (well, actually remove ->kill_sb).
>
> diff --git a/fs/romfs/super.c b/fs/romfs/super.c
> index c59b230d55b4..2b9f3e3c052a 100644
> --- a/fs/romfs/super.c
> +++ b/fs/romfs/super.c
> @@ -583,16 +583,20 @@ static int romfs_init_fs_context(struct fs_context *fc)
> */
> static void romfs_kill_sb(struct super_block *sb)
> {
> + generic_shutdown_super(sb);
> +
> #ifdef CONFIG_ROMFS_ON_MTD
> if (sb->s_mtd) {
> - kill_mtd_super(sb);
> - return;
> + put_mtd_device(sb->s_mtd);
> + sb->s_mtd = NULL;
> }
> #endif
> #ifdef CONFIG_ROMFS_ON_BLOCK
> if (sb->s_bdev) {
> - kill_block_super(sb);
> - return;
> + sb->s_bdev->bd_super = NULL;
> + sync_blockdev(sb->s_bdev);
> + blkdev_put(sb->s_bdev, sb->s_type);
> }
> #endif
> }
> diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c
> index 27c6597aa1be..0b6cc8a03b54 100644
> --- a/fs/cramfs/inode.c
> +++ b/fs/cramfs/inode.c
> @@ -485,12 +485,17 @@ static void cramfs_kill_sb(struct super_block *sb)
> {
> struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
>
> + generic_shutdown_super(sb);
> +
> if (IS_ENABLED(CONFIG_CRAMFS_MTD) && sb->s_mtd) {
> if (sbi && sbi->mtd_point_size)
> mtd_unpoint(sb->s_mtd, 0, sbi->mtd_point_size);
> - kill_mtd_super(sb);
> + put_mtd_device(sb->s_mtd);
> + sb->s_mtd = NULL;
> } else if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV) && sb->s_bdev) {
> - kill_block_super(sb);
> + sb->s_bdev->bd_super = NULL;
> + sync_blockdev(sb->s_bdev);
> + blkdev_put(sb->s_bdev, sb->s_type);
> }
> kfree(sbi);
> }
>
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