From: Christoph Hellwig <hch@xxxxxx> Subject: fs: explicitly unregister per-superblock BDIs Add a new SB_I_ flag to mark superblocks that have an ephemeral bdi associated with them, and unregister it when the superblock is shut down. Link: https://lkml.kernel.org/r/20211021124441.668816-4-hch@xxxxxx Signed-off-by: Christoph Hellwig <hch@xxxxxx> Reviewed-by: Jan Kara <jack@xxxxxxx> Cc: Miquel Raynal <miquel.raynal@xxxxxxxxxxx> Cc: Richard Weinberger <richard@xxxxxx> Cc: Vignesh Raghavendra <vigneshr@xxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/super.c | 3 +++ include/linux/fs.h | 1 + 2 files changed, 4 insertions(+) --- a/fs/super.c~fs-explicitly-unregister-per-superblock-bdis +++ a/fs/super.c @@ -476,6 +476,8 @@ void generic_shutdown_super(struct super spin_unlock(&sb_lock); up_write(&sb->s_umount); if (sb->s_bdi != &noop_backing_dev_info) { + if (sb->s_iflags & SB_I_PERSB_BDI) + bdi_unregister(sb->s_bdi); bdi_put(sb->s_bdi); sb->s_bdi = &noop_backing_dev_info; } @@ -1562,6 +1564,7 @@ int super_setup_bdi_name(struct super_bl } WARN_ON(sb->s_bdi != &noop_backing_dev_info); sb->s_bdi = bdi; + sb->s_iflags |= SB_I_PERSB_BDI; return 0; } --- a/include/linux/fs.h~fs-explicitly-unregister-per-superblock-bdis +++ a/include/linux/fs.h @@ -1443,6 +1443,7 @@ extern int send_sigurg(struct fown_struc #define SB_I_UNTRUSTED_MOUNTER 0x00000040 #define SB_I_SKIP_SYNC 0x00000100 /* Skip superblock at global sync */ +#define SB_I_PERSB_BDI 0x00000200 /* has a per-sb bdi */ /* Possible states of 'frozen' field */ enum { _
