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@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Vignesh Raghavendra <vigneshr@ti.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/super.c b/fs/super.c
index bcef3a6f4c4b586ad559c67c90cc61d262a9a21f..3bfc0f8fbd5bc7fbe3ee94b58e1724fffacf2eee 100644 (file)
--- a/fs/super.c
+++ b/fs/super.c
@@ -476,6 +476,8 @@ void generic_shutdown_super(struct super_block *sb)
        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_block *sb, char *fmt, ...)
        }
        WARN_ON(sb->s_bdi != &noop_backing_dev_info);
        sb->s_bdi = bdi;
+       sb->s_iflags |= SB_I_PERSB_BDI;
 
        return 0;
 }

diff --git a/include/linux/fs.h b/include/linux/fs.h
index e7a633353fd20c8adfbc159b55265f957af89824..226de651f52e6f9f01efdfe2aa374dab7a220895 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1443,6 +1443,7 @@ extern int send_sigurg(struct fown_struct *fown);
 #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 {