[patch 044/262] fs: explicitly unregister per-superblock BDIs

Andrew Morton
2021-11-05T20:37:01Z

From: Christoph Hellwig <hch@lst.de>
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@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>
---

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 {
_