Commit 5129a469 authored by Jörn Engel's avatar Jörn Engel Committed by Jens Axboe
Browse files

Catch filesystems lacking s_bdi 



noop_backing_dev_info is used only as a flag to mark filesystems that
don't have any backing store, like tmpfs, procfs, spufs, etc.

Signed-off-by: default avatarJoern Engel <joern@logfs.org>

Changed the BUG_ON() to a WARN_ON(). Note that adding dirty inodes
to the noop_backing_dev_info is not legal and will not result in
them being flushed, but we already catch this condition in
__mark_inode_dirty() when checking for a registered bdi.

Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 7e2455c1

fs/super.c

+5 −3
Original line number Diff line number Diff line
@@ -693,6 +693,7 @@ int set_anon_super(struct super_block *s, void *data) 
		return -EMFILE;

	}

	s->s_dev = MKDEV(0, dev & MINORMASK);

	s->s_bdi = &noop_backing_dev_info;

	return 0;

}
@@ -954,6 +955,7 @@ vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void 
	if (error < 0)

		goto out_free_secdata;

	BUG_ON(!mnt->mnt_sb);

	WARN_ON(!mnt->mnt_sb->s_bdi);



	error = security_sb_kern_mount(mnt->mnt_sb, flags, secdata);

	if (error)

fs/sync.c

+2 −1
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
#include <linux/pagemap.h>

#include <linux/quotaops.h>

#include <linux/buffer_head.h>

#include <linux/backing-dev.h>

#include "internal.h"



#define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \
@@ -32,7 +33,7 @@ static int __sync_filesystem(struct super_block *sb, int wait) 
	 * This should be safe, as we require bdi backing to actually

	 * write out data in the first place

	 */

	if (!sb->s_bdi)

	if (!sb->s_bdi || sb->s_bdi == &noop_backing_dev_info)

		return 0;



	if (sb->s_qcop && sb->s_qcop->quota_sync)

include/linux/backing-dev.h

+1 −0
Original line number Diff line number Diff line
@@ -247,6 +247,7 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio); 
#endif



extern struct backing_dev_info default_backing_dev_info;

extern struct backing_dev_info noop_backing_dev_info;

void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page);



int writeback_in_progress(struct backing_dev_info *bdi);

mm/backing-dev.c

+5 −0
Original line number Diff line number Diff line
@@ -27,6 +27,11 @@ struct backing_dev_info default_backing_dev_info = { 
};

EXPORT_SYMBOL_GPL(default_backing_dev_info);



struct backing_dev_info noop_backing_dev_info = {

	.name		= "noop",

};

EXPORT_SYMBOL_GPL(noop_backing_dev_info);



static struct class *bdi_class;



/*

CRA Git | Maintained and supported by SUSTech CRA and CCSE