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Catch filesystems lacking s_bdi

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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: Joern 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: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Jörn Engel 2010-04-25 08:54:42 +02:00 committed by Jens Axboe
parent 7e2455c1a1
commit 5129a469a9
4 changed files with 13 additions and 4 deletions
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8
fs/super.c
View file

@ -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;
}
@ -954,10 +955,11 @@ 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)
goto out_sb;
error = security_sb_kern_mount(mnt->mnt_sb, flags, secdata);
if (error)
goto out_sb;
/*
* filesystems should never set s_maxbytes larger than MAX_LFS_FILESIZE

3
fs/sync.c
View file

@ -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)

1
include/linux/backing-dev.h
View file

@ -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);

5
mm/backing-dev.c
View file

@ -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;
/*