[PATCH 12/12] fs: remove default_backing_dev_info

Christoph Hellwig
2015-01-08T17:45:33Z

Now that default_backing_dev_info is not used for writeback purposes we can
git rid of it easily:

- instead of using it's name for tracing unregistered bdi we just use
"unknown"
- btrfs and ceph can just assign the default read ahead window themselves
like several other filesystems already do.
- we can assign noop_backing_dev_info as the default one in alloc_super.
All filesystems already either assigned their own or
noop_backing_dev_info.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
fs/btrfs/disk-io.c | 2 +-
fs/ceph/super.c | 2 +-
fs/super.c | 8 ++------
include/linux/backing-dev.h | 1 -
include/trace/events/writeback.h | 6 ++----
mm/backing-dev.c | 9 ---------
6 files changed, 6 insertions(+), 22 deletions(-)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 1ec872e..1afb182 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1719,7 +1719,7 @@ static int setup_bdi(struct btrfs_fs_info *info, struct backing_dev_info *bdi)
if (err)
return err;

- bdi->ra_pages = default_backing_dev_info.ra_pages;
+ bdi->ra_pages = VM_MAX_READAHEAD * 1024 / PAGE_CACHE_SIZE;
bdi->congested_fn = btrfs_congested_fn;
bdi->congested_data = info;
return 0;
diff --git a/fs/ceph/super.c b/fs/ceph/super.c
index e350cc1..5ae6258 100644
--- a/fs/ceph/super.c
+++ b/fs/ceph/super.c
@@ -899,7 +899,7 @@ static int ceph_register_bdi(struct super_block *sb,
>> PAGE_SHIFT;
else
fsc->backing_dev_info.ra_pages =
- default_backing_dev_info.ra_pages;
+ VM_MAX_READAHEAD * 1024 / PAGE_CACHE_SIZE;

err = bdi_register(&fsc->backing_dev_info, NULL, "ceph-%ld",
atomic_long_inc_return(&bdi_seq));
diff --git a/fs/super.c b/fs/super.c
index eae088f..3b4dada 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -185,8 +185,8 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags)
}
init_waitqueue_head(&s->s_writers.wait);
init_waitqueue_head(&s->s_writers.wait_unfrozen);
+ s->s_bdi = &noop_backing_dev_info;
s->s_flags = flags;
- s->s_bdi = &default_backing_dev_info;
INIT_HLIST_NODE(&s->s_instances);
INIT_HLIST_BL_HEAD(&s->s_anon);
INIT_LIST_HEAD(&s->s_inodes);
@@ -863,10 +863,7 @@ EXPORT_SYMBOL(free_anon_bdev);

int set_anon_super(struct super_block *s, void *data)
{
- int error = get_anon_bdev(&s->s_dev);
- if (!error)
- s->s_bdi = &noop_backing_dev_info;
- return error;
+ return get_anon_bdev(&s->s_dev);
}

EXPORT_SYMBOL(set_anon_super);
@@ -1111,7 +1108,6 @@ mount_fs(struct file_system_type *type, int flags, const char *name, void *data)
sb = root->d_sb;
BUG_ON(!sb);
WARN_ON(!sb->s_bdi);
- WARN_ON(sb->s_bdi == &default_backing_dev_info);
sb->s_flags |= MS_BORN;

error = security_sb_kern_mount(sb, flags, secdata);
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index ed59dee..d94077f 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -241,7 +241,6 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
#define BDI_CAP_NO_ACCT_AND_WRITEBACK \
(BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)

-extern struct backing_dev_info default_backing_dev_info;
extern struct backing_dev_info noop_backing_dev_info;

int writeback_in_progress(struct backing_dev_info *bdi);
diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h
index 74f5207..0e93109 100644
--- a/include/trace/events/writeback.h
+++ b/include/trace/events/writeback.h
@@ -156,10 +156,8 @@ DECLARE_EVENT_CLASS(writeback_work_class,
__field(int, reason)
),
TP_fast_assign(
- struct device *dev = bdi->dev;
- if (!dev)
- dev = default_backing_dev_info.dev;
- strncpy(__entry->name, dev_name(dev), 32);
+ strncpy(__entry->name,
+ bdi->dev ? dev_name(bdi->dev) : "(unknown)", 32);
__entry->nr_pages = work->nr_pages;
__entry->sb_dev = work->sb ? work->sb->s_dev : 0;
__entry->sync_mode = work->sync_mode;
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 3ebba25..c49026d 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -14,12 +14,6 @@

static atomic_long_t bdi_seq = ATOMIC_LONG_INIT(0);

-struct backing_dev_info default_backing_dev_info = {
- .name = "default",
- .ra_pages = VM_MAX_READAHEAD * 1024 / PAGE_CACHE_SIZE,
-};
-EXPORT_SYMBOL_GPL(default_backing_dev_info);
-
struct backing_dev_info noop_backing_dev_info = {
.name = "noop",
.capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
@@ -250,9 +244,6 @@ static int __init default_bdi_init(void)
if (!bdi_wq)
return -ENOMEM;

- err = bdi_init(&default_backing_dev_info);
- if (!err)
- bdi_register(&default_backing_dev_info, NULL, "default");
err = bdi_init(&noop_backing_dev_info);

return err;
--
1.9.1