fs: remove default_backing_dev_info

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>
Reviewed-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 1ec872e..1afb182 100644 (file)
--- 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 (file)
--- 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 --cc fs/super.c
Simple merge

diff --cc include/linux/backing-dev.h
Simple merge

diff --cc include/trace/events/writeback.h
Simple merge

diff --cc mm/backing-dev.c
Simple merge