On Wed 14-01-15 10:42:41, Christoph Hellwig wrote:
> 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@xxxxxx>
> Reviewed-by: Tejun Heo <tj@xxxxxxxxxx>
Looks good. You can add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> ---
> 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
>
> --
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--
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
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