writeback: move backing_dev_info->bdi_stat[] into bdi_writeback
Currently, a bdi (backing_dev_info) embeds single wb (bdi_writeback)
and the role of the separation is unclear. For cgroup support for
writeback IOs, a bdi will be updated to host multiple wb's where each
wb serves writeback IOs of a different cgroup on the bdi. To achieve
that, a wb should carry all states necessary for servicing writeback
IOs for a cgroup independently.
This patch moves bdi->bdi_stat[] into wb.
* enum bdi_stat_item is renamed to wb_stat_item and the prefix of all
enums is changed from BDI_ to WB_.
* BDI_STAT_BATCH() -> WB_STAT_BATCH()
* [__]{add|inc|dec|sum}_wb_stat(bdi, ...) -> [__]{add|inc}_wb_stat(wb, ...)
* bdi_stat[_error]() -> wb_stat[_error]()
* bdi_writeout_inc() -> wb_writeout_inc()
* stat init is moved to bdi_wb_init() and bdi_wb_exit() is added and
frees stat.
* As there's still only one bdi_writeback per backing_dev_info, all
uses of bdi->stat[] are mechanically replaced with bdi->wb.stat[]
introducing no behavior changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index d12a4be..94c7ce0 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -853,7 +853,8 @@
nfs_clear_page_commit(struct page *page)
{
dec_zone_page_state(page, NR_UNSTABLE_NFS);
- dec_bdi_stat(inode_to_bdi(page_file_mapping(page)->host), BDI_RECLAIMABLE);
+ dec_wb_stat(&inode_to_bdi(page_file_mapping(page)->host)->wb,
+ WB_RECLAIMABLE);
}
/* Called holding inode (/cinfo) lock */