writeback: move dirty inodes from super_block to backing_dev_info

This is a first step at introducing per-bdi flusher threads. We should
have no change in behaviour, although sb_has_dirty_inodes() is now
ridiculously expensive, as there's no easy way to answer that question.
Not a huge problem, since it'll be deleted in subsequent patches.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

2 files changed, 10 insertions, 4 deletions

diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 1d52425a6118..928cd5484f4d 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -40,6 +40,8 @@ enum bdi_stat_item {
 #define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
 
 struct backing_dev_info {
+        struct list_head bdi_list;
+
         unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
         unsigned long state;    /* Always use atomic bitops on this */
         unsigned int capabilities; /* Device capabilities */
@@ -58,6 +60,10 @@ struct backing_dev_info {
 
         struct device *dev;
 
+        struct list_head        b_dirty;        /* dirty inodes */
+        struct list_head        b_io;           /* parked for writeback */
+        struct list_head        b_more_io;      /* parked for more writeback */
+
 #ifdef CONFIG_DEBUG_FS
         struct dentry *debug_dir;
         struct dentry *debug_stats;
@@ -72,6 +78,9 @@ int bdi_register(struct backing_dev_info *bdi, struct device *parent,
 int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
 void bdi_unregister(struct backing_dev_info *bdi);
 
+extern struct mutex bdi_lock;
+extern struct list_head bdi_list;
+
 static inline void __add_bdi_stat(struct backing_dev_info *bdi,
                 enum bdi_stat_item item, s64 amount)
 {
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 46ff7dd6e164..56371be1be65 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -715,7 +715,7 @@ struct posix_acl;
 
 struct inode {
         struct hlist_node       i_hash;
-        struct list_head        i_list;
+        struct list_head        i_list;         /* backing dev IO list */
         struct list_head        i_sb_list;
         struct list_head        i_dentry;
         unsigned long           i_ino;
@@ -1336,9 +1336,6 @@ struct super_block {
         struct xattr_handler    **s_xattr;
 
         struct list_head        s_inodes;       /* all inodes */
-        struct list_head        s_dirty;        /* dirty inodes */
-        struct list_head        s_io;           /* parked for writeback */
-        struct list_head        s_more_io;      /* parked for more writeback */
         struct hlist_head       s_anon;         /* anonymous dentries for (nfs) exporting */
         struct list_head        s_files;
         /* s_dentry_lru and s_nr_dentry_unused are protected by dcache_lock */