fs: inode split IO and LRU lists

The use of the same inode list structure (inode->i_list) for two
different list constructs with different lifecycles and purposes
makes it impossible to separate the locking of the different
operations. Therefore, to enable the separation of the locking of
the writeback and reclaim lists, split the inode->i_list into two
separate lists dedicated to their specific tracking functions.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 18 insertions, 17 deletions

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index e8f65290e836..7a24cc957f05 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -79,6 +79,11 @@ static inline struct backing_dev_info *inode_to_bdi(struct inode *inode)
         return sb->s_bdi;
 }
 
+static inline struct inode *wb_inode(struct list_head *head)
+{
+        return list_entry(head, struct inode, i_wb_list);
+}
+
 static void bdi_queue_work(struct backing_dev_info *bdi,
                 struct wb_writeback_work *work)
 {
@@ -172,11 +177,11 @@ static void redirty_tail(struct inode *inode)
         if (!list_empty(&wb->b_dirty)) {
                 struct inode *tail;
 
-                tail = list_entry(wb->b_dirty.next, struct inode, i_list);
+                tail = wb_inode(wb->b_dirty.next);
                 if (time_before(inode->dirtied_when, tail->dirtied_when))
                         inode->dirtied_when = jiffies;
         }
-        list_move(&inode->i_list, &wb->b_dirty);
+        list_move(&inode->i_wb_list, &wb->b_dirty);
 }
 
 /*
@@ -186,7 +191,7 @@ static void requeue_io(struct inode *inode)
 {
         struct bdi_writeback *wb = &inode_to_bdi(inode)->wb;
 
-        list_move(&inode->i_list, &wb->b_more_io);
+        list_move(&inode->i_wb_list, &wb->b_more_io);
 }
 
 static void inode_sync_complete(struct inode *inode)
@@ -227,14 +232,14 @@ static void move_expired_inodes(struct list_head *delaying_queue,
         int do_sb_sort = 0;
 
         while (!list_empty(delaying_queue)) {
-                inode = list_entry(delaying_queue->prev, struct inode, i_list);
+                inode = wb_inode(delaying_queue->prev);
                 if (older_than_this &&
                     inode_dirtied_after(inode, *older_than_this))
                         break;
                 if (sb && sb != inode->i_sb)
                         do_sb_sort = 1;
                 sb = inode->i_sb;
-                list_move(&inode->i_list, &tmp);
+                list_move(&inode->i_wb_list, &tmp);
         }
 
         /* just one sb in list, splice to dispatch_queue and we're done */
@@ -245,12 +250,11 @@ static void move_expired_inodes(struct list_head *delaying_queue,
 
         /* Move inodes from one superblock together */
         while (!list_empty(&tmp)) {
-                inode = list_entry(tmp.prev, struct inode, i_list);
-                sb = inode->i_sb;
+                sb = wb_inode(tmp.prev)->i_sb;
                 list_for_each_prev_safe(pos, node, &tmp) {
-                        inode = list_entry(pos, struct inode, i_list);
+                        inode = wb_inode(pos);
                         if (inode->i_sb == sb)
-                                list_move(&inode->i_list, dispatch_queue);
+                                list_move(&inode->i_wb_list, dispatch_queue);
                 }
         }
 }
@@ -414,7 +418,7 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
                          * a reference to the inode or it's on it's way out.
                          * No need to add it back to the LRU.
                          */
-                        list_del_init(&inode->i_list);
+                        list_del_init(&inode->i_wb_list);
                 }
         }
         inode_sync_complete(inode);
@@ -462,8 +466,7 @@ static int writeback_sb_inodes(struct super_block *sb, struct bdi_writeback *wb,
 {
         while (!list_empty(&wb->b_io)) {
                 long pages_skipped;
-                struct inode *inode = list_entry(wb->b_io.prev,
-                                                 struct inode, i_list);
+                struct inode *inode = wb_inode(wb->b_io.prev);
 
                 if (inode->i_sb != sb) {
                         if (only_this_sb) {
@@ -533,8 +536,7 @@ void writeback_inodes_wb(struct bdi_writeback *wb,
                 queue_io(wb, wbc->older_than_this);
 
         while (!list_empty(&wb->b_io)) {
-                struct inode *inode = list_entry(wb->b_io.prev,
-                                                 struct inode, i_list);
+                struct inode *inode = wb_inode(wb->b_io.prev);
                 struct super_block *sb = inode->i_sb;
 
                 if (!pin_sb_for_writeback(sb)) {
@@ -672,8 +674,7 @@ static long wb_writeback(struct bdi_writeback *wb,
                  */
                 spin_lock(&inode_lock);
                 if (!list_empty(&wb->b_more_io))  {
-                        inode = list_entry(wb->b_more_io.prev,
-                                                struct inode, i_list);
+                        inode = wb_inode(wb->b_more_io.prev);
                         trace_wbc_writeback_wait(&wbc, wb->bdi);
                         inode_wait_for_writeback(inode);
                 }
@@ -987,7 +988,7 @@ void __mark_inode_dirty(struct inode *inode, int flags)
                         }
 
                         inode->dirtied_when = jiffies;
-                        list_move(&inode->i_list, &bdi->wb.b_dirty);
+                        list_move(&inode->i_wb_list, &bdi->wb.b_dirty);
                 }
         }
 out: