fs-inode_lock-scale-10

Impelemnt lazy inode lru similarly to dcache. This should reduce inode list
lock acquisition (todo: measure).

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 10 insertions, 11 deletions

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 07d70704078e..df99a99f99a2 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -544,7 +544,7 @@ select_queue:
                         /*
                          * The inode is clean, inuse
                          */
-                        list_move(&inode->i_list, &inode_in_use);
+                        list_del_init(&inode->i_list);
                 } else {
                         /*
                          * The inode is clean, unused
@@ -1151,8 +1151,6 @@ static void wait_sb_inodes(struct super_block *sb)
          */
         WARN_ON(!rwsem_is_locked(&sb->s_umount));
 
-        spin_lock(&sb_inode_list_lock);
-
         /*
          * Data integrity sync. Must wait for all pages under writeback,
          * because there may have been pages dirtied before our sync
@@ -1160,7 +1158,8 @@ static void wait_sb_inodes(struct super_block *sb)
          * In which case, the inode may not be on the dirty list, but
          * we still have to wait for that writeout.
          */
-        list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
+        rcu_read_lock();
+        list_for_each_entry_rcu(inode, &sb->s_inodes, i_sb_list) {
                 struct address_space *mapping;
 
                 mapping = inode->i_mapping;
@@ -1174,13 +1173,13 @@ static void wait_sb_inodes(struct super_block *sb)
                 }
                 __iget(inode);
                 spin_unlock(&inode->i_lock);
-                spin_unlock(&sb_inode_list_lock);
+                rcu_read_unlock();
                 /*
                  * We hold a reference to 'inode' so it couldn't have been
-                 * removed from s_inodes list while we dropped the
-                 * sb_inode_list_lock.  We cannot iput the inode now as we can
-                 * be holding the last reference and we cannot iput it under
-                 * spinlock. So we keep the reference and iput it later.
+                 * removed from s_inodes list while we dropped the i_lock.  We
+                 * cannot iput the inode now as we can be holding the last
+                 * reference and we cannot iput it under spinlock. So we keep
+                 * the reference and iput it later.
                  */
                 iput(old_inode);
                 old_inode = inode;
@@ -1189,9 +1188,9 @@ static void wait_sb_inodes(struct super_block *sb)
 
                 cond_resched();
 
-                spin_lock(&sb_inode_list_lock);
+                rcu_read_lock();
         }
-        spin_unlock(&sb_inode_list_lock);
+        rcu_read_unlock();
         iput(old_inode);
 }