[PATCH v2] vfs: don't softlockup when evicting inodes

[Josef Bacik <jbacik@fb.com>]

If I run an fs_mark job that creates millions of empty files and then
immediately unmount the file system I will get a softlockup during unmount.
This box has ~140gb of RAM so we never hit sufficient memory pressure to evict
enough inodes during the runtime of the benchmark, which means I see around 80
million inodes being evicted at unmount time.  With this patch my box no longer
softlocks up.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fb.com>
---
V1->V2:
-Still occasionally saw a softlockup in evict_inodes so add a cond_resched_lock
 to that case as well.

 fs/inode.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/inode.c b/fs/inode.c
index ad60555..f266765 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -581,6 +581,7 @@ static void dispose_list(struct list_head *head)
 		list_del_init(&inode->i_lru);
 
 		evict(inode);
+		cond_resched();
 	}
 }
 
@@ -613,6 +614,7 @@ void evict_inodes(struct super_block *sb)
 		inode_lru_list_del(inode);
 		spin_unlock(&inode->i_lock);
 		list_add(&inode->i_lru, &dispose);
+		cond_resched_lock(&inode_sb_list_lock);
 	}
 	spin_unlock(&inode_sb_list_lock);
 
-- 
1.9.3