inode: convert inode_sb_list_lock to per-sb

The process of reducing contention on per-superblock inode lists
starts with moving the locking to match the per-superblock inode
list. This takes the global lock out of the picture and reduces the
contention problems to within a single filesystem. This doesn't get
rid of contention as the locks still have global CPU scope, but it
does isolate operations on different superblocks form each other.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Dave Chinner <dchinner@redhat.com>

1 files changed, 6 insertions, 4 deletions

diff --git a/fs/drop_caches.c b/fs/drop_caches.c
index 5718cb9f7273..d72d52b90433 100644
--- a/fs/drop_caches.c
+++ b/fs/drop_caches.c
@@ -17,7 +17,7 @@ static void drop_pagecache_sb(struct super_block *sb, void *unused)
 {
         struct inode *inode, *toput_inode = NULL;
 
-        spin_lock(&inode_sb_list_lock);
+        spin_lock(&sb->s_inode_list_lock);
         list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
                 spin_lock(&inode->i_lock);
                 if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||
@@ -27,13 +27,15 @@ static void drop_pagecache_sb(struct super_block *sb, void *unused)
                 }
                 __iget(inode);
                 spin_unlock(&inode->i_lock);
-                spin_unlock(&inode_sb_list_lock);
+                spin_unlock(&sb->s_inode_list_lock);
+
                 invalidate_mapping_pages(inode->i_mapping, 0, -1);
                 iput(toput_inode);
                 toput_inode = inode;
-                spin_lock(&inode_sb_list_lock);
+
+                spin_lock(&sb->s_inode_list_lock);
         }
-        spin_unlock(&inode_sb_list_lock);
+        spin_unlock(&sb->s_inode_list_lock);
         iput(toput_inode);
 }