vfs: dont chain pipe/anon/socket on superblock s_inodes list
Workloads using pipes and sockets hit inode_sb_list_lock contention.
superblock s_inodes list is needed for quota, dirty, pagecache and
fsnotify management. pipe/anon/socket fs are clearly not candidates for
these.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/inode.c b/fs/inode.c
index 96c77b8..319b93b 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -362,9 +362,11 @@
static inline void inode_sb_list_del(struct inode *inode)
{
- spin_lock(&inode_sb_list_lock);
- list_del_init(&inode->i_sb_list);
- spin_unlock(&inode_sb_list_lock);
+ if (!list_empty(&inode->i_sb_list)) {
+ spin_lock(&inode_sb_list_lock);
+ list_del_init(&inode->i_sb_list);
+ spin_unlock(&inode_sb_list_lock);
+ }
}
static unsigned long hash(struct super_block *sb, unsigned long hashval)
@@ -797,6 +799,29 @@
EXPORT_SYMBOL(get_next_ino);
/**
+ * new_inode_pseudo - obtain an inode
+ * @sb: superblock
+ *
+ * Allocates a new inode for given superblock.
+ * Inode wont be chained in superblock s_inodes list
+ * This means :
+ * - fs can't be unmount
+ * - quotas, fsnotify, writeback can't work
+ */
+struct inode *new_inode_pseudo(struct super_block *sb)
+{
+ struct inode *inode = alloc_inode(sb);
+
+ if (inode) {
+ spin_lock(&inode->i_lock);
+ inode->i_state = 0;
+ spin_unlock(&inode->i_lock);
+ INIT_LIST_HEAD(&inode->i_sb_list);
+ }
+ return inode;
+}
+
+/**
* new_inode - obtain an inode
* @sb: superblock
*
@@ -814,13 +839,9 @@
spin_lock_prefetch(&inode_sb_list_lock);
- inode = alloc_inode(sb);
- if (inode) {
- spin_lock(&inode->i_lock);
- inode->i_state = 0;
- spin_unlock(&inode->i_lock);
+ inode = new_inode_pseudo(sb);
+ if (inode)
inode_sb_list_add(inode);
- }
return inode;
}
EXPORT_SYMBOL(new_inode);
