Commit cbedaac6 authored by Josef Bacik's avatar Josef Bacik

inode: add hlist_fake to avoid the inode hash lock in evict

Some filesystems don't use the VFS inode hash and fake the fact they
are hashed so that all the writeback code works correctly. However,
this means the evict() path still tries to remove the inode from the
hash, meaning that the inode_hash_lock() needs to be taken
unnecessarily. Hence under certain workloads the inode_hash_lock can
be contended even if the inode is never actually hashed.

To avoid this add hlist_fake to test if the inode isn't actually
hashed to avoid taking the hash lock on inodes that have never been
hashed.  Based on Dave Chinner's

inode: add IOP_NOTHASHED to avoid inode hash lock in evict

basd on Al's suggestions.  Thanks,
Signed-off-by: default avatarJosef Bacik <jbacik@fb.com>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Tested-by: default avatarDave Chinner <dchinner@redhat.com>
parent d353d758
...@@ -2608,7 +2608,7 @@ static inline void insert_inode_hash(struct inode *inode) ...@@ -2608,7 +2608,7 @@ static inline void insert_inode_hash(struct inode *inode)
extern void __remove_inode_hash(struct inode *); extern void __remove_inode_hash(struct inode *);
static inline void remove_inode_hash(struct inode *inode) static inline void remove_inode_hash(struct inode *inode)
{ {
if (!inode_unhashed(inode)) if (!inode_unhashed(inode) && !hlist_fake(&inode->i_hash))
__remove_inode_hash(inode); __remove_inode_hash(inode);
} }
......
...@@ -672,6 +672,11 @@ static inline void hlist_add_fake(struct hlist_node *n) ...@@ -672,6 +672,11 @@ static inline void hlist_add_fake(struct hlist_node *n)
n->pprev = &n->next; n->pprev = &n->next;
} }
static inline bool hlist_fake(struct hlist_node *h)
{
return h->pprev == &h->next;
}
/* /*
* Move a list from one list head to another. Fixup the pprev * Move a list from one list head to another. Fixup the pprev
* reference of the first entry if it exists. * reference of the first entry if it exists.
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment