fs: scale inode alias list

Add a new lock, dcache_inode_lock, to protect the inode's i_dentry list
from concurrent modification. d_alias is also protected by d_lock.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index 34bf71b56542..47dfd5d29a6b 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -271,9 +271,11 @@ static struct dentry *v9fs_dentry_from_dir_inode(struct inode *inode)
         struct dentry *dentry;
 
         spin_lock(&dcache_lock);
+        spin_lock(&dcache_inode_lock);
         /* Directory should have only one entry. */
         BUG_ON(S_ISDIR(inode->i_mode) && !list_is_singular(&inode->i_dentry));
         dentry = list_entry(inode->i_dentry.next, struct dentry, d_alias);
+        spin_unlock(&dcache_inode_lock);
         spin_unlock(&dcache_lock);
         return dentry;
 }