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, 4 insertions, 0 deletions

diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c
index 51b304056f10..84b8c460a781 100644
--- a/fs/exportfs/expfs.c
+++ b/fs/exportfs/expfs.c
@@ -48,8 +48,10 @@ find_acceptable_alias(struct dentry *result,
                 return result;
 
         spin_lock(&dcache_lock);
+        spin_lock(&dcache_inode_lock);
         list_for_each_entry(dentry, &result->d_inode->i_dentry, d_alias) {
                 dget_locked(dentry);
+                spin_unlock(&dcache_inode_lock);
                 spin_unlock(&dcache_lock);
                 if (toput)
                         dput(toput);
@@ -58,8 +60,10 @@ find_acceptable_alias(struct dentry *result,
                         return dentry;
                 }
                 spin_lock(&dcache_lock);
+                spin_lock(&dcache_inode_lock);
                 toput = dentry;
         }
+        spin_unlock(&dcache_inode_lock);
         spin_unlock(&dcache_lock);
 
         if (toput)