fs: dcache per-inode inode alias locking

dcache_inode_lock can be replaced with per-inode locking. Use existing
inode->i_lock for this. This is slightly non-trivial because we sometimes
need to find the inode from the dentry, which requires d_inode to be
stabilised (either with refcount or d_lock).

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

1 files changed, 7 insertions, 5 deletions

diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c
index f06a940065f6..4b6825740dd5 100644
--- a/fs/exportfs/expfs.c
+++ b/fs/exportfs/expfs.c
@@ -43,24 +43,26 @@ find_acceptable_alias(struct dentry *result,
                 void *context)
 {
         struct dentry *dentry, *toput = NULL;
+        struct inode *inode;
 
         if (acceptable(context, result))
                 return result;
 
-        spin_lock(&dcache_inode_lock);
-        list_for_each_entry(dentry, &result->d_inode->i_dentry, d_alias) {
+        inode = result->d_inode;
+        spin_lock(&inode->i_lock);
+        list_for_each_entry(dentry, &inode->i_dentry, d_alias) {
                 dget(dentry);
-                spin_unlock(&dcache_inode_lock);
+                spin_unlock(&inode->i_lock);
                 if (toput)
                         dput(toput);
                 if (dentry != result && acceptable(context, dentry)) {
                         dput(result);
                         return dentry;
                 }
-                spin_lock(&dcache_inode_lock);
+                spin_lock(&inode->i_lock);
                 toput = dentry;
         }
-        spin_unlock(&dcache_inode_lock);
+        spin_unlock(&inode->i_lock);
 
         if (toput)
                 dput(toput);