new helper: inode_unhashed()

note: for race-free uses you inode_lock held
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/btrfs/inode.c

@@ -3849,7 +3849,7 @@ static void inode_tree_add(struct inode *inode)
 	p = &root->inode_tree.rb_node;
 	parent = NULL;
 
-	if (hlist_unhashed(&inode->i_hash))
+	if (inode_unhashed(inode))
 		return;
 
 	spin_lock(&root->inode_lock);

fs/fs-writeback.c

@@ -962,7 +962,7 @@ void __mark_inode_dirty(struct inode *inode, int flags)
 		 * dirty list.  Add blockdev inodes as well.
 		 */
 		if (!S_ISBLK(inode->i_mode)) {
-			if (hlist_unhashed(&inode->i_hash))
+			if (inode_unhashed(inode))
 				goto out;
 		}
 		if (inode->i_state & I_FREEING)

fs/inode.c

@@ -1094,7 +1094,7 @@ int insert_inode_locked(struct inode *inode)
 		__iget(old);
 		spin_unlock(&inode_lock);
 		wait_on_inode(old);
-		if (unlikely(!hlist_unhashed(&old->i_hash))) {
+		if (unlikely(!inode_unhashed(old))) {
 			iput(old);
 			return -EBUSY;
 		}
@@ -1133,7 +1133,7 @@ int insert_inode_locked4(struct inode *inode, unsigned long hashval,
 		__iget(old);
 		spin_unlock(&inode_lock);
 		wait_on_inode(old);
-		if (unlikely(!hlist_unhashed(&old->i_hash))) {
+		if (unlikely(!inode_unhashed(old))) {
 			iput(old);
 			return -EBUSY;
 		}
@@ -1186,7 +1186,7 @@ EXPORT_SYMBOL(generic_delete_inode);
  */
 int generic_drop_inode(struct inode *inode)
 {
-	return !inode->i_nlink || hlist_unhashed(&inode->i_hash);
+	return !inode->i_nlink || inode_unhashed(inode);
 }
 EXPORT_SYMBOL_GPL(generic_drop_inode);
 

fs/reiserfs/xattr.c

@@ -422,7 +422,7 @@ int reiserfs_commit_write(struct file *f, struct page *page,
 static void update_ctime(struct inode *inode)
 {
 	struct timespec now = current_fs_time(inode->i_sb);
-	if (hlist_unhashed(&inode->i_hash) || !inode->i_nlink ||
+	if (inode_unhashed(inode) || !inode->i_nlink ||
 	    timespec_equal(&inode->i_ctime, &now))
 		return;
 

include/linux/fs.h

@@ -786,6 +786,11 @@ struct inode {
 	void			*i_private; /* fs or device private pointer */
 };
 
+static inline int inode_unhashed(struct inode *inode)
+{
+	return hlist_unhashed(&inode->i_hash);
+}
+
 /*
  * inode->i_mutex nesting subclasses for the lock validator:
  *

mm/shmem.c

@@ -2146,7 +2146,7 @@ static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len,
 	if (*len < 3)
 		return 255;
 
-	if (hlist_unhashed(&inode->i_hash)) {
+	if (inode_unhashed(inode)) {
 		/* Unfortunately insert_inode_hash is not idempotent,
 		 * so as we hash inodes here rather than at creation
 		 * time, we need a lock to ensure we only try
@@ -2154,7 +2154,7 @@ static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len,
 		 */
 		static DEFINE_SPINLOCK(lock);
 		spin_lock(&lock);
-		if (hlist_unhashed(&inode->i_hash))
+		if (inode_unhashed(inode))
 			__insert_inode_hash(inode,
 					    inode->i_ino + inode->i_generation);
 		spin_unlock(&lock);