1 files changed, 46 insertions, 10 deletions

diff --git a/fs/libfs.c b/fs/libfs.c
index aada4e7c8713..4eda519c3002 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -28,12 +28,12 @@
 
 #include "internal.h"
 
-int simple_getattr(struct user_namespace *mnt_userns, const struct path *path,
+int simple_getattr(struct mnt_idmap *idmap, const struct path *path,
 		   struct kstat *stat, u32 request_mask,
 		   unsigned int query_flags)
 {
 	struct inode *inode = d_inode(path->dentry);
-	generic_fillattr(&init_user_ns, inode, stat);
+	generic_fillattr(&nop_mnt_idmap, inode, stat);
 	stat->blocks = inode->i_mapping->nrpages << (PAGE_SHIFT - 9);
 	return 0;
 }
@@ -473,7 +473,7 @@ int simple_rename_exchange(struct inode *old_dir, struct dentry *old_dentry,
 }
 EXPORT_SYMBOL_GPL(simple_rename_exchange);
 
-int simple_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
+int simple_rename(struct mnt_idmap *idmap, struct inode *old_dir,
 		  struct dentry *old_dentry, struct inode *new_dir,
 		  struct dentry *new_dentry, unsigned int flags)
 {
@@ -509,7 +509,7 @@ EXPORT_SYMBOL(simple_rename);
 
 /**
  * simple_setattr - setattr for simple filesystem
- * @mnt_userns: user namespace of the target mount
+ * @idmap: idmap of the target mount
  * @dentry: dentry
  * @iattr: iattr structure
  *
@@ -522,19 +522,19 @@ EXPORT_SYMBOL(simple_rename);
  * on simple regular filesystems.  Anything that needs to change on-disk
  * or wire state on size changes needs its own setattr method.
  */
-int simple_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+int simple_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 		   struct iattr *iattr)
 {
 	struct inode *inode = d_inode(dentry);
 	int error;
 
-	error = setattr_prepare(mnt_userns, dentry, iattr);
+	error = setattr_prepare(idmap, dentry, iattr);
 	if (error)
 		return error;
 
 	if (iattr->ia_valid & ATTR_SIZE)
 		truncate_setsize(inode, iattr->ia_size);
-	setattr_copy(mnt_userns, inode, iattr);
+	setattr_copy(idmap, inode, iattr);
 	mark_inode_dirty(inode);
 	return 0;
 }
@@ -1315,16 +1315,16 @@ static struct dentry *empty_dir_lookup(struct inode *dir, struct dentry *dentry,
 	return ERR_PTR(-ENOENT);
 }
 
-static int empty_dir_getattr(struct user_namespace *mnt_userns,
+static int empty_dir_getattr(struct mnt_idmap *idmap,
 			     const struct path *path, struct kstat *stat,
 			     u32 request_mask, unsigned int query_flags)
 {
 	struct inode *inode = d_inode(path->dentry);
-	generic_fillattr(&init_user_ns, inode, stat);
+	generic_fillattr(&nop_mnt_idmap, inode, stat);
 	return 0;
 }
 
-static int empty_dir_setattr(struct user_namespace *mnt_userns,
+static int empty_dir_setattr(struct mnt_idmap *idmap,
 			     struct dentry *dentry, struct iattr *attr)
 {
 	return -EPERM;
@@ -1582,3 +1582,39 @@ bool inode_maybe_inc_iversion(struct inode *inode, bool force)
 	return true;
 }
 EXPORT_SYMBOL(inode_maybe_inc_iversion);
+
+/**
+ * inode_query_iversion - read i_version for later use
+ * @inode: inode from which i_version should be read
+ *
+ * Read the inode i_version counter. This should be used by callers that wish
+ * to store the returned i_version for later comparison. This will guarantee
+ * that a later query of the i_version will result in a different value if
+ * anything has changed.
+ *
+ * In this implementation, we fetch the current value, set the QUERIED flag and
+ * then try to swap it into place with a cmpxchg, if it wasn't already set. If
+ * that fails, we try again with the newly fetched value from the cmpxchg.
+ */
+u64 inode_query_iversion(struct inode *inode)
+{
+	u64 cur, new;
+
+	cur = inode_peek_iversion_raw(inode);
+	do {
+		/* If flag is already set, then no need to swap */
+		if (cur & I_VERSION_QUERIED) {
+			/*
+			 * This barrier (and the implicit barrier in the
+			 * cmpxchg below) pairs with the barrier in
+			 * inode_maybe_inc_iversion().
+			 */
+			smp_mb();
+			break;
+		}
+
+		new = cur | I_VERSION_QUERIED;
+	} while (!atomic64_try_cmpxchg(&inode->i_version, &cur, new));
+	return cur >> I_VERSION_QUERIED_SHIFT;
+}
+EXPORT_SYMBOL(inode_query_iversion);