libfs: Add simple_offset_rename() API

I'm about to fix a tmpfs rename bug that requires the use of
internal simple_offset helpers that are not available in mm/shmem.c

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Link: https://lore.kernel.org/r/20240415152057.4605-3-cel@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/fs/libfs.c b/fs/libfs.c
index ab61fae92cde8b304dae01817a7f819304904680..c392a6edd3930503724ec65de5d35225ff745481 100644 (file)
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -357,6 +357,27 @@ int simple_offset_empty(struct dentry *dentry)
        return ret;
 }
 
+/**
+ * simple_offset_rename - handle directory offsets for rename
+ * @old_dir: parent directory of source entry
+ * @old_dentry: dentry of source entry
+ * @new_dir: parent_directory of destination entry
+ * @new_dentry: dentry of destination
+ *
+ * Caller provides appropriate serialization.
+ *
+ * Returns zero on success, a negative errno value on failure.
+ */
+int simple_offset_rename(struct inode *old_dir, struct dentry *old_dentry,
+                        struct inode *new_dir, struct dentry *new_dentry)
+{
+       struct offset_ctx *old_ctx = old_dir->i_op->get_offset_ctx(old_dir);
+       struct offset_ctx *new_ctx = new_dir->i_op->get_offset_ctx(new_dir);
+
+       simple_offset_remove(old_ctx, old_dentry);
+       return simple_offset_add(new_ctx, old_dentry);
+}
+
 /**
  * simple_offset_rename_exchange - exchange rename with directory offsets
  * @old_dir: parent of dentry being moved

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 00fc429b0af0fb9bbab2382a9e347fdbac383981..82c707e40fea832ebfd67aef41db62beec85921c 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3338,6 +3338,8 @@ void simple_offset_init(struct offset_ctx *octx);
 int simple_offset_add(struct offset_ctx *octx, struct dentry *dentry);
 void simple_offset_remove(struct offset_ctx *octx, struct dentry *dentry);
 int simple_offset_empty(struct dentry *dentry);
+int simple_offset_rename(struct inode *old_dir, struct dentry *old_dentry,
+                        struct inode *new_dir, struct dentry *new_dentry);
 int simple_offset_rename_exchange(struct inode *old_dir,
                                  struct dentry *old_dentry,
                                  struct inode *new_dir,

diff --git a/mm/shmem.c b/mm/shmem.c
index 0aad0d9a621b80e7a3f758125806bfb64e984c12..c0fb65223963d5a2d0c69980a81853c40ebccf86 100644 (file)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -3473,8 +3473,7 @@ static int shmem_rename2(struct mnt_idmap *idmap,
                        return error;
        }
 
-       simple_offset_remove(shmem_get_offset_ctx(old_dir), old_dentry);
-       error = simple_offset_add(shmem_get_offset_ctx(new_dir), old_dentry);
+       error = simple_offset_rename(old_dir, old_dentry, new_dir, new_dentry);
        if (error)
                return error;