fs: port inode_init_owner() to mnt_idmap

Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

1 files changed, 10 insertions, 16 deletions

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 74a2c3eae066..d10a508d95cd 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -2795,7 +2795,6 @@ static int ext4_add_nondir(handle_t *handle,
 static int ext4_create(struct mnt_idmap *idmap, struct inode *dir,
 		       struct dentry *dentry, umode_t mode, bool excl)
 {
-	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
 	handle_t *handle;
 	struct inode *inode;
 	int err, credits, retries = 0;
@@ -2807,7 +2806,7 @@ static int ext4_create(struct mnt_idmap *idmap, struct inode *dir,
 	credits = (EXT4_DATA_TRANS_BLOCKS(dir->i_sb) +
 		   EXT4_INDEX_EXTRA_TRANS_BLOCKS + 3);
 retry:
-	inode = ext4_new_inode_start_handle(mnt_userns, dir, mode, &dentry->d_name,
+	inode = ext4_new_inode_start_handle(idmap, dir, mode, &dentry->d_name,
 					    0, NULL, EXT4_HT_DIR, credits);
 	handle = ext4_journal_current_handle();
 	err = PTR_ERR(inode);
@@ -2831,7 +2830,6 @@ retry:
 static int ext4_mknod(struct mnt_idmap *idmap, struct inode *dir,
 		      struct dentry *dentry, umode_t mode, dev_t rdev)
 {
-	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
 	handle_t *handle;
 	struct inode *inode;
 	int err, credits, retries = 0;
@@ -2843,7 +2841,7 @@ static int ext4_mknod(struct mnt_idmap *idmap, struct inode *dir,
 	credits = (EXT4_DATA_TRANS_BLOCKS(dir->i_sb) +
 		   EXT4_INDEX_EXTRA_TRANS_BLOCKS + 3);
 retry:
-	inode = ext4_new_inode_start_handle(mnt_userns, dir, mode, &dentry->d_name,
+	inode = ext4_new_inode_start_handle(idmap, dir, mode, &dentry->d_name,
 					    0, NULL, EXT4_HT_DIR, credits);
 	handle = ext4_journal_current_handle();
 	err = PTR_ERR(inode);
@@ -2866,7 +2864,6 @@ retry:
 static int ext4_tmpfile(struct mnt_idmap *idmap, struct inode *dir,
 			struct file *file, umode_t mode)
 {
-	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
 	handle_t *handle;
 	struct inode *inode;
 	int err, retries = 0;
@@ -2876,7 +2873,7 @@ static int ext4_tmpfile(struct mnt_idmap *idmap, struct inode *dir,
 		return err;
 
 retry:
-	inode = ext4_new_inode_start_handle(mnt_userns, dir, mode,
+	inode = ext4_new_inode_start_handle(idmap, dir, mode,
 					    NULL, 0, NULL,
 					    EXT4_HT_DIR,
 			EXT4_MAXQUOTAS_INIT_BLOCKS(dir->i_sb) +
@@ -2978,7 +2975,6 @@ out:
 static int ext4_mkdir(struct mnt_idmap *idmap, struct inode *dir,
 		      struct dentry *dentry, umode_t mode)
 {
-	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
 	handle_t *handle;
 	struct inode *inode;
 	int err, err2 = 0, credits, retries = 0;
@@ -2993,7 +2989,7 @@ static int ext4_mkdir(struct mnt_idmap *idmap, struct inode *dir,
 	credits = (EXT4_DATA_TRANS_BLOCKS(dir->i_sb) +
 		   EXT4_INDEX_EXTRA_TRANS_BLOCKS + 3);
 retry:
-	inode = ext4_new_inode_start_handle(mnt_userns, dir, S_IFDIR | mode,
+	inode = ext4_new_inode_start_handle(idmap, dir, S_IFDIR | mode,
 					    &dentry->d_name,
 					    0, NULL, EXT4_HT_DIR, credits);
 	handle = ext4_journal_current_handle();
@@ -3346,7 +3342,6 @@ out:
 static int ext4_symlink(struct mnt_idmap *idmap, struct inode *dir,
 			struct dentry *dentry, const char *symname)
 {
-	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
 	handle_t *handle;
 	struct inode *inode;
 	int err, len = strlen(symname);
@@ -3375,7 +3370,7 @@ static int ext4_symlink(struct mnt_idmap *idmap, struct inode *dir,
 	credits = EXT4_DATA_TRANS_BLOCKS(dir->i_sb) +
 		  EXT4_INDEX_EXTRA_TRANS_BLOCKS + 3;
 retry:
-	inode = ext4_new_inode_start_handle(mnt_userns, dir, S_IFLNK|S_IRWXUGO,
+	inode = ext4_new_inode_start_handle(idmap, dir, S_IFLNK|S_IRWXUGO,
 					    &dentry->d_name, 0, NULL,
 					    EXT4_HT_DIR, credits);
 	handle = ext4_journal_current_handle();
@@ -3725,7 +3720,7 @@ static void ext4_update_dir_count(handle_t *handle, struct ext4_renament *ent)
 	}
 }
 
-static struct inode *ext4_whiteout_for_rename(struct user_namespace *mnt_userns,
+static struct inode *ext4_whiteout_for_rename(struct mnt_idmap *idmap,
 					      struct ext4_renament *ent,
 					      int credits, handle_t **h)
 {
@@ -3740,7 +3735,7 @@ static struct inode *ext4_whiteout_for_rename(struct user_namespace *mnt_userns,
 	credits += (EXT4_MAXQUOTAS_TRANS_BLOCKS(ent->dir->i_sb) +
 		    EXT4_XATTR_TRANS_BLOCKS + 4);
 retry:
-	wh = ext4_new_inode_start_handle(mnt_userns, ent->dir,
+	wh = ext4_new_inode_start_handle(idmap, ent->dir,
 					 S_IFCHR | WHITEOUT_MODE,
 					 &ent->dentry->d_name, 0, NULL,
 					 EXT4_HT_DIR, credits);
@@ -3768,7 +3763,7 @@ retry:
  * while new_{dentry,inode) refers to the destination dentry/inode
  * This comes from rename(const char *oldpath, const char *newpath)
  */
-static int ext4_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
+static int ext4_rename(struct mnt_idmap *idmap, struct inode *old_dir,
 		       struct dentry *old_dentry, struct inode *new_dir,
 		       struct dentry *new_dentry, unsigned int flags)
 {
@@ -3856,7 +3851,7 @@ static int ext4_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
 			goto release_bh;
 		}
 	} else {
-		whiteout = ext4_whiteout_for_rename(mnt_userns, &old, credits, &handle);
+		whiteout = ext4_whiteout_for_rename(idmap, &old, credits, &handle);
 		if (IS_ERR(whiteout)) {
 			retval = PTR_ERR(whiteout);
 			goto release_bh;
@@ -4168,7 +4163,6 @@ static int ext4_rename2(struct mnt_idmap *idmap,
 			struct inode *new_dir, struct dentry *new_dentry,
 			unsigned int flags)
 {
-	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
 	int err;
 
 	if (unlikely(ext4_forced_shutdown(EXT4_SB(old_dir->i_sb))))
@@ -4187,7 +4181,7 @@ static int ext4_rename2(struct mnt_idmap *idmap,
 					 new_dir, new_dentry);
 	}
 
-	return ext4_rename(mnt_userns, old_dir, old_dentry, new_dir, new_dentry, flags);
+	return ext4_rename(idmap, old_dir, old_dentry, new_dir, new_dentry, flags);
 }
 
 /*