fs: port ->getattr() to pass 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>

72 files changed, 152 insertions, 148 deletions

diff --git a/Documentation/filesystems/locking.rst b/Documentation/filesystems/locking.rst
index 04ad02dcd269..556a23af1edf 100644
--- a/Documentation/filesystems/locking.rst
+++ b/Documentation/filesystems/locking.rst
@@ -72,7 +72,7 @@ prototypes::
 	int (*permission) (struct inode *, int, unsigned int);
 	struct posix_acl * (*get_inode_acl)(struct inode *, int, bool);
 	int (*setattr) (struct mnt_idmap *, struct dentry *, struct iattr *);
-	int (*getattr) (const struct path *, struct kstat *, u32, unsigned int);
+	int (*getattr) (struct mnt_idmap *, const struct path *, struct kstat *, u32, unsigned int);
 	ssize_t (*listxattr) (struct dentry *, char *, size_t);
 	int (*fiemap)(struct inode *, struct fiemap_extent_info *, u64 start, u64 len);
 	void (*update_time)(struct inode *, struct timespec *, int);
diff --git a/Documentation/filesystems/vfs.rst b/Documentation/filesystems/vfs.rst
index 894e2a5c3603..09184d98fc8c 100644
--- a/Documentation/filesystems/vfs.rst
+++ b/Documentation/filesystems/vfs.rst
@@ -437,7 +437,7 @@ As of kernel 2.6.22, the following members are defined:
 		int (*permission) (struct user_namespace *, struct inode *, int);
 		struct posix_acl * (*get_inode_acl)(struct inode *, int, bool);
 		int (*setattr) (struct mnt_idmap *, struct dentry *, struct iattr *);
-		int (*getattr) (struct user_namespace *, const struct path *, struct kstat *, u32, unsigned int);
+		int (*getattr) (struct mnt_idmap *, const struct path *, struct kstat *, u32, unsigned int);
 		ssize_t (*listxattr) (struct dentry *, char *, size_t);
 		void (*update_time)(struct inode *, struct timespec *, int);
 		int (*atomic_open)(struct inode *, struct dentry *, struct file *,
diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index d8cd3f17bbf3..ee47b2bb3712 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -1018,7 +1018,7 @@ error:
 
 /**
  * v9fs_vfs_getattr - retrieve file metadata
- * @mnt_userns: The user namespace of the mount
+ * @idmap: idmap of the mount
  * @path: Object to query
  * @stat: metadata structure to populate
  * @request_mask: Mask of STATX_xxx flags indicating the caller's interests
@@ -1027,7 +1027,7 @@ error:
  */
 
 static int
-v9fs_vfs_getattr(struct user_namespace *mnt_userns, const struct path *path,
+v9fs_vfs_getattr(struct mnt_idmap *idmap, const struct path *path,
 		 struct kstat *stat, u32 request_mask, unsigned int flags)
 {
 	struct dentry *dentry = path->dentry;
@@ -1038,7 +1038,7 @@ v9fs_vfs_getattr(struct user_namespace *mnt_userns, const struct path *path,
 	p9_debug(P9_DEBUG_VFS, "dentry: %p\n", dentry);
 	v9ses = v9fs_dentry2v9ses(dentry);
 	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) {
-		generic_fillattr(&init_user_ns, d_inode(dentry), stat);
+		generic_fillattr(&nop_mnt_idmap, d_inode(dentry), stat);
 		return 0;
 	}
 	fid = v9fs_fid_lookup(dentry);
@@ -1051,7 +1051,7 @@ v9fs_vfs_getattr(struct user_namespace *mnt_userns, const struct path *path,
 		return PTR_ERR(st);
 
 	v9fs_stat2inode(st, d_inode(dentry), dentry->d_sb, 0);
-	generic_fillattr(&init_user_ns, d_inode(dentry), stat);
+	generic_fillattr(&nop_mnt_idmap, d_inode(dentry), stat);
 
 	p9stat_free(st);
 	kfree(st);
diff --git a/fs/9p/vfs_inode_dotl.c b/fs/9p/vfs_inode_dotl.c
index dfe6b4017bd0..08ec5e7b628d 100644
--- a/fs/9p/vfs_inode_dotl.c
+++ b/fs/9p/vfs_inode_dotl.c
@@ -450,7 +450,7 @@ error:
 }
 
 static int
-v9fs_vfs_getattr_dotl(struct user_namespace *mnt_userns,
+v9fs_vfs_getattr_dotl(struct mnt_idmap *idmap,
 		      const struct path *path, struct kstat *stat,
 		      u32 request_mask, unsigned int flags)
 {
@@ -462,7 +462,7 @@ v9fs_vfs_getattr_dotl(struct user_namespace *mnt_userns,
 	p9_debug(P9_DEBUG_VFS, "dentry: %p\n", dentry);
 	v9ses = v9fs_dentry2v9ses(dentry);
 	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) {
-		generic_fillattr(&init_user_ns, d_inode(dentry), stat);
+		generic_fillattr(&nop_mnt_idmap, d_inode(dentry), stat);
 		return 0;
 	}
 	fid = v9fs_fid_lookup(dentry);
@@ -479,7 +479,7 @@ v9fs_vfs_getattr_dotl(struct user_namespace *mnt_userns,
 		return PTR_ERR(st);
 
 	v9fs_stat2inode_dotl(st, d_inode(dentry), 0);
-	generic_fillattr(&init_user_ns, d_inode(dentry), stat);
+	generic_fillattr(&nop_mnt_idmap, d_inode(dentry), stat);
 	/* Change block size to what the server returned */
 	stat->blksize = st->st_blksize;
 
diff --git a/fs/afs/inode.c b/fs/afs/inode.c
index f001cf1750ec..0167e96e5198 100644
--- a/fs/afs/inode.c
+++ b/fs/afs/inode.c
@@ -737,7 +737,7 @@ error_unlock:
 /*
  * read the attributes of an inode
  */
-int afs_getattr(struct user_namespace *mnt_userns, const struct path *path,
+int afs_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);
@@ -761,7 +761,7 @@ int afs_getattr(struct user_namespace *mnt_userns, const struct path *path,
 
 	do {
 		read_seqbegin_or_lock(&vnode->cb_lock, &seq);
-		generic_fillattr(&init_user_ns, inode, stat);
+		generic_fillattr(&nop_mnt_idmap, inode, stat);
 		if (test_bit(AFS_VNODE_SILLY_DELETED, &vnode->flags) &&
 		    stat->nlink > 0)
 			stat->nlink -= 1;
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index e2a23efc91b6..d5e7cd465593 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -1170,7 +1170,7 @@ extern struct inode *afs_iget(struct afs_operation *, struct afs_vnode_param *);
 extern struct inode *afs_root_iget(struct super_block *, struct key *);
 extern bool afs_check_validity(struct afs_vnode *);
 extern int afs_validate(struct afs_vnode *, struct key *);
-extern int afs_getattr(struct user_namespace *mnt_userns, const struct path *,
+extern int afs_getattr(struct mnt_idmap *idmap, const struct path *,
 		       struct kstat *, u32, unsigned int);
 extern int afs_setattr(struct mnt_idmap *idmap, struct dentry *, struct iattr *);
 extern void afs_evict_inode(struct inode *);
diff --git a/fs/bad_inode.c b/fs/bad_inode.c
index 9cb95ff99047..63006ca5b581 100644
--- a/fs/bad_inode.c
+++ b/fs/bad_inode.c
@@ -95,7 +95,7 @@ static int bad_inode_permission(struct user_namespace *mnt_userns,
 	return -EIO;
 }
 
-static int bad_inode_getattr(struct user_namespace *mnt_userns,
+static int bad_inode_getattr(struct mnt_idmap *idmap,
 			     const struct path *path, struct kstat *stat,
 			     u32 request_mask, unsigned int query_flags)
 {
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 36a897e5d8de..8ba37e4c36fe 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -9005,7 +9005,7 @@ fail:
 	return -ENOMEM;
 }
 
-static int btrfs_getattr(struct user_namespace *mnt_userns,
+static int btrfs_getattr(struct mnt_idmap *idmap,
 			 const struct path *path, struct kstat *stat,
 			 u32 request_mask, unsigned int flags)
 {
@@ -9035,7 +9035,7 @@ static int btrfs_getattr(struct user_namespace *mnt_userns,
 				  STATX_ATTR_IMMUTABLE |
 				  STATX_ATTR_NODUMP);
 
-	generic_fillattr(mnt_userns, inode, stat);
+	generic_fillattr(idmap, inode, stat);
 	stat->dev = BTRFS_I(inode)->root->anon_dev;
 
 	spin_lock(&BTRFS_I(inode)->lock);
diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index 358aadd4329a..fcc84cc1d8f1 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -2445,7 +2445,7 @@ static int statx_to_caps(u32 want, umode_t mode)
  * Get all the attributes. If we have sufficient caps for the requested attrs,
  * then we can avoid talking to the MDS at all.
  */
-int ceph_getattr(struct user_namespace *mnt_userns, const struct path *path,
+int ceph_getattr(struct mnt_idmap *idmap, const struct path *path,
 		 struct kstat *stat, u32 request_mask, unsigned int flags)
 {
 	struct inode *inode = d_inode(path->dentry);
@@ -2466,7 +2466,7 @@ int ceph_getattr(struct user_namespace *mnt_userns, const struct path *path,
 			return err;
 	}
 
-	generic_fillattr(&init_user_ns, inode, stat);
+	generic_fillattr(&nop_mnt_idmap, inode, stat);
 	stat->ino = ceph_present_inode(inode);
 
 	/*
diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index a023a74b6650..063dad749a07 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -1045,7 +1045,7 @@ extern int ceph_permission(struct user_namespace *mnt_userns,
 extern int __ceph_setattr(struct inode *inode, struct iattr *attr);
 extern int ceph_setattr(struct mnt_idmap *idmap,
 			struct dentry *dentry, struct iattr *attr);
-extern int ceph_getattr(struct user_namespace *mnt_userns,
+extern int ceph_getattr(struct mnt_idmap *idmap,
 			const struct path *path, struct kstat *stat,
 			u32 request_mask, unsigned int flags);
 void ceph_inode_shutdown(struct inode *inode);
diff --git a/fs/cifs/cifsfs.h b/fs/cifs/cifsfs.h
index f93c295649df..6c42137f9499 100644
--- a/fs/cifs/cifsfs.h
+++ b/fs/cifs/cifsfs.h
@@ -72,7 +72,7 @@ extern int cifs_revalidate_dentry(struct dentry *);
 extern int cifs_invalidate_mapping(struct inode *inode);
 extern int cifs_revalidate_mapping(struct inode *inode);
 extern int cifs_zap_mapping(struct inode *inode);
-extern int cifs_getattr(struct user_namespace *, const struct path *,
+extern int cifs_getattr(struct mnt_idmap *, const struct path *,
 			struct kstat *, u32, unsigned int);
 extern int cifs_setattr(struct mnt_idmap *, struct dentry *,
 			struct iattr *);
diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
index 653f05ce287a..aad6a40c9721 100644
--- a/fs/cifs/inode.c
+++ b/fs/cifs/inode.c
@@ -2496,7 +2496,7 @@ int cifs_revalidate_dentry(struct dentry *dentry)
 	return cifs_revalidate_mapping(inode);
 }
 
-int cifs_getattr(struct user_namespace *mnt_userns, const struct path *path,
+int cifs_getattr(struct mnt_idmap *idmap, const struct path *path,
 		 struct kstat *stat, u32 request_mask, unsigned int flags)
 {
 	struct dentry *dentry = path->dentry;
@@ -2537,7 +2537,7 @@ int cifs_getattr(struct user_namespace *mnt_userns, const struct path *path,
 			return rc;
 	}
 
-	generic_fillattr(&init_user_ns, inode, stat);
+	generic_fillattr(&nop_mnt_idmap, inode, stat);
 	stat->blksize = cifs_sb->ctx->bsize;
 	stat->ino = CIFS_I(inode)->uniqueid;
 
diff --git a/fs/coda/coda_linux.h b/fs/coda/coda_linux.h
index b762525eb5a2..cc69a0f15b41 100644
--- a/fs/coda/coda_linux.h
+++ b/fs/coda/coda_linux.h
@@ -49,7 +49,7 @@ int coda_release(struct inode *i, struct file *f);
 int coda_permission(struct user_namespace *mnt_userns, struct inode *inode,
 		    int mask);
 int coda_revalidate_inode(struct inode *);
-int coda_getattr(struct user_namespace *, const struct path *, struct kstat *,
+int coda_getattr(struct mnt_idmap *, const struct path *, struct kstat *,
 		 u32, unsigned int);
 int coda_setattr(struct mnt_idmap *, struct dentry *, struct iattr *);
 
diff --git a/fs/coda/inode.c b/fs/coda/inode.c
index 8e5a431f7eb5..d661e6cf17ac 100644
--- a/fs/coda/inode.c
+++ b/fs/coda/inode.c
@@ -251,12 +251,12 @@ static void coda_evict_inode(struct inode *inode)
 	coda_cache_clear_inode(inode);
 }
 
-int coda_getattr(struct user_namespace *mnt_userns, const struct path *path,
+int coda_getattr(struct mnt_idmap *idmap, const struct path *path,
 		 struct kstat *stat, u32 request_mask, unsigned int flags)
 {
 	int err = coda_revalidate_inode(d_inode(path->dentry));
 	if (!err)
-		generic_fillattr(&init_user_ns, d_inode(path->dentry), stat);
+		generic_fillattr(&nop_mnt_idmap, d_inode(path->dentry), stat);
 	return err;
 }
 
diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index 011b03e5c9df..7854b71c769f 100644
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -972,7 +972,7 @@ out:
 	return rc;
 }
 
-static int ecryptfs_getattr_link(struct user_namespace *mnt_userns,
+static int ecryptfs_getattr_link(struct mnt_idmap *idmap,
 				 const struct path *path, struct kstat *stat,
 				 u32 request_mask, unsigned int flags)
 {
@@ -982,7 +982,7 @@ static int ecryptfs_getattr_link(struct user_namespace *mnt_userns,
 
 	mount_crypt_stat = &ecryptfs_superblock_to_private(
 						dentry->d_sb)->mount_crypt_stat;
-	generic_fillattr(&init_user_ns, d_inode(dentry), stat);
+	generic_fillattr(&nop_mnt_idmap, d_inode(dentry), stat);
 	if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
 		char *target;
 		size_t targetsiz;
@@ -998,7 +998,7 @@ static int ecryptfs_getattr_link(struct user_namespace *mnt_userns,
 	return rc;
 }
 
-static int ecryptfs_getattr(struct user_namespace *mnt_userns,
+static int ecryptfs_getattr(struct mnt_idmap *idmap,
 			    const struct path *path, struct kstat *stat,
 			    u32 request_mask, unsigned int flags)
 {
@@ -1011,7 +1011,7 @@ static int ecryptfs_getattr(struct user_namespace *mnt_userns,
 	if (!rc) {
 		fsstack_copy_attr_all(d_inode(dentry),
 				      ecryptfs_inode_to_lower(d_inode(dentry)));
-		generic_fillattr(&init_user_ns, d_inode(dentry), stat);
+		generic_fillattr(&nop_mnt_idmap, d_inode(dentry), stat);
 		stat->blocks = lower_stat.blocks;
 	}
 	return rc;
diff --git a/fs/erofs/inode.c b/fs/erofs/inode.c
index d3b8736fa124..a194e8ee5861 100644
--- a/fs/erofs/inode.c
+++ b/fs/erofs/inode.c
@@ -353,7 +353,7 @@ struct inode *erofs_iget(struct super_block *sb, erofs_nid_t nid)
 	return inode;
 }
 
-int erofs_getattr(struct user_namespace *mnt_userns, const struct path *path,
+int erofs_getattr(struct mnt_idmap *idmap, const struct path *path,
 		  struct kstat *stat, u32 request_mask,
 		  unsigned int query_flags)
 {
@@ -366,7 +366,7 @@ int erofs_getattr(struct user_namespace *mnt_userns, const struct path *path,
 	stat->attributes_mask |= (STATX_ATTR_COMPRESSED |
 				  STATX_ATTR_IMMUTABLE);
 
-	generic_fillattr(mnt_userns, inode, stat);
+	generic_fillattr(idmap, inode, stat);
 	return 0;
 }
 
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index bb8501c0ff5b..e05ae61069e8 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -494,7 +494,7 @@ extern const struct inode_operations erofs_symlink_iops;
 extern const struct inode_operations erofs_fast_symlink_iops;
 
 struct inode *erofs_iget(struct super_block *sb, erofs_nid_t nid);
-int erofs_getattr(struct user_namespace *mnt_userns, const struct path *path,
+int erofs_getattr(struct mnt_idmap *idmap, const struct path *path,
 		  struct kstat *stat, u32 request_mask,
 		  unsigned int query_flags);
 
diff --git a/fs/exfat/exfat_fs.h b/fs/exfat/exfat_fs.h
index 7fd693a668c7..1bf16abe3c84 100644
--- a/fs/exfat/exfat_fs.h
+++ b/fs/exfat/exfat_fs.h
@@ -452,7 +452,7 @@ int __exfat_truncate(struct inode *inode);
 void exfat_truncate(struct inode *inode);
 int exfat_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 		  struct iattr *attr);
-int exfat_getattr(struct user_namespace *mnt_userns, const struct path *path,
+int exfat_getattr(struct mnt_idmap *idmap, const struct path *path,
 		  struct kstat *stat, unsigned int request_mask,
 		  unsigned int query_flags);
 int exfat_file_fsync(struct file *file, loff_t start, loff_t end, int datasync);
diff --git a/fs/exfat/file.c b/fs/exfat/file.c
index da61838f8842..1fdb0a64b91d 100644
--- a/fs/exfat/file.c
+++ b/fs/exfat/file.c
@@ -226,14 +226,14 @@ write_size:
 	mutex_unlock(&sbi->s_lock);
 }
 
-int exfat_getattr(struct user_namespace *mnt_uerns, const struct path *path,
+int exfat_getattr(struct mnt_idmap *idmap, const struct path *path,
 		  struct kstat *stat, unsigned int request_mask,
 		  unsigned int query_flags)
 {
 	struct inode *inode = d_backing_inode(path->dentry);
 	struct exfat_inode_info *ei = EXFAT_I(inode);
 
-	generic_fillattr(&init_user_ns, inode, stat);
+	generic_fillattr(&nop_mnt_idmap, inode, stat);
 	exfat_truncate_atime(&stat->atime);
 	stat->result_mask |= STATX_BTIME;
 	stat->btime.tv_sec = ei->i_crtime.tv_sec;
diff --git a/fs/ext2/ext2.h b/fs/ext2/ext2.h
index 4a3e95406cce..9ca0fda28928 100644
--- a/fs/ext2/ext2.h
+++ b/fs/ext2/ext2.h
@@ -754,7 +754,7 @@ extern int ext2_write_inode (struct inode *, struct writeback_control *);
 extern void ext2_evict_inode(struct inode *);
 extern int ext2_get_block(struct inode *, sector_t, struct buffer_head *, int);
 extern int ext2_setattr (struct mnt_idmap *, struct dentry *, struct iattr *);
-extern int ext2_getattr (struct user_namespace *, const struct path *,
+extern int ext2_getattr (struct mnt_idmap *, const struct path *,
 			 struct kstat *, u32, unsigned int);
 extern void ext2_set_inode_flags(struct inode *inode);
 extern int ext2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index 792b974a5beb..bbc9941dbb43 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -1592,7 +1592,7 @@ int ext2_write_inode(struct inode *inode, struct writeback_control *wbc)
 	return __ext2_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
 }
 
-int ext2_getattr(struct user_namespace *mnt_userns, const struct path *path,
+int ext2_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);
@@ -1614,7 +1614,7 @@ int ext2_getattr(struct user_namespace *mnt_userns, const struct path *path,
 			STATX_ATTR_IMMUTABLE |
 			STATX_ATTR_NODUMP);
 
-	gene