[PATCH v2 16/25] fs: add inode operations to get/set/remove fscaps

[Seth Forshee (DigitalOcean)]

Add inode operations for getting, setting and removing filesystem
capabilities rather than passing around raw xattr data. This provides
better type safety for ids contained within xattrs.

Signed-off-by: Seth Forshee (DigitalOcean) <sforshee at kernel.org>
---
 Documentation/filesystems/locking.rst |  4 ++++
 Documentation/filesystems/vfs.rst     | 17 +++++++++++++++++
 include/linux/fs.h                    |  4 ++++
 3 files changed, 25 insertions(+)

diff --git a/Documentation/filesystems/locking.rst b/Documentation/filesystems/locking.rst
index d5bf4b6b7509..d208dd9f75ae 100644
--- a/Documentation/filesystems/locking.rst
+++ b/Documentation/filesystems/locking.rst
@@ -81,6 +81,8 @@ prototypes::
 				umode_t create_mode);
 	int (*tmpfile) (struct mnt_idmap *, struct inode *,
 			struct file *, umode_t);
+	int (*get_fscaps)(struct mnt_idmap *, struct dentry *, struct vfs_caps *);
+	int (*set_fscaps)(struct mnt_idmap *, struct dentry *, const struct vfs_caps *, int setxattr_flags);
 	int (*fileattr_set)(struct mnt_idmap *idmap,
 			    struct dentry *dentry, struct fileattr *fa);
 	int (*fileattr_get)(struct dentry *dentry, struct fileattr *fa);
@@ -114,6 +116,8 @@ fiemap:		no
 update_time:	no
 atomic_open:	shared (exclusive if O_CREAT is set in open flags)
 tmpfile:	no
+get_fscaps:     no
+set_fscaps:     exclusive
 fileattr_get:	no or exclusive
 fileattr_set:	exclusive
 get_offset_ctx  no
diff --git a/Documentation/filesystems/vfs.rst b/Documentation/filesystems/vfs.rst
index eebcc0f9e2bc..ed1cb03f271e 100644
--- a/Documentation/filesystems/vfs.rst
+++ b/Documentation/filesystems/vfs.rst
@@ -514,6 +514,8 @@ As of kernel 2.6.22, the following members are defined:
 		int (*tmpfile) (struct mnt_idmap *, struct inode *, struct file *, umode_t);
 		struct posix_acl * (*get_acl)(struct mnt_idmap *, struct dentry *, int);
 	        int (*set_acl)(struct mnt_idmap *, struct dentry *, struct posix_acl *, int);
+		int (*get_fscaps)(struct mnt_idmap *, struct dentry *, struct vfs_caps *);
+		int (*set_fscaps)(struct mnt_idmap *, struct dentry *, const struct vfs_caps *, int setxattr_flags);
 		int (*fileattr_set)(struct mnt_idmap *idmap,
 				    struct dentry *dentry, struct fileattr *fa);
 		int (*fileattr_get)(struct dentry *dentry, struct fileattr *fa);
@@ -667,6 +669,21 @@ otherwise noted.
 	open; this can be done by calling finish_open_simple() right at
 	the end.
 
+``get_fscaps``
+
+        called to get filesystem capabilites of an inode.  If unset,
+        xattr handlers will be used to get the raw xattr data.  Most
+        filesystems can rely on the generic handler.
+
+``set_fscaps``
+
+        called to set filesystem capabilites of an inode.  If unset,
+        xattr handlers will be used to set the raw xattr data.  Most
+        filesystems can rely on the generic handler.
+
+        If the new fscaps value is NULL the filesystem must remove any
+        fscaps from the inode.
+
 ``fileattr_get``
 	called on ioctl(FS_IOC_GETFLAGS) and ioctl(FS_IOC_FSGETXATTR) to
 	retrieve miscellaneous file flags and attributes.  Also called
diff --git a/include/linux/fs.h b/include/linux/fs.h
index ed5966a70495..89163e0f7aad 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2067,6 +2067,10 @@ struct inode_operations {
 				     int);
 	int (*set_acl)(struct mnt_idmap *, struct dentry *,
 		       struct posix_acl *, int);
+	int (*get_fscaps)(struct mnt_idmap *, struct dentry *,
+			  struct vfs_caps *);
+	int (*set_fscaps)(struct mnt_idmap *, struct dentry *,
+			  const struct vfs_caps *, int setxattr_flags);
 	int (*fileattr_set)(struct mnt_idmap *idmap,
 			    struct dentry *dentry, struct fileattr *fa);
 	int (*fileattr_get)(struct dentry *dentry, struct fileattr *fa);

-- 
2.43.0