xattr: Add __vfs_{get,set,remove}xattr helpers

Right now, various places in the kernel check for the existence of
getxattr, setxattr, and removexattr inode operations and directly call
those operations.  Switch to helper functions and test for the IOP_XATTR
flag instead.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Acked-by: James Morris <james.l.morris@oracle.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

7 files changed, 55 insertions, 36 deletions

diff --git a/fs/cachefiles/bind.c b/fs/cachefiles/bind.c
index 6af790f..3ff867f 100644
--- a/fs/cachefiles/bind.c
+++ b/fs/cachefiles/bind.c
@@ -20,6 +20,7 @@
 #include <linux/mount.h>
 #include <linux/statfs.h>
 #include <linux/ctype.h>
+#include <linux/xattr.h>
 #include "internal.h"
 
 static int cachefiles_daemon_add_cache(struct cachefiles_cache *caches);
@@ -126,8 +127,7 @@ static int cachefiles_daemon_add_cache(struct cachefiles_cache *cache)
 	if (d_is_negative(root) ||
 	    !d_backing_inode(root)->i_op->lookup ||
 	    !d_backing_inode(root)->i_op->mkdir ||
-	    !d_backing_inode(root)->i_op->setxattr ||
-	    !d_backing_inode(root)->i_op->getxattr ||
+	    !(d_backing_inode(root)->i_opflags & IOP_XATTR) ||
 	    !root->d_sb->s_op->statfs ||
 	    !root->d_sb->s_op->sync_fs)
 		goto error_unsupported;
diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c
index 3f7c2cd..6eb3dec 100644
--- a/fs/cachefiles/namei.c
+++ b/fs/cachefiles/namei.c
@@ -20,6 +20,7 @@
 #include <linux/namei.h>
 #include <linux/security.h>
 #include <linux/slab.h>
+#include <linux/xattr.h>
 #include "internal.h"
 
 #define CACHEFILES_KEYBUF_SIZE 512
@@ -799,8 +800,7 @@ struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
 	}
 
 	ret = -EPERM;
-	if (!d_backing_inode(subdir)->i_op->setxattr ||
-	    !d_backing_inode(subdir)->i_op->getxattr ||
+	if (!(d_backing_inode(subdir)->i_opflags & IOP_XATTR) ||
 	    !d_backing_inode(subdir)->i_op->lookup ||
 	    !d_backing_inode(subdir)->i_op->mkdir ||
 	    !d_backing_inode(subdir)->i_op->create ||
diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index cef32cc..32fee25 100644
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -1005,15 +1005,14 @@ ecryptfs_setxattr(struct dentry *dentry, struct inode *inode,
 		  const char *name, const void *value,
 		  size_t size, int flags)
 {
-	int rc = 0;
+	int rc;
 	struct dentry *lower_dentry;
 
 	lower_dentry = ecryptfs_dentry_to_lower(dentry);
-	if (!d_inode(lower_dentry)->i_op->setxattr) {
+	if (!(d_inode(lower_dentry)->i_opflags & IOP_XATTR)) {
 		rc = -EOPNOTSUPP;
 		goto out;
 	}
-
 	rc = vfs_setxattr(lower_dentry, name, value, size, flags);
 	if (!rc && inode)
 		fsstack_copy_attr_all(inode, d_inode(lower_dentry));
@@ -1025,15 +1024,14 @@ ssize_t
 ecryptfs_getxattr_lower(struct dentry *lower_dentry, struct inode *lower_inode,
 			const char *name, void *value, size_t size)
 {
-	int rc = 0;
+	int rc;
 
-	if (!lower_inode->i_op->getxattr) {
+	if (!(lower_inode->i_opflags & IOP_XATTR)) {
 		rc = -EOPNOTSUPP;
 		goto out;
 	}
 	inode_lock(lower_inode);
-	rc = lower_inode->i_op->getxattr(lower_dentry, lower_inode,
-					 name, value, size);
+	rc = __vfs_getxattr(lower_dentry, lower_inode, name, value, size);
 	inode_unlock(lower_inode);
 out:
 	return rc;
@@ -1069,18 +1067,18 @@ out:
 static int ecryptfs_removexattr(struct dentry *dentry, struct inode *inode,
 				const char *name)
 {
-	int rc = 0;
+	int rc;
 	struct dentry *lower_dentry;
 	struct inode *lower_inode;
 
 	lower_dentry = ecryptfs_dentry_to_lower(dentry);
 	lower_inode = ecryptfs_inode_to_lower(inode);
-	if (!lower_inode->i_op->removexattr) {
+	if (!(lower_inode->i_opflags & IOP_XATTR)) {
 		rc = -EOPNOTSUPP;
 		goto out;
 	}
 	inode_lock(lower_inode);
-	rc = lower_inode->i_op->removexattr(lower_dentry, name);
+	rc = __vfs_removexattr(lower_dentry, name);
 	inode_unlock(lower_inode);
 out:
 	return rc;
diff --git a/fs/ecryptfs/mmap.c b/fs/ecryptfs/mmap.c
index 9c3437c..1f0c471 100644
--- a/fs/ecryptfs/mmap.c
+++ b/fs/ecryptfs/mmap.c
@@ -32,6 +32,7 @@
 #include <linux/file.h>
 #include <linux/scatterlist.h>
 #include <linux/slab.h>
+#include <linux/xattr.h>
 #include <asm/unaligned.h>
 #include "ecryptfs_kernel.h"
 
@@ -422,7 +423,7 @@ static int ecryptfs_write_inode_size_to_xattr(struct inode *ecryptfs_inode)
 	struct inode *lower_inode = d_inode(lower_dentry);
 	int rc;
 
-	if (!lower_inode->i_op->getxattr || !lower_inode->i_op->setxattr) {
+	if (!(lower_inode->i_opflags & IOP_XATTR)) {
 		printk(KERN_WARNING
 		       "No support for setting xattr in lower filesystem\n");
 		rc = -ENOSYS;
@@ -436,15 +437,13 @@ static int ecryptfs_write_inode_size_to_xattr(struct inode *ecryptfs_inode)
 		goto out;
 	}
 	inode_lock(lower_inode);
-	size = lower_inode->i_op->getxattr(lower_dentry, lower_inode,
-					   ECRYPTFS_XATTR_NAME,
-					   xattr_virt, PAGE_SIZE);
+	size = __vfs_getxattr(lower_dentry, lower_inode, ECRYPTFS_XATTR_NAME,
+			      xattr_virt, PAGE_SIZE);
 	if (size < 0)
 		size = 8;
 	put_unaligned_be64(i_size_read(ecryptfs_inode), xattr_virt);
-	rc = lower_inode->i_op->setxattr(lower_dentry, lower_inode,
-					 ECRYPTFS_XATTR_NAME,
-					 xattr_virt, size, 0);
+	rc = __vfs_setxattr(lower_dentry, lower_inode, ECRYPTFS_XATTR_NAME,
+			    xattr_virt, size, 0);
 	inode_unlock(lower_inode);
 	if (rc)
 		printk(KERN_ERR "Error whilst attempting to write inode size "
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index 43fdc27..807951c 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -58,8 +58,8 @@ int ovl_copy_xattr(struct dentry *old, struct dentry *new)
 	char *buf, *name, *value = NULL;
 	int uninitialized_var(error);
 
-	if (!old->d_inode->i_op->getxattr ||
-	    !new->d_inode->i_op->getxattr)
+	if (!(old->d_inode->i_opflags & IOP_XATTR) ||
+	    !(new->d_inode->i_opflags & IOP_XATTR))
 		return 0;
 
 	list_size = vfs_listxattr(old, NULL, 0);
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index e2a94a2..f170114 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -275,10 +275,10 @@ static bool ovl_is_opaquedir(struct dentry *dentry)
 	char val;
 	struct inode *inode = dentry->d_inode;
 
-	if (!S_ISDIR(inode->i_mode) || !inode->i_op->getxattr)
+	if (!S_ISDIR(inode->i_mode) || !(inode->i_opflags & IOP_XATTR))
 		return false;
 
-	res = inode->i_op->getxattr(dentry, inode, OVL_XATTR_OPAQUE, &val, 1);
+	res = __vfs_getxattr(dentry, inode, OVL_XATTR_OPAQUE, &val, 1);
 	if (res == 1 && val == 'y')
 		return true;
 
diff --git a/fs/xattr.c b/fs/xattr.c
index 1f5d0b4..54a4115 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -136,6 +136,16 @@ xattr_permission(struct inode *inode, const char *name, int mask)
 	return inode_permission(inode, mask);
 }
 
+int
+__vfs_setxattr(struct dentry *dentry, struct inode *inode, const char *name,
+	       const void *value, size_t size, int flags)
+{
+	if (!inode->i_op->setxattr)
+		return -EOPNOTSUPP;
+	return inode->i_op->setxattr(dentry, inode, name, value, size, flags);
+}
+EXPORT_SYMBOL(__vfs_setxattr);
+
 /**
  *  __vfs_setxattr_noperm - perform setxattr operation without performing
  *  permission checks.
@@ -163,7 +173,7 @@ int __vfs_setxattr_noperm(struct dentry *dentry, const char *name,
 	if (issec)
 		inode->i_flags &= ~S_NOSEC;
 	if (inode->i_op->setxattr) {
-		error = inode->i_op->setxattr(dentry, inode, name, value, size, flags);
+		error = __vfs_setxattr(dentry, inode, name, value, size, flags);
 		if (!error) {
 			fsnotify_xattr(dentry);
 			security_inode_post_setxattr(dentry, name, value,
@@ -275,6 +285,16 @@ vfs_getxattr_alloc(struct dentry *dentry, const char *name, char **xattr_value,
 }
 
 ssize_t
+__vfs_getxattr(struct dentry *dentry, struct inode *inode, const char *name,
+	       void *value, size_t size)
+{
+	if (!inode->i_op->getxattr)
+		return -EOPNOTSUPP;
+	return inode->i_op->getxattr(dentry, inode, name, value, size);
+}
+EXPORT_SYMBOL(__vfs_getxattr);
+
+ssize_t
 vfs_getxattr(struct dentry *dentry, const char *name, void *value, size_t size)
 {
 	struct inode *inode = dentry->d_inode;
@@ -301,13 +321,7 @@ vfs_getxattr(struct dentry *dentry, const char *name, void *value, size_t size)
 		return ret;
 	}
 nolsm:
-	if (inode->i_op->getxattr)
-		error = inode->i_op->getxattr(dentry, inode, name, value, size);
-	else
-		error = -EOPNOTSUPP;
-
-	return error;
-
+	return __vfs_getxattr(dentry, inode, name, value, size);
 }
 EXPORT_SYMBOL_GPL(vfs_getxattr);
 
@@ -332,13 +346,21 @@ vfs_listxattr(struct dentry *d, char *list, size_t size)
 EXPORT_SYMBOL_GPL(vfs_listxattr);
 
 int
-vfs_removexattr(struct dentry *dentry, const char *name)
+__vfs_removexattr(struct dentry *dentry, const char *name)
 {
 	struct inode *inode = dentry->d_inode;
-	int error;
 
 	if (!inode->i_op->removexattr)
 		return -EOPNOTSUPP;
+	return inode->i_op->removexattr(dentry, name);
+}
+EXPORT_SYMBOL(__vfs_removexattr);
+
+int
+vfs_removexattr(struct dentry *dentry, const char *name)
+{
+	struct inode *inode = dentry->d_inode;
+	int error;
 
 	error = xattr_permission(inode, name, MAY_WRITE);
 	if (error)
@@ -349,7 +371,7 @@ vfs_removexattr(struct dentry *dentry, const char *name)
 	if (error)
 		goto out;
 
-	error = inode->i_op->removexattr(dentry, name);
+	error = __vfs_removexattr(dentry, name);
 
 	if (!error) {
 		fsnotify_xattr(dentry);