gfs2: Switch to generic xattr handlers

Switch to the generic xattr handlers and take the necessary glocks at
the layer below. The following are the new xattr "entry points"; they
are called with the glock held already in the following cases:

  gfs2_xattr_get: From SELinux, during lookups.
  gfs2_xattr_set: The glock is never held.
  gfs2_get_acl: From gfs2_create_inode -> posix_acl_create and
                gfs2_setattr -> posix_acl_chmod.
  gfs2_set_acl: From gfs2_setattr -> posix_acl_chmod.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

4 files changed, 99 insertions, 88 deletions

diff --git a/fs/gfs2/acl.c b/fs/gfs2/acl.c
index 7919326..363ba9e 100644
--- a/fs/gfs2/acl.c
+++ b/fs/gfs2/acl.c
@@ -24,6 +24,7 @@
 #include "glock.h"
 #include "inode.h"
 #include "meta_io.h"
+#include "rgrp.h"
 #include "trans.h"
 #include "util.h"
 
@@ -38,7 +39,7 @@ static const char *gfs2_acl_name(int type)
 	return NULL;
 }
 
-struct posix_acl *gfs2_get_acl(struct inode *inode, int type)
+static struct posix_acl *__gfs2_get_acl(struct inode *inode, int type)
 {
 	struct gfs2_inode *ip = GFS2_I(inode);
 	struct posix_acl *acl;
@@ -50,29 +51,41 @@ struct posix_acl *gfs2_get_acl(struct inode *inode, int type)
 		return NULL;
 
 	name = gfs2_acl_name(type);
-	if (name == NULL)
-		return ERR_PTR(-EINVAL);
-
 	len = gfs2_xattr_acl_get(ip, name, &data);
-	if (len < 0)
+	if (len <= 0)
 		return ERR_PTR(len);
-	if (len == 0)
-		return NULL;
-
 	acl = posix_acl_from_xattr(&init_user_ns, data, len);
 	kfree(data);
 	return acl;
 }
 
-int gfs2_set_acl(struct inode *inode, struct posix_acl *acl, int type)
+struct posix_acl *gfs2_get_acl(struct inode *inode, int type)
+{
+	struct gfs2_inode *ip = GFS2_I(inode);
+	struct gfs2_holder gh;
+	bool need_unlock = false;
+	struct posix_acl *acl;
+
+	if (!gfs2_glock_is_locked_by_me(ip->i_gl)) {
+		int ret = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED,
+					     LM_FLAG_ANY, &gh);
+		if (ret)
+			return ERR_PTR(ret);
+		need_unlock = true;
+	}
+	acl = __gfs2_get_acl(inode, type);
+	if (need_unlock)
+		gfs2_glock_dq_uninit(&gh);
+	return acl;
+}
+
+int __gfs2_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 {
 	int error;
 	int len;
 	char *data;
 	const char *name = gfs2_acl_name(type);
 
-	BUG_ON(name == NULL);
-
 	if (acl && acl->a_count > GFS2_ACL_MAX_ENTRIES(GFS2_SB(inode)))
 		return -E2BIG;
 
@@ -115,3 +128,26 @@ out:
 	kfree(data);
 	return error;
 }
+
+int gfs2_set_acl(struct inode *inode, struct posix_acl *acl, int type)
+{
+	struct gfs2_inode *ip = GFS2_I(inode);
+	struct gfs2_holder gh;
+	bool need_unlock = false;
+	int ret;
+
+	ret = gfs2_rsqa_alloc(ip);
+	if (ret)
+		return ret;
+
+	if (!gfs2_glock_is_locked_by_me(ip->i_gl)) {
+		ret = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &gh);
+		if (ret)
+			return ret;
+		need_unlock = true;
+	}
+	ret = __gfs2_set_acl(inode, acl, type);
+	if (need_unlock)
+		gfs2_glock_dq_uninit(&gh);
+	return ret;
+}
diff --git a/fs/gfs2/acl.h b/fs/gfs2/acl.h
index 3af4f40..f674fdd 100644
--- a/fs/gfs2/acl.h
+++ b/fs/gfs2/acl.h
@@ -15,6 +15,7 @@
 #define GFS2_ACL_MAX_ENTRIES(sdp) ((300 << (sdp)->sd_sb.sb_bsize_shift) >> 12)
 
 extern struct posix_acl *gfs2_get_acl(struct inode *inode, int type);
+extern int __gfs2_set_acl(struct inode *inode, struct posix_acl *acl, int type);
 extern int gfs2_set_acl(struct inode *inode, struct posix_acl *acl, int type);
 
 #endif /* __ACL_DOT_H__ */
diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c
index 45f516ca..72e9c64 100644
--- a/fs/gfs2/inode.c
+++ b/fs/gfs2/inode.c
@@ -692,12 +692,12 @@ static int gfs2_create_inode(struct inode *dir, struct dentry *dentry,
 			       considered free. Any failures need to undo
 			       the gfs2 structures. */
 	if (default_acl) {
-		error = gfs2_set_acl(inode, default_acl, ACL_TYPE_DEFAULT);
+		error = __gfs2_set_acl(inode, default_acl, ACL_TYPE_DEFAULT);
 		posix_acl_release(default_acl);
 	}
 	if (acl) {
 		if (!error)
-			error = gfs2_set_acl(inode, acl, ACL_TYPE_ACCESS);
+			error = __gfs2_set_acl(inode, acl, ACL_TYPE_ACCESS);
 		posix_acl_release(acl);
 	}
 
@@ -1948,66 +1948,6 @@ static int gfs2_getattr(struct vfsmount *mnt, struct dentry *dentry,
 	return 0;
 }
 
-static int gfs2_setxattr(struct dentry *dentry, const char *name,
-			 const void *data, size_t size, int flags)
-{
-	struct inode *inode = d_inode(dentry);
-	struct gfs2_inode *ip = GFS2_I(inode);
-	struct gfs2_holder gh;
-	int ret;
-
-	gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &gh);
-	ret = gfs2_glock_nq(&gh);
-	if (ret == 0) {
-		ret = gfs2_rsqa_alloc(ip);
-		if (ret == 0)
-			ret = generic_setxattr(dentry, name, data, size, flags);
-		gfs2_glock_dq(&gh);
-	}
-	gfs2_holder_uninit(&gh);
-	return ret;
-}
-
-static ssize_t gfs2_getxattr(struct dentry *dentry, struct inode *inode,
-			     const char *name, void *data, size_t size)
-{
-	struct gfs2_inode *ip = GFS2_I(inode);
-	struct gfs2_holder gh;
-	int ret;
-
-	/* For selinux during lookup */
-	if (gfs2_glock_is_locked_by_me(ip->i_gl))
-		return generic_getxattr(dentry, inode, name, data, size);
-
-	gfs2_holder_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &gh);
-	ret = gfs2_glock_nq(&gh);
-	if (ret == 0) {
-		ret = generic_getxattr(dentry, inode, name, data, size);
-		gfs2_glock_dq(&gh);
-	}
-	gfs2_holder_uninit(&gh);
-	return ret;
-}
-
-static int gfs2_removexattr(struct dentry *dentry, const char *name)
-{
-	struct inode *inode = d_inode(dentry);
-	struct gfs2_inode *ip = GFS2_I(inode);
-	struct gfs2_holder gh;
-	int ret;
-
-	gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &gh);
-	ret = gfs2_glock_nq(&gh);
-	if (ret == 0) {
-		ret = gfs2_rsqa_alloc(ip);
-		if (ret == 0)
-			ret = generic_removexattr(dentry, name);
-		gfs2_glock_dq(&gh);
-	}
-	gfs2_holder_uninit(&gh);
-	return ret;
-}
-
 static int gfs2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		       u64 start, u64 len)
 {
@@ -2054,10 +1994,10 @@ const struct inode_operations gfs2_file_iops = {
 	.permission = gfs2_permission,
 	.setattr = gfs2_setattr,
 	.getattr = gfs2_getattr,
-	.setxattr = gfs2_setxattr,
-	.getxattr = gfs2_getxattr,
+	.setxattr = generic_setxattr,
+	.getxattr = generic_getxattr,
 	.listxattr = gfs2_listxattr,
-	.removexattr = gfs2_removexattr,
+	.removexattr = generic_removexattr,
 	.fiemap = gfs2_fiemap,
 	.get_acl = gfs2_get_acl,
 	.set_acl = gfs2_set_acl,
@@ -2076,10 +2016,10 @@ const struct inode_operations gfs2_dir_iops = {
 	.permission = gfs2_permission,
 	.setattr = gfs2_setattr,
 	.getattr = gfs2_getattr,
-	.setxattr = gfs2_setxattr,
-	.getxattr = gfs2_getxattr,
+	.setxattr = generic_setxattr,
+	.getxattr = generic_getxattr,
 	.listxattr = gfs2_listxattr,
-	.removexattr = gfs2_removexattr,
+	.removexattr = generic_removexattr,
 	.fiemap = gfs2_fiemap,
 	.get_acl = gfs2_get_acl,
 	.set_acl = gfs2_set_acl,
@@ -2092,10 +2032,10 @@ const struct inode_operations gfs2_symlink_iops = {
 	.permission = gfs2_permission,
 	.setattr = gfs2_setattr,
 	.getattr = gfs2_getattr,
-	.setxattr = gfs2_setxattr,
-	.getxattr = gfs2_getxattr,
+	.setxattr = generic_setxattr,
+	.getxattr = generic_getxattr,
 	.listxattr = gfs2_listxattr,
-	.removexattr = gfs2_removexattr,
+	.removexattr = generic_removexattr,
 	.fiemap = gfs2_fiemap,
 };
 
diff --git a/fs/gfs2/xattr.c b/fs/gfs2/xattr.c
index 619886b..f42ab53b 100644
--- a/fs/gfs2/xattr.c
+++ b/fs/gfs2/xattr.c
@@ -583,13 +583,11 @@ out:
  *
  * Returns: actual size of data on success, -errno on error
  */
-static int gfs2_xattr_get(const struct xattr_handler *handler,
-			  struct dentry *unused, struct inode *inode,
-			  const char *name, void *buffer, size_t size)
+static int __gfs2_xattr_get(struct inode *inode, const char *name,
+			    void *buffer, size_t size, int type)
 {
 	struct gfs2_inode *ip = GFS2_I(inode);
 	struct gfs2_ea_location el;
-	int type = handler->flags;
 	int error;
 
 	if (!ip->i_eattr)
@@ -611,6 +609,29 @@ static int gfs2_xattr_get(const struct xattr_handler *handler,
 	return error;
 }
 
+static int gfs2_xattr_get(const struct xattr_handler *handler,
+			  struct dentry *unused, struct inode *inode,
+			  const char *name, void *buffer, size_t size)
+{
+	struct gfs2_inode *ip = GFS2_I(inode);
+	struct gfs2_holder gh;
+	bool need_unlock = false;
+	int ret;
+
+	/* During lookup, SELinux calls this function with the glock locked. */
+
+	if (!gfs2_glock_is_locked_by_me(ip->i_gl)) {
+		ret = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &gh);
+		if (ret)
+			return ret;
+		need_unlock = true;
+	}
+	ret = __gfs2_xattr_get(inode, name, buffer, size, handler->flags);
+	if (need_unlock)
+		gfs2_glock_dq_uninit(&gh);
+	return ret;
+}
+
 /**
  * ea_alloc_blk - allocates a new block for extended attributes.
  * @ip: A pointer to the inode that's getting extended attributes
@@ -1233,8 +1254,21 @@ static int gfs2_xattr_set(const struct xattr_handler *handler,
 			  struct dentry *dentry, const char *name,
 			  const void *value, size_t size, int flags)
 {
-	return __gfs2_xattr_set(d_inode(dentry), name, value,
-				size, flags, handler->flags);
+	struct inode *inode = d_inode(dentry);
+	struct gfs2_inode *ip = GFS2_I(inode);
+	struct gfs2_holder gh;
+	int ret;
+
+	ret = gfs2_rsqa_alloc(ip);
+	if (ret)
+		return ret;
+
+	ret = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &gh);
+	if (ret)
+		return ret;
+	ret = __gfs2_xattr_set(inode, name, value, size, flags, handler->flags);
+	gfs2_glock_dq_uninit(&gh);
+	return ret;
 }
 
 static int ea_dealloc_indirect(struct gfs2_inode *ip)