From db9f3de5e094fb0c8899abfb5077b4fa2e4c1738 Mon Sep 17 00:00:00 2001
From: Mimi Zohar <zohar@linux.vnet.ibm.com>
Date: Wed, 9 Mar 2011 14:23:34 -0500
Subject: [PATCH] --- yaml --- r: 264479 b: refs/heads/master c:
 1601fbad2b14e0b8d4dbb55e749bfe31e972818a h: refs/heads/master i:   264477:
 e57348303e6a7d8918916192eb0cc0f602b15351   264475:
 00dd51e91856a216a529a58534b1abf548ec71a2   264471:
 140cdca60d5ab8575cdd19fab8ace810a02971cb   264463:
 c83c7ea622b810c6fbd5b16f0f1d2f7b10bbba2f   264447:
 fdfc63b7ab56caad357bc64309ca42ac9e3e56e7 v: v3

---
 [refs]                      |  2 +-
 trunk/fs/xattr.c            | 58 +++++++++++++++++++++++++++++++++++++
 trunk/include/linux/xattr.h |  5 +++-
 3 files changed, 63 insertions(+), 2 deletions(-)

diff --git a/[refs] b/[refs]
index ef08f138e756..7dea720875ae 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: f381c272224f5f158f5cff64f8f3481fa0eee8b3
+refs/heads/master: 1601fbad2b14e0b8d4dbb55e749bfe31e972818a
diff --git a/trunk/fs/xattr.c b/trunk/fs/xattr.c
index f060663ab70c..851808c92b30 100644
--- a/trunk/fs/xattr.c
+++ b/trunk/fs/xattr.c
@@ -166,6 +166,64 @@ xattr_getsecurity(struct inode *inode, const char *name, void *value,
 }
 EXPORT_SYMBOL_GPL(xattr_getsecurity);
 
+/*
+ * vfs_getxattr_alloc - allocate memory, if necessary, before calling getxattr
+ *
+ * Allocate memory, if not already allocated, or re-allocate correct size,
+ * before retrieving the extended attribute.
+ *
+ * Returns the result of alloc, if failed, or the getxattr operation.
+ */
+ssize_t
+vfs_getxattr_alloc(struct dentry *dentry, const char *name, char **xattr_value,
+		   size_t xattr_size, gfp_t flags)
+{
+	struct inode *inode = dentry->d_inode;
+	char *value = *xattr_value;
+	int error;
+
+	error = xattr_permission(inode, name, MAY_READ);
+	if (error)
+		return error;
+
+	if (!inode->i_op->getxattr)
+		return -EOPNOTSUPP;
+
+	error = inode->i_op->getxattr(dentry, name, NULL, 0);
+	if (error < 0)
+		return error;
+
+	if (!value || (error > xattr_size)) {
+		value = krealloc(*xattr_value, error + 1, flags);
+		if (!value)
+			return -ENOMEM;
+		memset(value, 0, error + 1);
+	}
+
+	error = inode->i_op->getxattr(dentry, name, value, error);
+	*xattr_value = value;
+	return error;
+}
+
+/* Compare an extended attribute value with the given value */
+int vfs_xattr_cmp(struct dentry *dentry, const char *xattr_name,
+		  const char *value, size_t size, gfp_t flags)
+{
+	char *xattr_value = NULL;
+	int rc;
+
+	rc = vfs_getxattr_alloc(dentry, xattr_name, &xattr_value, 0, flags);
+	if (rc < 0)
+		return rc;
+
+	if ((rc != size) || (memcmp(xattr_value, value, rc) != 0))
+		rc = -EINVAL;
+	else
+		rc = 0;
+	kfree(xattr_value);
+	return rc;
+}
+
 ssize_t
 vfs_getxattr(struct dentry *dentry, const char *name, void *value, size_t size)
 {
diff --git a/trunk/include/linux/xattr.h b/trunk/include/linux/xattr.h
index 7a378662ddff..4703f6bd1f53 100644
--- a/trunk/include/linux/xattr.h
+++ b/trunk/include/linux/xattr.h
@@ -84,7 +84,10 @@ ssize_t generic_getxattr(struct dentry *dentry, const char *name, void *buffer,
 ssize_t generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size);
 int generic_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags);
 int generic_removexattr(struct dentry *dentry, const char *name);
-
+ssize_t vfs_getxattr_alloc(struct dentry *dentry, const char *name,
+			   char **xattr_value, size_t size, gfp_t flags);
+int vfs_xattr_cmp(struct dentry *dentry, const char *xattr_name,
+		  const char *value, size_t size, gfp_t flags);
 #endif  /*  __KERNEL__  */
 
 #endif	/* _LINUX_XATTR_H */