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Message-ID: <20121025183018.GI14085@redhat.com>
Date: Thu, 25 Oct 2012 14:30:18 -0400
From: Aristeu Rozanski <aris@...hat.com>
To: Tejun Heo <tj@...nel.org>
Cc: linux-kernel@...r.kernel.org, Li Zefan <lizefan@...wei.com>,
Al Viro <viro@...iv.linux.org.uk>,
linux-fsdevel@...r.kernel.org, Hugh Dickins <hughd@...gle.com>
Subject: [PATCH v2] fs: xattr: rewrite simple_xattr_set()
The way this function was written is confusing and already caused problems.
Rewriting it to be easier to understand and maintain.
v2:
- fix error return value in __simple_xattr_remove() (pointed by Tejun Heo)
Cc: Hugh Dickins <hughd@...gle.com>
Cc: Tejun Heo <tj@...nel.org>
Cc: Li Zefan <lizefan@...wei.com>
Cc: Al Viro <viro@...IV.linux.org.uk>
Signed-off-by: Aristeu Rozanski <aris@...hat.com>
---
fs/xattr.c | 124 +++++++++++++++++++++++++++++++++++++------------------------
1 file changed, 76 insertions(+), 48 deletions(-)
Index: github/fs/xattr.c
===================================================================
--- github.orig/fs/xattr.c 2012-10-23 16:02:41.155857391 -0400
+++ github/fs/xattr.c 2012-10-25 11:17:15.118197552 -0400
@@ -842,55 +842,46 @@
return ret;
}
-static int __simple_xattr_set(struct simple_xattrs *xattrs, const char *name,
- const void *value, size_t size, int flags)
+static struct simple_xattr *__find_xattr(struct simple_xattrs *xattrs,
+ const char *name)
{
struct simple_xattr *xattr;
- struct simple_xattr *new_xattr = NULL;
- int err = 0;
-
- /* value == NULL means remove */
- if (value) {
- new_xattr = simple_xattr_alloc(value, size);
- if (!new_xattr)
- return -ENOMEM;
-
- new_xattr->name = kstrdup(name, GFP_KERNEL);
- if (!new_xattr->name) {
- kfree(new_xattr);
- return -ENOMEM;
- }
- }
- spin_lock(&xattrs->lock);
list_for_each_entry(xattr, &xattrs->head, list) {
- if (!strcmp(name, xattr->name)) {
- if (flags & XATTR_CREATE) {
- xattr = new_xattr;
- err = -EEXIST;
- } else if (new_xattr) {
- list_replace(&xattr->list, &new_xattr->list);
- } else {
- list_del(&xattr->list);
- }
- goto out;
- }
+ if (!strcmp(name, xattr->name))
+ return xattr;
}
- if (flags & XATTR_REPLACE) {
- xattr = new_xattr;
- err = -ENODATA;
- } else {
- list_add(&new_xattr->list, &xattrs->head);
- xattr = NULL;
- }
-out:
- spin_unlock(&xattrs->lock);
+ return NULL;
+}
+
+static int __simple_xattr_remove(struct simple_xattrs *xattrs,
+ const char *name)
+{
+ struct simple_xattr *xattr;
+
+ xattr = __find_xattr(xattrs, name);
if (xattr) {
+ list_del(&xattr->list);
kfree(xattr->name);
kfree(xattr);
+ return 0;
}
- return err;
+ return -ENODATA;
+}
+
+/*
+ * xattr REMOVE operation for in-memory/pseudo filesystems
+ */
+int simple_xattr_remove(struct simple_xattrs *xattrs, const char *name)
+{
+ int rc;
+
+ spin_lock(&xattrs->lock);
+ rc = __simple_xattr_remove(xattrs, name);
+ spin_unlock(&xattrs->lock);
+
+ return rc;
}
/**
@@ -910,17 +901,54 @@
int simple_xattr_set(struct simple_xattrs *xattrs, const char *name,
const void *value, size_t size, int flags)
{
+ struct simple_xattr *found, *new_xattr;
+ int err = 0;
+
if (size == 0)
- value = ""; /* empty EA, do not remove */
- return __simple_xattr_set(xattrs, name, value, size, flags);
-}
+ value = ""; /* empty EA */
-/*
- * xattr REMOVE operation for in-memory/pseudo filesystems
- */
-int simple_xattr_remove(struct simple_xattrs *xattrs, const char *name)
-{
- return __simple_xattr_set(xattrs, name, NULL, 0, XATTR_REPLACE);
+ /* if value == NULL is specified, remove the item */
+ if (value == NULL)
+ return simple_xattr_remove(xattrs, name);
+
+ new_xattr = simple_xattr_alloc(value, size);
+ if (!new_xattr)
+ return -ENOMEM;
+
+ new_xattr->name = kstrdup(name, GFP_KERNEL);
+ if (!new_xattr->name) {
+ kfree(new_xattr);
+ return -ENOMEM;
+ }
+
+ spin_lock(&xattrs->lock);
+
+ found = __find_xattr(xattrs, name);
+ if (found) {
+ if (flags & XATTR_CREATE) {
+ err = -EEXIST;
+ goto free_new;
+ }
+
+ list_replace(&found->list, &new_xattr->list);
+ kfree(found->name);
+ kfree(found);
+ } else {
+ if (flags & XATTR_REPLACE) {
+ err = -ENODATA;
+ goto free_new;
+ }
+
+ list_add_tail(&new_xattr->list, &xattrs->head);
+ }
+
+out:
+ spin_unlock(&xattrs->lock);
+ return err;
+free_new:
+ kfree(new_xattr->name);
+ kfree(new_xattr);
+ goto out;
}
static bool xattr_is_trusted(const char *name)
--
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