[PATCH] vfs: Deduplicate code shared by xattr system calls operating on paths
From: Eric Biggers
Date: Sun Oct 12 2014 - 13:01:17 EST
The following pairs of system calls dealing with extended attributes only
differ in their behavior on whether the symbolic link is followed (when
the named file is a symbolic link):
- setxattr() and lsetxattr()
- getxattr() and lgetxattr()
- listxattr() and llistxattr()
- removexattr() and lremovexattr()
Despite this, the implementations all had duplicated code, so this commit
redirects each of the above pairs of system calls to a corresponding
function to which different lookup flags (LOOKUP_FOLLOW or 0) are passed.
For me this reduced the stripped size of xattr.o from 8824 to 8248 bytes.
Signed-off-by: Eric Biggers <ebiggers3@xxxxxxxxx>
---
fs/xattr.c | 116 +++++++++++++++++++++----------------------------------------
1 file changed, 39 insertions(+), 77 deletions(-)
diff --git a/fs/xattr.c b/fs/xattr.c
index c69e6d4..64e83ef 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -364,13 +364,12 @@ out:
return error;
}
-SYSCALL_DEFINE5(setxattr, const char __user *, pathname,
- const char __user *, name, const void __user *, value,
- size_t, size, int, flags)
+static int path_setxattr(const char __user *pathname,
+ const char __user *name, const void __user *value,
+ size_t size, int flags, unsigned int lookup_flags)
{
struct path path;
int error;
- unsigned int lookup_flags = LOOKUP_FOLLOW;
retry:
error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
if (error)
@@ -388,28 +387,18 @@ retry:
return error;
}
+SYSCALL_DEFINE5(setxattr, const char __user *, pathname,
+ const char __user *, name, const void __user *, value,
+ size_t, size, int, flags)
+{
+ return path_setxattr(pathname, name, value, size, flags, LOOKUP_FOLLOW);
+}
+
SYSCALL_DEFINE5(lsetxattr, const char __user *, pathname,
const char __user *, name, const void __user *, value,
size_t, size, int, flags)
{
- struct path path;
- int error;
- unsigned int lookup_flags = 0;
-retry:
- error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
- if (error)
- return error;
- error = mnt_want_write(path.mnt);
- if (!error) {
- error = setxattr(path.dentry, name, value, size, flags);
- mnt_drop_write(path.mnt);
- }
- path_put(&path);
- if (retry_estale(error, lookup_flags)) {
- lookup_flags |= LOOKUP_REVAL;
- goto retry;
- }
- return error;
+ return path_setxattr(pathname, name, value, size, flags, 0);
}
SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name,
@@ -481,12 +470,12 @@ getxattr(struct dentry *d, const char __user *name, void __user *value,
return error;
}
-SYSCALL_DEFINE4(getxattr, const char __user *, pathname,
- const char __user *, name, void __user *, value, size_t, size)
+static ssize_t path_getxattr(const char __user *pathname,
+ const char __user *name, void __user *value,
+ size_t size, unsigned int lookup_flags)
{
struct path path;
ssize_t error;
- unsigned int lookup_flags = LOOKUP_FOLLOW;
retry:
error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
if (error)
@@ -500,23 +489,16 @@ retry:
return error;
}
+SYSCALL_DEFINE4(getxattr, const char __user *, pathname,
+ const char __user *, name, void __user *, value, size_t, size)
+{
+ return path_getxattr(pathname, name, value, size, LOOKUP_FOLLOW);
+}
+
SYSCALL_DEFINE4(lgetxattr, const char __user *, pathname,
const char __user *, name, void __user *, value, size_t, size)
{
- struct path path;
- ssize_t error;
- unsigned int lookup_flags = 0;
-retry:
- error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
- if (error)
- return error;
- error = getxattr(path.dentry, name, value, size);
- path_put(&path);
- if (retry_estale(error, lookup_flags)) {
- lookup_flags |= LOOKUP_REVAL;
- goto retry;
- }
- return error;
+ return path_getxattr(pathname, name, value, size, 0);
}
SYSCALL_DEFINE4(fgetxattr, int, fd, const char __user *, name,
@@ -571,12 +553,11 @@ listxattr(struct dentry *d, char __user *list, size_t size)
return error;
}
-SYSCALL_DEFINE3(listxattr, const char __user *, pathname, char __user *, list,
- size_t, size)
+static ssize_t path_listxattr(const char __user *pathname, char __user *list,
+ size_t size, unsigned int lookup_flags)
{
struct path path;
ssize_t error;
- unsigned int lookup_flags = LOOKUP_FOLLOW;
retry:
error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
if (error)
@@ -590,23 +571,16 @@ retry:
return error;
}
+SYSCALL_DEFINE3(listxattr, const char __user *, pathname, char __user *, list,
+ size_t, size)
+{
+ return path_listxattr(pathname, list, size, LOOKUP_FOLLOW);
+}
+
SYSCALL_DEFINE3(llistxattr, const char __user *, pathname, char __user *, list,
size_t, size)
{
- struct path path;
- ssize_t error;
- unsigned int lookup_flags = 0;
-retry:
- error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
- if (error)
- return error;
- error = listxattr(path.dentry, list, size);
- path_put(&path);
- if (retry_estale(error, lookup_flags)) {
- lookup_flags |= LOOKUP_REVAL;
- goto retry;
- }
- return error;
+ return path_listxattr(pathname, list, size, 0);
}
SYSCALL_DEFINE3(flistxattr, int, fd, char __user *, list, size_t, size)
@@ -640,12 +614,11 @@ removexattr(struct dentry *d, const char __user *name)
return vfs_removexattr(d, kname);
}
-SYSCALL_DEFINE2(removexattr, const char __user *, pathname,
- const char __user *, name)
+static int path_removexattr(const char __user *pathname,
+ const char __user *name, unsigned int lookup_flags)
{
struct path path;
int error;
- unsigned int lookup_flags = LOOKUP_FOLLOW;
retry:
error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
if (error)
@@ -663,27 +636,16 @@ retry:
return error;
}
+SYSCALL_DEFINE2(removexattr, const char __user *, pathname,
+ const char __user *, name)
+{
+ return path_removexattr(pathname, name, LOOKUP_FOLLOW);
+}
+
SYSCALL_DEFINE2(lremovexattr, const char __user *, pathname,
const char __user *, name)
{
- struct path path;
- int error;
- unsigned int lookup_flags = 0;
-retry:
- error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
- if (error)
- return error;
- error = mnt_want_write(path.mnt);
- if (!error) {
- error = removexattr(path.dentry, name);
- mnt_drop_write(path.mnt);
- }
- path_put(&path);
- if (retry_estale(error, lookup_flags)) {
- lookup_flags |= LOOKUP_REVAL;
- goto retry;
- }
- return error;
+ return path_removexattr(pathname, name, 0);
}
SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name)
--
2.1.2
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