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Subject[PATCH 14/21] namei: saner calling conventions for filename_parentat()
Date
From: Al Viro <viro@zeniv.linux.org.uk>

a) make it reject ERR_PTR() for name
b) make it putname(name) on all other failure exits
c) make it return name on success

again, simplifies the callers

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
fs/namei.c | 60 ++++++++++++++++++++++--------------------------------------
1 file changed, 22 insertions(+), 38 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 4588e82..bd45300 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2164,13 +2164,16 @@ static int path_parentat(int dfd, const struct filename *name,
return err;
}

-static int filename_parentat(int dfd, struct filename *name,
+static struct filename *filename_parentat(int dfd, struct filename *name,
unsigned int flags, struct path *parent,
struct qstr *last, int *type)
{
int retval;
- struct nameidata nd, *saved_nd = set_nameidata(&nd);
+ struct nameidata nd, *saved_nd;

+ if (IS_ERR(name))
+ return name;
+ saved_nd = set_nameidata(&nd);
retval = path_parentat(dfd, name, flags | LOOKUP_RCU, &nd, parent);
if (unlikely(retval == -ECHILD))
retval = path_parentat(dfd, name, flags, &nd, parent);
@@ -2181,32 +2184,30 @@ static int filename_parentat(int dfd, struct filename *name,
*last = nd.last;
*type = nd.last_type;
audit_inode(name, parent->dentry, LOOKUP_PARENT);
+ } else {
+ putname(name);
+ name = ERR_PTR(retval);
}
restore_nameidata(saved_nd);
- return retval;
+ return name;
}

/* does lookup, returns the object with parent locked */
struct dentry *kern_path_locked(const char *name, struct path *path)
{
- struct filename *filename = getname_kernel(name);
+ struct filename *filename;
+ struct dentry *d;
struct qstr last;
int type;
- struct dentry *d;
- int err;

+ filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path,
+ &last, &type);
if (IS_ERR(filename))
return ERR_CAST(filename);
-
- err = filename_parentat(AT_FDCWD, filename, 0, path, &last, &type);
- if (err) {
- d = ERR_PTR(err);
- goto out;
- }
- if (type != LAST_NORM) {
+ if (unlikely(type != LAST_NORM)) {
path_put(path);
- d = ERR_PTR(-EINVAL);
- goto out;
+ putname(filename);
+ return ERR_PTR(-EINVAL);
}
mutex_lock_nested(&path->dentry->d_inode->i_mutex, I_MUTEX_PARENT);
d = __lookup_hash(&last, path->dentry, 0);
@@ -2214,7 +2215,6 @@ struct dentry *kern_path_locked(const char *name, struct path *path)
mutex_unlock(&path->dentry->d_inode->i_mutex);
path_put(path);
}
-out:
putname(filename);
return d;
}
@@ -2323,21 +2323,9 @@ user_path_parent(int dfd, const char __user *path,
int *type,
unsigned int flags)
{
- struct filename *s = getname(path);
- int error;
-
/* only LOOKUP_REVAL is allowed in extra flags */
- flags &= LOOKUP_REVAL;
-
- if (IS_ERR(s))
- return s;
-
- error = filename_parentat(dfd, s, flags, parent, last, type);
- if (error) {
- putname(s);
- s = ERR_PTR(error);
- }
- return s;
+ return filename_parentat(dfd, getname(path), flags & LOOKUP_REVAL,
+ parent, last, type);
}

/**
@@ -3401,25 +3389,21 @@ static struct dentry *filename_create(int dfd, struct filename *name,
int error;
bool is_dir = (lookup_flags & LOOKUP_DIRECTORY);

- if (IS_ERR(name))
- return ERR_CAST(name);
/*
* Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any
* other flags passed in are ignored!
*/
lookup_flags &= LOOKUP_REVAL;

- error = filename_parentat(dfd, name, lookup_flags, path, &last, &type);
- if (error) {
- putname(name);
- return ERR_PTR(error);
- }
+ name = filename_parentat(dfd, name, lookup_flags, path, &last, &type);
+ if (IS_ERR(name))
+ return ERR_CAST(name);

/*
* Yucky last component or no last component at all?
* (foo/., foo/.., /////)
*/
- if (type != LAST_NORM)
+ if (unlikely(type != LAST_NORM))
goto out;

/* don't fail immediately if it's r/o, at least try to report other errors */
--
2.1.4


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