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Subject[PATCH v3 027/110] name: shift nameidata down into user_path_walk()
Date
From: Al Viro <viro@zeniv.linux.org.uk>

that avoids having nameidata on stack during the calls of
->rmdir()/->unlink() and *two* of those during the calls
of ->rename().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
fs/namei.c | 124 +++++++++++++++++++++++++++++++++----------------------------
1 file changed, 67 insertions(+), 57 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 1439aa3..293300c 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2211,9 +2211,13 @@ EXPORT_SYMBOL(user_path_at);
* path-walking is complete.
*/
static struct filename *
-user_path_parent(int dfd, const char __user *path, struct nameidata *nd,
+user_path_parent(int dfd, const char __user *path,
+ struct path *parent,
+ struct qstr *last,
+ int *type,
unsigned int flags)
{
+ struct nameidata nd;
struct filename *s = getname(path);
int error;

@@ -2223,11 +2227,14 @@ user_path_parent(int dfd, const char __user *path, struct nameidata *nd,
if (IS_ERR(s))
return s;

- error = filename_lookup(dfd, s, flags | LOOKUP_PARENT, nd);
+ error = filename_lookup(dfd, s, flags | LOOKUP_PARENT, &nd);
if (error) {
putname(s);
return ERR_PTR(error);
}
+ *parent = nd.path;
+ *last = nd.last;
+ *type = nd.last_type;

return s;
}
@@ -3630,14 +3637,17 @@ static long do_rmdir(int dfd, const char __user *pathname)
int error = 0;
struct filename *name;
struct dentry *dentry;
- struct nameidata nd;
+ struct path path;
+ struct qstr last;
+ int type;
unsigned int lookup_flags = 0;
retry:
- name = user_path_parent(dfd, pathname, &nd, lookup_flags);
+ name = user_path_parent(dfd, pathname,
+ &path, &last, &type, lookup_flags);
if (IS_ERR(name))
return PTR_ERR(name);

- switch(nd.last_type) {
+ switch (type) {
case LAST_DOTDOT:
error = -ENOTEMPTY;
goto exit1;
@@ -3649,13 +3659,12 @@ retry:
goto exit1;
}

- nd.flags &= ~LOOKUP_PARENT;
- error = mnt_want_write(nd.path.mnt);
+ error = mnt_want_write(path.mnt);
if (error)
goto exit1;

- mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
- dentry = __lookup_hash(&nd.last, nd.path.dentry, nd.flags);
+ mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
+ dentry = __lookup_hash(&last, path.dentry, lookup_flags);
error = PTR_ERR(dentry);
if (IS_ERR(dentry))
goto exit2;
@@ -3663,17 +3672,17 @@ retry:
error = -ENOENT;
goto exit3;
}
- error = security_path_rmdir(&nd.path, dentry);
+ error = security_path_rmdir(&path, dentry);
if (error)
goto exit3;
- error = vfs_rmdir(nd.path.dentry->d_inode, dentry);
+ error = vfs_rmdir(path.dentry->d_inode, dentry);
exit3:
dput(dentry);
exit2:
- mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
- mnt_drop_write(nd.path.mnt);
+ mutex_unlock(&path.dentry->d_inode->i_mutex);
+ mnt_drop_write(path.mnt);
exit1:
- path_put(&nd.path);
+ path_put(&path);
putname(name);
if (retry_estale(error, lookup_flags)) {
lookup_flags |= LOOKUP_REVAL;
@@ -3756,43 +3765,45 @@ static long do_unlinkat(int dfd, const char __user *pathname)
int error;
struct filename *name;
struct dentry *dentry;
- struct nameidata nd;
+ struct path path;
+ struct qstr last;
+ int type;
struct inode *inode = NULL;
struct inode *delegated_inode = NULL;
unsigned int lookup_flags = 0;
retry:
- name = user_path_parent(dfd, pathname, &nd, lookup_flags);
+ name = user_path_parent(dfd, pathname,
+ &path, &last, &type, lookup_flags);
if (IS_ERR(name))
return PTR_ERR(name);

error = -EISDIR;
- if (nd.last_type != LAST_NORM)
+ if (type != LAST_NORM)
goto exit1;

- nd.flags &= ~LOOKUP_PARENT;
- error = mnt_want_write(nd.path.mnt);
+ error = mnt_want_write(path.mnt);
if (error)
goto exit1;
retry_deleg:
- mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
- dentry = __lookup_hash(&nd.last, nd.path.dentry, nd.flags);
+ mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
+ dentry = __lookup_hash(&last, path.dentry, lookup_flags);
error = PTR_ERR(dentry);
if (!IS_ERR(dentry)) {
/* Why not before? Because we want correct error value */
- if (nd.last.name[nd.last.len])
+ if (last.name[last.len])
goto slashes;
inode = dentry->d_inode;
if (d_is_negative(dentry))
goto slashes;
ihold(inode);
- error = security_path_unlink(&nd.path, dentry);
+ error = security_path_unlink(&path, dentry);
if (error)
goto exit2;
- error = vfs_unlink(nd.path.dentry->d_inode, dentry, &delegated_inode);
+ error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode);
exit2:
dput(dentry);
}
- mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
+ mutex_unlock(&path.dentry->d_inode->i_mutex);
if (inode)
iput(inode); /* truncate the inode here */
inode = NULL;
@@ -3801,9 +3812,9 @@ exit2:
if (!error)
goto retry_deleg;
}
- mnt_drop_write(nd.path.mnt);
+ mnt_drop_write(path.mnt);
exit1:
- path_put(&nd.path);
+ path_put(&path);
putname(name);
if (retry_estale(error, lookup_flags)) {
lookup_flags |= LOOKUP_REVAL;
@@ -4233,14 +4244,15 @@ EXPORT_SYMBOL(vfs_rename);
SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname,
int, newdfd, const char __user *, newname, unsigned int, flags)
{
- struct dentry *old_dir, *new_dir;
struct dentry *old_dentry, *new_dentry;
struct dentry *trap;
- struct nameidata oldnd, newnd;
+ struct path old_path, new_path;
+ struct qstr old_last, new_last;
+ int old_type, new_type;
struct inode *delegated_inode = NULL;
struct filename *from;
struct filename *to;
- unsigned int lookup_flags = 0;
+ unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET;
bool should_retry = false;
int error;

@@ -4254,47 +4266,45 @@ SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname,
if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD))
return -EPERM;

+ if (flags & RENAME_EXCHANGE)
+ target_flags = 0;
+
retry:
- from = user_path_parent(olddfd, oldname, &oldnd, lookup_flags);
+ from = user_path_parent(olddfd, oldname,
+ &old_path, &old_last, &old_type, lookup_flags);
if (IS_ERR(from)) {
error = PTR_ERR(from);
goto exit;
}

- to = user_path_parent(newdfd, newname, &newnd, lookup_flags);
+ to = user_path_parent(newdfd, newname,
+ &new_path, &new_last, &new_type, lookup_flags);
if (IS_ERR(to)) {
error = PTR_ERR(to);
goto exit1;
}

error = -EXDEV;
- if (oldnd.path.mnt != newnd.path.mnt)
+ if (old_path.mnt != new_path.mnt)
goto exit2;

- old_dir = oldnd.path.dentry;
error = -EBUSY;
- if (oldnd.last_type != LAST_NORM)
+ if (old_type != LAST_NORM)
goto exit2;

- new_dir = newnd.path.dentry;
if (flags & RENAME_NOREPLACE)
error = -EEXIST;
- if (newnd.last_type != LAST_NORM)
+ if (new_type != LAST_NORM)
goto exit2;

- error = mnt_want_write(oldnd.path.mnt);
+ error = mnt_want_write(old_path.mnt);
if (error)
goto exit2;

- oldnd.flags &= ~LOOKUP_PARENT;
- newnd.flags &= ~LOOKUP_PARENT;
- if (!(flags & RENAME_EXCHANGE))
- newnd.flags |= LOOKUP_RENAME_TARGET;
-
retry_deleg:
- trap = lock_rename(new_dir, old_dir);
+ trap = lock_rename(new_path.dentry, old_path.dentry);

- old_dentry = __lookup_hash(&oldnd.last, oldnd.path.dentry, oldnd.flags);
+ old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags);
error = PTR_ERR(old_dentry);
if (IS_ERR(old_dentry))
goto exit3;
@@ -4302,7 +4312,7 @@ retry_deleg:
error = -ENOENT;
if (d_is_negative(old_dentry))
goto exit4;
- new_dentry = __lookup_hash(&newnd.last, newnd.path.dentry, newnd.flags);
+ new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags);
error = PTR_ERR(new_dentry);
if (IS_ERR(new_dentry))
goto exit4;
@@ -4316,16 +4326,16 @@ retry_deleg:

if (!d_is_dir(new_dentry)) {
error = -ENOTDIR;
- if (newnd.last.name[newnd.last.len])
+ if (new_last.name[new_last.len])
goto exit5;
}
}
/* unless the source is a directory trailing slashes give -ENOTDIR */
if (!d_is_dir(old_dentry)) {
error = -ENOTDIR;
- if (oldnd.last.name[oldnd.last.len])
+ if (old_last.name[old_last.len])
goto exit5;
- if (!(flags & RENAME_EXCHANGE) && newnd.last.name[newnd.last.len])
+ if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len])
goto exit5;
}
/* source should not be ancestor of target */
@@ -4338,32 +4348,32 @@ retry_deleg:
if (new_dentry == trap)
goto exit5;

- error = security_path_rename(&oldnd.path, old_dentry,
- &newnd.path, new_dentry, flags);
+ error = security_path_rename(&old_path, old_dentry,
+ &new_path, new_dentry, flags);
if (error)
goto exit5;
- error = vfs_rename(old_dir->d_inode, old_dentry,
- new_dir->d_inode, new_dentry,
+ error = vfs_rename(old_path.dentry->d_inode, old_dentry,
+ new_path.dentry->d_inode, new_dentry,
&delegated_inode, flags);
exit5:
dput(new_dentry);
exit4:
dput(old_dentry);
exit3:
- unlock_rename(new_dir, old_dir);
+ unlock_rename(new_path.dentry, old_path.dentry);
if (delegated_inode) {
error = break_deleg_wait(&delegated_inode);
if (!error)
goto retry_deleg;
}
- mnt_drop_write(oldnd.path.mnt);
+ mnt_drop_write(old_path.mnt);
exit2:
if (retry_estale(error, lookup_flags))
should_retry = true;
- path_put(&newnd.path);
+ path_put(&new_path);
putname(to);
exit1:
- path_put(&oldnd.path);
+ path_put(&old_path);
putname(from);
if (should_retry) {
should_retry = false;
--
2.1.4


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