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mqueue: lift mnt_want_write() outside ->i_mutex, clean up a bit 

the way it abuses ->d_fsdata still needs to be killed, but that's
a separate story.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2012-08-06 10:18:17 +04:00
parent 20fb1936de
commit 312b90fbed
1 changed files with 28 additions and 33 deletions
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61
ipc/mqueue.c
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@ -726,7 +726,6 @@ static struct file *do_create(struct ipc_namespace *ipc_ns, struct inode *dir,
struct mq_attr *attr)
{
const struct cred *cred = current_cred();
struct file *result;
int ret;
if (attr) {
@ -748,21 +747,11 @@ static struct file *do_create(struct ipc_namespace *ipc_ns, struct inode *dir,
}
mode &= ~current_umask();
ret = mnt_want_write(path->mnt);
if (ret)
return ERR_PTR(ret);
ret = vfs_create(dir, path->dentry, mode, true);
path->dentry->d_fsdata = NULL;
if (!ret)
result = dentry_open(path, oflag, cred);
else
result = ERR_PTR(ret);
/*
* dentry_open() took a persistent mnt_want_write(),
* so we can now drop this one.
*/
mnt_drop_write(path->mnt);
return result;
if (ret)
return ERR_PTR(ret);
return dentry_open(path, oflag, cred);
}
/* Opens existing queue */
@ -788,7 +777,9 @@ SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode,
struct mq_attr attr;
int fd, error;
struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
struct dentry *root = ipc_ns->mq_mnt->mnt_root;
struct vfsmount *mnt = ipc_ns->mq_mnt;
struct dentry *root = mnt->mnt_root;
int ro;
if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
return -EFAULT;
@ -802,6 +793,7 @@ SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode,
if (fd < 0)
goto out_putname;
ro = mnt_want_write(mnt); /* we'll drop it in any case */
error = 0;
mutex_lock(&root->d_inode->i_mutex);
path.dentry = lookup_one_len(name, root, strlen(name));
@ -809,7 +801,7 @@ SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode,
error = PTR_ERR(path.dentry);
goto out_putfd;
}
path.mnt = mntget(ipc_ns->mq_mnt);
path.mnt = mntget(mnt);
if (oflag & O_CREAT) {
if (path.dentry->d_inode) { /* entry already exists */
@ -820,6 +812,10 @@ SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode,
}
filp = do_open(&path, oflag);
} else {
if (ro) {
error = ro;
goto out;
}
filp = do_create(ipc_ns, root->d_inode,
&path, oflag, mode,
u_attr ? &attr : NULL);
@ -845,6 +841,7 @@ out_putfd:
fd = error;
}
mutex_unlock(&root->d_inode->i_mutex);
mnt_drop_write(mnt);
out_putname:
putname(name);
return fd;
@ -857,40 +854,38 @@ SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
struct dentry *dentry;
struct inode *inode = NULL;
struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
struct vfsmount *mnt = ipc_ns->mq_mnt;
name = getname(u_name);
if (IS_ERR(name))
return PTR_ERR(name);
mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex,
I_MUTEX_PARENT);
dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
err = mnt_want_write(mnt);
if (err)
goto out_name;
mutex_lock_nested(&mnt->mnt_root->d_inode->i_mutex, I_MUTEX_PARENT);
dentry = lookup_one_len(name, mnt->mnt_root, strlen(name));
if (IS_ERR(dentry)) {
err = PTR_ERR(dentry);
goto out_unlock;
}
if (!dentry->d_inode) {
err = -ENOENT;
goto out_err;
}
inode = dentry->d_inode;
if (inode)
if (!inode) {
err = -ENOENT;
} else {
ihold(inode);
err = mnt_want_write(ipc_ns->mq_mnt);
if (err)
goto out_err;
err = vfs_unlink(dentry->d_parent->d_inode, dentry);
mnt_drop_write(ipc_ns->mq_mnt);
out_err:
err = vfs_unlink(dentry->d_parent->d_inode, dentry);
}
dput(dentry);
out_unlock:
mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
putname(name);
mutex_unlock(&mnt->mnt_root->d_inode->i_mutex);
if (inode)
iput(inode);
mnt_drop_write(mnt);
out_name:
putname(name);
return err;
}