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Date: Thu, 16 Sep 2010 15:11:52 -0700
From: Valerie Aurora <vaurora@...hat.com>
To: Alexander Viro <viro@...iv.linux.org.uk>
Cc: Miklos Szeredi <miklos@...redi.hu>,
Christoph Hellwig <hch@...radead.org>,
Andreas Gruenbacher <agruen@...e.de>,
Nick Piggin <npiggin@...nel.dk>, linux-kernel@...r.kernel.org,
linux-fsdevel@...r.kernel.org, Valerie Aurora <vaurora@...hat.com>
Subject: [PATCH 01/34] VFS: Make clone_mnt() and copy_tree() return error codes
copy_tree() can theoretically fail in a case other than ENOMEM, but
always returns NULL which is interpreted by callers as -ENOMEM.
Convert to return an explicit error. Convert clone_mnt() for
consistency and because union mounts will add new error cases.
Signed-off-by: Valerie Aurora <vaurora@...hat.com>
---
fs/namespace.c | 111 ++++++++++++++++++++++++++++++--------------------------
fs/pnode.c | 5 ++-
2 files changed, 63 insertions(+), 53 deletions(-)
diff --git a/fs/namespace.c b/fs/namespace.c
index e1ea335..5566524 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -559,53 +559,57 @@ static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root,
int flag)
{
struct super_block *sb = old->mnt_sb;
- struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname);
+ struct vfsmount *mnt;
+ int err;
- if (mnt) {
- if (flag & (CL_SLAVE | CL_PRIVATE))
- mnt->mnt_group_id = 0; /* not a peer of original */
- else
- mnt->mnt_group_id = old->mnt_group_id;
-
- if ((flag & CL_MAKE_SHARED) && !mnt->mnt_group_id) {
- int err = mnt_alloc_group_id(mnt);
- if (err)
- goto out_free;
- }
+ mnt = alloc_vfsmnt(old->mnt_devname);
+ if (!mnt)
+ return ERR_PTR(-ENOMEM);
- mnt->mnt_flags = old->mnt_flags;
- atomic_inc(&sb->s_active);
- mnt->mnt_sb = sb;
- mnt->mnt_root = dget(root);
- mnt->mnt_mountpoint = mnt->mnt_root;
- mnt->mnt_parent = mnt;
-
- if (flag & CL_SLAVE) {
- list_add(&mnt->mnt_slave, &old->mnt_slave_list);
- mnt->mnt_master = old;
- CLEAR_MNT_SHARED(mnt);
- } else if (!(flag & CL_PRIVATE)) {
- if ((flag & CL_MAKE_SHARED) || IS_MNT_SHARED(old))
- list_add(&mnt->mnt_share, &old->mnt_share);
- if (IS_MNT_SLAVE(old))
- list_add(&mnt->mnt_slave, &old->mnt_slave);
- mnt->mnt_master = old->mnt_master;
- }
- if (flag & CL_MAKE_SHARED)
- set_mnt_shared(mnt);
-
- /* stick the duplicate mount on the same expiry list
- * as the original if that was on one */
- if (flag & CL_EXPIRE) {
- if (!list_empty(&old->mnt_expire))
- list_add(&mnt->mnt_expire, &old->mnt_expire);
- }
+ if (flag & (CL_SLAVE | CL_PRIVATE))
+ mnt->mnt_group_id = 0; /* not a peer of original */
+ else
+ mnt->mnt_group_id = old->mnt_group_id;
+
+ if ((flag & CL_MAKE_SHARED) && !mnt->mnt_group_id) {
+ err = mnt_alloc_group_id(mnt);
+ if (err)
+ goto out_free;
}
+
+ mnt->mnt_flags = old->mnt_flags;
+ atomic_inc(&sb->s_active);
+ mnt->mnt_sb = sb;
+ mnt->mnt_root = dget(root);
+ mnt->mnt_mountpoint = mnt->mnt_root;
+ mnt->mnt_parent = mnt;
+
+ if (flag & CL_SLAVE) {
+ list_add(&mnt->mnt_slave, &old->mnt_slave_list);
+ mnt->mnt_master = old;
+ CLEAR_MNT_SHARED(mnt);
+ } else if (!(flag & CL_PRIVATE)) {
+ if ((flag & CL_MAKE_SHARED) || IS_MNT_SHARED(old))
+ list_add(&mnt->mnt_share, &old->mnt_share);
+ if (IS_MNT_SLAVE(old))
+ list_add(&mnt->mnt_slave, &old->mnt_slave);
+ mnt->mnt_master = old->mnt_master;
+ }
+ if (flag & CL_MAKE_SHARED)
+ set_mnt_shared(mnt);
+
+ /* stick the duplicate mount on the same expiry list
+ * as the original if that was on one */
+ if (flag & CL_EXPIRE) {
+ if (!list_empty(&old->mnt_expire))
+ list_add(&mnt->mnt_expire, &old->mnt_expire);
+ }
+
return mnt;
out_free:
free_vfsmnt(mnt);
- return NULL;
+ return ERR_PTR(err);
}
static inline void __mntput(struct vfsmount *mnt)
@@ -1212,11 +1216,12 @@ struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry,
struct path path;
if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(mnt))
- return NULL;
+ return ERR_PTR(-EINVAL);
res = q = clone_mnt(mnt, dentry, flag);
- if (!q)
- goto Enomem;
+ if (IS_ERR(q))
+ return q;
+
q->mnt_mountpoint = mnt->mnt_mountpoint;
p = mnt;
@@ -1237,8 +1242,8 @@ struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry,
path.mnt = q;
path.dentry = p->mnt_mountpoint;
q = clone_mnt(p, p->mnt_root, flag);
- if (!q)
- goto Enomem;
+ if (IS_ERR(q))
+ goto out;
spin_lock(&vfsmount_lock);
list_add_tail(&q->mnt_list, &res->mnt_list);
attach_mnt(q, &path);
@@ -1246,7 +1251,7 @@ struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry,
}
}
return res;
-Enomem:
+out:
if (res) {
LIST_HEAD(umount_list);
spin_lock(&vfsmount_lock);
@@ -1254,9 +1259,11 @@ Enomem:
spin_unlock(&vfsmount_lock);
release_mounts(&umount_list);
}
- return NULL;
+ return q;
}
+/* Caller should check returned pointer for errors */
+
struct vfsmount *collect_mounts(struct path *path)
{
struct vfsmount *tree;
@@ -1529,14 +1536,15 @@ static int do_loopback(struct path *path, char *old_name,
if (!check_mnt(path->mnt) || !check_mnt(old_path.mnt))
goto out;
- err = -ENOMEM;
if (recurse)
mnt = copy_tree(old_path.mnt, old_path.dentry, 0);
else
mnt = clone_mnt(old_path.mnt, old_path.dentry, 0);
- if (!mnt)
+ if (IS_ERR(mnt)) {
+ err = PTR_ERR(mnt);
goto out;
+ }
err = graft_tree(mnt, path);
if (err) {
@@ -2071,10 +2079,11 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns,
/* First pass: copy the tree topology */
new_ns->root = copy_tree(mnt_ns->root, mnt_ns->root->mnt_root,
CL_COPY_ALL | CL_EXPIRE);
- if (!new_ns->root) {
+ if (IS_ERR(new_ns->root)) {
+ int err = PTR_ERR(new_ns->root);
up_write(&namespace_sem);
kfree(new_ns);
- return ERR_PTR(-ENOMEM);
+ return ERR_PTR(err);
}
spin_lock(&vfsmount_lock);
list_add_tail(&new_ns->list, &new_ns->root->mnt_list);
diff --git a/fs/pnode.c b/fs/pnode.c
index 5cc564a..c4358d2 100644
--- a/fs/pnode.c
+++ b/fs/pnode.c
@@ -250,8 +250,9 @@ int propagate_mnt(struct vfsmount *dest_mnt, struct dentry *dest_dentry,
source = get_source(m, prev_dest_mnt, prev_src_mnt, &type);
- if (!(child = copy_tree(source, source->mnt_root, type))) {
- ret = -ENOMEM;
+ child = copy_tree(source, source->mnt_root, type);
+ if (IS_ERR(child)) {
+ ret = PTR_ERR(child);
list_splice(tree_list, tmp_list.prev);
goto out;
}
--
1.6.3.3
--
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