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Registered in England and Wales under Company Registration No. 3798903 From: David Howells Subject: [PATCH 02/73] VFS: Make clone_mnt()/copy_tree()/collect_mounts() return errors [ver #2] To: linux-fsdevel@vger.kernel.org, viro@ZenIV.linux.org.uk, valerie.aurora@gmail.com Cc: linux-kernel@vger.kernel.org, David Howells , Valerie Aurora , Andreas Gruenbacher Date: Tue, 21 Feb 2012 17:57:36 +0000 Message-ID: <20120221175736.25235.30929.stgit@warthog.procyon.org.uk> In-Reply-To: <20120221175721.25235.8901.stgit@warthog.procyon.org.uk> References: <20120221175721.25235.8901.stgit@warthog.procyon.org.uk> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7516 Lines: 265 copy_tree() can theoretically fail in a case other than ENOMEM, but always returns NULL which is interpreted by callers as -ENOMEM. Change it to return an explicit error. Also change clone_mnt() for consistency and because union mounts will add new error cases. Thanks to Andreas Gruenbacher for a bug fix. Original-author: Valerie Aurora Signed-off-by: David Howells Cc: Valerie Aurora Cc: Andreas Gruenbacher --- fs/namespace.c | 116 +++++++++++++++++++++++++++------------------------ fs/pnode.c | 5 +- kernel/audit_tree.c | 10 ++-- 3 files changed, 70 insertions(+), 61 deletions(-) diff --git a/fs/namespace.c b/fs/namespace.c index e608199..baedd0b 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -725,56 +725,60 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root, int flag) { struct super_block *sb = old->mnt.mnt_sb; - struct mount *mnt = alloc_vfsmnt(old->mnt_devname); + struct mount *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.mnt_flags = old->mnt.mnt_flags & ~MNT_WRITE_HOLD; - atomic_inc(&sb->s_active); - mnt->mnt.mnt_sb = sb; - mnt->mnt.mnt_root = dget(root); - mnt->mnt_mountpoint = mnt->mnt.mnt_root; - mnt->mnt_parent = mnt; - br_write_lock(vfsmount_lock); - list_add_tail(&mnt->mnt_instance, &sb->s_mounts); - br_write_unlock(vfsmount_lock); + 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_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_MAKE_SHARED) && !mnt->mnt_group_id) { + err = mnt_alloc_group_id(mnt); + if (err) + goto out_free; } + + mnt->mnt.mnt_flags = old->mnt.mnt_flags & ~MNT_WRITE_HOLD; + atomic_inc(&sb->s_active); + mnt->mnt.mnt_sb = sb; + mnt->mnt.mnt_root = dget(root); + mnt->mnt_mountpoint = mnt->mnt.mnt_root; + mnt->mnt_parent = mnt; + br_write_lock(vfsmount_lock); + list_add_tail(&mnt->mnt_instance, &sb->s_mounts); + br_write_unlock(vfsmount_lock); + + 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 mntfree(struct mount *mnt) @@ -1258,11 +1262,12 @@ struct mount *copy_tree(struct mount *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; @@ -1284,8 +1289,8 @@ struct mount *copy_tree(struct mount *mnt, struct dentry *dentry, path.mnt = &q->mnt; path.dentry = p->mnt_mountpoint; q = clone_mnt(p, p->mnt.mnt_root, flag); - if (!q) - goto Enomem; + if (IS_ERR(q)) + goto out; br_write_lock(vfsmount_lock); list_add_tail(&q->mnt_list, &res->mnt_list); attach_mnt(q, &path); @@ -1293,7 +1298,7 @@ struct mount *copy_tree(struct mount *mnt, struct dentry *dentry, } } return res; -Enomem: +out: if (res) { LIST_HEAD(umount_list); br_write_lock(vfsmount_lock); @@ -1301,9 +1306,11 @@ Enomem: br_write_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 mount *tree; @@ -1606,14 +1613,15 @@ static int do_loopback(struct path *path, char *old_name, if (!check_mnt(real_mount(path->mnt)) || !check_mnt(old)) goto out2; - err = -ENOMEM; if (recurse) mnt = copy_tree(old, old_path.dentry, 0); else mnt = clone_mnt(old, old_path.dentry, 0); - if (!mnt) - goto out2; + if (IS_ERR(mnt)) { + err = PTR_ERR(mnt); + goto out; + } err = graft_tree(mnt, path); if (err) { @@ -2244,10 +2252,10 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns, down_write(&namespace_sem); /* First pass: copy the tree topology */ new = copy_tree(old, old->mnt.mnt_root, CL_COPY_ALL | CL_EXPIRE); - if (!new) { + if (IS_ERR(new)) { up_write(&namespace_sem); kfree(new_ns); - return ERR_PTR(-ENOMEM); + return ERR_CAST(new); } new_ns->root = new; br_write_lock(vfsmount_lock); diff --git a/fs/pnode.c b/fs/pnode.c index ab5fa9e..b79d27c 100644 --- a/fs/pnode.c +++ b/fs/pnode.c @@ -237,8 +237,9 @@ int propagate_mnt(struct mount *dest_mnt, struct dentry *dest_dentry, source = get_source(m, prev_dest_mnt, prev_src_mnt, &type); - if (!(child = copy_tree(source, source->mnt.mnt_root, type))) { - ret = -ENOMEM; + child = copy_tree(source, source->mnt.mnt_root, type); + if (IS_ERR(child)) { + ret = PTR_ERR(child); list_splice(tree_list, tmp_list.prev); goto out; } diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c index 5bf0790..3a5ca58 100644 --- a/kernel/audit_tree.c +++ b/kernel/audit_tree.c @@ -595,7 +595,7 @@ void audit_trim_trees(void) root_mnt = collect_mounts(&path); path_put(&path); - if (!root_mnt) + if (IS_ERR(root_mnt)) goto skip_it; spin_lock(&hash_lock); @@ -669,8 +669,8 @@ int audit_add_tree_rule(struct audit_krule *rule) goto Err; mnt = collect_mounts(&path); path_put(&path); - if (!mnt) { - err = -ENOMEM; + if (IS_ERR(mnt)) { + err = PTR_ERR(mnt); goto Err; } @@ -719,8 +719,8 @@ int audit_tag_tree(char *old, char *new) return err; tagged = collect_mounts(&path2); path_put(&path2); - if (!tagged) - return -ENOMEM; + if (IS_ERR(tagged)) + return PTR_ERR(tagged); err = kern_path(old, 0, &path1); 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