[S390] hypfs: inode corruption due to missing locking
hypfs removes the whole hypfs directory tree and creates a new one, when a
process triggers an update by writing to the "update" attribute. When removing
and creating files, it is necessary to lock the inode of the parent directory
where the files live. Currently hypfs does not lock the parent inode, which
can lead to inode corruption. This patch:
* Introduces correct locking
* Fixes i_nlink reference counting for inodes, when creating directories
* Adds info printk, when hypfs filesystem has been mounted
Signed-off-by: Michael Holzheu <holzheu@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
diff --git a/arch/s390/hypfs/inode.c b/arch/s390/hypfs/inode.c
index ad4ca75..5245717 100644
--- a/arch/s390/hypfs/inode.c
+++ b/arch/s390/hypfs/inode.c
@@ -60,17 +60,28 @@
hypfs_last_dentry = dentry;
}
+static inline int hypfs_positive(struct dentry *dentry)
+{
+ return dentry->d_inode && !d_unhashed(dentry);
+}
+
static void hypfs_remove(struct dentry *dentry)
{
struct dentry *parent;
parent = dentry->d_parent;
- if (S_ISDIR(dentry->d_inode->i_mode))
- simple_rmdir(parent->d_inode, dentry);
- else
- simple_unlink(parent->d_inode, dentry);
+ if (!parent || !parent->d_inode)
+ return;
+ mutex_lock(&parent->d_inode->i_mutex);
+ if (hypfs_positive(dentry)) {
+ if (S_ISDIR(dentry->d_inode->i_mode))
+ simple_rmdir(parent->d_inode, dentry);
+ else
+ simple_unlink(parent->d_inode, dentry);
+ }
d_delete(dentry);
dput(dentry);
+ mutex_unlock(&parent->d_inode->i_mutex);
}
static void hypfs_delete_tree(struct dentry *root)
@@ -315,6 +326,7 @@
}
hypfs_update_update(sb);
sb->s_root = root_dentry;
+ printk(KERN_INFO "hypfs: Hypervisor filesystem mounted\n");
return 0;
err_tree:
@@ -356,13 +368,17 @@
qname.name = name;
qname.len = strlen(name);
qname.hash = full_name_hash(name, qname.len);
+ mutex_lock(&parent->d_inode->i_mutex);
dentry = lookup_one_len(name, parent, strlen(name));
- if (IS_ERR(dentry))
- return ERR_PTR(-ENOMEM);
+ if (IS_ERR(dentry)) {
+ dentry = ERR_PTR(-ENOMEM);
+ goto fail;
+ }
inode = hypfs_make_inode(sb, mode);
if (!inode) {
dput(dentry);
- return ERR_PTR(-ENOMEM);
+ dentry = ERR_PTR(-ENOMEM);
+ goto fail;
}
if (mode & S_IFREG) {
inode->i_fop = &hypfs_file_ops;
@@ -379,6 +395,8 @@
inode->i_private = data;
d_instantiate(dentry, inode);
dget(dentry);
+fail:
+ mutex_unlock(&parent->d_inode->i_mutex);
return dentry;
}
@@ -391,7 +409,6 @@
if (IS_ERR(dentry))
return dentry;
hypfs_add_dentry(dentry);
- parent->d_inode->i_nlink++;
return dentry;
}