mirrors
/
linux-stable
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
1
0
Fork 0
Code Issues Releases Wiki Activity

d_path: prepend_path(): lift the inner loop into a new helper 

... and leave the rename_lock/mount_lock handling in prepend_path()
itself

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2021-05-12 16:38:11 -04:00
parent 2dac0ad175
commit 008673ff74
1 changed files with 38 additions and 39 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

77
fs/d_path.c
View File

@ -68,6 +68,42 @@ static bool prepend_name(struct prepend_buffer *p, const struct qstr *name)
return true;
}
static int __prepend_path(const struct dentry *dentry, const struct mount *mnt,
const struct path *root, struct prepend_buffer *p)
{
while (dentry != root->dentry || &mnt->mnt != root->mnt) {
const struct dentry *parent = READ_ONCE(dentry->d_parent);
if (dentry == mnt->mnt.mnt_root) {
struct mount *m = READ_ONCE(mnt->mnt_parent);
struct mnt_namespace *mnt_ns;
if (likely(mnt != m)) {
dentry = READ_ONCE(mnt->mnt_mountpoint);
mnt = m;
continue;
}
/* Global root */
mnt_ns = READ_ONCE(mnt->mnt_ns);
/* open-coded is_mounted() to use local mnt_ns */
if (!IS_ERR_OR_NULL(mnt_ns) && !is_anon_ns(mnt_ns))
return 1; // absolute root
else
return 2; // detached or not attached yet
}
if (unlikely(dentry == parent))
/* Escaped? */
return 3;
prefetch(parent);
if (!prepend_name(p, &dentry->d_name))
break;
dentry = parent;
}
return 0;
}
/**
* prepend_path - Prepend path string to a buffer
* @path: the dentry/vfsmount to report
@ -89,11 +125,9 @@ static int prepend_path(const struct path *path,
const struct path *root,
struct prepend_buffer *p)
{
struct dentry *dentry;
struct mount *mnt;
int error = 0;
unsigned seq, m_seq = 0;
struct prepend_buffer b;
int error;
rcu_read_lock();
restart_mnt:
@ -102,43 +136,8 @@ restart_mnt:
rcu_read_lock();
restart:
b = *p;
error = 0;
dentry = path->dentry;
mnt = real_mount(path->mnt);
read_seqbegin_or_lock(&rename_lock, &seq);
while (dentry != root->dentry || &mnt->mnt != root->mnt) {
struct dentry * parent;
if (dentry == mnt->mnt.mnt_root || IS_ROOT(dentry)) {
struct mount *parent = READ_ONCE(mnt->mnt_parent);
struct mnt_namespace *mnt_ns;
/* Escaped? */
if (dentry != mnt->mnt.mnt_root) {
error = 3;
break;
}
/* Global root? */
if (mnt != parent) {
dentry = READ_ONCE(mnt->mnt_mountpoint);
mnt = parent;
continue;
}
mnt_ns = READ_ONCE(mnt->mnt_ns);
/* open-coded is_mounted() to use local mnt_ns */
if (!IS_ERR_OR_NULL(mnt_ns) && !is_anon_ns(mnt_ns))
error = 1; // absolute root
else
error = 2; // detached or not attached yet
break;
}
parent = dentry->d_parent;
prefetch(parent);
if (!prepend_name(&b, &dentry->d_name))
break;
dentry = parent;
}
error = __prepend_path(path->dentry, real_mount(path->mnt), root, &b);
if (!(seq & 1))
rcu_read_unlock();
if (need_seqretry(&rename_lock, seq)) {