kern_path_mountpoint() is only called from autofs4 to perform
lookups which need to identify autofs4 mount points.
Many of the differences between kern_path() and kern_path_mountpoint()
are related to the fact that we will never use O_CREAT with the
latter, and don't need to "open" the target.
The main differences that could be relevant to autofs4 are:
- kern_path_mountpoint() does not call complete_walk() in
mountpoint_last(), contrasting with do_last() which does call it.
This means ->d_weak_revalidate() is not called from autofs4.
- follow_managed() is not call from mountpoint_last().
- LOOKUP_NO_REVAL is used for lookup_slow on the last component,
if it isn't in cache.
As ->d_weak_revalidate() is now a no-op when LOOKUP_OPEN isn't
present, the first difference is no longer important.
The use of LOOKUP_NO_REVAL shouldn't cause autofs4 any problems
as no autofs4 dentry has ->d_revalidate().
follow_managed() might:
a/ call ->d_manage()
b/ might cross a mountpoint
c/ might call follow_automount()
'b' cannot be relevant as path_mountpoint calls follow_mount() after
mountpoint_last() is called.
'a' might only be interesting when ->d_manage is autofs4_d_manage(),
but autofs4 only calls kern_path_mountpoint from ioctls issued by the
automount daemon, and autofs4_d_manage() will exit quickly in that
case. So there is no risk of autofs4_d_manage() waiting for the
automount daemon (which it would be blocking) and causing a deadlock.
'c' could have been a problem before commit 42f461482178 ("autofs: fix
AT_NO_AUTOMOUNT not being honored"). Prior to that commit a lookup
for a negative autofs4 dentry could trigger an automount, even though
'flags' is 0. Since that commit and error is returned instead.
So follow_managed() is no longer a problem.
So there is no reason that autofs4 needs to use kern_path_mountpoint()
any more. It cannot deadlock.
So the whole 'path mountpoint' infrastructure can be discarded.
Signed-off-by: NeilBrown <neilb@xxxxxxxx>
---
fs/autofs4/dev-ioctl.c | 5 +-
fs/namei.c | 129 ------------------------------------------------
include/linux/namei.h | 1
3 files changed, 2 insertions(+), 133 deletions(-)
diff --git a/fs/autofs4/dev-ioctl.c b/fs/autofs4/dev-ioctl.c
index b7c816f39404..716c44593117 100644
--- a/fs/autofs4/dev-ioctl.c
+++ b/fs/autofs4/dev-ioctl.c
@@ -209,7 +209,7 @@ static int find_autofs_mount(const char *pathname,
struct path path;
int err;
- err = kern_path_mountpoint(AT_FDCWD, pathname, &path, 0);
+ err = kern_path(pathname,0 , &path);
if (err)
return err;
err = -ENOENT;
@@ -547,8 +547,7 @@ static int autofs_dev_ioctl_ismountpoint(struct file *fp,
if (!fp || param->ioctlfd == -1) {
if (autofs_type_any(type))
- err = kern_path_mountpoint(AT_FDCWD,
- name, &path, LOOKUP_FOLLOW);
+ err = kern_path(name, LOOKUP_FOLLOW, &path);
else
err = find_autofs_mount(name, &path,
test_by_type, &type);
diff --git a/fs/namei.c b/fs/namei.c
index 6639203d7eba..e90680a3f6f1 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2601,135 +2601,6 @@ int user_path_at_empty(int dfd, const char __user *name, unsigned flags,
}
EXPORT_SYMBOL(user_path_at_empty);
-/**
- * mountpoint_last - look up last component for umount
- * @nd: pathwalk nameidata - currently pointing at parent directory of "last"
- *
- * This is a special lookup_last function just for umount. In this case, we
- * need to resolve the path without doing any revalidation.
- *
- * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since
- * mountpoints are always pinned in the dcache, their ancestors are too. Thus,
- * in almost all cases, this lookup will be served out of the dcache. The only
- * cases where it won't are if nd->last refers to a symlink or the path is
- * bogus and it doesn't exist.
- *
- * Returns:
- * -error: if there was an error during lookup. This includes -ENOENT if the
- * lookup found a negative dentry.
- *
- * 0: if we successfully resolved nd->last and found it to not to be a
- * symlink that needs to be followed.
- *
- * 1: if we successfully resolved nd->last and found it to be a symlink
- * that needs to be followed.
- */
-static int
-mountpoint_last(struct nameidata *nd)
-{
- int error = 0;
- struct dentry *dir = nd->path.dentry;
- struct path path;
-
- /* If we're in rcuwalk, drop out of it to handle last component */
- if (nd->flags & LOOKUP_RCU) {
- if (unlazy_walk(nd))
- return -ECHILD;
- }
-
- nd->flags &= ~LOOKUP_PARENT;
-
- if (unlikely(nd->last_type != LAST_NORM)) {
- error = handle_dots(nd, nd->last_type);
- if (error)
- return error;
- path.dentry = dget(nd->path.dentry);
- } else {
- path.dentry = d_lookup(dir, &nd->last);
- if (!path.dentry) {
- /*
- * No cached dentry. Mounted dentries are pinned in the
- * cache, so that means that this dentry is probably
- * a symlink or the path doesn't actually point
- * to a mounted dentry.
- */
- path.dentry = lookup_slow(&nd->last, dir,
- nd->flags | LOOKUP_NO_REVAL);
- if (IS_ERR(path.dentry))
- return PTR_ERR(path.dentry);
- }
- }
- if (d_is_negative(path.dentry)) {
- dput(path.dentry);
- return -ENOENT;
- }
- path.mnt = nd->path.mnt;
- return step_into(nd, &path, 0, d_backing_inode(path.dentry), 0);
-}
-
-/**
- * path_mountpoint - look up a path to be umounted
- * @nd: lookup context
- * @flags: lookup flags
- * @path: pointer to container for result
- *
- * Look up the given name, but don't attempt to revalidate the last component.
- * Returns 0 and "path" will be valid on success; Returns error otherwise.
- */
-static int
-path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path)
-{
- const char *s = path_init(nd, flags);
- int err;
- if (IS_ERR(s))
- return PTR_ERR(s);
- while (!(err = link_path_walk(s, nd)) &&
- (err = mountpoint_last(nd)) > 0) {
- s = trailing_symlink(nd);
- if (IS_ERR(s)) {
- err = PTR_ERR(s);
- break;
- }
- }
- if (!err) {
- *path = nd->path;
- nd->path.mnt = NULL;
- nd->path.dentry = NULL;
- follow_mount(path);
- }
- terminate_walk(nd);
- return err;
-}
-
-static int
-filename_mountpoint(int dfd, struct filename *name, struct path *path,
- unsigned int flags)
-{
- struct nameidata nd;
- int error;
- if (IS_ERR(name))
- return PTR_ERR(name);
- set_nameidata(&nd, dfd, name);
- error = path_mountpoint(&nd, flags | LOOKUP_RCU, path);
- if (unlikely(error == -ECHILD))
- error = path_mountpoint(&nd, flags, path);
- if (unlikely(error == -ESTALE))
- error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path);
- if (likely(!error))
- audit_inode(name, path->dentry, 0);
- restore_nameidata();
- putname(name);
- return error;
-}
-
-int
-kern_path_mountpoint(int dfd, const char *name, struct path *path,
- unsigned int flags)
-{
- return filename_mountpoint(dfd, getname_kernel(name), path, flags);
-}
-EXPORT_SYMBOL(kern_path_mountpoint);
-
int __check_sticky(struct inode *dir, struct inode *inode)
{
kuid_t fsuid = current_fsuid();
diff --git a/include/linux/namei.h b/include/linux/namei.h
index a982bb7cd480..e576bf40d761 100644
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -79,7 +79,6 @@ extern struct dentry *kern_path_create(int, const char *, struct path *, unsigne
extern struct dentry *user_path_create(int, const char __user *, struct path *, unsigned int);
extern void done_path_create(struct path *, struct dentry *);
extern struct dentry *kern_path_locked(const char *, struct path *);
-extern int kern_path_mountpoint(int, const char *, struct path *, unsigned int);
extern struct dentry *lookup_one_len(const char *, struct dentry *, int);
extern struct dentry *lookup_one_len_unlocked(const char *, struct dentry *, int);
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