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Message-ID: <20130908084714.14798.32490.stgit@perseus.fritz.box>
Date: Sun, 08 Sep 2013 16:47:15 +0800
From: Ian Kent <raven@...maw.net>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: linux-fsdevel <linux-fsdevel@...r.kernel.org>,
autofs mailing list <autofs@...r.kernel.org>,
Al Viro <viro@...IV.linux.org.uk>,
Jeff Layton <jlayton@...hat.com>,
Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [PATCH 1/2] vfs - rename user_path_umountat() to
user_path_mntpointat()
The function user_path_umountat() not only avoids revalidation but
avoids the managed dentry code as well.
This function has other uses, such as the case where autofs is
reconnecting to a tree of mounts and needs to avoid the managed
dentry call since that would incorrectly cause a callback to the
daemon.
So give the function a more descriptive name.
Signed-off-by: Ian Kent <raven@...maw.net>
Cc: Jeff Layton <jlayton@...hat.com>
Cc: Al Viro <viro@...IV.linux.org.uk>
---
fs/namei.c | 34 +++++++++++++++++++---------------
fs/namespace.c | 2 +-
include/linux/namei.h | 2 +-
3 files changed, 21 insertions(+), 17 deletions(-)
diff --git a/fs/namei.c b/fs/namei.c
index f415c66..24f7562 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2250,7 +2250,7 @@ user_path_parent(int dfd, const char __user *path, struct nameidata *nd,
* to the link, and nd->path will *not* be put.
*/
static int
-umount_lookup_last(struct nameidata *nd, struct path *path)
+mntpoint_lookup_last(struct nameidata *nd, struct path *path)
{
int error = 0;
struct dentry *dentry;
@@ -2309,17 +2309,19 @@ error_check:
}
/**
- * path_umountat - look up a path to be umounted
+ * path_mntpointat - look up a path to a mount point
* @dfd: directory file descriptor to start walk from
* @name: full pathname to walk
* @flags: lookup flags
* @nd: pathwalk nameidata
*
- * Look up the given name, but don't attempt to revalidate the last component.
+ * Look up the given name, but don't attempt to revalidate the last component
+ * or call the managed dentry code.
* Returns 0 and "path" will be valid on success; Retuns error otherwise.
*/
static int
-path_umountat(int dfd, const char *name, struct path *path, unsigned int flags)
+path_mntpointat(int dfd, const char *name,
+ struct path *path, unsigned int flags)
{
struct file *base = NULL;
struct nameidata nd;
@@ -2343,7 +2345,7 @@ path_umountat(int dfd, const char *name, struct path *path, unsigned int flags)
}
}
- err = umount_lookup_last(&nd, path);
+ err = mntpoint_lookup_last(&nd, path);
while (err > 0) {
void *cookie;
struct path link = *path;
@@ -2354,7 +2356,7 @@ path_umountat(int dfd, const char *name, struct path *path, unsigned int flags)
err = follow_link(&link, &nd, &cookie);
if (err)
break;
- err = umount_lookup_last(&nd, path);
+ err = mntpoint_lookup_last(&nd, path);
put_link(&nd, &link, cookie);
}
out:
@@ -2368,21 +2370,23 @@ out:
}
/**
- * user_path_umountat - lookup a path from userland in order to umount it
+ * user_path_mntpointat - lookup a mountpoint path from userland without
+ * revalidating it or calling the managed dentry code
* @dfd: directory file descriptor
* @name: pathname from userland
* @flags: lookup flags
* @path: pointer to container to hold result
*
- * A umount is a special case for path walking. We're not actually interested
- * in the inode in this situation, and ESTALE errors can be a problem. We
- * simply want track down the dentry and vfsmount attached at the mountpoint
- * and avoid revalidating the last component.
+ * A mount point (when being umounted for example) is a special case for path
+ * walking. We're not actually interested in the inode in this situation, and
+ * ESTALE errors can be a problem. We simply want track down the dentry and
+ * vfsmount attached at the mountpoint and avoid revalidating or calling the
+ * managed dentry code for the last component.
*
* Returns 0 and populates "path" on success.
*/
int
-user_path_umountat(int dfd, const char __user *name, unsigned int flags,
+user_path_mntpointat(int dfd, const char __user *name, unsigned int flags,
struct path *path)
{
struct filename *s = getname(name);
@@ -2391,11 +2395,11 @@ user_path_umountat(int dfd, const char __user *name, unsigned int flags,
if (IS_ERR(s))
return PTR_ERR(s);
- error = path_umountat(dfd, s->name, path, flags | LOOKUP_RCU);
+ error = path_mntpointat(dfd, s->name, path, flags | LOOKUP_RCU);
if (unlikely(error == -ECHILD))
- error = path_umountat(dfd, s->name, path, flags);
+ error = path_mntpointat(dfd, s->name, path, flags);
if (unlikely(error == -ESTALE))
- error = path_umountat(dfd, s->name, path, flags | LOOKUP_REVAL);
+ error = path_mntpointat(dfd, s->name, path, flags|LOOKUP_REVAL);
if (likely(!error))
audit_inode(s, path->dentry, 0);
diff --git a/fs/namespace.c b/fs/namespace.c
index fc2b522..c48ad96 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1321,7 +1321,7 @@ SYSCALL_DEFINE2(umount, char __user *, name, int, flags)
if (!(flags & UMOUNT_NOFOLLOW))
lookup_flags |= LOOKUP_FOLLOW;
- retval = user_path_umountat(AT_FDCWD, name, lookup_flags, &path);
+ retval = user_path_mntpointat(AT_FDCWD, name, lookup_flags, &path);
if (retval)
goto out;
mnt = real_mount(path.mnt);
diff --git a/include/linux/namei.h b/include/linux/namei.h
index cd09751..7908abf 100644
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -58,7 +58,7 @@ enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT, LAST_BIND};
extern int user_path_at(int, const char __user *, unsigned, struct path *);
extern int user_path_at_empty(int, const char __user *, unsigned, struct path *, int *empty);
-extern int user_path_umountat(int, const char __user *, unsigned int, struct path *);
+extern int user_path_mntpointat(int, const char __user *, unsigned int, struct path *);
#define user_path(name, path) user_path_at(AT_FDCWD, name, LOOKUP_FOLLOW, path)
#define user_lpath(name, path) user_path_at(AT_FDCWD, name, 0, path)
--
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