On Sun, 08 Sep 2013 16:47:15 +0800 Ian Kent <[email protected]> wrote:
> 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 <[email protected]> > Cc: Jeff Layton <[email protected]> > Cc: Al Viro <[email protected]> > --- > 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) > Looks good to me. Acked-by: Jeff Layton <[email protected]> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
