| Message ID | 20210726102816.612434-2-brauner@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v3,01/21] namei: add mapping aware lookup helper | expand |
On Mon, Jul 26, 2021 at 12:27:56PM +0200, Christian Brauner wrote: > +/** > + * lookup_mapped_one_len - filesystem helper to lookup single pathname component Can we think about the name a bit? In the ur-times (2.3.99), we had lookup_dentry(), which as far as I can tell walked an entire path. That got augmented with lookup_one() which just walked a single path entry. That was replaced with lookup_one_len() which added the 'len' parameter. Now we have: struct dentry *try_lookup_one_len(const char *, struct dentry *, int); struct dentry *lookup_one_len(const char *, struct dentry *, int); struct dentry *lookup_one_len_unlocked(const char *, struct dentry *, int); struct dentry *lookup_positive_unlocked(const char *, struct dentry *, int); I think the 'len' part of the name has done its job, and this new helper should be 'lookup_one_mapped'.
On Mon, Jul 26, 2021 at 03:41:05PM +0100, Matthew Wilcox wrote: > On Mon, Jul 26, 2021 at 12:27:56PM +0200, Christian Brauner wrote: > > +/** > > + * lookup_mapped_one_len - filesystem helper to lookup single pathname component > > Can we think about the name a bit? In the ur-times (2.3.99), we had > lookup_dentry(), which as far as I can tell walked an entire path. > That got augmented with lookup_one() which just walked a single path > entry. That was replaced with lookup_one_len() which added the 'len' > parameter. Now we have: > > struct dentry *try_lookup_one_len(const char *, struct dentry *, int); > struct dentry *lookup_one_len(const char *, struct dentry *, int); > struct dentry *lookup_one_len_unlocked(const char *, struct dentry *, int); > struct dentry *lookup_positive_unlocked(const char *, struct dentry *, int); > > I think the 'len' part of the name has done its job, and this new > helper should be 'lookup_one_mapped'. Heh. I'd drop the mapped as well as this should be the new normal going ahead.
On Mon, Jul 26, 2021 at 04:45:40PM +0200, Christoph Hellwig wrote: > On Mon, Jul 26, 2021 at 03:41:05PM +0100, Matthew Wilcox wrote: > > On Mon, Jul 26, 2021 at 12:27:56PM +0200, Christian Brauner wrote: > > > +/** > > > + * lookup_mapped_one_len - filesystem helper to lookup single pathname component > > > > Can we think about the name a bit? In the ur-times (2.3.99), we had > > lookup_dentry(), which as far as I can tell walked an entire path. > > That got augmented with lookup_one() which just walked a single path > > entry. That was replaced with lookup_one_len() which added the 'len' > > parameter. Now we have: > > > > struct dentry *try_lookup_one_len(const char *, struct dentry *, int); > > struct dentry *lookup_one_len(const char *, struct dentry *, int); > > struct dentry *lookup_one_len_unlocked(const char *, struct dentry *, int); > > struct dentry *lookup_positive_unlocked(const char *, struct dentry *, int); > > > > I think the 'len' part of the name has done its job, and this new > > helper should be 'lookup_one_mapped'. > > Heh. I'd drop the mapped as well as this should be the new normal > going ahead. I'm fine with either. Though lookup_one() is shorter and sounds nicest. :)
diff --git a/fs/namei.c b/fs/namei.c index bf6d8a738c59..8f416698ee34 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -2575,8 +2575,9 @@ int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, } EXPORT_SYMBOL(vfs_path_lookup); -static int lookup_one_len_common(const char *name, struct dentry *base, - int len, struct qstr *this) +static int lookup_one_len_common(struct user_namespace *mnt_userns, + const char *name, struct dentry *base, int len, + struct qstr *this) { this->name = name; this->len = len; @@ -2604,7 +2605,7 @@ static int lookup_one_len_common(const char *name, struct dentry *base, return err; } - return inode_permission(&init_user_ns, base->d_inode, MAY_EXEC); + return inode_permission(mnt_userns, base->d_inode, MAY_EXEC); } /** @@ -2628,7 +2629,7 @@ struct dentry *try_lookup_one_len(const char *name, struct dentry *base, int len WARN_ON_ONCE(!inode_is_locked(base->d_inode)); - err = lookup_one_len_common(name, base, len, &this); + err = lookup_one_len_common(&init_user_ns, name, base, len, &this); if (err) return ERR_PTR(err); @@ -2655,7 +2656,7 @@ struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) WARN_ON_ONCE(!inode_is_locked(base->d_inode)); - err = lookup_one_len_common(name, base, len, &this); + err = lookup_one_len_common(&init_user_ns, name, base, len, &this); if (err) return ERR_PTR(err); @@ -2664,6 +2665,37 @@ struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) } EXPORT_SYMBOL(lookup_one_len); +/** + * lookup_mapped_one_len - filesystem helper to lookup single pathname component + * @mnt_userns: user namespace of the mount the lookup is performed from + * @name: pathname component to lookup + * @base: base directory to lookup from + * @len: maximum length @len should be interpreted to + * + * Note that this routine is purely a helper for filesystem usage and should + * not be called by generic code. + * + * The caller must hold base->i_mutex. + */ +struct dentry *lookup_mapped_one_len(struct user_namespace *mnt_userns, + const char *name, struct dentry *base, + int len) +{ + struct dentry *dentry; + struct qstr this; + int err; + + WARN_ON_ONCE(!inode_is_locked(base->d_inode)); + + err = lookup_one_len_common(mnt_userns, name, base, len, &this); + if (err) + return ERR_PTR(err); + + dentry = lookup_dcache(&this, base, 0); + return dentry ? dentry : __lookup_slow(&this, base, 0); +} +EXPORT_SYMBOL(lookup_mapped_one_len); + /** * lookup_one_len_unlocked - filesystem helper to lookup single pathname component * @name: pathname component to lookup @@ -2683,7 +2715,7 @@ struct dentry *lookup_one_len_unlocked(const char *name, int err; struct dentry *ret; - err = lookup_one_len_common(name, base, len, &this); + err = lookup_one_len_common(&init_user_ns, name, base, len, &this); if (err) return ERR_PTR(err); diff --git a/include/linux/namei.h b/include/linux/namei.h index be9a2b349ca7..fd9d22128df6 100644 --- a/include/linux/namei.h +++ b/include/linux/namei.h @@ -68,6 +68,8 @@ extern struct dentry *try_lookup_one_len(const char *, struct dentry *, int); extern struct dentry *lookup_one_len(const char *, struct dentry *, int); extern struct dentry *lookup_one_len_unlocked(const char *, struct dentry *, int); extern struct dentry *lookup_positive_unlocked(const char *, struct dentry *, int); +extern struct dentry *lookup_mapped_one_len(struct user_namespace *, + const char *, struct dentry *, int); extern int follow_down_one(struct path *); extern int follow_down(struct path *);