diff options
| -rw-r--r-- | fs/namei.c | 121 |
1 files changed, 40 insertions, 81 deletions
@@ -469,43 +469,6 @@ err_root: } /** - * nameidata_drop_rcu_last - drop nameidata ending path walk out of rcu-walk - * @nd: nameidata pathwalk data to drop - * Returns: 0 on success, -ECHILD on failure - * - * nameidata_drop_rcu_last attempts to drop the current nd->path into ref-walk. - * nd->path should be the final element of the lookup, so nd->root is discarded. - * Must be called from rcu-walk context. - */ -static int nameidata_drop_rcu_last(struct nameidata *nd) -{ - struct dentry *dentry = nd->path.dentry; - - BUG_ON(!(nd->flags & LOOKUP_RCU)); - nd->flags &= ~LOOKUP_RCU; - if (!(nd->flags & LOOKUP_ROOT)) - nd->root.mnt = NULL; - spin_lock(&dentry->d_lock); - if (!__d_rcu_to_refcount(dentry, nd->seq)) - goto err_unlock; - BUG_ON(nd->inode != dentry->d_inode); - spin_unlock(&dentry->d_lock); - - mntget(nd->path.mnt); - - rcu_read_unlock(); - br_read_unlock(vfsmount_lock); - - return 0; - -err_unlock: - spin_unlock(&dentry->d_lock); - rcu_read_unlock(); - br_read_unlock(vfsmount_lock); - return -ECHILD; -} - -/** * release_open_intent - free up open intent resources * @nd: pointer to nameidata */ @@ -548,26 +511,39 @@ do_revalidate(struct dentry *dentry, struct nameidata *nd) return dentry; } -/* - * handle_reval_path - force revalidation of a dentry - * - * In some situations the path walking code will trust dentries without - * revalidating them. This causes problems for filesystems that depend on - * d_revalidate to handle file opens (e.g. NFSv4). When FS_REVAL_DOT is set - * (which indicates that it's possible for the dentry to go stale), force - * a d_revalidate call before proceeding. +/** + * complete_walk - successful completion of path walk + * @nd: pointer nameidata * - * Returns 0 if the revalidation was successful. If the revalidation fails, - * either return the error returned by d_revalidate or -ESTALE if the - * revalidation it just returned 0. If d_revalidate returns 0, we attempt to - * invalidate the dentry. It's up to the caller to handle putting references - * to the path if necessary. + * If we had been in RCU mode, drop out of it and legitimize nd->path. + * Revalidate the final result, unless we'd already done that during + * the path walk or the filesystem doesn't ask for it. Return 0 on + * success, -error on failure. In case of failure caller does not + * need to drop nd->path. */ -static inline int handle_reval_path(struct nameidata *nd) +static int complete_walk(struct nameidata *nd) { struct dentry *dentry = nd->path.dentry; int status; + if (nd->flags & LOOKUP_RCU) { + nd->flags &= ~LOOKUP_RCU; + if (!(nd->flags & LOOKUP_ROOT)) + nd->root.mnt = NULL; + spin_lock(&dentry->d_lock); + if (unlikely(!__d_rcu_to_refcount(dentry, nd->seq))) { + spin_unlock(&dentry->d_lock); + rcu_read_unlock(); + br_read_unlock(vfsmount_lock); + return -ECHILD; + } + BUG_ON(nd->inode != dentry->d_inode); + spin_unlock(&dentry->d_lock); + mntget(nd->path.mnt); + rcu_read_unlock(); + br_read_unlock(vfsmount_lock); + } + if (likely(!(nd->flags & LOOKUP_JUMPED))) return 0; @@ -585,6 +561,7 @@ static inline int handle_reval_path(struct nameidata *nd) if (!status) status = -ESTALE; + path_put(&nd->path); return status; } @@ -1598,18 +1575,8 @@ static int path_lookupat(int dfd, const char *name, } } - if (nd->flags & LOOKUP_RCU) { - /* went all way through without dropping RCU */ - BUG_ON(err); - if (nameidata_drop_rcu_last(nd)) - err = -ECHILD; - } - - if (!err) { - err = handle_reval_path(nd); - if (err) - path_put(&nd->path); - } + if (!err) + err = complete_walk(nd); if (!err && nd->flags & LOOKUP_DIRECTORY) { if (!nd->inode->i_op->lookup) { @@ -2075,13 +2042,9 @@ static struct file *do_last(struct nameidata *nd, struct path *path, return ERR_PTR(error); /* fallthrough */ case LAST_ROOT: - if (nd->flags & LOOKUP_RCU) { - if (nameidata_drop_rcu_last(nd)) - return ERR_PTR(-ECHILD); - } - error = handle_reval_path(nd); + error = complete_walk(nd); if (error) - goto exit; + return ERR_PTR(error); audit_inode(pathname, nd->path.dentry); if (open_flag & O_CREAT) { error = -EISDIR; @@ -2089,10 +2052,9 @@ static struct file *do_last(struct nameidata *nd, struct path *path, } goto ok; case LAST_BIND: - /* can't be RCU mode here */ - error = handle_reval_path(nd); + error = complete_walk(nd); if (error) - goto exit; + return ERR_PTR(error); audit_inode(pathname, dir); goto ok; } @@ -2111,10 +2073,9 @@ static struct file *do_last(struct nameidata *nd, struct path *path, if (error) /* symlink */ return NULL; /* sayonara */ - if (nd->flags & LOOKUP_RCU) { - if (nameidata_drop_rcu_last(nd)) - return ERR_PTR(-ECHILD); - } + error = complete_walk(nd); + if (error) + return ERR_PTR(-ECHILD); error = -ENOTDIR; if (nd->flags & LOOKUP_DIRECTORY) { @@ -2126,11 +2087,9 @@ static struct file *do_last(struct nameidata *nd, struct path *path, } /* create side of things */ - - if (nd->flags & LOOKUP_RCU) { - if (nameidata_drop_rcu_last(nd)) - return ERR_PTR(-ECHILD); - } + error = complete_walk(nd); + if (error) + return ERR_PTR(error); audit_inode(pathname, dir); error = -EISDIR; |
