diff options
| -rw-r--r-- | fs/namei.c | 122 |
1 files changed, 57 insertions, 65 deletions
diff --git a/fs/namei.c b/fs/namei.c index ec4b2d0190a8..9e701e28a329 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -455,14 +455,6 @@ static int nameidata_dentry_drop_rcu(struct nameidata *nd, struct dentry *dentry struct fs_struct *fs = current->fs; struct dentry *parent = nd->path.dentry; - /* - * It can be possible to revalidate the dentry that we started - * the path walk with. force_reval_path may also revalidate the - * dentry already committed to the nameidata. - */ - if (unlikely(parent == dentry)) - return nameidata_drop_rcu(nd); - BUG_ON(!(nd->flags & LOOKUP_RCU)); if (nd->root.mnt) { spin_lock(&fs->lock); @@ -571,33 +563,15 @@ void release_open_intent(struct nameidata *nd) } } -/* - * Call d_revalidate and handle filesystems that request rcu-walk - * to be dropped. This may be called and return in rcu-walk mode, - * regardless of success or error. If -ECHILD is returned, the caller - * must return -ECHILD back up the path walk stack so path walk may - * be restarted in ref-walk mode. - */ -static int d_revalidate(struct dentry *dentry, struct nameidata *nd) +static inline int d_revalidate(struct dentry *dentry, struct nameidata *nd) { - int status; - - status = dentry->d_op->d_revalidate(dentry, nd); - if (status == -ECHILD) { - if (nameidata_dentry_drop_rcu(nd, dentry)) - return status; - status = dentry->d_op->d_revalidate(dentry, nd); - } - - return status; + return dentry->d_op->d_revalidate(dentry, nd); } -static inline struct dentry * +static struct dentry * do_revalidate(struct dentry *dentry, struct nameidata *nd) { - int status; - - status = d_revalidate(dentry, nd); + int status = d_revalidate(dentry, nd); if (unlikely(status <= 0)) { /* * The dentry failed validation. @@ -606,24 +580,39 @@ do_revalidate(struct dentry *dentry, struct nameidata *nd) * to return a fail status. */ if (status < 0) { - /* If we're in rcu-walk, we don't have a ref */ - if (!(nd->flags & LOOKUP_RCU)) - dput(dentry); + dput(dentry); dentry = ERR_PTR(status); - - } else { - /* Don't d_invalidate in rcu-walk mode */ - if (nameidata_dentry_drop_rcu_maybe(nd, dentry)) - return ERR_PTR(-ECHILD); - if (!d_invalidate(dentry)) { - dput(dentry); - dentry = NULL; - } + } else if (!d_invalidate(dentry)) { + dput(dentry); + dentry = NULL; } } return dentry; } +static inline struct dentry * +do_revalidate_rcu(struct dentry *dentry, struct nameidata *nd) +{ + int status = d_revalidate(dentry, nd); + if (likely(status > 0)) + return dentry; + if (status == -ECHILD) { + if (nameidata_dentry_drop_rcu(nd, dentry)) + return ERR_PTR(-ECHILD); + return do_revalidate(dentry, nd); + } + if (status < 0) + return ERR_PTR(status); + /* Don't d_invalidate in rcu-walk mode */ + if (nameidata_dentry_drop_rcu(nd, dentry)) + return ERR_PTR(-ECHILD); + if (!d_invalidate(dentry)) { + dput(dentry); + dentry = NULL; + } + return dentry; +} + static inline int need_reval_dot(struct dentry *dentry) { if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE))) @@ -668,9 +657,6 @@ force_reval_path(struct path *path, struct nameidata *nd) return 0; if (!status) { - /* Don't d_invalidate in rcu-walk mode */ - if (nameidata_drop_rcu(nd)) - return -ECHILD; d_invalidate(dentry); status = -ESTALE; } @@ -777,6 +763,8 @@ __do_follow_link(const struct path *link, struct nameidata *nd, void **p) int error; struct dentry *dentry = link->dentry; + BUG_ON(nd->flags & LOOKUP_RCU); + touch_atime(link->mnt, dentry); nd_set_link(nd, NULL); @@ -811,6 +799,11 @@ static inline int do_follow_link(struct path *path, struct nameidata *nd) { void *cookie; int err = -ELOOP; + + /* We drop rcu-walk here */ + if (nameidata_dentry_drop_rcu_maybe(nd, path->dentry)) + return -ECHILD; + if (current->link_count >= MAX_NESTED_LINKS) goto loop; if (current->total_link_count >= 40) @@ -1255,9 +1248,15 @@ static int do_lookup(struct nameidata *nd, struct qstr *name, return -ECHILD; nd->seq = seq; - if (dentry->d_flags & DCACHE_OP_REVALIDATE) - goto need_revalidate; -done2: + if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { + dentry = do_revalidate_rcu(dentry, nd); + if (!dentry) + goto need_lookup; + if (IS_ERR(dentry)) + goto fail; + if (!(nd->flags & LOOKUP_RCU)) + goto done; + } path->mnt = mnt; path->dentry = dentry; if (likely(__follow_mount_rcu(nd, path, inode, false))) @@ -1270,8 +1269,13 @@ done2: if (!dentry) goto need_lookup; found: - if (dentry->d_flags & DCACHE_OP_REVALIDATE) - goto need_revalidate; + if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { + dentry = do_revalidate(dentry, nd); + if (!dentry) + goto need_lookup; + if (IS_ERR(dentry)) + goto fail; + } done: path->mnt = mnt; path->dentry = dentry; @@ -1313,16 +1317,6 @@ need_lookup: mutex_unlock(&dir->i_mutex); goto found; -need_revalidate: - dentry = do_revalidate(dentry, nd); - if (!dentry) - goto need_lookup; - if (IS_ERR(dentry)) - goto fail; - if (nd->flags & LOOKUP_RCU) - goto done2; - goto done; - fail: return PTR_ERR(dentry); } @@ -1419,9 +1413,6 @@ exec_again: goto out_dput; if (inode->i_op->follow_link) { - /* We commonly drop rcu-walk here */ - if (nameidata_dentry_drop_rcu_maybe(nd, next.dentry)) - return -ECHILD; BUG_ON(inode != next.dentry->d_inode); err = do_follow_link(&next, nd); if (err) @@ -1467,8 +1458,6 @@ last_component: break; if (inode && unlikely(inode->i_op->follow_link) && (lookup_flags & LOOKUP_FOLLOW)) { - if (nameidata_dentry_drop_rcu_maybe(nd, next.dentry)) - return -ECHILD; BUG_ON(inode != next.dentry->d_inode); err = do_follow_link(&next, nd); if (err) @@ -1504,12 +1493,15 @@ return_reval: * We may need to check the cached dentry for staleness. */ if (need_reval_dot(nd->path.dentry)) { + if (nameidata_drop_rcu_last_maybe(nd)) + return -ECHILD; /* Note: we do not d_invalidate() */ err = d_revalidate(nd->path.dentry, nd); if (!err) err = -ESTALE; if (err < 0) break; + return 0; } return_base: if (nameidata_drop_rcu_last_maybe(nd)) |