diff options
Diffstat (limited to 'fs/namei.c')
-rw-r--r-- | fs/namei.c | 151 |
1 files changed, 71 insertions, 80 deletions
diff --git a/fs/namei.c b/fs/namei.c index 7d77f24d32a..0087cf9c2c6 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); @@ -561,39 +553,25 @@ static inline int nameidata_drop_rcu_last_maybe(struct nameidata *nd) */ void release_open_intent(struct nameidata *nd) { - if (nd->intent.open.file->f_path.dentry == NULL) - put_filp(nd->intent.open.file); - else - fput(nd->intent.open.file); -} - -/* - * 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) -{ - int status; + struct file *file = nd->intent.open.file; - 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); + if (file && !IS_ERR(file)) { + if (file->f_path.dentry == NULL) + put_filp(file); + else + fput(file); } +} - return status; +static inline int d_revalidate(struct dentry *dentry, struct nameidata *nd) +{ + 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. @@ -602,24 +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))) @@ -664,9 +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; } @@ -773,6 +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); @@ -803,10 +795,16 @@ __do_follow_link(const struct path *link, struct nameidata *nd, void **p) * Without that kind of total limit, nasty chains of consecutive * symlinks can cause almost arbitrarily long lookups. */ -static inline int do_follow_link(struct path *path, struct nameidata *nd) +static inline int do_follow_link(struct inode *inode, 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; + BUG_ON(inode != path->dentry->d_inode); + if (current->link_count >= MAX_NESTED_LINKS) goto loop; if (current->total_link_count >= 40) @@ -1251,9 +1249,15 @@ 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))) @@ -1266,8 +1270,13 @@ 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; @@ -1309,16 +1318,6 @@ 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); } @@ -1415,11 +1414,7 @@ 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); + err = do_follow_link(inode, &next, nd); if (err) goto return_err; nd->inode = nd->path.dentry->d_inode; @@ -1463,10 +1458,7 @@ 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); + err = do_follow_link(inode, &next, nd); if (err) goto return_err; nd->inode = nd->path.dentry->d_inode; @@ -1500,12 +1492,15 @@ 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)) @@ -2265,8 +2260,6 @@ static struct file *finish_open(struct nameidata *nd, return filp; exit: - if (!IS_ERR(nd->intent.open.file)) - release_open_intent(nd); path_put(&nd->path); return ERR_PTR(error); } @@ -2389,8 +2382,6 @@ exit_mutex_unlock: exit_dput: path_put_conditional(path, nd); exit: - if (!IS_ERR(nd->intent.open.file)) - release_open_intent(nd); path_put(&nd->path); return ERR_PTR(error); } @@ -2477,6 +2468,7 @@ struct file *do_filp_open(int dfd, const char *pathname, } audit_inode(pathname, nd.path.dentry); filp = finish_open(&nd, open_flag, acc_mode); + release_open_intent(&nd); return filp; creat: @@ -2553,6 +2545,7 @@ out: path_put(&nd.root); if (filp == ERR_PTR(-ESTALE) && !(flags & LOOKUP_REVAL)) goto reval; + release_open_intent(&nd); return filp; exit_dput: @@ -2560,8 +2553,6 @@ exit_dput: out_path: path_put(&nd.path); out_filp: - if (!IS_ERR(nd.intent.open.file)) - release_open_intent(&nd); filp = ERR_PTR(error); goto out; } |