From 574197e0de46a8a4db5c54ef7b65e43ffa8873a7 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Mon, 14 Mar 2011 22:20:34 -0400 Subject: [PATCH] tidy the trailing symlinks traversal up * pull the handling of current->total_link_count into __do_follow_link() * put the common "do ->put_link() if needed and path_put() the link" stuff into a helper (put_link(nd, link, cookie)) * rename __do_follow_link() to follow_link(), while we are at it Signed-off-by: Al Viro --- fs/namei.c | 71 +++++++++++++++++++++++--------------------------------------- 1 file changed, 26 insertions(+), 45 deletions(-) diff --git a/fs/namei.c b/fs/namei.c index 017c3fa..0a601ca 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -737,14 +737,31 @@ static inline void path_to_nameidata(const struct path *path, nd->path.dentry = path->dentry; } +static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) +{ + struct inode *inode = link->dentry->d_inode; + if (!IS_ERR(cookie) && inode->i_op->put_link) + inode->i_op->put_link(link->dentry, nd, cookie); + path_put(link); +} + static __always_inline int -__do_follow_link(const struct path *link, struct nameidata *nd, void **p) +follow_link(struct path *link, struct nameidata *nd, void **p) { int error; struct dentry *dentry = link->dentry; BUG_ON(nd->flags & LOOKUP_RCU); + if (unlikely(current->total_link_count >= 40)) { + *p = ERR_PTR(-ELOOP); /* no ->put_link(), please */ + path_put_conditional(link, nd); + path_put(&nd->path); + return -ELOOP; + } + cond_resched(); + current->total_link_count++; + touch_atime(link->mnt, dentry); nd_set_link(nd, NULL); @@ -1356,21 +1373,12 @@ static inline int nested_symlink(struct path *path, struct nameidata *nd) do { struct path link = *path; void *cookie; - if (unlikely(current->total_link_count >= 40)) { - path_put_conditional(path, nd); - path_put(&nd->path); - res = -ELOOP; - break; - } - cond_resched(); - current->total_link_count++; - res = __do_follow_link(&link, nd, &cookie); + + res = follow_link(&link, nd, &cookie); if (!res) res = walk_component(nd, path, &nd->last, nd->last_type, LOOKUP_FOLLOW); - if (!IS_ERR(cookie) && link.dentry->d_inode->i_op->put_link) - link.dentry->d_inode->i_op->put_link(link.dentry, nd, cookie); - path_put(&link); + put_link(nd, &link, cookie); } while (res > 0); current->link_count--; @@ -1619,27 +1627,15 @@ static int path_lookupat(int dfd, const char *name, err = link_path_walk(name, nd); if (!err && !(flags & LOOKUP_PARENT)) { - int count = 0; err = lookup_last(nd, &path); while (err > 0) { void *cookie; struct path link = path; - struct inode *inode = link.dentry->d_inode; - - if (count++ > 32) { - path_put_conditional(&path, nd); - path_put(&nd->path); - err = -ELOOP; - break; - } - cond_resched(); nd->flags |= LOOKUP_PARENT; - err = __do_follow_link(&link, nd, &cookie); + err = follow_link(&link, nd, &cookie); if (!err) err = lookup_last(nd, &path); - if (!IS_ERR(cookie) && inode->i_op->put_link) - inode->i_op->put_link(link.dentry, nd, cookie); - path_put(&link); + put_link(nd, &link, cookie); } } @@ -2298,7 +2294,6 @@ static struct file *path_openat(int dfd, const char *pathname, struct file *base = NULL; struct file *filp; struct path path; - int count = 0; int error; filp = get_empty_filp(); @@ -2322,35 +2317,21 @@ static struct file *path_openat(int dfd, const char *pathname, filp = do_last(nd, &path, op, pathname); while (unlikely(!filp)) { /* trailing symlink */ struct path link = path; - struct inode *linki = link.dentry->d_inode; void *cookie; - if (!(nd->flags & LOOKUP_FOLLOW) || count++ == 32) { + if (!(nd->flags & LOOKUP_FOLLOW)) { path_put_conditional(&path, nd); path_put(&nd->path); filp = ERR_PTR(-ELOOP); break; } - /* - * This is subtle. Instead of calling do_follow_link() we do - * the thing by hands. The reason is that this way we have zero - * link_count and path_walk() (called from ->follow_link) - * honoring LOOKUP_PARENT. After that we have the parent and - * last component, i.e. we are in the same situation as after - * the first path_walk(). Well, almost - if the last component - * is normal we get its copy stored in nd->last.name and we will - * have to putname() it when we are done. Procfs-like symlinks - * just set LAST_BIND. - */ nd->flags |= LOOKUP_PARENT; nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); - error = __do_follow_link(&link, nd, &cookie); + error = follow_link(&link, nd, &cookie); if (unlikely(error)) filp = ERR_PTR(error); else filp = do_last(nd, &path, op, pathname); - if (!IS_ERR(cookie) && linki->i_op->put_link) - linki->i_op->put_link(link.dentry, nd, cookie); - path_put(&link); + put_link(nd, &link, cookie); } out: if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) -- 2.7.4