diff options
Diffstat (limited to 'fs/namei.c')
-rw-r--r-- | fs/namei.c | 154 |
1 files changed, 87 insertions, 67 deletions
diff --git a/fs/namei.c b/fs/namei.c index defe6781e00..a7f7f44119b 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -493,12 +493,21 @@ fail: return PTR_ERR(link); } -static inline int __do_follow_link(struct dentry *dentry, struct nameidata *nd) +struct path { + struct vfsmount *mnt; + struct dentry *dentry; +}; + +static inline int __do_follow_link(struct path *path, struct nameidata *nd) { int error; + struct dentry *dentry = path->dentry; - touch_atime(nd->mnt, dentry); + touch_atime(path->mnt, dentry); nd_set_link(nd, NULL); + + if (path->mnt == nd->mnt) + mntget(path->mnt); error = dentry->d_inode->i_op->follow_link(dentry, nd); if (!error) { char *s = nd_get_link(nd); @@ -507,6 +516,8 @@ static inline int __do_follow_link(struct dentry *dentry, struct nameidata *nd) if (dentry->d_inode->i_op->put_link) dentry->d_inode->i_op->put_link(dentry, nd); } + dput(dentry); + mntput(path->mnt); return error; } @@ -518,7 +529,7 @@ static inline int __do_follow_link(struct dentry *dentry, struct nameidata *nd) * Without that kind of total limit, nasty chains of consecutive * symlinks can cause almost arbitrarily long lookups. */ -static inline int do_follow_link(struct dentry *dentry, struct nameidata *nd) +static inline int do_follow_link(struct path *path, struct nameidata *nd) { int err = -ELOOP; if (current->link_count >= MAX_NESTED_LINKS) @@ -527,17 +538,20 @@ static inline int do_follow_link(struct dentry *dentry, struct nameidata *nd) goto loop; BUG_ON(nd->depth >= MAX_NESTED_LINKS); cond_resched(); - err = security_inode_follow_link(dentry, nd); + err = security_inode_follow_link(path->dentry, nd); if (err) goto loop; current->link_count++; current->total_link_count++; nd->depth++; - err = __do_follow_link(dentry, nd); + err = __do_follow_link(path, nd); current->link_count--; nd->depth--; return err; loop: + dput(path->dentry); + if (path->mnt != nd->mnt) + mntput(path->mnt); path_release(nd); return err; } @@ -565,87 +579,91 @@ int follow_up(struct vfsmount **mnt, struct dentry **dentry) /* no need for dcache_lock, as serialization is taken care in * namespace.c */ -static int follow_mount(struct vfsmount **mnt, struct dentry **dentry) +static int __follow_mount(struct path *path) { int res = 0; + while (d_mountpoint(path->dentry)) { + struct vfsmount *mounted = lookup_mnt(path->mnt, path->dentry); + if (!mounted) + break; + dput(path->dentry); + if (res) + mntput(path->mnt); + path->mnt = mounted; + path->dentry = dget(mounted->mnt_root); + res = 1; + } + return res; +} + +static void follow_mount(struct vfsmount **mnt, struct dentry **dentry) +{ while (d_mountpoint(*dentry)) { struct vfsmount *mounted = lookup_mnt(*mnt, *dentry); if (!mounted) break; + dput(*dentry); mntput(*mnt); *mnt = mounted; - dput(*dentry); *dentry = dget(mounted->mnt_root); - res = 1; } - return res; } /* no need for dcache_lock, as serialization is taken care in * namespace.c */ -static inline int __follow_down(struct vfsmount **mnt, struct dentry **dentry) +int follow_down(struct vfsmount **mnt, struct dentry **dentry) { struct vfsmount *mounted; mounted = lookup_mnt(*mnt, *dentry); if (mounted) { + dput(*dentry); mntput(*mnt); *mnt = mounted; - dput(*dentry); *dentry = dget(mounted->mnt_root); return 1; } return 0; } -int follow_down(struct vfsmount **mnt, struct dentry **dentry) -{ - return __follow_down(mnt,dentry); -} - -static inline void follow_dotdot(struct vfsmount **mnt, struct dentry **dentry) +static inline void follow_dotdot(struct nameidata *nd) { while(1) { struct vfsmount *parent; - struct dentry *old = *dentry; + struct dentry *old = nd->dentry; read_lock(¤t->fs->lock); - if (*dentry == current->fs->root && - *mnt == current->fs->rootmnt) { + if (nd->dentry == current->fs->root && + nd->mnt == current->fs->rootmnt) { read_unlock(¤t->fs->lock); break; } read_unlock(¤t->fs->lock); spin_lock(&dcache_lock); - if (*dentry != (*mnt)->mnt_root) { - *dentry = dget((*dentry)->d_parent); + if (nd->dentry != nd->mnt->mnt_root) { + nd->dentry = dget(nd->dentry->d_parent); spin_unlock(&dcache_lock); dput(old); break; } spin_unlock(&dcache_lock); spin_lock(&vfsmount_lock); - parent = (*mnt)->mnt_parent; - if (parent == *mnt) { + parent = nd->mnt->mnt_parent; + if (parent == nd->mnt) { spin_unlock(&vfsmount_lock); break; } mntget(parent); - *dentry = dget((*mnt)->mnt_mountpoint); + nd->dentry = dget(nd->mnt->mnt_mountpoint); spin_unlock(&vfsmount_lock); dput(old); - mntput(*mnt); - *mnt = parent; + mntput(nd->mnt); + nd->mnt = parent; } - follow_mount(mnt, dentry); + follow_mount(&nd->mnt, &nd->dentry); } -struct path { - struct vfsmount *mnt; - struct dentry *dentry; -}; - /* * It's more convoluted than I'd like it to be, but... it's still fairly * small and for now I'd prefer to have fast path as straight as possible. @@ -664,6 +682,7 @@ static int do_lookup(struct nameidata *nd, struct qstr *name, done: path->mnt = mnt; path->dentry = dentry; + __follow_mount(path); return 0; need_lookup: @@ -751,7 +770,7 @@ static fastcall int __link_path_walk(const char * name, struct nameidata *nd) case 2: if (this.name[1] != '.') break; - follow_dotdot(&nd->mnt, &nd->dentry); + follow_dotdot(nd); inode = nd->dentry->d_inode; /* fallthrough */ case 1: @@ -771,8 +790,6 @@ static fastcall int __link_path_walk(const char * name, struct nameidata *nd) err = do_lookup(nd, &this, &next); if (err) break; - /* Check mountpoints.. */ - follow_mount(&next.mnt, &next.dentry); err = -ENOENT; inode = next.dentry->d_inode; @@ -783,10 +800,7 @@ static fastcall int __link_path_walk(const char * name, struct nameidata *nd) goto out_dput; if (inode->i_op->follow_link) { - mntget(next.mnt); - err = do_follow_link(next.dentry, nd); - dput(next.dentry); - mntput(next.mnt); + err = do_follow_link(&next, nd); if (err) goto return_err; err = -ENOENT; @@ -798,6 +812,8 @@ static fastcall int __link_path_walk(const char * name, struct nameidata *nd) break; } else { dput(nd->dentry); + if (nd->mnt != next.mnt) + mntput(nd->mnt); nd->mnt = next.mnt; nd->dentry = next.dentry; } @@ -819,7 +835,7 @@ last_component: case 2: if (this.name[1] != '.') break; - follow_dotdot(&nd->mnt, &nd->dentry); + follow_dotdot(nd); inode = nd->dentry->d_inode; /* fallthrough */ case 1: @@ -833,19 +849,17 @@ last_component: err = do_lookup(nd, &this, &next); if (err) break; - follow_mount(&next.mnt, &next.dentry); inode = next.dentry->d_inode; if ((lookup_flags & LOOKUP_FOLLOW) && inode && inode->i_op && inode->i_op->follow_link) { - mntget(next.mnt); - err = do_follow_link(next.dentry, nd); - dput(next.dentry); - mntput(next.mnt); + err = do_follow_link(&next, nd); if (err) goto return_err; inode = nd->dentry->d_inode; } else { dput(nd->dentry); + if (nd->mnt != next.mnt) + mntput(nd->mnt); nd->mnt = next.mnt; nd->dentry = next.dentry; } @@ -885,6 +899,8 @@ return_base: return 0; out_dput: dput(next.dentry); + if (nd->mnt != next.mnt) + mntput(next.mnt); break; } path_release(nd); @@ -1398,7 +1414,7 @@ int may_open(struct nameidata *nd, int acc_mode, int flag) int open_namei(const char * pathname, int flag, int mode, struct nameidata *nd) { int acc_mode, error = 0; - struct dentry *dentry; + struct path path; struct dentry *dir; int count = 0; @@ -1442,23 +1458,24 @@ int open_namei(const char * pathname, int flag, int mode, struct nameidata *nd) dir = nd->dentry; nd->flags &= ~LOOKUP_PARENT; down(&dir->d_inode->i_sem); - dentry = __lookup_hash(&nd->last, nd->dentry, nd); + path.dentry = __lookup_hash(&nd->last, nd->dentry, nd); + path.mnt = nd->mnt; do_last: - error = PTR_ERR(dentry); - if (IS_ERR(dentry)) { + error = PTR_ERR(path.dentry); + if (IS_ERR(path.dentry)) { up(&dir->d_inode->i_sem); goto exit; } /* Negative dentry, just create the file */ - if (!dentry->d_inode) { + if (!path.dentry->d_inode) { if (!IS_POSIXACL(dir->d_inode)) mode &= ~current->fs->umask; - error = vfs_create(dir->d_inode, dentry, mode, nd); + error = vfs_create(dir->d_inode, path.dentry, mode, nd); up(&dir->d_inode->i_sem); dput(nd->dentry); - nd->dentry = dentry; + nd->dentry = path.dentry; if (error) goto exit; /* Don't check for write permission, don't truncate */ @@ -1476,22 +1493,24 @@ do_last: if (flag & O_EXCL) goto exit_dput; - if (d_mountpoint(dentry)) { + if (__follow_mount(&path)) { error = -ELOOP; if (flag & O_NOFOLLOW) goto exit_dput; - while (__follow_down(&nd->mnt,&dentry) && d_mountpoint(dentry)); } error = -ENOENT; - if (!dentry->d_inode) + if (!path.dentry->d_inode) goto exit_dput; - if (dentry->d_inode->i_op && dentry->d_inode->i_op->follow_link) + if (path.dentry->d_inode->i_op && path.dentry->d_inode->i_op->follow_link) goto do_link; dput(nd->dentry); - nd->dentry = dentry; + nd->dentry = path.dentry; + if (nd->mnt != path.mnt) + mntput(nd->mnt); + nd->mnt = path.mnt; error = -EISDIR; - if (dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode)) + if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode)) goto exit; ok: error = may_open(nd, acc_mode, flag); @@ -1500,7 +1519,9 @@ ok: return 0; exit_dput: - dput(dentry); + dput(path.dentry); + if (nd->mnt != path.mnt) + mntput(path.mnt); exit: path_release(nd); return error; @@ -1520,18 +1541,15 @@ do_link: * are done. Procfs-like symlinks just set LAST_BIND. */ nd->flags |= LOOKUP_PARENT; - error = security_inode_follow_link(dentry, nd); + error = security_inode_follow_link(path.dentry, nd); if (error) goto exit_dput; - error = __do_follow_link(dentry, nd); - dput(dentry); + error = __do_follow_link(&path, nd); if (error) return error; nd->flags &= ~LOOKUP_PARENT; - if (nd->last_type == LAST_BIND) { - dentry = nd->dentry; + if (nd->last_type == LAST_BIND) goto ok; - } error = -EISDIR; if (nd->last_type != LAST_NORM) goto exit; @@ -1546,7 +1564,8 @@ do_link: } dir = nd->dentry; down(&dir->d_inode->i_sem); - dentry = __lookup_hash(&nd->last, nd->dentry, nd); + path.dentry = __lookup_hash(&nd->last, nd->dentry, nd); + path.mnt = nd->mnt; putname(nd->last.name); goto do_last; } @@ -1580,6 +1599,7 @@ enoent: fail: return dentry; } +EXPORT_SYMBOL_GPL(lookup_create); int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) { |