From 211db0ac9e3dc6c46f2dd53395b34d76af929faf Mon Sep 17 00:00:00 2001 From: Namjae Jeon Date: Thu, 16 Mar 2023 07:34:33 +0900 Subject: [PATCH 1/2] ksmbd: remove internal.h include Since vfs_path_lookup is exported, It should not be internal. Move vfs_path_lookup prototype in internal.h to linux/namei.h. Suggested-by: Al Viro Reviewed-by: Christian Brauner Signed-off-by: Namjae Jeon Signed-off-by: Al Viro --- fs/internal.h | 2 -- fs/ksmbd/vfs.c | 2 -- include/linux/namei.h | 2 ++ 3 files changed, 2 insertions(+), 4 deletions(-) diff --git a/fs/internal.h b/fs/internal.h index dc4eb91a577a..071a7517f1a7 100644 --- a/fs/internal.h +++ b/fs/internal.h @@ -59,8 +59,6 @@ extern int finish_clean_context(struct fs_context *fc); */ extern int filename_lookup(int dfd, struct filename *name, unsigned flags, struct path *path, struct path *root); -extern int vfs_path_lookup(struct dentry *, struct vfsmount *, - const char *, unsigned int, struct path *); int do_rmdir(int dfd, struct filename *name); int do_unlinkat(int dfd, struct filename *name); int may_linkat(struct mnt_idmap *idmap, const struct path *link); diff --git a/fs/ksmbd/vfs.c b/fs/ksmbd/vfs.c index 5ea9229dad2c..cef07d7fb7dc 100644 --- a/fs/ksmbd/vfs.c +++ b/fs/ksmbd/vfs.c @@ -19,8 +19,6 @@ #include #include -#include "../internal.h" /* for vfs_path_lookup */ - #include "glob.h" #include "oplock.h" #include "connection.h" diff --git a/include/linux/namei.h b/include/linux/namei.h index 0d797f3367ca..ba9b32b4d1b0 100644 --- a/include/linux/namei.h +++ b/include/linux/namei.h @@ -63,6 +63,8 @@ extern struct dentry *kern_path_create(int, const char *, struct path *, unsigne extern struct dentry *user_path_create(int, const char __user *, struct path *, unsigned int); extern void done_path_create(struct path *, struct dentry *); extern struct dentry *kern_path_locked(const char *, struct path *); +int vfs_path_lookup(struct dentry *, struct vfsmount *, const char *, + unsigned int, struct path *); extern struct dentry *try_lookup_one_len(const char *, struct dentry *, int); extern struct dentry *lookup_one_len(const char *, struct dentry *, int); From 9bc37e04823b5280dd0f22b6680fc23fe81ca325 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Thu, 16 Mar 2023 07:34:34 +0900 Subject: [PATCH 2/2] fs: introduce lock_rename_child() helper Pass the dentry of a source file and the dentry of a destination directory to lock parent inodes for rename. As soon as this function returns, ->d_parent of the source file dentry is stable and inodes are properly locked for calling vfs-rename. This helper is needed for ksmbd server. rename request of SMB protocol has to rename an opened file, no matter which directory it's in. Signed-off-by: Al Viro Signed-off-by: Namjae Jeon Signed-off-by: Al Viro --- fs/namei.c | 68 ++++++++++++++++++++++++++++++++++++------- include/linux/namei.h | 1 + 2 files changed, 58 insertions(+), 11 deletions(-) diff --git a/fs/namei.c b/fs/namei.c index edfedfbccaef..6bc1964e2214 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -2980,20 +2980,10 @@ static inline int may_create(struct mnt_idmap *idmap, return inode_permission(idmap, dir, MAY_WRITE | MAY_EXEC); } -/* - * p1 and p2 should be directories on the same fs. - */ -struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) +static struct dentry *lock_two_directories(struct dentry *p1, struct dentry *p2) { struct dentry *p; - if (p1 == p2) { - inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); - return NULL; - } - - mutex_lock(&p1->d_sb->s_vfs_rename_mutex); - p = d_ancestor(p2, p1); if (p) { inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); @@ -3012,8 +3002,64 @@ struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); return NULL; } + +/* + * p1 and p2 should be directories on the same fs. + */ +struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) +{ + if (p1 == p2) { + inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); + return NULL; + } + + mutex_lock(&p1->d_sb->s_vfs_rename_mutex); + return lock_two_directories(p1, p2); +} EXPORT_SYMBOL(lock_rename); +/* + * c1 and p2 should be on the same fs. + */ +struct dentry *lock_rename_child(struct dentry *c1, struct dentry *p2) +{ + if (READ_ONCE(c1->d_parent) == p2) { + /* + * hopefully won't need to touch ->s_vfs_rename_mutex at all. + */ + inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); + /* + * now that p2 is locked, nobody can move in or out of it, + * so the test below is safe. + */ + if (likely(c1->d_parent == p2)) + return NULL; + + /* + * c1 got moved out of p2 while we'd been taking locks; + * unlock and fall back to slow case. + */ + inode_unlock(p2->d_inode); + } + + mutex_lock(&c1->d_sb->s_vfs_rename_mutex); + /* + * nobody can move out of any directories on this fs. + */ + if (likely(c1->d_parent != p2)) + return lock_two_directories(c1->d_parent, p2); + + /* + * c1 got moved into p2 while we were taking locks; + * we need p2 locked and ->s_vfs_rename_mutex unlocked, + * for consistency with lock_rename(). + */ + inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); + mutex_unlock(&c1->d_sb->s_vfs_rename_mutex); + return NULL; +} +EXPORT_SYMBOL(lock_rename_child); + void unlock_rename(struct dentry *p1, struct dentry *p2) { inode_unlock(p1->d_inode); diff --git a/include/linux/namei.h b/include/linux/namei.h index ba9b32b4d1b0..5864e4d82e56 100644 --- a/include/linux/namei.h +++ b/include/linux/namei.h @@ -83,6 +83,7 @@ extern int follow_down(struct path *path, unsigned int flags); extern int follow_up(struct path *); extern struct dentry *lock_rename(struct dentry *, struct dentry *); +extern struct dentry *lock_rename_child(struct dentry *, struct dentry *); extern void unlock_rename(struct dentry *, struct dentry *); extern int __must_check nd_jump_link(const struct path *path);