From 01de85e057328ecbef36e108673b1e81059d54c1 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Tue, 17 Oct 2006 19:50:36 +0200 Subject: [PATCH] [PATCH] Add lockless helpers for remove_suid() Right now users have to grab i_mutex before calling remove_suid(), in the unlikely event that a call to ->setattr() may be needed. Split up the function in two parts: - One to check if we need to remove suid - One to actually remove it The first we can call lockless. Signed-off-by: Jens Axboe --- include/linux/fs.h | 2 ++ mm/filemap.c | 30 ++++++++++++++++++++++-------- 2 files changed, 24 insertions(+), 8 deletions(-) diff --git a/include/linux/fs.h b/include/linux/fs.h index d695ba2346a3..2fe6e3f900ba 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1712,6 +1712,8 @@ extern void __iget(struct inode * inode); extern void clear_inode(struct inode *); extern void destroy_inode(struct inode *); extern struct inode *new_inode(struct super_block *); +extern int __remove_suid(struct dentry *, int); +extern int should_remove_suid(struct dentry *); extern int remove_suid(struct dentry *); extern void remove_dquot_ref(struct super_block *, int, struct list_head *); diff --git a/mm/filemap.c b/mm/filemap.c index 3464b681f844..7c7addb9333c 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1884,11 +1884,10 @@ repeat: * if suid or (sgid and xgrp) * remove privs */ -int remove_suid(struct dentry *dentry) +int should_remove_suid(struct dentry *dentry) { mode_t mode = dentry->d_inode->i_mode; int kill = 0; - int result = 0; /* suid always must be killed */ if (unlikely(mode & S_ISUID)) @@ -1901,13 +1900,28 @@ int remove_suid(struct dentry *dentry) if (unlikely((mode & S_ISGID) && (mode & S_IXGRP))) kill |= ATTR_KILL_SGID; - if (unlikely(kill && !capable(CAP_FSETID))) { - struct iattr newattrs; + if (unlikely(kill && !capable(CAP_FSETID))) + return kill; - newattrs.ia_valid = ATTR_FORCE | kill; - result = notify_change(dentry, &newattrs); - } - return result; + return 0; +} + +int __remove_suid(struct dentry *dentry, int kill) +{ + struct iattr newattrs; + + newattrs.ia_valid = ATTR_FORCE | kill; + return notify_change(dentry, &newattrs); +} + +int remove_suid(struct dentry *dentry) +{ + int kill = should_remove_suid(dentry); + + if (unlikely(kill)) + return __remove_suid(dentry, kill); + + return 0; } EXPORT_SYMBOL(remove_suid); -- 2.20.1