Messages in this thread Patch in this message | | | Date | Fri, 16 Dec 2011 12:55:56 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH] mm: add missing mutex lock arround notify_change |
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On Fri, 16 Dec 2011 12:25:34 +0100 Djalal Harouni <tixxdz@opendz.org> wrote:
> > Calls to notify_change() must hold i_mutex. >
It seems that this is true. It's tersely documented in Documentation/filesystems/porting. It should be mentioned in the non-existent notify_change() kerneldoc.
<does a quick audit>
fs/hpfs/namei.c and fs/nfsd/vfs.c:nfsd_setattr() aren't obviosuly holding that lock when calling notify_change(). Everything else under fs/ looks OK.
I'll add the below to my tree and shall slip it into linux-next, but not mainline:
--- a/fs/attr.c~a +++ a/fs/attr.c @@ -171,6 +171,8 @@ int notify_change(struct dentry * dentry struct timespec now; unsigned int ia_valid = attr->ia_valid; + WARN_ON_ONCE(!mutex_is_locked(&inode->i_mutex)); + if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_TIMES_SET)) { if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) return -EPERM; @@ -245,5 +247,4 @@ int notify_change(struct dentry * dentry return error; } - EXPORT_SYMBOL(notify_change);
> --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -1994,10 +1994,16 @@ EXPORT_SYMBOL(should_remove_suid); > > static int __remove_suid(struct dentry *dentry, int kill) > { > + int ret; > struct iattr newattrs; > > newattrs.ia_valid = ATTR_FORCE | kill; > - return notify_change(dentry, &newattrs); > + > + mutex_lock(&dentry->d_inode->i_mutex); > + ret = notify_change(dentry, &newattrs); > + mutex_unlock(&dentry->d_inode->i_mutex); > + > + return ret; > } > > int file_remove_suid(struct file *file)
Looks good to me.
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