Quoting Eric W. Biederman (ebiederm@xxxxxxxxxxxx): > From: Eric W. Biederman <ebiederm@xxxxxxxxxxxxxxxxxx> > > The way the vfs is structured only calls to the filesystem > methods actually update the vfs inode. We add to the > normal number of places where the vfs inode is updated by > also updating the vfs inode in sysfs_refresh_inode. > > Grabbing the inode mutex in sysfs_permission and sysfs_getattr > causes deadlocks, because somtimes those operations are called > with the inode mutex held, but not always. Therefore we can > not depend upon the inode mutex to serialize all updates > to the vfs inode. > > We take the sysfs_mutex in all of those places so we can > also use it to protect the vfs inode. To accomplish that > we simply requires extending the vfs inode in sysfs_setattr > over inode_change_ok (so we have an unchanging inode > when we perform the check), and inode_setattr. > > Signed-off-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxxxxxxxx> I'm a little confused about the patch intro: it makes it sound like this is preparatory for a followup, but in fact it is a bugfix, right? Hard to exploit i think, but should it go to -stable? Acked-by: Serge Hallyn <serue@xxxxxxxxxx> > --- > fs/sysfs/inode.c | 8 ++++---- > 1 files changed, 4 insertions(+), 4 deletions(-) > > diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c > index 220b758..104cbc1 100644 > --- a/fs/sysfs/inode.c > +++ b/fs/sysfs/inode.c > @@ -112,20 +112,20 @@ int sysfs_setattr(struct dentry *dentry, struct iattr *iattr) > if (!sd) > return -EINVAL; > > + mutex_lock(&sysfs_mutex); > error = inode_change_ok(inode, iattr); > if (error) > - return error; > + goto out; > > iattr->ia_valid &= ~ATTR_SIZE; /* ignore size changes */ > > error = inode_setattr(inode, iattr); > if (error) > - return error; > + goto out; > > - mutex_lock(&sysfs_mutex); > error = sysfs_sd_setattr(sd, iattr); > +out: > mutex_unlock(&sysfs_mutex); > - > return error; > } > > -- > 1.6.5.2.143.g8cc62 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
