Nick Piggin <npiggin@xxxxxxxxx> writes: > On 25 April 2012 22:44, Miklos Szeredi <miklos@xxxxxxxxxx> wrote: >> From: Miklos Szeredi <mszeredi@xxxxxxx> >> >> Use helper variable instead of path->dentry->d_inode before complete_walk(). >> This will allow this code to be used in RCU mode. > > What do you mean, allow it to be used? I mean allow the code to be shared between RCU and non-RCU mode. See 10/16. > >> >> Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxx> >> --- >> fs/namei.c | 7 ++++--- >> 1 files changed, 4 insertions(+), 3 deletions(-) >> >> diff --git a/fs/namei.c b/fs/namei.c >> index 46d4bf6..f21ddb3 100644 >> --- a/fs/namei.c >> +++ b/fs/namei.c >> @@ -2360,15 +2360,16 @@ static struct file *do_last(struct nameidata *nd, struct path *path, >> if (error) >> nd->flags |= LOOKUP_JUMPED; >> >> + inode = path->dentry->d_inode ; >> error = -ENOENT; >> - if (!path->dentry->d_inode) >> + if (!inode) >> goto exit_dput; >> >> - if (path->dentry->d_inode->i_op->follow_link) >> + if (inode->i_op->follow_link) >> return NULL; >> >> path_to_nameidata(path, nd); >> - nd->inode = path->dentry->d_inode; >> + nd->inode = inode; >> /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ >> error = complete_walk(nd); >> if (error) > > In rcu-walk mode, dentry->d_inode should not be accessed at all, > outside of the core lookup code that (should) have the correct > barriers and sequence locks. > > That logic should not escape into here, so I'm just not sure what > you're doing here. Right, dentry->d_inode is *not* going to be dereferenced in RCU mode. In RCU mode it will jump to the place just after the "inode = path->dentry->d_inode;" line. See patch 10/16. Thanks, Miklos -- 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
