Messages in this thread | | | Date | Sat, 11 Oct 2014 23:01:42 -0500 | From | Eric Biggers <> | Subject | Re: fs/namei.c: Misuse of sequence counts? |
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On Sun, Oct 12, 2014 at 01:12:59AM +0100, Al Viro wrote: > > Huh? What's to guarantee that dentry hasn't become negative since the > moment we'd fetched the seqcount? _That_ is the problem we are dealing > with here - link_path_walk() relies on nd->inode being non-NULL.
Hmm, I guess that makes sense. So the code is actually verifying that the inode is still the inode that was referenced from the current or root directory when nd->path was set. But couldn't the problem also be solved by setting nd->inode directly in the fs->seq retry loops? (The file descriptor case could be 'nd->inode = file_inode(f.file);'.) Then there would be no need for the extra read_seqcount_retry() just for the inode. The patch you posted looks correct, but I wonder if this approach would be better.
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