Re: [PATCH] tmpfs symlink corrupts mempolicy
From: Hugh Dickins
Date: Mon Nov 15 2004 - 19:29:16 EST
On Mon, 15 Nov 2004, Andrea Arcangeli wrote:
> this patch is completely broken, delete_inode isn't going to be called
> when the inode is being shrunk. delete_inode is only good for truncate,
Do you mean "when the inode cache is being shrunk"?
By "truncate" there you mean "unlink"?
> mpol_free_shared_policy has nothing to do with the nlink value.
I didn't think that it would.
> this patch will tend to work until the vm shrink the dcache, then it'll
> crash, sorry.
Sorry, you can see I'm having some trouble understanding your reply.
I think you're forgetting that tmpfs inodes live nowhere but in memory:
if shrinking the inode cache were to remove tmpfs inodes, it would be a
considerably more temporary fs than could ever be useful. There's an
extra dget that keeps dentry and inode safe from pruning.
mpol_shared_policy_init is appropriate when we might want to allocate
pages to the inode (regular file or long symlink); mpol_free_shared_policy
is appropriate when we've given up the possibility of allocating pages to
such an inode - that's after shmem_delete_inode's shmem_truncate.
Whereas shmem_destroy_inode is the complement of shmem_alloc_inode,
neither of which should get into this mpol stuff.
If you're unconvinced, please suggest a test case which will do the
wrong thing, and I'll check it out tomorrow - thanks.
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