On Fri, 13 Nov 2009, Eric Paris wrote:
quoted text
> mount         S ffff88001f86bd28     0  4126   4120 0x00000080
> mount         S ffff88001f86bd28     0  4126   4120 0x00000080
> ffff88001f86bc38 0000000000000086 0000000000000011 ffff88001f86bc08
> 0000000000000700 0000000000000000 0000000000000013 ffffffff815884cd
> ffff8800377532c8 000000000000f8e0 ffff8800377532c8 0000000000015600
> Call Trace:
> [<ffffffffa01bec71>] fuse_get_req+0xb8/0x15b [fuse]
> [<ffffffffa01bf359>] fuse_getxattr+0x58/0x14f [fuse]
> [<ffffffff811b9ea2>] get_vfs_caps_from_disk+0x52/0xcd
> [<ffffffff81093809>] audit_copy_inode+0x83/0xb1
> [<ffffffff81093d4f>] __audit_inode+0x1ee/0x1fd
> [<ffffffff81104789>] audit_inode+0x28/0x2a
> [<ffffffff811066b4>] do_path_lookup+0x63/0x8b
> [<ffffffff81107c9c>] user_path_at+0x56/0x93
> [<ffffffff810ffaf0>] sys_readlinkat+0x2d/0x91
> [<ffffffff810ffb6f>] sys_readlink+0x1b/0x1d
> [<ffffffff81011cf2>] system_call_fastpath+0x16/0x1b
> 
> Userspace called readlink() and the audit system (after the vfs worked
> out the path) needs to collect any fcaps.

OK, this is a different problem than what I thought.  Agreed, audit is
not doing anything wrong here.

The cause seems to be that fuse calls "mount -i -f ..." to add the
filesystem entry to /etc/mtab.  mount(8) then goes off and tries to
canonicalize the path, calling readlink() on the mountpoint.  Which is
unnecessary, really.  The path has already been canonicalized, but
unfortunately there's no way currently to tell this to mount.

In this light, the patch by Josef might be OK as a workaround, but
I'll look at better ways to fix this.

Josef, can you check whether the mtab is still correctly updated with
your patch?

Thanks,
Miklos
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