sysfs: fix some bin_vm_ops errors
commit095160aee954688a9bad225952c4bee546541e19
authorHugh Dickins <hugh@veritas.com>
Mon, 23 Mar 2009 01:41:27 +0000 (23 01:41 +0000)
committerGreg Kroah-Hartman <gregkh@suse.de>
Tue, 24 Mar 2009 23:38:26 +0000 (24 16:38 -0700)
tree5f2ceb17b0a414da00b7173384efda8c56c1755c
parentf520360d93cdc37de5d972dac4bf3bdef6a7f6a7
sysfs: fix some bin_vm_ops errors

Commit 86c9508eb1c0ce5aa07b5cf1d36b60c54efc3d7a
"sysfs: don't block indefinitely for unmapped files" in linux-next
crashes the PowerMac G5 when X starts up.  It's caught out by the way
powerpc's pci_mmap of legacy_mem uses shmem_zero_setup(), substituting
a new vma->vm_file whose private_data no longer points to the bin_buffer
(substitution done because some versions of X crash if that mmap fails).

The fix to this is straightforward: the original vm_file is fput() in
that case, so this mmap won't block sysfs at all, so just don't switch
over to bin_vm_ops if vm_file has changed.

But more fixes made before realizing that was the problem:-

It should not be an error if bin_page_mkwrite() finds no underlying
page_mkwrite().

Check that a file already mmap'ed has the same underlying vm_ops
_before_ pointing vma->vm_ops at bin_vm_ops.

If the file being mmap'ed is a shmem/tmpfs file, don't fail the mmap
on CONFIG_NUMA=y, just because that has a set_policy and get_policy:
provide bin_set_policy, bin_get_policy and bin_migrate.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Acked-by: Eric Biederman <ebiederm@aristanetworks.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
fs/sysfs/bin.c