diff options
| author | Paul Cassella <cassella@cray.com> | 2014-08-15 12:48:08 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-08-17 09:38:42 -0700 |
| commit | 6aa5107281ea065b9a7818a1c640e022d41a421b (patch) | |
| tree | 1a07f0b28a60e52d4c22a267db09d7dac55c362d | |
| parent | 7591805af511b7f71fec87c69a539d1d0cfb93a1 (diff) | |
staging/lustre/llite: Make sure ft_flags is valid
In ll_fault0, the 'fault' struct is mostly cleared before the call to
cl_io_loop, but ft_flags is not reset. It is ordinarily set by
the call to filemap_fault in vvp_io_kernel_fault, but if Lustre
returns before calling filemap_fault, it still has the old value of
ft_flags.
ll_fault0 will then consume the ft_flags field. If it has the
VM_FAULT_RETRY bit set, it will be used as ll_fault0() and
ll_fault()'s return value.
This is a problem when VM_FAULT_RETRY is in ft_flags:
When fault/filemap_fault return with that flag set, they have already
released the mmap semaphore, and do_page_fault does not need to
release it.
Incorrectly returning this flag from ll_fault means mmap_sem
is not upped in the kernel's do_page_fault().
In addition to clearing ft_flags, this patch does not use it unless
it is valid. It's potentially misleading to return ft_flags in
"fault_ret" if ft_flags has not been set by filemap_fault.
This adds clarity, but does not change the current behavior:
When not valid, ft_flags is replaced by fault_ret, which is zero,
as is ft_flags when not set by filemap_fault.
Signed-off-by: Patrick Farrell <paf@cray.com>
Reviewed-on: http://review.whamcloud.com/10956
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-5291
Reviewed-by: Bobi Jam <bobijam@gmail.com>
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Signed-off-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/staging/lustre/lustre/llite/llite_internal.h | 4 | ||||
| -rw-r--r-- | drivers/staging/lustre/lustre/llite/llite_mmap.c | 8 | ||||
| -rw-r--r-- | drivers/staging/lustre/lustre/llite/vvp_io.c | 1 |
3 files changed, 12 insertions, 1 deletions
diff --git a/drivers/staging/lustre/lustre/llite/llite_internal.h b/drivers/staging/lustre/lustre/llite/llite_internal.h index 634ffa645e06..684405e26b58 100644 --- a/drivers/staging/lustre/lustre/llite/llite_internal.h +++ b/drivers/staging/lustre/lustre/llite/llite_internal.h @@ -894,6 +894,10 @@ struct vvp_io { * fault API used bitflags for return code. */ unsigned int ft_flags; + /** + * check that flags are from filemap_fault + */ + bool ft_flags_valid; } fault; } fault; } u; diff --git a/drivers/staging/lustre/lustre/llite/llite_mmap.c b/drivers/staging/lustre/lustre/llite/llite_mmap.c index 7dae610f5c86..59166481e1a2 100644 --- a/drivers/staging/lustre/lustre/llite/llite_mmap.c +++ b/drivers/staging/lustre/lustre/llite/llite_mmap.c @@ -310,10 +310,16 @@ static int ll_fault0(struct vm_area_struct *vma, struct vm_fault *vmf) vio->u.fault.ft_vma = vma; vio->u.fault.ft_vmpage = NULL; vio->u.fault.fault.ft_vmf = vmf; + vio->u.fault.fault.ft_flags = 0; + vio->u.fault.fault.ft_flags_valid = 0; result = cl_io_loop(env, io); - fault_ret = vio->u.fault.fault.ft_flags; + /* ft_flags are only valid if we reached + * the call to filemap_fault */ + if (vio->u.fault.fault.ft_flags_valid) + fault_ret = vio->u.fault.fault.ft_flags; + vmpage = vio->u.fault.ft_vmpage; if (result != 0 && vmpage != NULL) { page_cache_release(vmpage); diff --git a/drivers/staging/lustre/lustre/llite/vvp_io.c b/drivers/staging/lustre/lustre/llite/vvp_io.c index a4117d6a3866..fd248745cbff 100644 --- a/drivers/staging/lustre/lustre/llite/vvp_io.c +++ b/drivers/staging/lustre/lustre/llite/vvp_io.c @@ -615,6 +615,7 @@ static int vvp_io_kernel_fault(struct vvp_fault_io *cfio) struct vm_fault *vmf = cfio->fault.ft_vmf; cfio->fault.ft_flags = filemap_fault(cfio->ft_vma, vmf); + cfio->fault.ft_flags_valid = 1; if (vmf->page) { CDEBUG(D_PAGE, |