linux/drivers/nvdimm/pfn.h

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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright (c) 2014-2015, Intel Corporation.
*/
#ifndef __NVDIMM_PFN_H
#define __NVDIMM_PFN_H
#include <linux/types.h>
#include <linux/mmzone.h>
#define PFN_SIG_LEN 16
#define PFN_SIG "NVDIMM_PFN_INFO\0"
#define DAX_SIG "NVDIMM_DAX_INFO\0"
struct nd_pfn_sb {
u8 signature[PFN_SIG_LEN];
u8 uuid[16];
u8 parent_uuid[16];
__le32 flags;
__le16 version_major;
__le16 version_minor;
__le64 dataoff; /* relative to namespace_base + start_pad */
__le64 npfns;
__le32 mode;
/* minor-version-1 additions for section alignment */
/**
* @start_pad: Deprecated attribute to pad start-misaligned namespaces
*
* start_pad is deprecated because the original definition did
* not comprehend that dataoff is relative to the base address
* of the namespace not the start_pad adjusted base. The result
* is that the dax path is broken, but the block-I/O path is
* not. The kernel will no longer create namespaces using start
* padding, but it still supports block-I/O for legacy
* configurations mainly to allow a backup, reconfigure the
* namespace, and restore flow to repair dax operation.
*/
__le32 start_pad;
__le32 end_trunc;
/* minor-version-2 record the base alignment of the mapping */
__le32 align;
libnvdimm/pfn: fix fsdax-mode namespace info-block zero-fields At namespace creation time there is the potential for the "expected to be zero" fields of a 'pfn' info-block to be filled with indeterminate data. While the kernel buffer is zeroed on allocation it is immediately overwritten by nd_pfn_validate() filling it with the current contents of the on-media info-block location. For fields like, 'flags' and the 'padding' it potentially means that future implementations can not rely on those fields being zero. In preparation to stop using the 'start_pad' and 'end_trunc' fields for section alignment, arrange for fields that are not explicitly initialized to be guaranteed zero. Bump the minor version to indicate it is safe to assume the 'padding' and 'flags' are zero. Otherwise, this corruption is expected to benign since all other critical fields are explicitly initialized. Note The cc: stable is about spreading this new policy to as many kernels as possible not fixing an issue in those kernels. It is not until the change titled "libnvdimm/pfn: Stop padding pmem namespaces to section alignment" where this improper initialization becomes a problem. So if someone decides to backport "libnvdimm/pfn: Stop padding pmem namespaces to section alignment" (which is not tagged for stable), make sure this pre-requisite is flagged. Link: http://lkml.kernel.org/r/156092356065.979959.6681003754765958296.stgit@dwillia2-desk3.amr.corp.intel.com Fixes: 32ab0a3f5170 ("libnvdimm, pmem: 'struct page' for pmem") Signed-off-by: Dan Williams <dan.j.williams@intel.com> Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> [ppc64] Cc: <stable@vger.kernel.org> Cc: David Hildenbrand <david@redhat.com> Cc: Jane Chu <jane.chu@oracle.com> Cc: Jeff Moyer <jmoyer@redhat.com> Cc: Jérôme Glisse <jglisse@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Logan Gunthorpe <logang@deltatee.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Toshi Kani <toshi.kani@hpe.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Wei Yang <richardw.yang@linux.intel.com> Cc: Jason Gunthorpe <jgg@mellanox.com> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-18 22:58:36 +00:00
/* minor-version-3 guarantee the padding and flags are zero */
/* minor-version-4 record the page size and struct page size */
__le32 page_size;
__le16 page_struct_size;
u8 padding[3994];
__le64 checksum;
};
#endif /* __NVDIMM_PFN_H */