This pull requests contains fixes for two critical bugs in UBI and UBIFS:

1. Fixes the possibility of losing data upon a power cut when UBI tries
    to recover from a write error.
 2. Fixes page migration on UBIFS. It turned out that the default page
    migration function is not suitable for UBIFS.
 -----BEGIN PGP SIGNATURE-----
 Version: GnuPG v2
 
 iQIcBAABAgAGBQJXa5tEAAoJEEtJtSqsAOnW090P/RcQjIfVf2g3r8VRp38OQPbb
 MTd4sD/rnyt5Eq0QYUPWG5xcYK2BWI1PwpdB81JvW5hxnXPgG8DpVIxjzt/7Xgnp
 QheYe9tMfgYjDntz1rzGVa/uHSAldP9V4czgczrBW/0lwnRsZ6mLY1RA9Oz0hRdG
 cp53I8CSD0DPyqU0XkgzLkzVUstmySwQ5i46C0kQEnlRcytReOLgcjSrXXn+/Zih
 yZxhtDQSCKmQAfVmERggPXVHo8jFtVfej52ja7RFcMA2uXvXqljOBNCyLUYPdYka
 XdQEKsXRLl69ktFUXwZwPAYAW23I8+PMpsoljHDVc0hF25p8omp3D+7HE18SsMSv
 6RNnUwz+PDbiFApyoTu0SBgHN/OO9o6rjNNoRIInoKpk0NvWmrMQOo6BIFsX4yq1
 0dOVJiKXVoFuo75Yw9mOKdrV/Z5P1TvgdTBj6g03aUM9vcX1Gz6+1xKkvcXGgh02
 8qFDZdZ5L87TlpMkvtWO87Ir0ssrfjxpvxR8pPsxxqvxbfUuVmss4ILuh9AVSVk+
 d1zrz30+JZzTbIrky/7R31i6Bx2+reYdTKiPIkST9sF5WblUPSeyUoKq1OlNRYxj
 n+0Q8S5Tm/6AHXUOQFxurbXU+D7G7TaL/CsBeepvV/AqJb07+vBxUuGFH1rDbmLB
 r5dTfOXn3iNEmmNyrhgN
 =EDeX
 -----END PGP SIGNATURE-----

Merge tag 'upstream-4.7-rc5' of git://git.infradead.org/linux-ubifs

Pull UBI/UBIFS fixes from Richard Weinberger:
 "This contains fixes for two critical bugs in UBI and UBIFS:

   - fix the possibility of losing data upon a power cut when UBI tries
     to recover from a write error

   - fix page migration on UBIFS.  It turned out that the default page
     migration function is not suitable for UBIFS"

* tag 'upstream-4.7-rc5' of git://git.infradead.org/linux-ubifs:
  UBIFS: Implement ->migratepage()
  mm: Export migrate_page_move_mapping and migrate_page_copy
  ubi: Make recover_peb power cut aware
  gpio: make library immune to error pointers
  gpio: make sure gpiod_to_irq() returns negative on NULL desc
  gpio: 104-idi-48: Fix missing spin_lock_init for ack_lock

drivers/mtd/ubi/eba.c

@@ -575,6 +575,7 @@ static int recover_peb(struct ubi_device *ubi, int pnum, int vol_id, int lnum,
 	int err, idx = vol_id2idx(ubi, vol_id), new_pnum, data_size, tries = 0;
 	struct ubi_volume *vol = ubi->volumes[idx];
 	struct ubi_vid_hdr *vid_hdr;
+	uint32_t crc;
 
 	vid_hdr = ubi_zalloc_vid_hdr(ubi, GFP_NOFS);
 	if (!vid_hdr)
@@ -599,14 +600,8 @@ static int recover_peb(struct ubi_device *ubi, int pnum, int vol_id, int lnum,
 		goto out_put;
 	}
 
-	vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
+	ubi_assert(vid_hdr->vol_type == UBI_VID_DYNAMIC);
-	err = ubi_io_write_vid_hdr(ubi, new_pnum, vid_hdr);
-	if (err) {
-		up_read(&ubi->fm_eba_sem);
-		goto write_error;
-	}
 
-	data_size = offset + len;
 	mutex_lock(&ubi->buf_mutex);
 	memset(ubi->peb_buf + offset, 0xFF, len);
 
@@ -621,6 +616,19 @@ static int recover_peb(struct ubi_device *ubi, int pnum, int vol_id, int lnum,
 
 	memcpy(ubi->peb_buf + offset, buf, len);
 
+	data_size = offset + len;
+	crc = crc32(UBI_CRC32_INIT, ubi->peb_buf, data_size);
+	vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
+	vid_hdr->copy_flag = 1;
+	vid_hdr->data_size = cpu_to_be32(data_size);
+	vid_hdr->data_crc = cpu_to_be32(crc);
+	err = ubi_io_write_vid_hdr(ubi, new_pnum, vid_hdr);
+	if (err) {
+		mutex_unlock(&ubi->buf_mutex);
+		up_read(&ubi->fm_eba_sem);
+		goto write_error;
+	}
+
 	err = ubi_io_write_data(ubi, ubi->peb_buf, new_pnum, 0, data_size);
 	if (err) {
 		mutex_unlock(&ubi->buf_mutex);

fs/ubifs/file.c

@@ -52,6 +52,7 @@
 #include "ubifs.h"
 #include <linux/mount.h>
 #include <linux/slab.h>
+#include <linux/migrate.h>
 
 static int read_block(struct inode *inode, void *addr, unsigned int block,
 		      struct ubifs_data_node *dn)
@@ -1452,6 +1453,26 @@ static int ubifs_set_page_dirty(struct page *page)
 	return ret;
 }
 
+#ifdef CONFIG_MIGRATION
+static int ubifs_migrate_page(struct address_space *mapping,
+		struct page *newpage, struct page *page, enum migrate_mode mode)
+{
+	int rc;
+
+	rc = migrate_page_move_mapping(mapping, newpage, page, NULL, mode, 0);
+	if (rc != MIGRATEPAGE_SUCCESS)
+		return rc;
+
+	if (PagePrivate(page)) {
+		ClearPagePrivate(page);
+		SetPagePrivate(newpage);
+	}
+
+	migrate_page_copy(newpage, page);
+	return MIGRATEPAGE_SUCCESS;
+}
+#endif
+
 static int ubifs_releasepage(struct page *page, gfp_t unused_gfp_flags)
 {
 	/*
@@ -1591,6 +1612,9 @@ const struct address_space_operations ubifs_file_address_operations = {
 	.write_end      = ubifs_write_end,
 	.invalidatepage = ubifs_invalidatepage,
 	.set_page_dirty = ubifs_set_page_dirty,
+#ifdef CONFIG_MIGRATION
+	.migratepage	= ubifs_migrate_page,
+#endif
 	.releasepage    = ubifs_releasepage,
 };
 

mm/migrate.c

@@ -431,6 +431,7 @@ int migrate_page_move_mapping(struct address_space *mapping,
 
 	return MIGRATEPAGE_SUCCESS;
 }
+EXPORT_SYMBOL(migrate_page_move_mapping);
 
 /*
  * The expected number of remaining references is the same as that
@@ -586,6 +587,7 @@ void migrate_page_copy(struct page *newpage, struct page *page)
 
 	mem_cgroup_migrate(page, newpage);
 }
+EXPORT_SYMBOL(migrate_page_copy);
 
 /************************************************************
  *                    Migration functions