3 files changed, 74 insertions, 10 deletions

diff --git a/fs/Kconfig b/fs/Kconfig
index e9c5b81dd665..e19423a2aa7d 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -1228,6 +1228,14 @@ config JFFS2_FS_WRITEBUFFER
             - NOR flash with transparent ECC
             - DataFlash
 
+config JFFS2_FS_WBUF_VERIFY
+        bool "Verify JFFS2 write-buffer reads"
+        depends on JFFS2_FS_WRITEBUFFER
+        default n
+        help
+          This causes JFFS2 to read back every page written through the
+          write-buffer, and check for errors.
+
 config JFFS2_SUMMARY
         bool "JFFS2 summary support (EXPERIMENTAL)"
         depends on JFFS2_FS && EXPERIMENTAL
diff --git a/fs/jffs2/jffs2_fs_sb.h b/fs/jffs2/jffs2_fs_sb.h
index b13298a824ed..ae99cd7fd43b 100644
--- a/fs/jffs2/jffs2_fs_sb.h
+++ b/fs/jffs2/jffs2_fs_sb.h
@@ -106,6 +106,9 @@ struct jffs2_sb_info {
 
         uint32_t wbuf_pagesize; /* 0 for NOR and other flashes with no wbuf */
 
+#ifdef CONFIG_JFFS2_FS_WBUF_VERIFY
+        unsigned char *wbuf_verify; /* read-back buffer for verification */
+#endif
 #ifdef CONFIG_JFFS2_FS_WRITEBUFFER
         unsigned char *wbuf; /* Write-behind buffer for NAND flash */
         uint32_t wbuf_ofs;
diff --git a/fs/jffs2/wbuf.c b/fs/jffs2/wbuf.c
index 64f8d7add7e8..ec99c8ec83ae 100644
--- a/fs/jffs2/wbuf.c
+++ b/fs/jffs2/wbuf.c
@@ -220,6 +220,47 @@ static struct jffs2_raw_node_ref **jffs2_incore_replace_raw(struct jffs2_sb_info
         return NULL;
 }
 
+#ifdef CONFIG_JFFS2_FS_WBUF_VERIFY
+static int jffs2_verify_write(struct jffs2_sb_info *c, unsigned char *buf,
+                              uint32_t ofs)
+{
+        int ret;
+        size_t retlen;
+        char *eccstr;
+
+        ret = c->mtd->read(c->mtd, ofs, c->wbuf_pagesize, &retlen, c->wbuf_verify);
+        if (ret && ret != -EUCLEAN && ret != -EBADMSG) {
+                printk(KERN_WARNING "jffs2_verify_write(): Read back of page at %08x failed: %d\n", c->wbuf_ofs, ret);
+                return ret;
+        } else if (retlen != c->wbuf_pagesize) {
+                printk(KERN_WARNING "jffs2_verify_write(): Read back of page at %08x gave short read: %zd not %d.\n", ofs, retlen, c->wbuf_pagesize);
+                return -EIO;
+        }
+        if (!memcmp(buf, c->wbuf_verify, c->wbuf_pagesize))
+                return 0;
+
+        if (ret == -EUCLEAN)
+                eccstr = "corrected";
+        else if (ret == -EBADMSG)
+                eccstr = "correction failed";
+        else
+                eccstr = "OK or unused";
+
+        printk(KERN_WARNING "Write verify error (ECC %s) at %08x. Wrote:\n",
+               eccstr, c->wbuf_ofs);
+        print_hex_dump(KERN_WARNING, "", DUMP_PREFIX_OFFSET, 16, 1,
+                       c->wbuf, c->wbuf_pagesize, 0);
+
+        printk(KERN_WARNING "Read back:\n");
+        print_hex_dump(KERN_WARNING, "", DUMP_PREFIX_OFFSET, 16, 1,
+                       c->wbuf_verify, c->wbuf_pagesize, 0);
+
+        return -EIO;
+}
+#else
+#define jffs2_verify_write(c,b,o) (0)
+#endif
+
 /* Recover from failure to write wbuf. Recover the nodes up to the
  * wbuf, not the one which we were starting to try to write. */
 
@@ -380,7 +421,7 @@ static void jffs2_wbuf_recover(struct jffs2_sb_info *c)
                         ret = c->mtd->write(c->mtd, ofs, towrite, &retlen,
                                             rewrite_buf);
 
-                if (ret || retlen != towrite) {
+                if (ret || retlen != towrite || jffs2_verify_write(c, rewrite_buf, ofs)) {
                         /* Argh. We tried. Really we did. */
                         printk(KERN_CRIT "Recovery of wbuf failed due to a second write error\n");
                         kfree(buf);
@@ -587,15 +628,16 @@ static int __jffs2_flush_wbuf(struct jffs2_sb_info *c, int pad)
 
                 ret = c->mtd->write(c->mtd, c->wbuf_ofs, c->wbuf_pagesize, &retlen, c->wbuf);
 
-        if (ret || retlen != c->wbuf_pagesize) {
-                if (ret)
-                        printk(KERN_WARNING "jffs2_flush_wbuf(): Write failed with %d\n",ret);
-                else {
-                        printk(KERN_WARNING "jffs2_flush_wbuf(): Write was short: %zd instead of %d\n",
-                                retlen, c->wbuf_pagesize);
-                        ret = -EIO;
-                }
-
+        if (ret) {
+                printk(KERN_WARNING "jffs2_flush_wbuf(): Write failed with %d\n", ret);
+                goto wfail;
+        } else if (retlen != c->wbuf_pagesize) {
+                printk(KERN_WARNING "jffs2_flush_wbuf(): Write was short: %zd instead of %d\n",
+                       retlen, c->wbuf_pagesize);
+                ret = -EIO;
+                goto wfail;
+        } else if ((ret = jffs2_verify_write(c, c->wbuf, c->wbuf_ofs))) {
+        wfail:
                 jffs2_wbuf_recover(c);
 
                 return ret;
@@ -1138,11 +1180,22 @@ int jffs2_nand_flash_setup(struct jffs2_sb_info *c)
                 return -ENOMEM;
         }
 
+#ifdef CONFIG_JFFS2_FS_WBUF_VERIFY
+        c->wbuf_verify = kmalloc(c->wbuf_pagesize, GFP_KERNEL);
+        if (!c->wbuf_verify) {
+                kfree(c->oobbuf);
+                kfree(c->wbuf);
+                return -ENOMEM;
+        }
+#endif
         return 0;
 }
 
 void jffs2_nand_flash_cleanup(struct jffs2_sb_info *c)
 {
+#ifdef CONFIG_JFFS2_FS_WBUF_VERIFY
+        kfree(c->wbuf_verify);
+#endif
         kfree(c->wbuf);
         kfree(c->oobbuf);
 }