[PATCH 3/6] jffs2: add write verification to direct page writes in flash_writev

[zhouminqiang]

jffs2_flash_writev() performs writes in three phases: phase 1 fills
the write buffer and flushes it when full, phase 2 writes full pages
directly via mtd_write() bypassing the buffer, and phase 3 fills the
remaining data into the write buffer.

Phases 1 and 3 both invoke __jffs2_flush_wbuf() when the buffer is
full, which includes write-back verification when
CONFIG_JFFS2_FS_WBUF_VERIFY is enabled. However phase 2, which
handles the bulk of the write data, calls mtd_write() directly
without any verification.

Phase 2 direct writes may span multiple wbuf_pagesize pages. Extend
jffs2_verify_write() with a len parameter to specify the data length
to verify, and add the verification call after the phase 2
mtd_write() to cover this gap.

Signed-off-by: zhouminqiang <zhouminqiang2 at huawei.com>
---
 fs/jffs2/wbuf.c | 33 ++++++++++++++++++++-------------
 1 file changed, 20 insertions(+), 13 deletions(-)

diff --git a/fs/jffs2/wbuf.c b/fs/jffs2/wbuf.c
index da6da813a4ef..3e99587f40e4 100644
--- a/fs/jffs2/wbuf.c
+++ b/fs/jffs2/wbuf.c
@@ -229,33 +229,33 @@ static struct jffs2_raw_node_ref **jffs2_incore_replace_raw(struct jffs2_sb_info
 
 #ifdef CONFIG_JFFS2_FS_WBUF_VERIFY
 static int jffs2_verify_write(struct jffs2_sb_info *c, unsigned char *buf,
-			      uint32_t ofs)
+			      uint32_t ofs, size_t len)
 {
 	int ret = 0;
 	size_t retlen, i;
 	char *eccstr;
 	void *verify_buf;
 
-	verify_buf = __vmalloc(c->wbuf_pagesize, GFP_NOFS);
+	verify_buf = __vmalloc(len, GFP_NOFS);
 	if (!verify_buf) {
 		pr_warn("%s(): verify buffer allocation failed, skipping verification\n",
 			__func__);
 		return 0;
 	}
 
-	ret = mtd_read(c->mtd, ofs, c->wbuf_pagesize, &retlen, verify_buf);
+	ret = mtd_read(c->mtd, ofs, len, &retlen, verify_buf);
 	if (ret && ret != -EUCLEAN && ret != -EBADMSG) {
 		pr_warn("%s(): Read back of page at %08x failed: %d\n",
 			__func__, ofs, ret);
 		goto out_free;
-	} else if (retlen != c->wbuf_pagesize) {
-		pr_warn("%s(): Read back of page at %08x gave short read: %zu not %d\n",
-			__func__, ofs, retlen, c->wbuf_pagesize);
+	} else if (retlen != len) {
+		pr_warn("%s(): Read back of page at %08x gave short read: %zu not %zu\n",
+			__func__, ofs, retlen, len);
 		ret = -EIO;
 		goto out_free;
 	}
 
-	for (i = 0; i < c->wbuf_pagesize; i++) {
+	for (i = 0; i < len; i++) {
 		uint8_t c1 = ((uint8_t *)buf)[i];
 		uint8_t c2 = ((uint8_t *)verify_buf)[i];
 		int dump_len;
@@ -270,9 +270,9 @@ static int jffs2_verify_write(struct jffs2_sb_info *c, unsigned char *buf,
 		else
 			eccstr = "OK or unused";
 
-		dump_len = min_t(int, 128, c->wbuf_pagesize - i);
-		pr_warn("Write verify error (ECC %s) at %08x (+%zu/%d). Wrote:\n",
-			eccstr, ofs, i, c->wbuf_pagesize);
+		dump_len = min_t(int, 128, len - i);
+		pr_warn("Write verify error (ECC %s) at %08x (+%zu/%zu). Wrote:\n",
+			eccstr, ofs, i, len);
 		print_hex_dump(KERN_WARNING, "", DUMP_PREFIX_OFFSET, 16, 1,
 			       buf + i, dump_len, 0);
 
@@ -292,7 +292,7 @@ static int jffs2_verify_write(struct jffs2_sb_info *c, unsigned char *buf,
 	return ret;
 }
 #else
-#define jffs2_verify_write(c,b,o) (0)
+#define jffs2_verify_write(c,b,o,l) (0)
 #endif
 
 /* Recover from failure to write wbuf. Recover the nodes up to the
@@ -455,7 +455,7 @@ static void jffs2_wbuf_recover(struct jffs2_sb_info *c)
 			ret = mtd_write(c->mtd, ofs, towrite, &retlen,
 					rewrite_buf);
 
-		if (ret || retlen != towrite || jffs2_verify_write(c, rewrite_buf, ofs)) {
+		if (ret || retlen != towrite || jffs2_verify_write(c, rewrite_buf, ofs, towrite)) {
 			/* Argh. We tried. Really we did. */
 			pr_crit("Recovery of wbuf failed due to a second write error\n");
 			kfree(buf);
@@ -672,7 +672,10 @@ static int __jffs2_flush_wbuf(struct jffs2_sb_info *c, int pad)
 			retlen, c->wbuf_pagesize);
 		ret = -EIO;
 		goto wfail;
-	} else if ((ret = jffs2_verify_write(c, c->wbuf, c->wbuf_ofs))) {
+	}
+
+	ret = jffs2_verify_write(c, c->wbuf, c->wbuf_ofs, c->wbuf_pagesize);
+	if (ret) {
 	wfail:
 		jffs2_wbuf_recover(c);
 
@@ -904,6 +907,10 @@ int jffs2_flash_writev(struct jffs2_sb_info *c, const struct kvec *invecs,
 			if (ret < 0 || wbuf_retlen != PAGE_DIV(vlen))
 				goto outfile;
 
+			ret = jffs2_verify_write(c, v, outvec_to, PAGE_DIV(vlen));
+			if (ret)
+				goto outfile;
+
 			vlen -= wbuf_retlen;
 			outvec_to += wbuf_retlen;
 			c->wbuf_ofs = outvec_to;
-- 
2.52.0