From 7a2f70495aebdb605ffc1a623cd3e867136c22cf Mon Sep 17 00:00:00 2001
From: Gregory Nutt <gnutt@nuttx.org>
Date: Wed, 26 Sep 2018 20:00:25 -0600
Subject: [PATCH] fs/spiffs:  Fix yet another interface with NuttX MTD.  This
 time, the calculation of the number of whole blocks.

---
 fs/spiffs/src/spiffs_mtd.c | 36 ++++++++++++++++++++++++++++++++----
 1 file changed, 32 insertions(+), 4 deletions(-)

diff --git a/fs/spiffs/src/spiffs_mtd.c b/fs/spiffs/src/spiffs_mtd.c
index f3ada51c35..69bafb10d6 100644
--- a/fs/spiffs/src/spiffs_mtd.c
+++ b/fs/spiffs/src/spiffs_mtd.c
@@ -118,6 +118,9 @@ ssize_t spiffs_mtd_write(FAR struct spiffs_s *fs, off_t offset, size_t len,
       blkstart  = offset / blksize;
       blkend    = (offset + len - 1) / blksize;
 
+      finfo("blkoffset=%lu blkstart=%ld blkend=%ld\n",
+            blkoffset, blkstart, blkend);
+
       /* Check if we have to do a read-modify-write on the first block.  We
        * need to do this if the blkoffset is not zero.  In that case we need
        * write only the data at the end of the block.
@@ -163,8 +166,19 @@ ssize_t spiffs_mtd_write(FAR struct spiffs_s *fs, off_t offset, size_t len,
 
       /* Write all intervening complete blocks... all at once */
 
-      nblocks = blkend - blkstart + 1;
-      if (nblocks > 0 && remaining >= blksize)
+      nblocks = blkend - blkstart;
+      if (remaining > 0 && (remaining & blkmask) == 0)
+        {
+          /* The final block is a complete transfer */
+
+          nblocks++;
+        }
+
+      finfo("Whole blocks=%d blkstart=%lu remaining=%lu\n",
+            nblocks, (unsigned long)blkstart,
+            (unsigned long)remaining);
+
+      if (nblocks > 0)
         {
           ret = MTD_BWRITE(fs->mtd, blkstart, nblocks, src);
           if (ret < 0)
@@ -271,6 +285,9 @@ ssize_t spiffs_mtd_read(FAR struct spiffs_s *fs, off_t offset, size_t len,
       blkstart  = offset / blksize;
       blkend    = (offset + len - 1) / blksize;
 
+      finfo("blkoffset=%lu blkstart=%ld blkend=%ld\n",
+            blkoffset, blkstart, blkend);
+
       /* Check if we have to do a partial read on the first block.  We
        * need to do this if the blkoffset is not zero.  In that case we need
        * read only the data at the end of the block.
@@ -307,8 +324,19 @@ ssize_t spiffs_mtd_read(FAR struct spiffs_s *fs, off_t offset, size_t len,
 
       /* Read all intervening complete blocks... all at once */
 
-      nblocks = blkend - blkstart + 1;
-      if (nblocks > 0 && remaining >= blksize)
+      nblocks = blkend - blkstart;
+      if (remaining > 0 && (remaining & blkmask) == 0)
+        {
+          /* The final block is a complete transfer */
+
+          nblocks++;
+        }
+
+      finfo("Whole blocks=%d blkstart=%lu remaining=%lu\n",
+            nblocks, (unsigned long)blkstart,
+            (unsigned long)remaining);
+
+      if (nblocks > 0)
         {
           ret = MTD_BREAD(fs->mtd, blkstart, nblocks, dest);
           if (ret < 0)