fs: fat: write to non-cluster-aligned root directory

With the commit below, fat now correctly handles a file read under
a non-cluster-aligned root directory of fat12/16.
Write operation should be fixed in the same manner.

Fixes: commit 9b18358dc05d ("fs: fat: fix reading non-cluster-aligned
       root directory")
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Anssi Hannula <anssi.hannula@bitwise.fi>
Tested-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

diff --git a/fs/fat/fat_write.c b/fs/fat/fat_write.c
index 2a74199236d8398575beb8dd833bbca3ba4c84fd..11b85d35eded4a55b55b475d3a77f09d5a639a97 100644 (file)
--- a/fs/fat/fat_write.c
+++ b/fs/fat/fat_write.c
@@ -388,29 +388,23 @@ static __u32 determine_fatent(fsdata *mydata, __u32 entry)
 }
 
 /**
- * set_cluster() - write data to cluster
+ * set_sectors() - write data to sectors
  *
- * Write 'size' bytes from 'buffer' into the specified cluster.
+ * Write 'size' bytes from 'buffer' into the specified sector.
  *
  * @mydata:    data to be written
- * @clustnum:  cluster to be written to
+ * @startsect: sector to be written to
  * @buffer:    data to be written
  * @size:      bytes to be written (but not more than the size of a cluster)
  * Return:     0 on success, -1 otherwise
  */
 static int
-set_cluster(fsdata *mydata, u32 clustnum, u8 *buffer, u32 size)
+set_sectors(fsdata *mydata, u32 startsect, u8 *buffer, u32 size)
 {
-       u32 idx = 0;
-       u32 startsect;
+       u32 nsects = 0;
        int ret;
 
-       if (clustnum > 0)
-               startsect = clust_to_sect(mydata, clustnum);
-       else
-               startsect = mydata->rootdir_sect;
-
-       debug("clustnum: %d, startsect: %d\n", clustnum, startsect);
+       debug("startsect: %d\n", startsect);
 
        if ((unsigned long)buffer & (ARCH_DMA_MINALIGN - 1)) {
                ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size);
@@ -429,17 +423,16 @@ set_cluster(fsdata *mydata, u32 clustnum, u8 *buffer, u32 size)
                        size -= mydata->sect_size;
                }
        } else if (size >= mydata->sect_size) {
-               idx = size / mydata->sect_size;
-               ret = disk_write(startsect, idx, buffer);
-               if (ret != idx) {
+               nsects = size / mydata->sect_size;
+               ret = disk_write(startsect, nsects, buffer);
+               if (ret != nsects) {
                        debug("Error writing data (got %d)\n", ret);
                        return -1;
                }
 
-               startsect += idx;
-               idx *= mydata->sect_size;
-               buffer += idx;
-               size -= idx;
+               startsect += nsects;
+               buffer += nsects * mydata->sect_size;
+               size -= nsects * mydata->sect_size;
        }
 
        if (size) {
@@ -457,6 +450,44 @@ set_cluster(fsdata *mydata, u32 clustnum, u8 *buffer, u32 size)
        return 0;
 }
 
+/**
+ * set_cluster() - write data to cluster
+ *
+ * Write 'size' bytes from 'buffer' into the specified cluster.
+ *
+ * @mydata:    data to be written
+ * @clustnum:  cluster to be written to
+ * @buffer:    data to be written
+ * @size:      bytes to be written (but not more than the size of a cluster)
+ * Return:     0 on success, -1 otherwise
+ */
+static int
+set_cluster(fsdata *mydata, u32 clustnum, u8 *buffer, u32 size)
+{
+       return set_sectors(mydata, clust_to_sect(mydata, clustnum),
+                          buffer, size);
+}
+
+static int
+flush_dir(fat_itr *itr)
+{
+       fsdata *mydata = itr->fsdata;
+       u32 startsect, sect_offset, nsects;
+
+       if (!itr->is_root || mydata->fatsize == 32)
+               return set_cluster(mydata, itr->clust, itr->block,
+                                  mydata->clust_size * mydata->sect_size);
+
+       sect_offset = itr->clust * mydata->clust_size;
+       startsect = mydata->rootdir_sect + sect_offset;
+       /* do not write past the end of rootdir */
+       nsects = min_t(u32, mydata->clust_size,
+                      mydata->rootdir_size - sect_offset);
+
+       return set_sectors(mydata, startsect, itr->block,
+                          nsects * mydata->sect_size);
+}
+
 static __u8 tmpbuf_cluster[MAX_CLUSTSIZE] __aligned(ARCH_DMA_MINALIGN);
 
 /*
@@ -1163,8 +1194,7 @@ int file_fat_write_at(const char *filename, loff_t pos, void *buffer,
        }
 
        /* Write directory table to device */
-       ret = set_cluster(mydata, itr->clust, itr->block,
-                         mydata->clust_size * mydata->sect_size);
+       ret = flush_dir(itr);
        if (ret) {
                printf("Error: writing directory entry\n");
                ret = -EIO;
@@ -1241,8 +1271,7 @@ static int delete_dentry(fat_itr *itr)
        memset(dentptr, 0, sizeof(*dentptr));
        dentptr->name[0] = 0xe5;
 
-       if (set_cluster(mydata, itr->clust, itr->block,
-                       mydata->clust_size * mydata->sect_size) != 0) {
+       if (flush_dir(itr)) {
                printf("error: writing directory entry\n");
                return -EIO;
        }
@@ -1444,8 +1473,7 @@ int fat_mkdir(const char *new_dirname)
        }
 
        /* Write directory table to device */
-       ret = set_cluster(mydata, itr->clust, itr->block,
-                         mydata->clust_size * mydata->sect_size);
+       ret = flush_dir(itr);
        if (ret)
                printf("Error: writing directory entry\n");