fs/fat: Do not write unmodified fat entries to disk

[u-boot] / fs / fat / fat_write.c

diff --git a/fs/fat/fat_write.c b/fs/fat/fat_write.c
index 961ccd8e24643e6f626551de0e3356e8a4489957..babe9c8dd025eff59f9ee226d278ec000662c883 100644 (file)
--- a/fs/fat/fat_write.c
+++ b/fs/fat/fat_write.c
@@ -104,13 +104,19 @@ static __u8 num_of_fats;
 /*
  * Write fat buffer into block device
  */
-static int flush_fat_buffer(fsdata *mydata)
+static int flush_dirty_fat_buffer(fsdata *mydata)
 {
        int getsize = FATBUFBLOCKS;
        __u32 fatlength = mydata->fatlength;
        __u8 *bufptr = mydata->fatbuf;
        __u32 startblock = mydata->fatbufnum * FATBUFBLOCKS;
 
+       debug("debug: evicting %d, dirty: %d\n", mydata->fatbufnum,
+             (int)mydata->fat_dirty);
+
+       if ((!mydata->fat_dirty) || (mydata->fatbufnum == -1))
+               return 0;
+
        startblock += mydata->fat_sect;
 
        if (getsize > fatlength)
@@ -130,6 +136,7 @@ static int flush_fat_buffer(fsdata *mydata)
                        return -1;
                }
        }
+       mydata->fat_dirty = 0;
 
        return 0;
 }
@@ -186,10 +193,8 @@ static __u32 get_fatent_value(fsdata *mydata, __u32 entry)
                startblock += mydata->fat_sect; /* Offset from start of disk */
 
                /* Write back the fatbuf to the disk */
-               if (mydata->fatbufnum != -1) {
-                       if (flush_fat_buffer(mydata) < 0)
-                               return -1;
-               }
+               if (flush_dirty_fat_buffer(mydata) < 0)
+                       return -1;
 
                if (disk_read(startblock, getsize, bufptr) < 0) {
                        debug("Error reading FAT blocks\n");
@@ -494,10 +499,8 @@ static int set_fatent_value(fsdata *mydata, __u32 entry, __u32 entry_value)
                if (getsize > fatlength)
                        getsize = fatlength;
 
-               if (mydata->fatbufnum != -1) {
-                       if (flush_fat_buffer(mydata) < 0)
-                               return -1;
-               }
+               if (flush_dirty_fat_buffer(mydata) < 0)
+                       return -1;
 
                if (disk_read(startblock, getsize, bufptr) < 0) {
                        debug("Error reading FAT blocks\n");
@@ -506,6 +509,9 @@ static int set_fatent_value(fsdata *mydata, __u32 entry, __u32 entry_value)
                mydata->fatbufnum = bufnum;
        }
 
+       /* Mark as dirty */
+       mydata->fat_dirty = 1;
+
        /* Set the actual entry */
        switch (mydata->fatsize) {
        case 32:
@@ -645,7 +651,7 @@ static void flush_dir_table(fsdata *mydata, dir_entry **dentptr)
 
        dir_curclust = dir_newclust;
 
-       if (flush_fat_buffer(mydata) < 0)
+       if (flush_dirty_fat_buffer(mydata) < 0)
                return;
 
        memset(get_dentfromdir_block, 0x00,
@@ -675,7 +681,7 @@ static int clear_fatent(fsdata *mydata, __u32 entry)
        }
 
        /* Flush fat buffer */
-       if (flush_fat_buffer(mydata) < 0)
+       if (flush_dirty_fat_buffer(mydata) < 0)
                return -1;
 
        return 0;
@@ -1011,6 +1017,7 @@ static int do_fat_write(const char *filename, void *buffer, loff_t size,
        }
 
        mydata->fatbufnum = -1;
+       mydata->fat_dirty = 0;
        mydata->fatbuf = memalign(ARCH_DMA_MINALIGN, FATBUFSIZE);
        if (mydata->fatbuf == NULL) {
                debug("Error: allocating memory\n");
@@ -1111,7 +1118,7 @@ static int do_fat_write(const char *filename, void *buffer, loff_t size,
        debug("attempt to write 0x%llx bytes\n", *actwrite);
 
        /* Flush fat buffer */
-       ret = flush_fat_buffer(mydata);
+       ret = flush_dirty_fat_buffer(mydata);
        if (ret) {
                printf("Error: flush fat buffer\n");
                goto exit;