[U-Boot] [PATCH v1] fs: fat: dynamically allocate memory for temporary buffer

[Stefan Agner]

From: Stefan Agner <stefan.agner at toradex.com>

Drop the statically allocated get_contents_vfatname_block and
dynamically allocate a buffer only if required. This saves
64KiB of memory.

Signed-off-by: Stefan Agner <stefan.agner at toradex.com>
---

 fs/fat/fat.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/fs/fat/fat.c b/fs/fat/fat.c
index 4bc3030ab8..06bcd02835 100644
--- a/fs/fat/fat.c
+++ b/fs/fat/fat.c
@@ -305,9 +305,6 @@ get_cluster(fsdata *mydata, __u32 clustnum, __u8 *buffer, unsigned long size)
  * into 'buffer'.
  * Update the number of bytes read in *gotsize or return -1 on fatal errors.
  */
-__u8 get_contents_vfatname_block[MAX_CLUSTSIZE]
-	__aligned(ARCH_DMA_MINALIGN);
-
 static int get_contents(fsdata *mydata, dir_entry *dentptr, loff_t pos,
 			__u8 *buffer, loff_t maxsize, loff_t *gotsize)
 {
@@ -318,7 +315,7 @@ static int get_contents(fsdata *mydata, dir_entry *dentptr, loff_t pos,
 	loff_t actsize;
 
 	*gotsize = 0;
-	debug("Filesize: %llu bytes\n", filesize);
+	debug("Filesize: %llu bytes, starting at pos %llu\n", filesize, pos);
 
 	if (pos >= filesize) {
 		debug("Read position past EOF: %llu\n", pos);
@@ -350,15 +347,26 @@ static int get_contents(fsdata *mydata, dir_entry *dentptr, loff_t pos,
 
 	/* align to beginning of next cluster if any */
 	if (pos) {
+		__u8 *tmp_buffer;
+
+		tmp_buffer = malloc_cache_aligned(MAX_CLUSTSIZE);
+		if (tmp_buffer == NULL) {
+			debug("Error: allocating buffer\n");
+			return -1;
+		}
+
 		actsize = min(filesize, (loff_t)bytesperclust);
-		if (get_cluster(mydata, curclust, get_contents_vfatname_block,
+		if (get_cluster(mydata, curclust, tmp_buffer,
 				(int)actsize) != 0) {
 			printf("Error reading cluster\n");
+			free(tmp_buffer);
 			return -1;
 		}
 		filesize -= actsize;
 		actsize -= pos;
-		memcpy(buffer, get_contents_vfatname_block + pos, actsize);
+		memcpy(tmp_buffer, buffer + pos, actsize);
+		free(tmp_buffer);
+
 		*gotsize += actsize;
 		if (!filesize)
 			return 0;
-- 
2.19.2