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

On 06.12.2018 14:58, Stefan Agner wrote:

From: Stefan Agner stefan.agner@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@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);
  

I somehow managed to mix up copy direction here. Will send a v2.

-- Stefan

• free(tmp_buffer);
  

• *gotsize += actsize; if (!filesize) return 0;