Re: [U-Boot] [PATCH v3 1/6] fat: write: fix broken write to fragmented files

On Tue, Nov 26, 2019 at 09:15:07AM +0100, Marek Szyprowski wrote:

The code for handing file overwrite incorrectly assumed that the file on disk is always contiguous. This resulted in corrupting disk structure every time when write to existing fragmented file happened. Fix this by adding proper check for cluster discontinuity and adjust chunk size on each partial write.

Signed-off-by: Marek Szyprowski m.szyprowski@samsung.com Reviewed-by: Oleksandr Suvorov oleksandr.suvorov@toradex.com Reviewed-by: Lukasz Majewski lukma@denx.de

---

fs/fat/fat_write.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/fat/fat_write.c b/fs/fat/fat_write.c index 729cf39630..6cfa5b4565 100644 --- a/fs/fat/fat_write.c +++ b/fs/fat/fat_write.c @@ -794,6 +794,8 @@ set_contents(fsdata *mydata, dir_entry *dentptr, loff_t pos, __u8 *buffer,

	newclust = get_fatent(mydata, endclust);

• 	if ((newclust - 1) != endclust)
  

• 		break;
  if (IS_LAST_CLUST(newclust, mydata->fatsize))
  	break;
  if (CHECK_CLUST(newclust, mydata->fatsize)) {
  

@@ -811,7 +813,7 @@ set_contents(fsdata *mydata, dir_entry *dentptr, loff_t pos, __u8 *buffer, offset = 0; else offset = pos - cur_pos;

• wsize = min(cur_pos + actsize, filesize) - pos;
  

• wsize = min_t(unsigned long long, actsize, filesize - cur_pos);
  

  if (get_set_cluster(mydata, curclust, offset, buffer, wsize, &actsize)) { printf("Error get-and-setting cluster\n");

@@ -824,8 +826,6 @@ set_contents(fsdata *mydata, dir_entry *dentptr, loff_t pos, __u8 *buffer, if (filesize <= cur_pos) break;

• /* CHECK: newclust = get_fatent(mydata, endclust); */
  

• if (IS_LAST_CLUST(newclust, mydata->fatsize)) /* no more clusters */ break;

Adding in Heinrich and Akashi-san for more review on this, thanks!