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

[AKASHI Takahiro]

Thank you for the heads-up.

On Tue, Nov 26, 2019 at 11:57:29AM -0500, Tom Rini wrote:
> 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 at samsung.com>
> > Reviewed-by: Oleksandr Suvorov <oleksandr.suvorov at toradex.com>
> > Reviewed-by: Lukasz Majewski <lukma at 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)

"newclust != (endclust + 1)" would be more intuitive?
But it's just my preference.

> > +				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);

This hunk is not directly related to the issue, is it?

> >  		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!

Otherwise, it looks good.
Reviewed-by: AKASHI Takahiro <takahiro.akashi at linaro.org>


> -- 
> Tom