[U-Boot] [PATCH v4 1/6] fat: write: fix broken write to fragmented files

[Tom Rini]

On Mon, Dec 02, 2019 at 12:11:13PM +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>
> 
> This patch partially fixes the issue revealed by the following test
> script:
> 
> --->8-fat_test1.sh---
> #!/bin/bash
> make sandbox_defconfig
> make
> dd if=/dev/zero of=/tmp/10M.img bs=1024 count=10k
> mkfs.vfat -v /tmp/10M.img
> cat >/tmp/cmds <<EOF
> x
> host bind 0 /tmp/10M.img
> fatls host 0
> mw 0x1000000 0x0a434241 0x1000 # "ABC\n"
> mw 0x1100000 0x0a464544 0x8000 # "DEF\n"

> fatwrite host 0 0x1000000 file0001.raw 0x1000
> fatwrite host 0 0x1000000 file0002.raw 0x1000
> fatwrite host 0 0x1000000 file0003.raw 0x1000
> fatwrite host 0 0x1000000 file0004.raw 0x1000
> fatwrite host 0 0x1000000 file0005.raw 0x1000
> fatrm host 0 file0002.raw
> fatrm host 0 file0004.raw
> fatls host 0
> fatwrite host 0 0x1100000 file0007.raw 0x4000
> fatwrite host 0 0x1100000 file0007.raw 0x4000
> reset
> EOF
> ./u-boot </tmp/cmds
> #verify
> rm -r /tmp/result /tmp/model
> mkdir /tmp/result
> mkdir /tmp/model
> yes ABC | head -c 4096 >/tmp/model/file0001.raw
> yes ABC | head -c 4096 >/tmp/model/file0003.raw
> yes ABC | head -c 4096 >/tmp/model/file0005.raw
> yes DEF | head -c 16384 >/tmp/model/file0007.raw
> mcopy -n -i /tmp/10M.img ::file0001.raw /tmp/result
> mcopy -n -i /tmp/10M.img ::file0003.raw /tmp/result
> mcopy -n -i /tmp/10M.img ::file0005.raw /tmp/result
> mcopy -n -i /tmp/10M.img ::file0007.raw /tmp/result
> hd /tmp/10M.img
> if diff -urq /tmp/model /tmp/result
> then
> 	echo Test okay
> else
> 	echo Test fail
> fi

Applied to u-boot/master, thanks!

-- 
Tom
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