[U-Boot] [PATCH] fs: fat: read: fix fat16 ls/read issue
Simon Glass
sjg at chromium.org
Thu Dec 18 14:14:34 CET 2014
Hi Przemyslaw,
On 18 December 2014 at 03:26, Przemyslaw Marczak <p.marczak at samsung.com> wrote:
> Hello Simon,
>
>
> On 12/18/2014 04:39 AM, Simon Glass wrote:
>>
>> Hi Przemyslaw,
>>
>> On 17 December 2014 at 02:03, Przemyslaw Marczak <p.marczak at samsung.com>
>> wrote:
>>>
>>> Hello,
>>>
>>>
>>> On 12/16/2014 11:26 PM, Simon Glass wrote:
>>>>
>>>>
>>>> Hi Przemyslaw,
>>>>
>>>> On 12 December 2014 at 08:30, Przemyslaw Marczak <p.marczak at samsung.com>
>>>> wrote:
>>>>>
>>>>>
>>>>> Hello,
>>>>>
>>>>>
>>>>> On 12/12/2014 01:32 AM, Simon Glass wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>> Hi Przemyslaw,
>>>>>>
>>>>>> On 11 December 2014 at 05:01, Przemyslaw Marczak
>>>>>> <p.marczak at samsung.com>
>>>>>> wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> The present fat implementation ignores FAT16 long name
>>>>>>> directory entries which aren't placed in a single sector.
>>>>>>>
>>>>>>> This was becouse of the buffer was always filled by the
>>>>>>> two sectors, and the loop was made also for two sectors.
>>>>>>>
>>>>>>> If some file long name entries are stored in two sectors,
>>>>>>> the we have two cases:
>>>>>>>
>>>>>>> Case 1:
>>>>>>> Both of sectors are in the buffer - all required data
>>>>>>> for long file name is in the buffer.
>>>>>>> - Read OK!
>>>>>>>
>>>>>>> Case 2:
>>>>>>> The current directory entry is placed at the end of the
>>>>>>> second buffered sector. And the next entries are placed
>>>>>>> in a sector which is not buffered yet. Then two next
>>>>>>> sectors are buffered and the mentioned entry is ignored.
>>>>>>> - Read fail!
>>>>>>>
>>>>>>> This commit fixes this issue by:
>>>>>>> - read two sectors after loop on each single is done
>>>>>>> - keep the last used sector as a first in the buffer
>>>>>>> before the read of two next
>>>>>>>
>>>>>>> The commit doesn't affects the fat32 imlementation,
>>>>>>> which works good as previous.
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> This is very interesting\! Is this the same failure that I saw on this
>>>>>> thread?
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> http://u-boot.10912.n7.nabble.com/PATCH-U-Boot-ARM-rpi-b-detect-board-revision-td196720.html
>>>>>>
>>>>>> (search for fatload)
>>>>>>
>>>>>> "I tried this out. It worked OK for me except that it can't find the
>>>>>> device tree file bcm2835-rpi-b-rev2.dtb.
>>>>>>
>>>>>> Oddly I can fatload it from /bcm2835-rpi-b-rev2.dtb but when I try
>>>>>> from /syslinux/..//bcm2835-rpi-b-rev2.dtb it fails and cannot find the
>>>>>> file. Reducing the filename length to 8 chars works. I wonder what
>>>>>> year of my life FAT will stop plaguing me? "
>>>>>>
>>>>>>
>>>>>> Also can you write a test for this in test/fs/fs-test.sh?
>>>>>>
>>>>>> Regards,
>>>>>> Simon
>>>>>>
>>>>>> [snip]
>>>>>>
>>>>>
>>>>> Probably this is an another case which is caused by the sector buffer
>>>>> bug.
>>>>> Does this patch fixed your issue?
>>>>>
>>>>> I have some simple test for manual use with the ums tool.
>>>>> It just copy the test files to the tested fat16 partition mounted using
>>>>> the
>>>>> UMS, next it computes CRC32 of those files on the host and next using
>>>>> U-Boot
>>>>> fatload/crc32 commands - it tests the read feature. But it's not full
>>>>> automated - I didn't work on getting the log from U-Boot console.
>>>>>
>>>>> So I could check if the file checksums are proper and if all files were
>>>>> found on the partiion, by the U-Boot read command. It's not useful for
>>>>> the
>>>>> "test/fs/fs-test.sh" because this is not designed for the sandbox.
>>>>> My test writes some commands directly to U-Boot console, like this:
>>>>> echo
>>>>> "some cmd" > /dev/ttyS0.
>>>>>
>>>>> Unfortunately the sandbox config seems to be broken.
>>>>>
>>>>> The bug was not so obvious, any read/write on fat partition can change
>>>>> fat
>>>>> directory entries or add the new ones and then all data can be read
>>>>> right.
>>>>>
>>>>> I will send the scripts for such simple test.
>>>>
>>>>
>>>>
>>>> I'm not sure if it fixes my problem but it seems likely. I will see if
>>>> I can make time to test it.
>>>>
>>>> If you want to write input data to U-Boot sandbox we can do that
>>>> fairly easily. You can import cros_subprocess and use the function
>>>> there to generate output from your test and inspect the input from
>>>> U-Boot's command line. Let me know if you'd like an example.
>>>>
>>>> Regards,
>>>> Simon
>>>>
>>>
>>> Before, I wrote, that sandbox seems to be broken, sorry for this - it was
>>> just my dirty repo - sandbox compiles and works well.
>>
>>
>> Somewhat bewildering, but it does not in fact fix my problem.
>>
>> Here is a compressed version of the fat filesystem if you want to take a
>> look:
>>
>>
>> https://drive.google.com/file/d/0B7WYZbZ9zd-3NGRMNkFQQTdtV2M/view?usp=sharing
>>
>> Regards,
>> Simon
>>
>
> I had put this image on my Trats2 device on partition mmc 0:6 using ums and
> dd linux command. Next I put latest mainline u-boot, commit:
> e3bf81b1e841ecabe7c8b3d48621256db8b8623e : "Merge branch 'master' of
> git://git.denx.de/u-boot-mpc85xx"
>
> So this is the version with the fat bug. But I can see and load the file:
> "bcm2835-rpi-b-rev2.dtb".
>
> Trats2 # fatls mmc 0:6
> 17840 bootcode.bin
> 120 cmdline.txt
> 1331 config.txt
> 6115 fixup.dat
> 2324 fixup_cd.dat
> 9166 fixup_x.dat
> 3232856 kernel.img
> 2615064 start.elf
> 533080 start_cd.elf
> 3572200 start_x.elf
> 137 issue.txt
> 18974 license.oracle
> 295524 u-boot.bin
> 1331 config.txt~
> extlinux/
> 3368648 zimage
> 3963 bcm2835-rpi-b.dtb
> 3963 bcm2835.dtb
> 3963 bcm2835-rpi-b-rev2.dtb
>
> 18 file(s), 1 dir(s)
>
> Trats2 # fatload mmc 0:6 0x40000000 bcm2835-rpi-b-rev2.dtb
> reading bcm2835-rpi-b-rev2.dtb
> 3963 bytes read in 5 ms (773.4 KiB/s)
> Trats2 # crc32 0x40000000 0xf7b
> CRC32 for 40000000 ... 40000f7a ==> c36ee8db
> Trats2 #
>
> The only missing file is "boot.scr", it's ignored by "ls" command but can be
> loaded...
>
> Trats2 # fatload mmc 0:6 0x40000000 boot.scr
> reading boot.scr
> 256 bytes read in 2 ms (125 KiB/s)
> Trats2 # crc32 0x40000000 0x100
> CRC32 for 40000000 ... 400000ff ==> dc5c79b3
>
> I suppose that the partition image which you shared for me is little
> different, than this mentioned in the topic "[PATCH U-Boot] ARM: rpi_b:
> detect board revision"
>
> Probably the sequence of writing files to this partition was different, and
> the different file is ignored.
>
> After putting the debug macro on the top of fs/fat/fat.c:
>
> Trats2 # fatls mmc 0:6
> VFAT Support enabled
> FAT16, fat_sect: 16, fatlength: 32
> Rootdir begins at cluster: 0, sector: 80, offset: a000
> Data begins at: 80
> Sector size: 512, cluster size: 16
> FAT read sect=80, clust_size=16, DIRENTSPERBLOCK=16
> 17840 bootcode.bin
> 120 cmdline.txt
> 1331 config.txt
> 6115 fixup.dat
> 2324 fixup_cd.dat
> 9166 fixup_x.dat
> 3232856 kernel.img
> 2615064 start.elf
> END LOOP: j=0 clust_size=16
> 533080 start_cd.elf
> 3572200 start_x.elf
> 137 issue.txt
> 18974 license.oracle
> 295524 u-boot.bin
> 1331 config.txt~
> END LOOP: j=1 clust_size=16
> FAT read sect=82, clust_size=16, DIRENTSPERBLOCK=16
> extlinux/
> 3368648 zimage
> 3963 bcm2835-rpi-b.dtb
> 3963 bcm2835.dtb
> 3963 bcm2835-rpi-b-rev2.dtb
> END LOOP: j=0 clust_size=16
> RootDentname == NULL - 0
>
> 18 file(s), 1 dir(s)
>
> And next test on commit 9b416a9f4ca7cf5ac4d5f7143d67edde7f7d7326 with my fat
> patch.
>
> Trats2 # fatls mmc 0:6
> 17840 bootcode.bin
> 120 cmdline.txt
> 1331 config.txt
> 6115 fixup.dat
> 2324 fixup_cd.dat
> 9166 fixup_x.dat
> 3232856 kernel.img
> 2615064 start.elf
> 533080 start_cd.elf
> 3572200 start_x.elf
> 137 issue.txt
> 18974 license.oracle
> 295524 u-boot.bin
> 1331 config.txt~
> 256 boot.scr
> extlinux/
> 3368648 zimage
> 3963 bcm2835-rpi-b.dtb
> 3963 bcm2835.dtb
> 3963 bcm2835-rpi-b-rev2.dtb
>
> 19 file(s), 1 dir(s)
>
> Trats2 # fatload mmc 0:6 0x40000000 bcm2835-rpi-b-rev2.dtb
> reading bcm2835-rpi-b-rev2.dtb
> 3963 bytes read in 5 ms (773.4 KiB/s)
> Trats2 # crc32 0x40000000 0xf7b
> CRC32 for 40000000 ... 40000f7a ==> c36ee8db
> Trats2 # fatload mmc 0:6 0x40000000 boot.scr
> reading boot.scr
> 256 bytes read in 2 ms (125 KiB/s)
> Trats2 # crc32 0x40000000 0x100
> CRC32 for 40000000 ... 400000ff ==> dc5c79b3
>
> So the only difference on this image is, that with my patch, the file
> "boot.scr" ignored by ls command is now visible - but in both cases it can
> be loaded into memory and the crc is correct.
>
> After enabling the debug:
>
> Trats2 # fatls mmc 0:6
> VFAT Support enabled
> FAT16, fat_sect: 16, fatlength: 32
> Rootdir begins at cluster: 0, sector: 80, offset: a000
> Data begins at: 80
> Sector size: 512, cluster size: 16
> FAT read sect=80, clust_size=16, DIRENTSPERBLOCK=16
> 17840 bootcode.bin
> 120 cmdline.txt
> 1331 config.txt
> 6115 fixup.dat
> 2324 fixup_cd.dat
> 9166 fixup_x.dat
> 3232856 kernel.img
> 2615064 start.elf
> END LOOP: j=0 clust_size=16
> FAT read sect=81, clust_size=16, DIRENTSPERBLOCK=16
> 533080 start_cd.elf
> 3572200 start_x.elf
> 137 issue.txt
> 18974 license.oracle
> 295524 u-boot.bin
> 1331 config.txt~
> 256 boot.scr
> END LOOP: j=1 clust_size=16
> FAT read sect=82, clust_size=16, DIRENTSPERBLOCK=16
> extlinux/
> 3368648 zimage
> 3963 bcm2835-rpi-b.dtb
> 3963 bcm2835.dtb
> 3963 bcm2835-rpi-b-rev2.dtb
> END LOOP: j=0 clust_size=16
> FAT read sect=83, clust_size=16, DIRENTSPERBLOCK=16
> RootDentname == NULL - 0
>
> 19 file(s), 1 dir(s)
>
> So as I checked the file:
> 256 boot.scr
> is next behind to the:
> 1331 config.txt~
>
> And this can be checked with hex dump:
> hd -s 0xa400 -n 512 bad-fat.dd
>
> Your fat image is good example of what my patch fixes.
>
> As you can see on the simple debug info, without the fix,the sector 80 and
> 81 is stored in the buffer (there are always 2 sectors in the buffer). If
> you see the hex dump of the second sector:
>
> hd -s 0xa200 -n 512 bad-fat.dd
>
> You will see that at the end of this sector, there is a long name entry for
> file "boot.scr".
>
> In the next loop (without the fix):
> END LOOP: j=1 clust_size=16
> FAT read sect=82, clust_size=16, DIRENTSPERBLOCK=16
> extlinux/
> the sector 82 and 83 is loaded in to the buffer, so the long name entry of
> "boot.scr" file from the end of sector 81 is now in the heaven, and the file
> will be ignored by the ls command.
>
> The sector 82 can be checked by:
> hd -s 0xa400 -n 512 bad-fat.dd
>
> It begins with the short name entry of file "boot.scr".
>
> After applying my fix, there are always three sectors in the buffer, because
> the last one is moved into the buffer begin and two next are loaded into the
> buffer next to the last one.
> And the buffer pointer is always on the second buffered sector beside first
> loop.
>
> So I think this patch fixes the issue well.
>
> Could you describe your issue more precisely?
I think you left out the path. The file I tried to load was:
/syslinux/..//bcm2835-rpi-b-rev2.dtb
It works OK without the path on the front.
Regards,
Simon
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