[U-Boot] [PATCH] fs: fat: handle deleted directory entries correctly

[Tom Rini <trini@konsulko.com>]

On Tue, Nov 26, 2019 at 05:29:31PM +0900, AKASHI Takahiro wrote:

> Unlink test for FAT file system seems to fail at test_unlink2.
> (When I added this test, I haven't seen any errors though.)
> for example,
> ===8<===
> fs_obj_unlink = ['fat', '/home/akashi/tmp/uboot_sandbox_test/128MB.fat32.img']
> 
>     def test_unlink2(self, u_boot_console, fs_obj_unlink):
>         """
>         Test Case 2 - delete many files
>         """
>         fs_type,fs_img = fs_obj_unlink
>         with u_boot_console.log.section('Test Case 2 - unlink (many)'):
>             output = u_boot_console.run_command('host bind 0 %s' % fs_img)
> 
>             for i in range(0, 20):
>                 output = u_boot_console.run_command_list([
>                     '%srm host 0:0 dir2/0123456789abcdef%02x' % (fs_type, i),
>                     '%sls host 0:0 dir2/0123456789abcdef%02x' % (fs_type, i)])
>                 assert('' == ''.join(output))
> 
>             output = u_boot_console.run_command(
>                 '%sls host 0:0 dir2' % fs_type)
> >           assert('0 file(s), 2 dir(s)' in output)
> E           AssertionError: assert '0 file(s), 2 dir(s)' in '            ./\r\r\n            ../\r\r\n        0   0123456789abcdef11\r\r\n\r\r\n1 file(s), 2 dir(s)'
> 
> test/py/tests/test_fs/test_unlink.py:52: AssertionError
> ===>8===
> 
> This can happen when fat_itr_next() wrongly detects an already-
> deleted directory entry.
> 
> File deletion, which was added in the commit f8240ce95d64 ("fs: fat:
> support unlink"), is implemented by marking its entry for a short name
> with DELETED_FLAG, but related entry slots for a long file name are kept
> unmodified. (So entries will never be actually deleted from media.)
> 
> To handle this case correctly, an additional check for a directory slot
> will be needed in fat_itr_next().
> 
> In addition, I added extra comments about long file name and short file
> name format in FAT file system. Although they are not directly related
> to the issue, I hope it will be helpful for better understandings
> in general.
> 
> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>

Applied to u-boot/master, thanks!

-- 
Tom
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