[LTP] [PATCH] lapi/fs.h: Replace MAX_LFS_FILESIZE constant with own implementation

[Yang Xu <xuyang2018.jy@cn.fujitsu.com>]

on 2019/08/21 15:27, Li Wang wrote:

> On Tue, Aug 20, 2019 at 5:10 PM Yang Xu<xuyang2018.jy@cn.fujitsu.com>  wrote:
> ...
>>> But I don't understand why to define MAX_OFF as (MAX_LEN - MIN_OFF),
>>> the failure indicates that not to write at a position past the maximum
>>> allowed offset. Shouldn't we give a dst_off large than
>>> MAX_LFS_FILESIZE?
>> Yes, we should use a dst_off large than MAX_LFS_FILESIZE because it used pos to compare
>> in kernel code as below:
>>
>> mm/filemap.c
>>    static int generic_write_check_limits(struct file *file, loff_t pos, loff_t *count)
>> ...
>> if (unlikely(pos>= max_size))
>>     return -EFBIG;
>> ...
>>
>> I strace xfstest generic/564 code( I follow this test code to ltp), as below:
>> #max_off=$((8 * 2**60 - 65536 - 1))
>> #min_off=65537
>> #xfs_io -f -c "pwrite -S 0x61 0 128k" file
>> #touch copy
>> #strace xfs_io -c "copy_range -l $min_off -s 0 -d $max_off file" copy
>> ....
>>    openat(AT_FDCWD, "file", O_RDONLY)      = 4
>>    copy_file_range(4, [0], 3, [9223372036854710271], 65537, 0) = 65536
>>    copy_file_range(4, [65536], 3, [9223372036854775807], 1, 0) = -1 EFBIG (File too large)
>> ....
>>
>> xfsprogs used a loop to call copy_file_range, and get EFBIG when pos greater than LLONG_MAX.
>>
>> I think we should  use tst_max_lfs_filesize instead of (tst_max_lfs_filesize -MIN_OFF)
>> and this case will pass whether xfs,btrfs and ext4.
> Good job, Xu. I think you can format a new patch to fix this problem.
> Because Petr's patch is used for solving the cross-compiling issue and
> looks good.
Hi Li

OK. I will send a new patch to fix this problem. But copy_file_range02.c still has a problem as Murphy found,
we set all_filesystem but use the same tmpdir instead of mntpoint.  I think we can remove all_filesystem and mountpoint.

@Murphy Zhou  Hi Murphy, would you like to send a new patch to remove useless all_filesystem or I do it in my
new patch by adding your signed-off-by tag? What do you think about it?

> @Petr Vorel Hi Petr, what do you think? any more comments?
>