lkml.org 
[lkml]   [2024]   [Jan]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH v2 00/16] block atomic writes
From

>
>>> I think this still needs a check if the fs needs alignment for
>>> atomic writes at all. i.e.
>>>
>>> struct statx statx;
>>> struct fsxattr fsxattr;
>>> int fd = open('/foofile', O_RDWR | O_DIRECT);
>>>
>>> ioctl(fd, FS_IOC_GETXATTR, &fsxattr);
>>> statx(fd, "", AT_EMPTY_PATH, STATX_ALL | STATX_WRITE_ATOMIC, &statx);
>>> if (statx.stx_atomic_write_unit_max < 16384) {
>>> bailout();
>>> }
>>
>> How could this value be >= 16384 initially? Would it be from pre-configured
>> FS alignment, like XFS RT extsize? Or is this from some special CoW-based
>> atomic write support? Or FS block size of 16384?
>
> Sorry, this check should not be here at all, we should only check it
> later.
>
>> Incidentally, for consistency only setting FS_XFLAG_WRITE_ATOMIC will lead
>> to FMODE_CAN_ATOMIC_WRITE being set. So until FS_XFLAG_WRITE_ATOMIC is set
>> would it make sense to have statx return 0 for STATX_WRITE_ATOMIC.
>
> True. We might need to report the limits even without that, though.

Could we just error the SETXATTR ioctl when FS_XFLAG_FORCEALIGN is not
set (and it is required)? The problem is that ioctl reports -EINVAL for
any such errors, so hard for the user to know the issue...

Thanks,
John


\
 
 \ /
  Last update: 2024-01-11 17:14    [W:0.148 / U:0.556 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site