LTP test case dio04 test failed on 32bit kernel running linux next
20191107 kernel.
Linux version 5.4.0-rc6-next-20191107.
diotest4 1 TPASS : Negative Offset
diotest4 2 TPASS : removed
diotest4 3 TPASS : Odd count of read and write
diotest4 4 TPASS : Read beyond the file size
diotest4 5 TPASS : Invalid file descriptor
diotest4 6 TPASS : Out of range file descriptor
diotest4 7 TPASS : Closed file descriptor
diotest4 8 TPASS : removed
diotest4 9 TCONF : diotest4.c:345: Direct I/O on /dev/null is
not supported
diotest4 10 TPASS : read, write to a mmaped file
diotest4 11 TPASS : read, write to an unmapped file
diotest4 12 TPASS : read from file not open for reading
diotest4 13 TPASS : write to file not open for writing
diotest4 14 TPASS : read, write with non-aligned buffer
diotest4 15 TFAIL : diotest4.c:476: read to read-only space.
returns 0: Success
diotest4 16 TFAIL : diotest4.c:180: read, write buffer in read-only space
diotest4 17 TFAIL : diotest4.c:114: read allows nonexistant
space. returns 0: Success
diotest4 18 TFAIL : diotest4.c:129: write allows nonexistant
space.returns -1: Invalid argument
diotest4 19 TFAIL : diotest4.c:180: read, write in non-existant space
diotest4 20 TPASS : read, write for file with O_SYNC
diotest4 0 TINFO : 2/15 test blocks failed
Test results comparison link,
https://qa-reports.linaro.org/lkft/linux-next-oe/tests/ltp-dio-tests/dio04
Test case source link,
https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/io/direct_io/diotest4.c
Test case description:
* NAME
* diotest4.c
*
* DESCRIPTION
* The program generates error conditions and verifies the error
* code generated with the expected error value. The program also
* tests some of the boundary condtions. The size of test file created
* is filesize_in_blocks * 4k.
* Test blocks:
* [1] Negative Offset
* [2] Negative count - removed 08/01/2003 - robbiew
* [3] Odd count of read and write
* [4] Read beyond the file size
* [5] Invalid file descriptor
* [6] Out of range file descriptor
* [7] Closed file descriptor
* [8] Directory read, write - removed 10/7/2002 - plars
* [9] Character device (/dev/null) read, write
* [10] read, write to a mmaped file
* [11] read, write to an unmaped file with munmap
* [12] read from file not open for reading
* [13] write to file not open for writing
* [14] read, write with non-aligned buffer
* [15] read, write buffer in read-only space
* [16] read, write in non-existant space
* [17] read, write for file with O_SYNC
metadata:
git branch: master
git repo: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
git commit: c68c5373c504078cc0e0edc7d5c88b47ca308144
git describe: next-20191107
make_kernelversion: 5.4.0-rc6
kernel-config:
http://snapshots.linaro.org/openembedded/lkft/lkft/sumo/intel-core2-32/lkft/linux-next/641/config
build-location:
http://snapshots.linaro.org/openembedded/lkft/lkft/sumo/intel-core2-32/lkft/linux-next/641
Best regards
Naresh Kamboju
----- Original Message -----
> LTP test case dio04 test failed on 32bit kernel running linux next
> 20191107 kernel.
> Linux version 5.4.0-rc6-next-20191107.
>
> diotest4 1 TPASS : Negative Offset
> diotest4 2 TPASS : removed
> diotest4 3 TPASS : Odd count of read and write
> diotest4 4 TPASS : Read beyond the file size
> diotest4 5 TPASS : Invalid file descriptor
> diotest4 6 TPASS : Out of range file descriptor
> diotest4 7 TPASS : Closed file descriptor
> diotest4 8 TPASS : removed
> diotest4 9 TCONF : diotest4.c:345: Direct I/O on /dev/null is
> not supported
> diotest4 10 TPASS : read, write to a mmaped file
> diotest4 11 TPASS : read, write to an unmapped file
> diotest4 12 TPASS : read from file not open for reading
> diotest4 13 TPASS : write to file not open for writing
> diotest4 14 TPASS : read, write with non-aligned buffer
> diotest4 15 TFAIL : diotest4.c:476: read to read-only space.
> returns 0: Success
> diotest4 16 TFAIL : diotest4.c:180: read, write buffer in read-only
> space
> diotest4 17 TFAIL : diotest4.c:114: read allows nonexistant
> space. returns 0: Success
> diotest4 18 TFAIL : diotest4.c:129: write allows nonexistant
> space.returns -1: Invalid argument
> diotest4 19 TFAIL : diotest4.c:180: read, write in non-existant space
> diotest4 20 TPASS : read, write for file with O_SYNC
> diotest4 0 TINFO : 2/15 test blocks failed
Smaller reproducer for 32-bit system and ext4 is:
openat(AT_FDCWD, "testdata-4.5918", O_RDWR|O_DIRECT) = 4
mmap2(NULL, 4096, PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7f7b000
read(4, 0xb7f7b000, 4096) = 0 // expects -EFAULT
Problem appears to be conversion in ternary operator at
iomap_dio_bio_actor() return. Test passes for me with
following tweak:
diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index 2f88d64c2a4d..8615b1f78389 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -318,7 +318,7 @@ iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length,
if (pad)
iomap_dio_zero(dio, iomap, pos, fs_block_size - pad);
}
- return copied ? copied : ret;
+ return copied ? (loff_t) copied : ret;
}
static loff_t
On Mon, Nov 11, 2019 at 03:19:40AM -0500, Jan Stancek wrote:
> > > loff_t length,
> > > if (pad)
> > > iomap_dio_zero(dio, iomap, pos, fs_block_size -
> > > pad);
> > > }
> > > - return copied ? copied : ret;
> > > + return copied ? (loff_t) copied : ret;
> >
> > I'm a little confused on this proposed fix -- why does casting size_t
> > (aka unsigned long) to loff_t (long long) on a 32-bit system change the
> > test outcome?
>
> Ternary operator has a return type and an attempt is made to convert
> each of operands to the type of the other. So, in this case "ret"
> appears to be converted to type of "copied" first. Both have size of
> 4 bytes on 32-bit x86:
Sounds like we should use a good old if here to avoid that whole problem
spacE:
if (copied)
return copied;
return ret;
> size_t copied = 0;
> int ret = -14;
> long long actor_ret = copied ? copied : ret;
>
> On x86_64: actor_ret == -14;
> On x86 : actor_ret == 4294967282
>
> > Does this same diotest4 failure happen with XFS? I ask
> > because XFS has been using iomap for directio for ages.
>
> Yes, it fails on XFS too.
Is this a new test? If not why was this never reported? Sounds like
we should add this test case to xfstests.
----- Original Message -----
> Is this a new test?
No, it's not new.
> If not why was this never reported? Sounds like
> we should add this test case to xfstests.
I'm guessing not that many users still run 32bit kernels.
Naresh' setup is using ext4, so I assume he noticed only
after recent changes in linux-next wrt. directio and ext4.
Regards,
Jan