OpenE2K
/
linux
6
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

iomap: fix return value of iomap_dio_bio_actor on 32bit systems 

[ Upstream commit e9f930ac88 ]

Naresh reported LTP diotest4 failing for 32bit x86 and arm -next
kernels on ext4. Same problem exists in 5.4-rc7 on xfs.

The failure comes down to:
  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 is conversion at iomap_dio_bio_actor() return. Ternary
operator has a return type and an attempt is made to convert each
of operands to the type of the other. In this case "ret" (int)
is converted to type of "copied" (unsigned long). Both have size
of 4 bytes:
    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

Replace ternary operator with 2 return statements to avoid this
unwanted conversion.

Fixes: 4721a60109 ("iomap: dio data corruption and spurious errors when pipes fill")
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Jan Stancek <jstancek@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Jan Stancek 2019-11-11 12:58:24 -08:00 committed by Greg Kroah-Hartman
parent 1558fadfca
commit 185563ec11
1 changed files with 3 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
fs/iomap/direct-io.c
View File

@ -318,7 +318,9 @@ zero_tail:
if (pad)
iomap_dio_zero(dio, iomap, pos, fs_block_size - pad);
}
return copied ? copied : ret;
if (copied)
return copied;
return ret;
}
static loff_t