From: Jan Stancek jstancek@redhat.com
[ Upstream commit e9f930ac88a8936ccc2d021110c98810cf5aa810 ]
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: 4721a6010990 ("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 --- fs/iomap/direct-io.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c index fd46ec83cb04..7b5f76efef02 100644 --- a/fs/iomap/direct-io.c +++ b/fs/iomap/direct-io.c @@ -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