From e9f930ac88a8936ccc2d021110c98810cf5aa810 Mon Sep 17 00:00:00 2001 From: Jan Stancek Date: Mon, 11 Nov 2019 12:58:24 -0800 Subject: [PATCH] iomap: fix return value of iomap_dio_bio_actor on 32bit systems 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 Signed-off-by: Jan Stancek Reviewed-by: Christoph Hellwig Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong --- 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 2f88d64c2a4d..b77ec2acb066 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