From e9f930ac88a8936ccc2d021110c98810cf5aa810 Mon Sep 17 00:00:00 2001
From: Jan Stancek <jstancek@redhat.com>
Date: Mon, 11 Nov 2019 12:58:24 -0800
Subject: [PATCH] iomap: fix return value of iomap_dio_bio_actor on 32bit
systems
Git-commit: e9f930ac88a8936ccc2d021110c98810cf5aa810
Patch-mainline: v5.5-rc1
References: bsc#1158455
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>
Acked-by: Jan Kara <jack@suse.cz>
---
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 @@ 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;
+ if (copied)
+ return copied;
+ return ret;
}
static loff_t
--
2.16.4