From 2ab8ecbe62cf4d558a0e37f1c8cc283ab5f7b199 Mon Sep 17 00:00:00 2001 From: Dmitry Monakhov Date: Mon, 29 Feb 2016 10:46:42 +1100 Subject: [PATCH] xfs_io: Prevent devide by zero from {pread,pwrite}_random Math is wrong if range requested is less or equals to block size xfs_io -c 'pwrite -b 4k 8k 4k -R' \ -c 'pread -b 4k 4k 4k -R' -f file Signed-off-by: Dmitry Monakhov Reviewed-by: Dave Chinner Signed-off-by: Dave Chinner --- io/pread.c | 6 +++++- io/pwrite.c | 6 +++++- 2 files changed, 10 insertions(+), 2 deletions(-) diff --git a/io/pread.c b/io/pread.c index f16c86c1a..b98355f5b 100644 --- a/io/pread.c +++ b/io/pread.c @@ -245,7 +245,11 @@ read_random( *total = 0; while (count > 0) { - off = ((offset + (random() % range)) / buffersize) * buffersize; + if (range) + off = ((offset + (random() % range)) / buffersize) * + buffersize; + else + off = offset; bytes = do_pread(fd, off, buffersize, buffersize); if (bytes == 0) break; diff --git a/io/pwrite.c b/io/pwrite.c index 4fc8de63c..67631ce58 100644 --- a/io/pwrite.c +++ b/io/pwrite.c @@ -128,7 +128,11 @@ write_random( *total = 0; while (count > 0) { - off = ((offset + (random() % range)) / buffersize) * buffersize; + if (range) + off = ((offset + (random() % range)) / buffersize) * + buffersize; + else + off = offset; bytes = do_pwrite(file->fd, off, buffersize, buffersize); if (bytes == 0) break; -- 2.47.2