From 89b259eeaa0f4ad3fa89cbe500da9335536e20ee Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Wed, 7 Feb 2018 16:38:05 +0100 Subject: file-posix: Fix no-op bdrv_truncate() with falloc preallocation If bdrv_truncate() is called, but the requested size is the same as before, don't call posix_fallocate(), which returns -EINVAL for length zero and would therefore make bdrv_truncate() fail. The problem can be triggered by creating a zero-sized raw image with 'falloc' preallocation mode. Signed-off-by: Kevin Wolf Reviewed-by: Max Reitz Reviewed-by: Eric Blake --- block/file-posix.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) (limited to 'block/file-posix.c') diff --git a/block/file-posix.c b/block/file-posix.c index fbc21a9921..d7fb772c14 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -1686,11 +1686,15 @@ static int raw_regular_truncate(int fd, int64_t offset, PreallocMode prealloc, * file systems that do not support fallocate(), trying to check if a * block is allocated before allocating it, so don't do that here. */ - result = -posix_fallocate(fd, current_length, offset - current_length); - if (result != 0) { - /* posix_fallocate() doesn't set errno. */ - error_setg_errno(errp, -result, - "Could not preallocate new data"); + if (offset != current_length) { + result = -posix_fallocate(fd, current_length, offset - current_length); + if (result != 0) { + /* posix_fallocate() doesn't set errno. */ + error_setg_errno(errp, -result, + "Could not preallocate new data"); + } + } else { + result = 0; } goto out; #endif -- cgit v1.2.1