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 <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
master
Kevin Wolf 2018-02-07 16:38:05 +01:00
parent 4906da7e4d
commit 89b259eeaa
1 changed files with 9 additions and 5 deletions

View File

@ -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