Commit 89b259ee authored by Kevin Wolf's avatar Kevin Wolf
Browse files

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: default avatarKevin Wolf <kwolf@redhat.com>
Reviewed-by: default avatarMax Reitz <mreitz@redhat.com>
Reviewed-by: default avatarEric Blake <eblake@redhat.com>
parent 4906da7e

block/file-posix.c

+9 −5
Original line number Diff line number Diff line
@@ -1686,12 +1686,16 @@ 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.

         */

        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

    case PREALLOC_MODE_FULL: