mmap's offset must be aligned to page size or mapping will fail. mmap-based safezero is only used if posix_fallocate isn't available. Signed-off-by: Oskari Saarenmaa <os@ohmu.fi> --- src/util/virfile.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/src/util/virfile.c b/src/util/virfile.c index 20ca89f..16f8101 100644 --- a/src/util/virfile.c +++ b/src/util/virfile.c @@ -1038,9 +1038,16 @@ safezero(int fd, off_t offset, off_t len) int safezero(int fd, off_t offset, off_t len) { + static long pagemask = 0; + off_t map_skip; int r; char *buf; + /* align offset and length, rounding offset down and length up */ + if (pagemask == 0) + pagemask = ~(sysconf(_SC_PAGESIZE) - 1); + map_skip = offset - (offset & pagemask); + /* memset wants the mmap'ed file to be present on disk so create a * sparse file */ @@ -1048,12 +1055,13 @@ safezero(int fd, off_t offset, off_t len) if (r < 0) return -1; - buf = mmap(NULL, len, PROT_READ | PROT_WRITE, MAP_SHARED, fd, offset); + buf = mmap(NULL, len + map_skip, PROT_READ | PROT_WRITE, MAP_SHARED, + fd, offset - map_skip); if (buf == MAP_FAILED) return -1; - memset(buf, 0, len); - munmap(buf, len); + memset(buf + map_skip, 0, len); + munmap(buf, len + map_skip); return 0; } -- 1.8.3.1