diff options
Diffstat (limited to 'util')
| -rw-r--r-- | util/cutils.c | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/util/cutils.c b/util/cutils.c index 77acadc70a..2380165230 100644 --- a/util/cutils.c +++ b/util/cutils.c @@ -164,6 +164,44 @@ int qemu_fdatasync(int fd) #endif } +/** + * Sync changes made to the memory mapped file back to the backing + * storage. For POSIX compliant systems this will fallback + * to regular msync call. Otherwise it will trigger whole file sync + * (including the metadata case there is no support to skip that otherwise) + * + * @addr - start of the memory area to be synced + * @length - length of the are to be synced + * @fd - file descriptor for the file to be synced + * (mandatory only for POSIX non-compliant systems) + */ +int qemu_msync(void *addr, size_t length, int fd) +{ +#ifdef CONFIG_POSIX + size_t align_mask = ~(qemu_real_host_page_size - 1); + + /** + * There are no strict reqs as per the length of mapping + * to be synced. Still the length needs to follow the address + * alignment changes. Additionally - round the size to the multiple + * of PAGE_SIZE + */ + length += ((uintptr_t)addr & (qemu_real_host_page_size - 1)); + length = (length + ~align_mask) & align_mask; + + addr = (void *)((uintptr_t)addr & align_mask); + + return msync(addr, length, MS_SYNC); +#else /* CONFIG_POSIX */ + /** + * Perform the sync based on the file descriptor + * The sync range will most probably be wider than the one + * requested - but it will still get the job done + */ + return qemu_fdatasync(fd); +#endif /* CONFIG_POSIX */ +} + #ifndef _WIN32 /* Sets a specific flag */ int fcntl_setfl(int fd, int flag) |