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file-posix: Make .bdrv_co_truncate asynchronous
This moves the code to resize an image file to the thread pool to avoid blocking. Creating large images with preallocation with blockdev-create is now actually a background job instead of blocking the monitor (and most other things) until the preallocation has completed. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Kevin Wolf
parent
1bc5f09f2e
commit
93f4e2ff4b
@ -188,8 +188,16 @@ typedef struct RawPosixAIOData {
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#define aio_ioctl_cmd aio_nbytes /* for QEMU_AIO_IOCTL */
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off_t aio_offset;
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int aio_type;
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union {
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struct {
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int aio_fd2;
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off_t aio_offset2;
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};
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struct {
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PreallocMode prealloc;
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Error **errp;
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};
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};
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} RawPosixAIOData;
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#if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
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@ -1539,6 +1547,122 @@ static ssize_t handle_aiocb_discard(RawPosixAIOData *aiocb)
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return ret;
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}
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static int handle_aiocb_truncate(RawPosixAIOData *aiocb)
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{
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int result = 0;
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int64_t current_length = 0;
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char *buf = NULL;
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struct stat st;
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int fd = aiocb->aio_fildes;
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int64_t offset = aiocb->aio_offset;
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Error **errp = aiocb->errp;
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if (fstat(fd, &st) < 0) {
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result = -errno;
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error_setg_errno(errp, -result, "Could not stat file");
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return result;
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}
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current_length = st.st_size;
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if (current_length > offset && aiocb->prealloc != PREALLOC_MODE_OFF) {
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error_setg(errp, "Cannot use preallocation for shrinking files");
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return -ENOTSUP;
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}
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switch (aiocb->prealloc) {
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#ifdef CONFIG_POSIX_FALLOCATE
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case PREALLOC_MODE_FALLOC:
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/*
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* Truncating before posix_fallocate() makes it about twice slower on
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* file systems that do not support fallocate(), trying to check if a
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* block is allocated before allocating it, so don't do that here.
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*/
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if (offset != current_length) {
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result = -posix_fallocate(fd, current_length,
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offset - current_length);
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if (result != 0) {
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/* posix_fallocate() doesn't set errno. */
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error_setg_errno(errp, -result,
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"Could not preallocate new data");
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}
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} else {
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result = 0;
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}
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goto out;
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#endif
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case PREALLOC_MODE_FULL:
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{
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int64_t num = 0, left = offset - current_length;
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off_t seek_result;
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/*
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* Knowing the final size from the beginning could allow the file
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* system driver to do less allocations and possibly avoid
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* fragmentation of the file.
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*/
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if (ftruncate(fd, offset) != 0) {
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result = -errno;
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error_setg_errno(errp, -result, "Could not resize file");
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goto out;
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}
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buf = g_malloc0(65536);
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seek_result = lseek(fd, current_length, SEEK_SET);
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if (seek_result < 0) {
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result = -errno;
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error_setg_errno(errp, -result,
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"Failed to seek to the old end of file");
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goto out;
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}
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while (left > 0) {
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num = MIN(left, 65536);
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result = write(fd, buf, num);
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if (result < 0) {
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result = -errno;
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error_setg_errno(errp, -result,
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"Could not write zeros for preallocation");
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goto out;
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}
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left -= result;
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}
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if (result >= 0) {
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result = fsync(fd);
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if (result < 0) {
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result = -errno;
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error_setg_errno(errp, -result,
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"Could not flush file to disk");
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goto out;
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}
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}
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goto out;
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}
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case PREALLOC_MODE_OFF:
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if (ftruncate(fd, offset) != 0) {
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result = -errno;
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error_setg_errno(errp, -result, "Could not resize file");
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}
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return result;
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default:
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result = -ENOTSUP;
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error_setg(errp, "Unsupported preallocation mode: %s",
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PreallocMode_str(aiocb->prealloc));
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return result;
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}
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out:
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if (result < 0) {
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if (ftruncate(fd, current_length) < 0) {
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error_report("Failed to restore old file length: %s",
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strerror(errno));
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}
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}
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g_free(buf);
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return result;
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}
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static int aio_worker(void *arg)
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{
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RawPosixAIOData *aiocb = arg;
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@ -1582,6 +1706,9 @@ static int aio_worker(void *arg)
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case QEMU_AIO_COPY_RANGE:
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ret = handle_aiocb_copy_range(aiocb);
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break;
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case QEMU_AIO_TRUNCATE:
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ret = handle_aiocb_truncate(aiocb);
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break;
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default:
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fprintf(stderr, "invalid aio request (0x%x)\n", aiocb->aio_type);
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ret = -EINVAL;
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@ -1765,117 +1892,25 @@ static void raw_close(BlockDriverState *bs)
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*
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* Returns: 0 on success, -errno on failure.
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*/
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static int raw_regular_truncate(int fd, int64_t offset, PreallocMode prealloc,
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Error **errp)
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static int coroutine_fn
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raw_regular_truncate(BlockDriverState *bs, int fd, int64_t offset,
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PreallocMode prealloc, Error **errp)
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{
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int result = 0;
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int64_t current_length = 0;
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char *buf = NULL;
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struct stat st;
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RawPosixAIOData *acb = g_new(RawPosixAIOData, 1);
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ThreadPool *pool;
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if (fstat(fd, &st) < 0) {
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result = -errno;
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error_setg_errno(errp, -result, "Could not stat file");
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return result;
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}
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*acb = (RawPosixAIOData) {
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.bs = bs,
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.aio_fildes = fd,
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.aio_type = QEMU_AIO_TRUNCATE,
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.aio_offset = offset,
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.prealloc = prealloc,
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.errp = errp,
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};
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current_length = st.st_size;
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if (current_length > offset && prealloc != PREALLOC_MODE_OFF) {
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error_setg(errp, "Cannot use preallocation for shrinking files");
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return -ENOTSUP;
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}
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switch (prealloc) {
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#ifdef CONFIG_POSIX_FALLOCATE
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case PREALLOC_MODE_FALLOC:
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/*
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* Truncating before posix_fallocate() makes it about twice slower on
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* file systems that do not support fallocate(), trying to check if a
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* block is allocated before allocating it, so don't do that here.
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*/
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if (offset != current_length) {
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result = -posix_fallocate(fd, current_length, offset - current_length);
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if (result != 0) {
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/* posix_fallocate() doesn't set errno. */
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error_setg_errno(errp, -result,
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"Could not preallocate new data");
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}
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} else {
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result = 0;
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}
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goto out;
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#endif
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case PREALLOC_MODE_FULL:
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{
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int64_t num = 0, left = offset - current_length;
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off_t seek_result;
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/*
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* Knowing the final size from the beginning could allow the file
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* system driver to do less allocations and possibly avoid
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* fragmentation of the file.
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*/
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if (ftruncate(fd, offset) != 0) {
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result = -errno;
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error_setg_errno(errp, -result, "Could not resize file");
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goto out;
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}
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buf = g_malloc0(65536);
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seek_result = lseek(fd, current_length, SEEK_SET);
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if (seek_result < 0) {
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result = -errno;
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error_setg_errno(errp, -result,
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"Failed to seek to the old end of file");
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goto out;
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}
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while (left > 0) {
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num = MIN(left, 65536);
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result = write(fd, buf, num);
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if (result < 0) {
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result = -errno;
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error_setg_errno(errp, -result,
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"Could not write zeros for preallocation");
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goto out;
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}
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left -= result;
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}
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if (result >= 0) {
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result = fsync(fd);
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if (result < 0) {
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result = -errno;
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error_setg_errno(errp, -result,
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"Could not flush file to disk");
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goto out;
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}
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}
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goto out;
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}
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case PREALLOC_MODE_OFF:
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if (ftruncate(fd, offset) != 0) {
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result = -errno;
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error_setg_errno(errp, -result, "Could not resize file");
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}
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return result;
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default:
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result = -ENOTSUP;
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error_setg(errp, "Unsupported preallocation mode: %s",
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PreallocMode_str(prealloc));
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return result;
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}
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out:
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if (result < 0) {
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if (ftruncate(fd, current_length) < 0) {
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error_report("Failed to restore old file length: %s",
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strerror(errno));
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}
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}
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g_free(buf);
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return result;
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/* @bs can be NULL, bdrv_get_aio_context() returns the main context then */
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pool = aio_get_thread_pool(bdrv_get_aio_context(bs));
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return thread_pool_submit_co(pool, aio_worker, acb);
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}
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static int coroutine_fn raw_co_truncate(BlockDriverState *bs, int64_t offset,
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@ -1892,7 +1927,7 @@ static int coroutine_fn raw_co_truncate(BlockDriverState *bs, int64_t offset,
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}
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if (S_ISREG(st.st_mode)) {
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return raw_regular_truncate(s->fd, offset, prealloc, errp);
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return raw_regular_truncate(bs, s->fd, offset, prealloc, errp);
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}
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if (prealloc != PREALLOC_MODE_OFF) {
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@ -2094,7 +2129,8 @@ static int64_t raw_get_allocated_file_size(BlockDriverState *bs)
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return (int64_t)st.st_blocks * 512;
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}
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static int raw_co_create(BlockdevCreateOptions *options, Error **errp)
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static int coroutine_fn
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raw_co_create(BlockdevCreateOptions *options, Error **errp)
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{
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BlockdevCreateOptionsFile *file_opts;
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int fd;
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@ -2146,7 +2182,7 @@ static int raw_co_create(BlockdevCreateOptions *options, Error **errp)
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}
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/* Clear the file by truncating it to 0 */
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result = raw_regular_truncate(fd, 0, PREALLOC_MODE_OFF, errp);
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result = raw_regular_truncate(NULL, fd, 0, PREALLOC_MODE_OFF, errp);
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if (result < 0) {
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goto out_close;
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}
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@ -2168,8 +2204,8 @@ static int raw_co_create(BlockdevCreateOptions *options, Error **errp)
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/* Resize and potentially preallocate the file to the desired
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* final size */
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result = raw_regular_truncate(fd, file_opts->size, file_opts->preallocation,
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errp);
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result = raw_regular_truncate(NULL, fd, file_opts->size,
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file_opts->preallocation, errp);
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if (result < 0) {
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goto out_close;
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}
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@ -26,6 +26,7 @@
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#define QEMU_AIO_DISCARD 0x0010
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#define QEMU_AIO_WRITE_ZEROES 0x0020
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#define QEMU_AIO_COPY_RANGE 0x0040
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#define QEMU_AIO_TRUNCATE 0x0080
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#define QEMU_AIO_TYPE_MASK \
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(QEMU_AIO_READ | \
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QEMU_AIO_WRITE | \
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@ -33,7 +34,8 @@
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QEMU_AIO_FLUSH | \
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QEMU_AIO_DISCARD | \
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QEMU_AIO_WRITE_ZEROES | \
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QEMU_AIO_COPY_RANGE)
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QEMU_AIO_COPY_RANGE | \
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QEMU_AIO_TRUNCATE)
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/* AIO flags */
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#define QEMU_AIO_MISALIGNED 0x1000
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