/* * QEMU Enhanced Disk Format * * Copyright IBM, Corp. 2010 * * Authors: * Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> * Anthony Liguori <aliguori@us.ibm.com> * * This work is licensed under the terms of the GNU LGPL, version 2 or later. * See the COPYING.LIB file in the top-level directory. * */ #include "trace.h" #include "qed.h" static void qed_aio_cancel(BlockDriverAIOCB *blockacb) { QEDAIOCB *acb = (QEDAIOCB *)blockacb; bool finished = false; /* Wait for the request to finish */ acb->finished = &finished; while (!finished) { qemu_aio_wait(); } } static AIOPool qed_aio_pool = { .aiocb_size = sizeof(QEDAIOCB), .cancel = qed_aio_cancel, }; static int bdrv_qed_probe(const uint8_t *buf, int buf_size, const char *filename) { const QEDHeader *header = (const QEDHeader *)buf; if (buf_size < sizeof(*header)) { return 0; } if (le32_to_cpu(header->magic) != QED_MAGIC) { return 0; } return 100; } /** * Check whether an image format is raw * * @fmt: Backing file format, may be NULL */ static bool qed_fmt_is_raw(const char *fmt) { return fmt && strcmp(fmt, "raw") == 0; } static void qed_header_le_to_cpu(const QEDHeader *le, QEDHeader *cpu) { cpu->magic = le32_to_cpu(le->magic); cpu->cluster_size = le32_to_cpu(le->cluster_size); cpu->table_size = le32_to_cpu(le->table_size); cpu->header_size = le32_to_cpu(le->header_size); cpu->features = le64_to_cpu(le->features); cpu->compat_features = le64_to_cpu(le->compat_features); cpu->autoclear_features = le64_to_cpu(le->autoclear_features); cpu->l1_table_offset = le64_to_cpu(le->l1_table_offset); cpu->image_size = le64_to_cpu(le->image_size); cpu->backing_filename_offset = le32_to_cpu(le->backing_filename_offset); cpu->backing_filename_size = le32_to_cpu(le->backing_filename_size); } static void qed_header_cpu_to_le(const QEDHeader *cpu, QEDHeader *le) { le->magic = cpu_to_le32(cpu->magic); le->cluster_size = cpu_to_le32(cpu->cluster_size); le->table_size = cpu_to_le32(cpu->table_size); le->header_size = cpu_to_le32(cpu->header_size); le->features = cpu_to_le64(cpu->features); le->compat_features = cpu_to_le64(cpu->compat_features); le->autoclear_features = cpu_to_le64(cpu->autoclear_features); le->l1_table_offset = cpu_to_le64(cpu->l1_table_offset); le->image_size = cpu_to_le64(cpu->image_size); le->backing_filename_offset = cpu_to_le32(cpu->backing_filename_offset); le->backing_filename_size = cpu_to_le32(cpu->backing_filename_size); } static int qed_write_header_sync(BDRVQEDState *s) { QEDHeader le; int ret; qed_header_cpu_to_le(&s->header, &le); ret = bdrv_pwrite(s->bs->file, 0, &le, sizeof(le)); if (ret != sizeof(le)) { return ret; } return 0; } typedef struct { GenericCB gencb; BDRVQEDState *s; struct iovec iov; QEMUIOVector qiov; int nsectors; uint8_t *buf; } QEDWriteHeaderCB; static void qed_write_header_cb(void *opaque, int ret) { QEDWriteHeaderCB *write_header_cb = opaque; qemu_vfree(write_header_cb->buf); gencb_complete(write_header_cb, ret); } static void qed_write_header_read_cb(void *opaque, int ret) { QEDWriteHeaderCB *write_header_cb = opaque; BDRVQEDState *s = write_header_cb->s; BlockDriverAIOCB *acb; if (ret) { qed_write_header_cb(write_header_cb, ret); return; } /* Update header */ qed_header_cpu_to_le(&s->header, (QEDHeader *)write_header_cb->buf); acb = bdrv_aio_writev(s->bs->file, 0, &write_header_cb->qiov, write_header_cb->nsectors, qed_write_header_cb, write_header_cb); if (!acb) { qed_write_header_cb(write_header_cb, -EIO); } } /** * Update header in-place (does not rewrite backing filename or other strings) * * This function only updates known header fields in-place and does not affect * extra data after the QED header. */ static void qed_write_header(BDRVQEDState *s, BlockDriverCompletionFunc cb, void *opaque) { /* We must write full sectors for O_DIRECT but cannot necessarily generate * the data following the header if an unrecognized compat feature is * active. Therefore, first read the sectors containing the header, update * them, and write back. */ BlockDriverAIOCB *acb; int nsectors = (sizeof(QEDHeader) + BDRV_SECTOR_SIZE - 1) / BDRV_SECTOR_SIZE; size_t len = nsectors * BDRV_SECTOR_SIZE; QEDWriteHeaderCB *write_header_cb = gencb_alloc(sizeof(*write_header_cb), cb, opaque); write_header_cb->s = s; write_header_cb->nsectors = nsectors; write_header_cb->buf = qemu_blockalign(s->bs, len); write_header_cb->iov.iov_base = write_header_cb->buf; write_header_cb->iov.iov_len = len; qemu_iovec_init_external(&write_header_cb->qiov, &write_header_cb->iov, 1); acb = bdrv_aio_readv(s->bs->file, 0, &write_header_cb->qiov, nsectors, qed_write_header_read_cb, write_header_cb); if (!acb) { qed_write_header_cb(write_header_cb, -EIO); } } static uint64_t qed_max_image_size(uint32_t cluster_size, uint32_t table_size) { uint64_t table_entries; uint64_t l2_size; table_entries = (table_size * cluster_size) / sizeof(uint64_t); l2_size = table_entries * cluster_size; return l2_size * table_entries; } static bool qed_is_cluster_size_valid(uint32_t cluster_size) { if (cluster_size < QED_MIN_CLUSTER_SIZE || cluster_size > QED_MAX_CLUSTER_SIZE) { return false; } if (cluster_size & (cluster_size - 1)) { return false; /* not power of 2 */ } return true; } static bool qed_is_table_size_valid(uint32_t table_size) { if (table_size < QED_MIN_TABLE_SIZE || table_size > QED_MAX_TABLE_SIZE) { return false; } if (table_size & (table_size - 1)) { return false; /* not power of 2 */ } return true; } static bool qed_is_image_size_valid(uint64_t image_size, uint32_t cluster_size, uint32_t table_size) { if (image_size % BDRV_SECTOR_SIZE != 0) { return false; /* not multiple of sector size */ } if (image_size > qed_max_image_size(cluster_size, table_size)) { return false; /* image is too large */ } return true; } /** * Read a string of known length from the image file * * @file: Image file * @offset: File offset to start of string, in bytes * @n: String length in bytes * @buf: Destination buffer * @buflen: Destination buffer length in bytes * @ret: 0 on success, -errno on failure * * The string is NUL-terminated. */ static int qed_read_string(BlockDriverState *file, uint64_t offset, size_t n, char *buf, size_t buflen) { int ret; if (n >= buflen) { return -EINVAL; } ret = bdrv_pread(file, offset, buf, n); if (ret < 0) { return ret; } buf[n] = '\0'; return 0; } /** * Allocate new clusters * * @s: QED state * @n: Number of contiguous clusters to allocate * @ret: Offset of first allocated cluster * * This function only produces the offset where the new clusters should be * written. It updates BDRVQEDState but does not make any changes to the image * file. */ static uint64_t qed_alloc_clusters(BDRVQEDState *s, unsigned int n) { uint64_t offset = s->file_size; s->file_size += n * s->header.cluster_size; return offset; } QEDTable *qed_alloc_table(BDRVQEDState *s) { /* Honor O_DIRECT memory alignment requirements */ return qemu_blockalign(s->bs, s->header.cluster_size * s->header.table_size); } /** * Allocate a new zeroed L2 table */ static CachedL2Table *qed_new_l2_table(BDRVQEDState *s) { CachedL2Table *l2_table = qed_alloc_l2_cache_entry(&s->l2_cache); l2_table->table = qed_alloc_table(s); l2_table->offset = qed_alloc_clusters(s, s->header.table_size); memset(l2_table->table->offsets, 0, s->header.cluster_size * s->header.table_size); return l2_table; } static void qed_aio_next_io(void *opaque, int ret); static int bdrv_qed_open(BlockDriverState *bs, int flags) { BDRVQEDState *s = bs->opaque; QEDHeader le_header; int64_t file_size; int ret; s->bs = bs; QSIMPLEQ_INIT(&s->allocating_write_reqs); ret = bdrv_pread(bs->file, 0, &le_header, sizeof(le_header)); if (ret < 0) { return ret; } ret = 0; /* ret should always be 0 or -errno */ qed_header_le_to_cpu(&le_header, &s->header); if (s->header.magic != QED_MAGIC) { return -EINVAL; } if (s->header.features & ~QED_FEATURE_MASK) { return -ENOTSUP; /* image uses unsupported feature bits */ } if (!qed_is_cluster_size_valid(s->header.cluster_size)) { return -EINVAL; } /* Round down file size to the last cluster */ file_size = bdrv_getlength(bs->file); if (file_size < 0) { return file_size; } s->file_size = qed_start_of_cluster(s, file_size); if (!qed_is_table_size_valid(s->header.table_size)) { return -EINVAL; } if (!qed_is_image_size_valid(s->header.image_size, s->header.cluster_size, s->header.table_size)) { return -EINVAL; } if (!qed_check_table_offset(s, s->header.l1_table_offset)) { return -EINVAL; } s->table_nelems = (s->header.cluster_size * s->header.table_size) / sizeof(uint64_t); s->l2_shift = ffs(s->header.cluster_size) - 1; s->l2_mask = s->table_nelems - 1; s->l1_shift = s->l2_shift + ffs(s->table_nelems) - 1; if ((s->header.features & QED_F_BACKING_FILE)) { if ((uint64_t)s->header.backing_filename_offset + s->header.backing_filename_size > s->header.cluster_size * s->header.header_size) { return -EINVAL; } ret = qed_read_string(bs->file, s->header.backing_filename_offset, s->header.backing_filename_size, bs->backing_file, sizeof(bs->backing_file)); if (ret < 0) { return ret; } if (s->header.features & QED_F_BACKING_FORMAT_NO_PROBE) { pstrcpy(bs->backing_format, sizeof(bs->backing_format), "raw"); } } /* Reset unknown autoclear feature bits. This is a backwards * compatibility mechanism that allows images to be opened by older * programs, which "knock out" unknown feature bits. When an image is * opened by a newer program again it can detect that the autoclear * feature is no longer valid. */ if ((s->header.autoclear_features & ~QED_AUTOCLEAR_FEATURE_MASK) != 0 && !bdrv_is_read_only(bs->file)) { s->header.autoclear_features &= QED_AUTOCLEAR_FEATURE_MASK; ret = qed_write_header_sync(s); if (ret) { return ret; } /* From here on only known autoclear feature bits are valid */ bdrv_flush(bs->file); } s->l1_table = qed_alloc_table(s); qed_init_l2_cache(&s->l2_cache); ret = qed_read_l1_table_sync(s); if (ret) { goto out; } /* If image was not closed cleanly, check consistency */ if (s->header.features & QED_F_NEED_CHECK) { /* Read-only images cannot be fixed. There is no risk of corruption * since write operations are not possible. Therefore, allow * potentially inconsistent images to be opened read-only. This can * aid data recovery from an otherwise inconsistent image. */ if (!bdrv_is_read_only(bs->file)) { BdrvCheckResult result = {0}; ret = qed_check(s, &result, true); if (!ret && !result.corruptions && !result.check_errors) { /* Ensure fixes reach storage before clearing check bit */ bdrv_flush(s->bs); s->header.features &= ~QED_F_NEED_CHECK; qed_write_header_sync(s); } } } out: if (ret) { qed_free_l2_cache(&s->l2_cache); qemu_vfree(s->l1_table); } return ret; } static void bdrv_qed_close(BlockDriverState *bs) { BDRVQEDState *s = bs->opaque; /* Ensure writes reach stable storage */ bdrv_flush(bs->file); /* Clean shutdown, no check required on next open */ if (s->header.features & QED_F_NEED_CHECK) { s->header.features &= ~QED_F_NEED_CHECK; qed_write_header_sync(s); } qed_free_l2_cache(&s->l2_cache); qemu_vfree(s->l1_table); } static int bdrv_qed_flush(BlockDriverState *bs) { return bdrv_flush(bs->file); } static int qed_create(const char *filename, uint32_t cluster_size, uint64_t image_size, uint32_t table_size, const char *backing_file, const char *backing_fmt) { QEDHeader header = { .magic = QED_MAGIC, .cluster_size = cluster_size, .table_size = table_size, .header_size = 1, .features = 0, .compat_features = 0, .l1_table_offset = cluster_size, .image_size = image_size, }; QEDHeader le_header; uint8_t *l1_table = NULL; size_t l1_size = header.cluster_size * header.table_size; int ret = 0; BlockDriverState *bs = NULL; ret = bdrv_create_file(filename, NULL); if (ret < 0) { return ret; } ret = bdrv_file_open(&bs, filename, BDRV_O_RDWR | BDRV_O_CACHE_WB); if (ret < 0) { return ret; } /* File must start empty and grow, check truncate is supported */ ret = bdrv_truncate(bs, 0); if (ret < 0) { goto out; } if (backing_file) { header.features |= QED_F_BACKING_FILE; header.backing_filename_offset = sizeof(le_header); header.backing_filename_size = strlen(backing_file); if (qed_fmt_is_raw(backing_fmt)) { header.features |= QED_F_BACKING_FORMAT_NO_PROBE; } } qed_header_cpu_to_le(&header, &le_header); ret = bdrv_pwrite(bs, 0, &le_header, sizeof(le_header)); if (ret < 0) { goto out; } ret = bdrv_pwrite(bs, sizeof(le_header), backing_file, header.backing_filename_size); if (ret < 0) { goto out; } l1_table = qemu_mallocz(l1_size); ret = bdrv_pwrite(bs, header.l1_table_offset, l1_table, l1_size); if (ret < 0) { goto out; } ret = 0; /* success */ out: qemu_free(l1_table); bdrv_delete(bs); return ret; } static int bdrv_qed_create(const char *filename, QEMUOptionParameter *options) { uint64_t image_size = 0; uint32_t cluster_size = QED_DEFAULT_CLUSTER_SIZE; uint32_t table_size = QED_DEFAULT_TABLE_SIZE; const char *backing_file = NULL; const char *backing_fmt = NULL; while (options && options->name) { if (!strcmp(options->name, BLOCK_OPT_SIZE)) { image_size = options->value.n; } else if (!strcmp(options->name, BLOCK_OPT_BACKING_FILE)) { backing_file = options->value.s; } else if (!strcmp(options->name, BLOCK_OPT_BACKING_FMT)) { backing_fmt = options->value.s; } else if (!strcmp(options->name, BLOCK_OPT_CLUSTER_SIZE)) { if (options->value.n) { cluster_size = options->value.n; } } else if (!strcmp(options->name, BLOCK_OPT_TABLE_SIZE)) { if (options->value.n) { table_size = options->value.n; } } options++; } if (!qed_is_cluster_size_valid(cluster_size)) { fprintf(stderr, "QED cluster size must be within range [%u, %u] and power of 2\n", QED_MIN_CLUSTER_SIZE, QED_MAX_CLUSTER_SIZE); return -EINVAL; } if (!qed_is_table_size_valid(table_size)) { fprintf(stderr, "QED table size must be within range [%u, %u] and power of 2\n", QED_MIN_TABLE_SIZE, QED_MAX_TABLE_SIZE); return -EINVAL; } if (!qed_is_image_size_valid(image_size, cluster_size, table_size)) { fprintf(stderr, "QED image size must be a non-zero multiple of " "cluster size and less than %" PRIu64 " bytes\n", qed_max_image_size(cluster_size, table_size)); return -EINVAL; } return qed_create(filename, cluster_size, image_size, table_size, backing_file, backing_fmt); } typedef struct { int is_allocated; int *pnum; } QEDIsAllocatedCB; static void qed_is_allocated_cb(void *opaque, int ret, uint64_t offset, size_t len) { QEDIsAllocatedCB *cb = opaque; *cb->pnum = len / BDRV_SECTOR_SIZE; cb->is_allocated = ret == QED_CLUSTER_FOUND; } static int bdrv_qed_is_allocated(BlockDriverState *bs, int64_t sector_num, int nb_sectors, int *pnum) { BDRVQEDState *s = bs->opaque; uint64_t pos = (uint64_t)sector_num * BDRV_SECTOR_SIZE; size_t len = (size_t)nb_sectors * BDRV_SECTOR_SIZE; QEDIsAllocatedCB cb = { .is_allocated = -1, .pnum = pnum, }; QEDRequest request = { .l2_table = NULL }; async_context_push(); qed_find_cluster(s, &request, pos, len, qed_is_allocated_cb, &cb); while (cb.is_allocated == -1) { qemu_aio_wait(); } async_context_pop(); qed_unref_l2_cache_entry(request.l2_table); return cb.is_allocated; } static int bdrv_qed_make_empty(BlockDriverState *bs) { return -ENOTSUP; } static BDRVQEDState *acb_to_s(QEDAIOCB *acb) { return acb->common.bs->opaque; } /** * Read from the backing file or zero-fill if no backing file * * @s: QED state * @pos: Byte position in device * @qiov: Destination I/O vector * @cb: Completion function * @opaque: User data for completion function * * This function reads qiov->size bytes starting at pos from the backing file. * If there is no backing file then zeroes are read. */ static void qed_read_backing_file(BDRVQEDState *s, uint64_t pos, QEMUIOVector *qiov, BlockDriverCompletionFunc *cb, void *opaque) { BlockDriverAIOCB *aiocb; uint64_t backing_length = 0; size_t size; /* If there is a backing file, get its length. Treat the absence of a * backing file like a zero length backing file. */ if (s->bs->backing_hd) { int64_t l = bdrv_getlength(s->bs->backing_hd); if (l < 0) { cb(opaque, l); return; } backing_length = l; } /* Zero all sectors if reading beyond the end of the backing file */ if (pos >= backing_length || pos + qiov->size > backing_length) { qemu_iovec_memset(qiov, 0, qiov->size); } /* Complete now if there are no backing file sectors to read */ if (pos >= backing_length) { cb(opaque, 0); return; } /* If the read straddles the end of the backing file, shorten it */ size = MIN((uint64_t)backing_length - pos, qiov->size); BLKDBG_EVENT(s->bs->file, BLKDBG_READ_BACKING); aiocb = bdrv_aio_readv(s->bs->backing_hd, pos / BDRV_SECTOR_SIZE, qiov, size / BDRV_SECTOR_SIZE, cb, opaque); if (!aiocb) { cb(opaque, -EIO); } } typedef struct { GenericCB gencb; BDRVQEDState *s; QEMUIOVector qiov; struct iovec iov; uint64_t offset; } CopyFromBackingFileCB; static void qed_copy_from_backing_file_cb(void *opaque, int ret) { CopyFromBackingFileCB *copy_cb = opaque; qemu_vfree(copy_cb->iov.iov_base); gencb_complete(©_cb->gencb, ret); } static void qed_copy_from_backing_file_write(void *opaque, int ret) { CopyFromBackingFileCB *copy_cb = opaque; BDRVQEDState *s = copy_cb->s; BlockDriverAIOCB *aiocb; if (ret) { qed_copy_from_backing_file_cb(copy_cb, ret); return; } BLKDBG_EVENT(s->bs->file, BLKDBG_COW_WRITE); aiocb = bdrv_aio_writev(s->bs->file, copy_cb->offset / BDRV_SECTOR_SIZE, ©_cb->qiov, copy_cb->qiov.size / BDRV_SECTOR_SIZE, qed_copy_from_backing_file_cb, copy_cb); if (!aiocb) { qed_copy_from_backing_file_cb(copy_cb, -EIO); } } /** * Copy data from backing file into the image * * @s: QED state * @pos: Byte position in device * @len: Number of bytes * @offset: Byte offset in image file * @cb: Completion function * @opaque: User data for completion function */ static void qed_copy_from_backing_file(BDRVQEDState *s, uint64_t pos, uint64_t len, uint64_t offset, BlockDriverCompletionFunc *cb, void *opaque) { CopyFromBackingFileCB *copy_cb; /* Skip copy entirely if there is no work to do */ if (len == 0) { cb(opaque, 0); return; } copy_cb = gencb_alloc(sizeof(*copy_cb), cb, opaque); copy_cb->s = s; copy_cb->offset = offset; copy_cb->iov.iov_base = qemu_blockalign(s->bs, len); copy_cb->iov.iov_len = len; qemu_iovec_init_external(©_cb->qiov, ©_cb->iov, 1); qed_read_backing_file(s, pos, ©_cb->qiov, qed_copy_from_backing_file_write, copy_cb); } /** * Link one or more contiguous clusters into a table * * @s: QED state * @table: L2 table * @index: First cluster index * @n: Number of contiguous clusters * @cluster: First cluster byte offset in image file */ static void qed_update_l2_table(BDRVQEDState *s, QEDTable *table, int index, unsigned int n, uint64_t cluster) { int i; for (i = index; i < index + n; i++) { table->offsets[i] = cluster; cluster += s->header.cluster_size; } } static void qed_aio_complete_bh(void *opaque) { QEDAIOCB *acb = opaque; BlockDriverCompletionFunc *cb = acb->common.cb; void *user_opaque = acb->common.opaque; int ret = acb->bh_ret; bool *finished = acb->finished; qemu_bh_delete(acb->bh); qemu_aio_release(acb); /* Invoke callback */ cb(user_opaque, ret); /* Signal cancel completion */ if (finished) { *finished = true; } } static void qed_aio_complete(QEDAIOCB *acb, int ret) { BDRVQEDState *s = acb_to_s(acb); trace_qed_aio_complete(s, acb, ret); /* Free resources */ qemu_iovec_destroy(&acb->cur_qiov); qed_unref_l2_cache_entry(acb->request.l2_table); /* Arrange for a bh to invoke the completion function */ acb->bh_ret = ret; acb->bh = qemu_bh_new(qed_aio_complete_bh, acb); qemu_bh_schedule(acb->bh); /* Start next allocating write request waiting behind this one. Note that * requests enqueue themselves when they first hit an unallocated cluster * but they wait until the entire request is finished before waking up the * next request in the queue. This ensures that we don't cycle through * requests multiple times but rather finish one at a time completely. */ if (acb == QSIMPLEQ_FIRST(&s->allocating_write_reqs)) { QSIMPLEQ_REMOVE_HEAD(&s->allocating_write_reqs, next); acb = QSIMPLEQ_FIRST(&s->allocating_write_reqs); if (acb) { qed_aio_next_io(acb, 0); } } } /** * Commit the current L2 table to the cache */ static void qed_commit_l2_update(void *opaque, int ret) { QEDAIOCB *acb = opaque; BDRVQEDState *s = acb_to_s(acb); CachedL2Table *l2_table = acb->request.l2_table; qed_commit_l2_cache_entry(&s->l2_cache, l2_table); /* This is guaranteed to succeed because we just committed the entry to the * cache. */ acb->request.l2_table = qed_find_l2_cache_entry(&s->l2_cache, l2_table->offset); assert(acb->request.l2_table != NULL); qed_aio_next_io(opaque, ret); } /** * Update L1 table with new L2 table offset and write it out */ static void qed_aio_write_l1_update(void *opaque, int ret) { QEDAIOCB *acb = opaque; BDRVQEDState *s = acb_to_s(acb); int index; if (ret) { qed_aio_complete(acb, ret); return; } index = qed_l1_index(s, acb->cur_pos); s->l1_table->offsets[index] = acb->request.l2_table->offset; qed_write_l1_table(s, index, 1, qed_commit_l2_update, acb); } /** * Update L2 table with new cluster offsets and write them out */ static void qed_aio_write_l2_update(void *opaque, int ret) { QEDAIOCB *acb = opaque; BDRVQEDState *s = acb_to_s(acb); bool need_alloc = acb->find_cluster_ret == QED_CLUSTER_L1; int index; if (ret) { goto err; } if (need_alloc) { qed_unref_l2_cache_entry(acb->request.l2_table); acb->request.l2_table = qed_new_l2_table(s); } index = qed_l2_index(s, acb->cur_pos); qed_update_l2_table(s, acb->request.l2_table->table, index, acb->cur_nclusters, acb->cur_cluster); if (need_alloc) { /* Write out the whole new L2 table */ qed_write_l2_table(s, &acb->request, 0, s->table_nelems, true, qed_aio_write_l1_update, acb); } else { /* Write out only the updated part of the L2 table */ qed_write_l2_table(s, &acb->request, index, acb->cur_nclusters, false, qed_aio_next_io, acb); } return; err: qed_aio_complete(acb, ret); } /** * Flush new data clusters before updating the L2 table * * This flush is necessary when a backing file is in use. A crash during an * allocating write could result in empty clusters in the image. If the write * only touched a subregion of the cluster, then backing image sectors have * been lost in the untouched region. The solution is to flush after writing a * new data cluster and before updating the L2 table. */ static void qed_aio_write_flush_before_l2_update(void *opaque, int ret) { QEDAIOCB *acb = opaque; BDRVQEDState *s = acb_to_s(acb); if (!bdrv_aio_flush(s->bs->file, qed_aio_write_l2_update, opaque)) { qed_aio_complete(acb, -EIO); } } /** * Write data to the image file */ static void qed_aio_write_main(void *opaque, int ret) { QEDAIOCB *acb = opaque; BDRVQEDState *s = acb_to_s(acb); uint64_t offset = acb->cur_cluster + qed_offset_into_cluster(s, acb->cur_pos); BlockDriverCompletionFunc *next_fn; BlockDriverAIOCB *file_acb; trace_qed_aio_write_main(s, acb, ret, offset, acb->cur_qiov.size); if (ret) { qed_aio_complete(acb, ret); return; } if (acb->find_cluster_ret == QED_CLUSTER_FOUND) { next_fn = qed_aio_next_io; } else { if (s->bs->backing_hd) { next_fn = qed_aio_write_flush_before_l2_update; } else { next_fn = qed_aio_write_l2_update; } } BLKDBG_EVENT(s->bs->file, BLKDBG_WRITE_AIO); file_acb = bdrv_aio_writev(s->bs->file, offset / BDRV_SECTOR_SIZE, &acb->cur_qiov, acb->cur_qiov.size / BDRV_SECTOR_SIZE, next_fn, acb); if (!file_acb) { qed_aio_complete(acb, -EIO); } } /** * Populate back untouched region of new data cluster */ static void qed_aio_write_postfill(void *opaque, int ret) { QEDAIOCB *acb = opaque; BDRVQEDState *s = acb_to_s(acb); uint64_t start = acb->cur_pos + acb->cur_qiov.size; uint64_t len = qed_start_of_cluster(s, start + s->header.cluster_size - 1) - start; uint64_t offset = acb->cur_cluster + qed_offset_into_cluster(s, acb->cur_pos) + acb->cur_qiov.size; if (ret) { qed_aio_complete(acb, ret); return; } trace_qed_aio_write_postfill(s, acb, start, len, offset); qed_copy_from_backing_file(s, start, len, offset, qed_aio_write_main, acb); } /** * Populate front untouched region of new data cluster */ static void qed_aio_write_prefill(void *opaque, int ret) { QEDAIOCB *acb = opaque; BDRVQEDState *s = acb_to_s(acb); uint64_t start = qed_start_of_cluster(s, acb->cur_pos); uint64_t len = qed_offset_into_cluster(s, acb->cur_pos); trace_qed_aio_write_prefill(s, acb, start, len, acb->cur_cluster); qed_copy_from_backing_file(s, start, len, acb->cur_cluster, qed_aio_write_postfill, acb); } /** * Check if the QED_F_NEED_CHECK bit should be set during allocating write */ static bool qed_should_set_need_check(BDRVQEDState *s) { /* The flush before L2 update path ensures consistency */ if (s->bs->backing_hd) { return false; } return !(s->header.features & QED_F_NEED_CHECK); } /** * Write new data cluster * * @acb: Write request * @len: Length in bytes * * This path is taken when writing to previously unallocated clusters. */ static void qed_aio_write_alloc(QEDAIOCB *acb, size_t len) { BDRVQEDState *s = acb_to_s(acb); /* Freeze this request if another allocating write is in progress */ if (acb != QSIMPLEQ_FIRST(&s->allocating_write_reqs)) { QSIMPLEQ_INSERT_TAIL(&s->allocating_write_reqs, acb, next); } if (acb != QSIMPLEQ_FIRST(&s->allocating_write_reqs)) { return; /* wait for existing request to finish */ } acb->cur_nclusters = qed_bytes_to_clusters(s, qed_offset_into_cluster(s, acb->cur_pos) + len); acb->cur_cluster = qed_alloc_clusters(s, acb->cur_nclusters); qemu_iovec_copy(&acb->cur_qiov, acb->qiov, acb->qiov_offset, len); if (qed_should_set_need_check(s)) { s->header.features |= QED_F_NEED_CHECK; qed_write_header(s, qed_aio_write_prefill, acb); } else { qed_aio_write_prefill(acb, 0); } } /** * Write data cluster in place * * @acb: Write request * @offset: Cluster offset in bytes * @len: Length in bytes * * This path is taken when writing to already allocated clusters. */ static void qed_aio_write_inplace(QEDAIOCB *acb, uint64_t offset, size_t len) { /* Calculate the I/O vector */ acb->cur_cluster = offset; qemu_iovec_copy(&acb->cur_qiov, acb->qiov, acb->qiov_offset, len); /* Do the actual write */ qed_aio_write_main(acb, 0); } /** * Write data cluster * * @opaque: Write request * @ret: QED_CLUSTER_FOUND, QED_CLUSTER_L2, QED_CLUSTER_L1, * or -errno * @offset: Cluster offset in bytes * @len: Length in bytes * * Callback from qed_find_cluster(). */ static void qed_aio_write_data(void *opaque, int ret, uint64_t offset, size_t len) { QEDAIOCB *acb = opaque; trace_qed_aio_write_data(acb_to_s(acb), acb, ret, offset, len); acb->find_cluster_ret = ret; switch (ret) { case QED_CLUSTER_FOUND: qed_aio_write_inplace(acb, offset, len); break; case QED_CLUSTER_L2: case QED_CLUSTER_L1: qed_aio_write_alloc(acb, len); break; default: qed_aio_complete(acb, ret); break; } } /** * Read data cluster * * @opaque: Read request * @ret: QED_CLUSTER_FOUND, QED_CLUSTER_L2, QED_CLUSTER_L1, * or -errno * @offset: Cluster offset in bytes * @len: Length in bytes * * Callback from qed_find_cluster(). */ static void qed_aio_read_data(void *opaque, int ret, uint64_t offset, size_t len) { QEDAIOCB *acb = opaque; BDRVQEDState *s = acb_to_s(acb); BlockDriverState *bs = acb->common.bs; BlockDriverAIOCB *file_acb; /* Adjust offset into cluster */ offset += qed_offset_into_cluster(s, acb->cur_pos); trace_qed_aio_read_data(s, acb, ret, offset, len); if (ret < 0) { goto err; } qemu_iovec_copy(&acb->cur_qiov, acb->qiov, acb->qiov_offset, len); /* Handle backing file and unallocated sparse hole reads */ if (ret != QED_CLUSTER_FOUND) { qed_read_backing_file(s, acb->cur_pos, &acb->cur_qiov, qed_aio_next_io, acb); return; } BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO); file_acb = bdrv_aio_readv(bs->file, offset / BDRV_SECTOR_SIZE, &acb->cur_qiov, acb->cur_qiov.size / BDRV_SECTOR_SIZE, qed_aio_next_io, acb); if (!file_acb) { ret = -EIO; goto err; } return; err: qed_aio_complete(acb, ret); } /** * Begin next I/O or complete the request */ static void qed_aio_next_io(void *opaque, int ret) { QEDAIOCB *acb = opaque; BDRVQEDState *s = acb_to_s(acb); QEDFindClusterFunc *io_fn = acb->is_write ? qed_aio_write_data : qed_aio_read_data; trace_qed_aio_next_io(s, acb, ret, acb->cur_pos + acb->cur_qiov.size); /* Handle I/O error */ if (ret) { qed_aio_complete(acb, ret); return; } acb->qiov_offset += acb->cur_qiov.size; acb->cur_pos += acb->cur_qiov.size; qemu_iovec_reset(&acb->cur_qiov); /* Complete request */ if (acb->cur_pos >= acb->end_pos) { qed_aio_complete(acb, 0); return; } /* Find next cluster and start I/O */ qed_find_cluster(s, &acb->request, acb->cur_pos, acb->end_pos - acb->cur_pos, io_fn, acb); } static BlockDriverAIOCB *qed_aio_setup(BlockDriverState *bs, int64_t sector_num, QEMUIOVector *qiov, int nb_sectors, BlockDriverCompletionFunc *cb, void *opaque, bool is_write) { QEDAIOCB *acb = qemu_aio_get(&qed_aio_pool, bs, cb, opaque); trace_qed_aio_setup(bs->opaque, acb, sector_num, nb_sectors, opaque, is_write); acb->is_write = is_write; acb->finished = NULL; acb->qiov = qiov; acb->qiov_offset = 0; acb->cur_pos = (uint64_t)sector_num * BDRV_SECTOR_SIZE; acb->end_pos = acb->cur_pos + nb_sectors * BDRV_SECTOR_SIZE; acb->request.l2_table = NULL; qemu_iovec_init(&acb->cur_qiov, qiov->niov); /* Start request */ qed_aio_next_io(acb, 0); return &acb->common; } static BlockDriverAIOCB *bdrv_qed_aio_readv(BlockDriverState *bs, int64_t sector_num, QEMUIOVector *qiov, int nb_sectors, BlockDriverCompletionFunc *cb, void *opaque) { return qed_aio_setup(bs, sector_num, qiov, nb_sectors, cb, opaque, false); } static BlockDriverAIOCB *bdrv_qed_aio_writev(BlockDriverState *bs, int64_t sector_num, QEMUIOVector *qiov, int nb_sectors, BlockDriverCompletionFunc *cb, void *opaque) { return qed_aio_setup(bs, sector_num, qiov, nb_sectors, cb, opaque, true); } static BlockDriverAIOCB *bdrv_qed_aio_flush(BlockDriverState *bs, BlockDriverCompletionFunc *cb, void *opaque) { return bdrv_aio_flush(bs->file, cb, opaque); } static int bdrv_qed_truncate(BlockDriverState *bs, int64_t offset) { return -ENOTSUP; } static int64_t bdrv_qed_getlength(BlockDriverState *bs) { BDRVQEDState *s = bs->opaque; return s->header.image_size; } static int bdrv_qed_get_info(BlockDriverState *bs, BlockDriverInfo *bdi) { BDRVQEDState *s = bs->opaque; memset(bdi, 0, sizeof(*bdi)); bdi->cluster_size = s->header.cluster_size; return 0; } static int bdrv_qed_change_backing_file(BlockDriverState *bs, const char *backing_file, const char *backing_fmt) { BDRVQEDState *s = bs->opaque; QEDHeader new_header, le_header; void *buffer; size_t buffer_len, backing_file_len; int ret; /* Refuse to set backing filename if unknown compat feature bits are * active. If the image uses an unknown compat feature then we may not * know the layout of data following the header structure and cannot safely * add a new string. */ if (backing_file && (s->header.compat_features & ~QED_COMPAT_FEATURE_MASK)) { return -ENOTSUP; } memcpy(&new_header, &s->header, sizeof(new_header)); new_header.features &= ~(QED_F_BACKING_FILE | QED_F_BACKING_FORMAT_NO_PROBE); /* Adjust feature flags */ if (backing_file) { new_header.features |= QED_F_BACKING_FILE; if (qed_fmt_is_raw(backing_fmt)) { new_header.features |= QED_F_BACKING_FORMAT_NO_PROBE; } } /* Calculate new header size */ backing_file_len = 0; if (backing_file) { backing_file_len = strlen(backing_file); } buffer_len = sizeof(new_header); new_header.backing_filename_offset = buffer_len; new_header.backing_filename_size = backing_file_len; buffer_len += backing_file_len; /* Make sure we can rewrite header without failing */ if (buffer_len > new_header.header_size * new_header.cluster_size) { return -ENOSPC; } /* Prepare new header */ buffer = qemu_malloc(buffer_len); qed_header_cpu_to_le(&new_header, &le_header); memcpy(buffer, &le_header, sizeof(le_header)); buffer_len = sizeof(le_header); memcpy(buffer + buffer_len, backing_file, backing_file_len); buffer_len += backing_file_len; /* Write new header */ ret = bdrv_pwrite_sync(bs->file, 0, buffer, buffer_len); qemu_free(buffer); if (ret == 0) { memcpy(&s->header, &new_header, sizeof(new_header)); } return ret; } static int bdrv_qed_check(BlockDriverState *bs, BdrvCheckResult *result) { BDRVQEDState *s = bs->opaque; return qed_check(s, result, false); } static QEMUOptionParameter qed_create_options[] = { { .name = BLOCK_OPT_SIZE, .type = OPT_SIZE, .help = "Virtual disk size (in bytes)" }, { .name = BLOCK_OPT_BACKING_FILE, .type = OPT_STRING, .help = "File name of a base image" }, { .name = BLOCK_OPT_BACKING_FMT, .type = OPT_STRING, .help = "Image format of the base image" }, { .name = BLOCK_OPT_CLUSTER_SIZE, .type = OPT_SIZE, .help = "Cluster size (in bytes)" }, { .name = BLOCK_OPT_TABLE_SIZE, .type = OPT_SIZE, .help = "L1/L2 table size (in clusters)" }, { /* end of list */ } }; static BlockDriver bdrv_qed = { .format_name = "qed", .instance_size = sizeof(BDRVQEDState), .create_options = qed_create_options, .bdrv_probe = bdrv_qed_probe, .bdrv_open = bdrv_qed_open, .bdrv_close = bdrv_qed_close, .bdrv_create = bdrv_qed_create, .bdrv_flush = bdrv_qed_flush, .bdrv_is_allocated = bdrv_qed_is_allocated, .bdrv_make_empty = bdrv_qed_make_empty, .bdrv_aio_readv = bdrv_qed_aio_readv, .bdrv_aio_writev = bdrv_qed_aio_writev, .bdrv_aio_flush = bdrv_qed_aio_flush, .bdrv_truncate = bdrv_qed_truncate, .bdrv_getlength = bdrv_qed_getlength, .bdrv_get_info = bdrv_qed_get_info, .bdrv_change_backing_file = bdrv_qed_change_backing_file, .bdrv_check = bdrv_qed_check, }; static void bdrv_qed_init(void) { bdrv_register(&bdrv_qed); } block_init(bdrv_qed_init);