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envelope-from=vsementsov@virtuozzo.com; helo=EUR04-VI1-obe.outbound.protection.outlook.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/28 05:44:18 X-ACL-Warn: Detected OS = Windows NT kernel [generic] [fuzzy] X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, MSGID_FROM_MTA_HEADER=0.001, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, fam@euphon.net, vsementsov@virtuozzo.com, ronniesahlberg@gmail.com, codyprime@gmail.com, sw@weilnetz.de, pl@kamp.de, qemu-devel@nongnu.org, mreitz@redhat.com, stefanha@redhat.com, pbonzini@redhat.com, den@openvz.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" From: Eric Blake The other four drivers that support backing files (qcow, qcow2, parallels, vmdk) all rely on the block layer to populate zeroes when reading beyond EOF of a short backing file. We can simplify the qed code by doing likewise. Signed-off-by: Eric Blake Reviewed-by: Vladimir Sementsov-Ogievskiy --- block/qed.h | 1 - block/qed.c | 64 +++++------------------------------------------------ 2 files changed, 6 insertions(+), 59 deletions(-) diff --git a/block/qed.h b/block/qed.h index 42c115d822..3d12bf78d4 100644 --- a/block/qed.h +++ b/block/qed.h @@ -140,7 +140,6 @@ typedef struct QEDAIOCB { /* Current cluster scatter-gather list */ QEMUIOVector cur_qiov; - QEMUIOVector *backing_qiov; uint64_t cur_pos; /* position on block device, in bytes */ uint64_t cur_cluster; /* cluster offset in image file */ unsigned int cur_nclusters; /* number of clusters being accessed */ diff --git a/block/qed.c b/block/qed.c index a2dd952699..ece8b9bb60 100644 --- a/block/qed.c +++ b/block/qed.c @@ -849,56 +849,18 @@ static BDRVQEDState *acb_to_s(QEDAIOCB *acb) * @s: QED state * @pos: Byte position in device * @qiov: Destination I/O vector - * @backing_qiov: Possibly shortened copy of qiov, to be allocated here - * @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 int coroutine_fn qed_read_backing_file(BDRVQEDState *s, uint64_t pos, - QEMUIOVector *qiov, - QEMUIOVector **backing_qiov) + QEMUIOVector *qiov) { - uint64_t backing_length = 0; - size_t size; - int ret; - - /* 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) { - int64_t l = bdrv_getlength(s->bs->backing->bs); - if (l < 0) { - return l; - } - 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, 0, qiov->size); - } - - /* Complete now if there are no backing file sectors to read */ - if (pos >= backing_length) { - return 0; - } - - /* If the read straddles the end of the backing file, shorten it */ - size = MIN((uint64_t)backing_length - pos, qiov->size); - - assert(*backing_qiov == NULL); - *backing_qiov = g_new(QEMUIOVector, 1); - qemu_iovec_init(*backing_qiov, qiov->niov); - qemu_iovec_concat(*backing_qiov, qiov, 0, size); - - BLKDBG_EVENT(s->bs->file, BLKDBG_READ_BACKING_AIO); - ret = bdrv_co_preadv(s->bs->backing, pos, size, *backing_qiov, 0); - if (ret < 0) { - return ret; + BLKDBG_EVENT(s->bs->file, BLKDBG_READ_BACKING_AIO); + return bdrv_co_preadv(s->bs->backing, pos, qiov->size, qiov, 0); } + qemu_iovec_memset(qiov, 0, 0, qiov->size); return 0; } @@ -915,7 +877,6 @@ static int coroutine_fn qed_copy_from_backing_file(BDRVQEDState *s, uint64_t offset) { QEMUIOVector qiov; - QEMUIOVector *backing_qiov = NULL; int ret; /* Skip copy entirely if there is no work to do */ @@ -925,13 +886,7 @@ static int coroutine_fn qed_copy_from_backing_file(BDRVQEDState *s, qemu_iovec_init_buf(&qiov, qemu_blockalign(s->bs, len), len); - ret = qed_read_backing_file(s, pos, &qiov, &backing_qiov); - - if (backing_qiov) { - qemu_iovec_destroy(backing_qiov); - g_free(backing_qiov); - backing_qiov = NULL; - } + ret = qed_read_backing_file(s, pos, &qiov); if (ret) { goto out; @@ -1339,8 +1294,7 @@ static int coroutine_fn qed_aio_read_data(void *opaque, int ret, qemu_iovec_memset(&acb->cur_qiov, 0, 0, acb->cur_qiov.size); r = 0; } else if (ret != QED_CLUSTER_FOUND) { - r = qed_read_backing_file(s, acb->cur_pos, &acb->cur_qiov, - &acb->backing_qiov); + r = qed_read_backing_file(s, acb->cur_pos, &acb->cur_qiov); } else { BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO); r = bdrv_co_preadv(bs->file, offset, acb->cur_qiov.size, @@ -1365,12 +1319,6 @@ static int coroutine_fn qed_aio_next_io(QEDAIOCB *acb) while (1) { trace_qed_aio_next_io(s, acb, 0, acb->cur_pos + acb->cur_qiov.size); - if (acb->backing_qiov) { - qemu_iovec_destroy(acb->backing_qiov); - g_free(acb->backing_qiov); - acb->backing_qiov = NULL; - } - acb->qiov_offset += acb->cur_qiov.size; acb->cur_pos += acb->cur_qiov.size; qemu_iovec_reset(&acb->cur_qiov); -- 2.18.0