[Qemu-devel] [PATCH v7 01/19] block: Allow BDRV_REQ_FUA through blk_pwrite()

[Eric Blake <eblake@redhat.com>]

We have several block drivers that understand BDRV_REQ_FUA,
and emulate it in the block layer for the rest by a full flush.
But without a way to actually request BDRV_REQ_FUA during a
pass-through blk_pwrite(), FUA-aware block drivers like NBD are
forced to repeat the emulation logic of a full flush regardless
of whether the backend they are writing to could do it more
efficiently.

This patch just wires up a flags argument; followup patches
will actually make use of it in the NBD driver and in qemu-io.

Signed-off-by: Eric Blake <eblake@redhat.com>
Acked-by: Denis V. Lunev <den@openvz.org>
---
 include/sysemu/block-backend.h |  3 ++-
 block/block-backend.c          |  6 ++++--
 block/crypto.c                 |  2 +-
 block/parallels.c              |  2 +-
 block/qcow.c                   |  8 ++++----
 block/qcow2.c                  |  4 ++--
 block/qed.c                    |  6 +++---
 block/sheepdog.c               |  2 +-
 block/vdi.c                    |  4 ++--
 block/vhdx.c                   |  5 +++--
 block/vmdk.c                   | 10 +++++-----
 block/vpc.c                    | 10 +++++-----
 hw/nvram/spapr_nvram.c         |  4 ++--
 nbd/server.c                   |  2 +-
 qemu-io-cmds.c                 |  2 +-
 15 files changed, 37 insertions(+), 33 deletions(-)

diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h
index c62b6fe..6991b26 100644
--- a/include/sysemu/block-backend.h
+++ b/include/sysemu/block-backend.h
@@ -102,7 +102,8 @@ BlockAIOCB *blk_aio_write_zeroes(BlockBackend *blk, int64_t sector_num,
                                  int nb_sectors, BdrvRequestFlags flags,
                                  BlockCompletionFunc *cb, void *opaque);
 int blk_pread(BlockBackend *blk, int64_t offset, void *buf, int count);
-int blk_pwrite(BlockBackend *blk, int64_t offset, const void *buf, int count);
+int blk_pwrite(BlockBackend *blk, int64_t offset, const void *buf, int count,
+               BdrvRequestFlags flags);
 int64_t blk_getlength(BlockBackend *blk);
 void blk_get_geometry(BlockBackend *blk, uint64_t *nb_sectors_ptr);
 int64_t blk_nb_sectors(BlockBackend *blk);
diff --git a/block/block-backend.c b/block/block-backend.c
index a7623e8..96c1d7c 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -953,9 +953,11 @@ int blk_pread(BlockBackend *blk, int64_t offset, void *buf, int count)
     return count;
 }

-int blk_pwrite(BlockBackend *blk, int64_t offset, const void *buf, int count)
+int blk_pwrite(BlockBackend *blk, int64_t offset, const void *buf, int count,
+               BdrvRequestFlags flags)
 {
-    int ret = blk_prw(blk, offset, (void*) buf, count, blk_write_entry, 0);
+    int ret = blk_prw(blk, offset, (void *) buf, count, blk_write_entry,
+                      flags);
     if (ret < 0) {
         return ret;
     }
diff --git a/block/crypto.c b/block/crypto.c
index 1903e84..32ba17c 100644
--- a/block/crypto.c
+++ b/block/crypto.c
@@ -91,7 +91,7 @@ static ssize_t block_crypto_write_func(QCryptoBlock *block,
     struct BlockCryptoCreateData *data = opaque;
     ssize_t ret;

-    ret = blk_pwrite(data->blk, offset, buf, buflen);
+    ret = blk_pwrite(data->blk, offset, buf, buflen, 0);
     if (ret < 0) {
         error_setg_errno(errp, -ret, "Could not write encryption header");
         return ret;
diff --git a/block/parallels.c b/block/parallels.c
index 324ed43..2d8bc87 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -512,7 +512,7 @@ static int parallels_create(const char *filename, QemuOpts *opts, Error **errp)
     memset(tmp, 0, sizeof(tmp));
     memcpy(tmp, &header, sizeof(header));

-    ret = blk_pwrite(file, 0, tmp, BDRV_SECTOR_SIZE);
+    ret = blk_pwrite(file, 0, tmp, BDRV_SECTOR_SIZE, 0);
     if (ret < 0) {
         goto exit;
     }
diff --git a/block/qcow.c b/block/qcow.c
index 60ddb12..d6dc1b0 100644
--- a/block/qcow.c
+++ b/block/qcow.c
@@ -853,14 +853,14 @@ static int qcow_create(const char *filename, QemuOpts *opts, Error **errp)
     }

     /* write all the data */
-    ret = blk_pwrite(qcow_blk, 0, &header, sizeof(header));
+    ret = blk_pwrite(qcow_blk, 0, &header, sizeof(header), 0);
     if (ret != sizeof(header)) {
         goto exit;
     }

     if (backing_file) {
         ret = blk_pwrite(qcow_blk, sizeof(header),
-            backing_file, backing_filename_len);
+                         backing_file, backing_filename_len, 0);
         if (ret != backing_filename_len) {
             goto exit;
         }
@@ -869,8 +869,8 @@ static int qcow_create(const char *filename, QemuOpts *opts, Error **errp)
     tmp = g_malloc0(BDRV_SECTOR_SIZE);
     for (i = 0; i < ((sizeof(uint64_t)*l1_size + BDRV_SECTOR_SIZE - 1)/
         BDRV_SECTOR_SIZE); i++) {
-        ret = blk_pwrite(qcow_blk, header_size +
-            BDRV_SECTOR_SIZE*i, tmp, BDRV_SECTOR_SIZE);
+        ret = blk_pwrite(qcow_blk, header_size + BDRV_SECTOR_SIZE * i,
+                         tmp, BDRV_SECTOR_SIZE, 0);
         if (ret != BDRV_SECTOR_SIZE) {
             g_free(tmp);
             goto exit;
diff --git a/block/qcow2.c b/block/qcow2.c
index 470734b..3090538 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -2207,7 +2207,7 @@ static int qcow2_create2(const char *filename, int64_t total_size,
             cpu_to_be64(QCOW2_COMPAT_LAZY_REFCOUNTS);
     }

-    ret = blk_pwrite(blk, 0, header, cluster_size);
+    ret = blk_pwrite(blk, 0, header, cluster_size, 0);
     g_free(header);
     if (ret < 0) {
         error_setg_errno(errp, -ret, "Could not write qcow2 header");
@@ -2217,7 +2217,7 @@ static int qcow2_create2(const char *filename, int64_t total_size,
     /* Write a refcount table with one refcount block */
     refcount_table = g_malloc0(2 * cluster_size);
     refcount_table[0] = cpu_to_be64(2 * cluster_size);
-    ret = blk_pwrite(blk, cluster_size, refcount_table, 2 * cluster_size);
+    ret = blk_pwrite(blk, cluster_size, refcount_table, 2 * cluster_size, 0);
     g_free(refcount_table);

     if (ret < 0) {
diff --git a/block/qed.c b/block/qed.c
index 0af5274..6cfd4c1 100644
--- a/block/qed.c
+++ b/block/qed.c
@@ -601,18 +601,18 @@ static int qed_create(const char *filename, uint32_t cluster_size,
     }

     qed_header_cpu_to_le(&header, &le_header);
-    ret = blk_pwrite(blk, 0, &le_header, sizeof(le_header));
+    ret = blk_pwrite(blk, 0, &le_header, sizeof(le_header), 0);
     if (ret < 0) {
         goto out;
     }
     ret = blk_pwrite(blk, sizeof(le_header), backing_file,
-                     header.backing_filename_size);
+                     header.backing_filename_size, 0);
     if (ret < 0) {
         goto out;
     }

     l1_table = g_malloc0(l1_size);
-    ret = blk_pwrite(blk, header.l1_table_offset, l1_table, l1_size);
+    ret = blk_pwrite(blk, header.l1_table_offset, l1_table, l1_size, 0);
     if (ret < 0) {
         goto out;
     }
diff --git a/block/sheepdog.c b/block/sheepdog.c
index 9023686..23fbace 100644
--- a/block/sheepdog.c
+++ b/block/sheepdog.c
@@ -1681,7 +1681,7 @@ static int sd_prealloc(const char *filename, Error **errp)
         if (ret < 0) {
             goto out;
         }
-        ret = blk_pwrite(blk, idx * buf_size, buf, buf_size);
+        ret = blk_pwrite(blk, idx * buf_size, buf, buf_size, 0);
         if (ret < 0) {
             goto out;
         }
diff --git a/block/vdi.c b/block/vdi.c
index e5fe4e8..54e1144 100644
--- a/block/vdi.c
+++ b/block/vdi.c
@@ -827,7 +827,7 @@ static int vdi_create(const char *filename, QemuOpts *opts, Error **errp)
     vdi_header_print(&header);
 #endif
     vdi_header_to_le(&header);
-    ret = blk_pwrite(blk, offset, &header, sizeof(header));
+    ret = blk_pwrite(blk, offset, &header, sizeof(header), 0);
     if (ret < 0) {
         error_setg(errp, "Error writing header to %s", filename);
         goto exit;
@@ -848,7 +848,7 @@ static int vdi_create(const char *filename, QemuOpts *opts, Error **errp)
                 bmap[i] = VDI_UNALLOCATED;
             }
         }
-        ret = blk_pwrite(blk, offset, bmap, bmap_size);
+        ret = blk_pwrite(blk, offset, bmap, bmap_size, 0);
         if (ret < 0) {
             error_setg(errp, "Error writing bmap to %s", filename);
             goto exit;
diff --git a/block/vhdx.c b/block/vhdx.c
index 2b7b332..ec778fe 100644
--- a/block/vhdx.c
+++ b/block/vhdx.c
@@ -1856,13 +1856,14 @@ static int vhdx_create(const char *filename, QemuOpts *opts, Error **errp)
     creator = g_utf8_to_utf16("QEMU v" QEMU_VERSION, -1, NULL,
                               &creator_items, NULL);
     signature = cpu_to_le64(VHDX_FILE_SIGNATURE);
-    ret = blk_pwrite(blk, VHDX_FILE_ID_OFFSET, &signature, sizeof(signature));
+    ret = blk_pwrite(blk, VHDX_FILE_ID_OFFSET, &signature, sizeof(signature),
+                     0);
     if (ret < 0) {
         goto delete_and_exit;
     }
     if (creator) {
         ret = blk_pwrite(blk, VHDX_FILE_ID_OFFSET + sizeof(signature),
-                         creator, creator_items * sizeof(gunichar2));
+                         creator, creator_items * sizeof(gunichar2), 0);
         if (ret < 0) {
             goto delete_and_exit;
         }
diff --git a/block/vmdk.c b/block/vmdk.c
index 61e20af..e6c97c2 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -1808,12 +1808,12 @@ static int vmdk_create_extent(const char *filename, int64_t filesize,
     header.check_bytes[3] = 0xa;

     /* write all the data */
-    ret = blk_pwrite(blk, 0, &magic, sizeof(magic));
+    ret = blk_pwrite(blk, 0, &magic, sizeof(magic), 0);
     if (ret < 0) {
         error_setg(errp, QERR_IO_ERROR);
         goto exit;
     }
-    ret = blk_pwrite(blk, sizeof(magic), &header, sizeof(header));
+    ret = blk_pwrite(blk, sizeof(magic), &header, sizeof(header), 0);
     if (ret < 0) {
         error_setg(errp, QERR_IO_ERROR);
         goto exit;
@@ -1833,7 +1833,7 @@ static int vmdk_create_extent(const char *filename, int64_t filesize,
         gd_buf[i] = cpu_to_le32(tmp);
     }
     ret = blk_pwrite(blk, le64_to_cpu(header.rgd_offset) * BDRV_SECTOR_SIZE,
-                     gd_buf, gd_buf_size);
+                     gd_buf, gd_buf_size, 0);
     if (ret < 0) {
         error_setg(errp, QERR_IO_ERROR);
         goto exit;
@@ -1845,7 +1845,7 @@ static int vmdk_create_extent(const char *filename, int64_t filesize,
         gd_buf[i] = cpu_to_le32(tmp);
     }
     ret = blk_pwrite(blk, le64_to_cpu(header.gd_offset) * BDRV_SECTOR_SIZE,
-                     gd_buf, gd_buf_size);
+                     gd_buf, gd_buf_size, 0);
     if (ret < 0) {
         error_setg(errp, QERR_IO_ERROR);
         goto exit;
@@ -2120,7 +2120,7 @@ static int vmdk_create(const char *filename, QemuOpts *opts, Error **errp)

     blk_set_allow_write_beyond_eof(new_blk, true);

-    ret = blk_pwrite(new_blk, desc_offset, desc, desc_len);
+    ret = blk_pwrite(new_blk, desc_offset, desc, desc_len, 0);
     if (ret < 0) {
         error_setg_errno(errp, -ret, "Could not write description");
         goto exit;
diff --git a/block/vpc.c b/block/vpc.c
index 2da4126..0379813 100644
--- a/block/vpc.c
+++ b/block/vpc.c
@@ -788,13 +788,13 @@ static int create_dynamic_disk(BlockBackend *blk, uint8_t *buf,
     block_size = 0x200000;
     num_bat_entries = (total_sectors + block_size / 512) / (block_size / 512);

-    ret = blk_pwrite(blk, offset, buf, HEADER_SIZE);
+    ret = blk_pwrite(blk, offset, buf, HEADER_SIZE, 0);
     if (ret < 0) {
         goto fail;
     }

     offset = 1536 + ((num_bat_entries * 4 + 511) & ~511);
-    ret = blk_pwrite(blk, offset, buf, HEADER_SIZE);
+    ret = blk_pwrite(blk, offset, buf, HEADER_SIZE, 0);
     if (ret < 0) {
         goto fail;
     }
@@ -804,7 +804,7 @@ static int create_dynamic_disk(BlockBackend *blk, uint8_t *buf,

     memset(buf, 0xFF, 512);
     for (i = 0; i < (num_bat_entries * 4 + 511) / 512; i++) {
-        ret = blk_pwrite(blk, offset, buf, 512);
+        ret = blk_pwrite(blk, offset, buf, 512, 0);
         if (ret < 0) {
             goto fail;
         }
@@ -831,7 +831,7 @@ static int create_dynamic_disk(BlockBackend *blk, uint8_t *buf,
     /* Write the header */
     offset = 512;

-    ret = blk_pwrite(blk, offset, buf, 1024);
+    ret = blk_pwrite(blk, offset, buf, 1024, 0);
     if (ret < 0) {
         goto fail;
     }
@@ -853,7 +853,7 @@ static int create_fixed_disk(BlockBackend *blk, uint8_t *buf,
         return ret;
     }

-    ret = blk_pwrite(blk, total_size - HEADER_SIZE, buf, HEADER_SIZE);
+    ret = blk_pwrite(blk, total_size - HEADER_SIZE, buf, HEADER_SIZE, 0);
     if (ret < 0) {
         return ret;
     }
diff --git a/hw/nvram/spapr_nvram.c b/hw/nvram/spapr_nvram.c
index 802636e..019f25d 100644
--- a/hw/nvram/spapr_nvram.c
+++ b/hw/nvram/spapr_nvram.c
@@ -124,7 +124,7 @@ static void rtas_nvram_store(PowerPCCPU *cpu, sPAPRMachineState *spapr,

     alen = len;
     if (nvram->blk) {
-        alen = blk_pwrite(nvram->blk, offset, membuf, len);
+        alen = blk_pwrite(nvram->blk, offset, membuf, len, 0);
     }

     assert(nvram->buf);
@@ -190,7 +190,7 @@ static int spapr_nvram_post_load(void *opaque, int version_id)
     sPAPRNVRAM *nvram = VIO_SPAPR_NVRAM(opaque);

     if (nvram->blk) {
-        int alen = blk_pwrite(nvram->blk, 0, nvram->buf, nvram->size);
+        int alen = blk_pwrite(nvram->blk, 0, nvram->buf, nvram->size, 0);

         if (alen < 0) {
             return alen;
diff --git a/nbd/server.c b/nbd/server.c
index 2184c64..fa862cd 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -1115,7 +1115,7 @@ static void nbd_trip(void *opaque)
         TRACE("Writing to device");

         ret = blk_pwrite(exp->blk, request.from + exp->dev_offset,
-                        req->data, request.len);
+                         req->data, request.len, 0);
         if (ret < 0) {
             LOG("writing to file failed");
             reply.error = -ret;
diff --git a/qemu-io-cmds.c b/qemu-io-cmds.c
index e34f777..e26e543 100644
--- a/qemu-io-cmds.c
+++ b/qemu-io-cmds.c
@@ -474,7 +474,7 @@ static int do_pwrite(BlockBackend *blk, char *buf, int64_t offset,
         return -ERANGE;
     }

-    *total = blk_pwrite(blk, offset, (uint8_t *)buf, count);
+    *total = blk_pwrite(blk, offset, (uint8_t *)buf, count, 0);
     if (*total < 0) {
         return *total;
     }
-- 
2.5.5