[Qemu-devel] [PATCH v2 0/5] Remove bdrv_read() and bdrv_write()

[Qemu-devel] [PATCH v2 0/5] Remove bdrv_read() and bdrv_write()

[Alberto Garcia]

Hi,

this API only had a few users left so it can be easily removed.

Regards,

Berto

v2:
- Patch 2: Add QEMU_BUILD_BUG_ON(sizeof(VdiHeader) != 512) [Kevin]
           Correct size parameter in bdrv_pwrite() call [Kevin]
           Return 0 on success, never a positive number [Kevin]
- Patch 3: Check that the return values of bdrv_pread()/bdrv_pwrite()
           are strictly < 0 for errors, not simply != 0 [Kevin]
- Patch 4: Reuse the documenation of bdrv_write() for bdrv_pwrite()

v1: https://lists.gnu.org/archive/html/qemu-block/2019-04/msg00832.html

Output of git backport-diff against v1:

Key:
[----] : patches are identical
[####] : number of functional differences between upstream/downstream patch
[down] : patch is downstream-only
The flags [FC] indicate (F)unctional and (C)ontextual differences, respectively

001/5:[----] [--] 'qcow2: Replace bdrv_write() with bdrv_pwrite()'
002/5:[0006] [FC] 'vdi: Replace bdrv_{read,write}() with bdrv_{pread,pwrite}()'
003/5:[0004] [FC] 'vvfat: Replace bdrv_{read,write}() with bdrv_{pread,pwrite}()'
004/5:[0007] [FC] 'block: Remove bdrv_read() and bdrv_write()'
005/5:[----] [--] 'qcow2: Remove BDRVQcow2State.cluster_sectors'

Alberto Garcia (5):
  qcow2: Replace bdrv_write() with bdrv_pwrite()
  vdi: Replace bdrv_{read,write}() with bdrv_{pread,pwrite}()
  vvfat: Replace bdrv_{read,write}() with bdrv_{pread,pwrite}()
  block: Remove bdrv_read() and bdrv_write()
  qcow2: Remove BDRVQcow2State.cluster_sectors

 block/io.c             | 43 +++++++------------------------------------
 block/qcow2-refcount.c |  4 ++--
 block/qcow2.c          |  1 -
 block/qcow2.h          |  1 -
 block/vdi.c            | 15 +++++++++------
 block/vvfat.c          | 12 +++++++-----
 include/block/block.h  |  4 ----
 7 files changed, 25 insertions(+), 55 deletions(-)

-- 
2.11.0

[Qemu-devel] [PATCH v2 0/5] Remove bdrv_read() and bdrv_write()

[Alberto Garcia]

Hi,

this API only had a few users left so it can be easily removed.

Regards,

Berto

v2:
- Patch 2: Add QEMU_BUILD_BUG_ON(sizeof(VdiHeader) != 512) [Kevin]
           Correct size parameter in bdrv_pwrite() call [Kevin]
           Return 0 on success, never a positive number [Kevin]
- Patch 3: Check that the return values of bdrv_pread()/bdrv_pwrite()
           are strictly < 0 for errors, not simply != 0 [Kevin]
- Patch 4: Reuse the documenation of bdrv_write() for bdrv_pwrite()

v1: https://lists.gnu.org/archive/html/qemu-block/2019-04/msg00832.html

Output of git backport-diff against v1:

Key:
[----] : patches are identical
[####] : number of functional differences between upstream/downstream patch
[down] : patch is downstream-only
The flags [FC] indicate (F)unctional and (C)ontextual differences, respectively

001/5:[----] [--] 'qcow2: Replace bdrv_write() with bdrv_pwrite()'
002/5:[0006] [FC] 'vdi: Replace bdrv_{read,write}() with bdrv_{pread,pwrite}()'
003/5:[0004] [FC] 'vvfat: Replace bdrv_{read,write}() with bdrv_{pread,pwrite}()'
004/5:[0007] [FC] 'block: Remove bdrv_read() and bdrv_write()'
005/5:[----] [--] 'qcow2: Remove BDRVQcow2State.cluster_sectors'

Alberto Garcia (5):
  qcow2: Replace bdrv_write() with bdrv_pwrite()
  vdi: Replace bdrv_{read,write}() with bdrv_{pread,pwrite}()
  vvfat: Replace bdrv_{read,write}() with bdrv_{pread,pwrite}()
  block: Remove bdrv_read() and bdrv_write()
  qcow2: Remove BDRVQcow2State.cluster_sectors

 block/io.c             | 43 +++++++------------------------------------
 block/qcow2-refcount.c |  4 ++--
 block/qcow2.c          |  1 -
 block/qcow2.h          |  1 -
 block/vdi.c            | 15 +++++++++------
 block/vvfat.c          | 12 +++++++-----
 include/block/block.h  |  4 ----
 7 files changed, 25 insertions(+), 55 deletions(-)

-- 
2.11.0

[Qemu-devel] [PATCH v2 1/5] qcow2: Replace bdrv_write() with bdrv_pwrite()

[Alberto Garcia]

There's only one bdrv_write() call left in the qcow2 code, and it can
be trivially replaced with the byte-based bdrv_pwrite().

Signed-off-by: Alberto Garcia <berto@igalia.com>
---
 block/qcow2-refcount.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index e0fe322500..83f66eed7a 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -2409,8 +2409,8 @@ write_refblocks:
         on_disk_refblock = (void *)((char *) *refcount_table +
                                     refblock_index * s->cluster_size);
 
-        ret = bdrv_write(bs->file, refblock_offset / BDRV_SECTOR_SIZE,
-                         on_disk_refblock, s->cluster_sectors);
+        ret = bdrv_pwrite(bs->file, refblock_offset, on_disk_refblock,
+                          s->cluster_size);
         if (ret < 0) {
             fprintf(stderr, "ERROR writing refblock: %s\n", strerror(-ret));
             goto fail;
-- 
2.11.0

[Qemu-devel] [PATCH v2 1/5] qcow2: Replace bdrv_write() with bdrv_pwrite()

[Alberto Garcia]

There's only one bdrv_write() call left in the qcow2 code, and it can
be trivially replaced with the byte-based bdrv_pwrite().

Signed-off-by: Alberto Garcia <berto@igalia.com>
---
 block/qcow2-refcount.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index e0fe322500..83f66eed7a 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -2409,8 +2409,8 @@ write_refblocks:
         on_disk_refblock = (void *)((char *) *refcount_table +
                                     refblock_index * s->cluster_size);
 
-        ret = bdrv_write(bs->file, refblock_offset / BDRV_SECTOR_SIZE,
-                         on_disk_refblock, s->cluster_sectors);
+        ret = bdrv_pwrite(bs->file, refblock_offset, on_disk_refblock,
+                          s->cluster_size);
         if (ret < 0) {
             fprintf(stderr, "ERROR writing refblock: %s\n", strerror(-ret));
             goto fail;
-- 
2.11.0

[Qemu-devel] [PATCH v2 2/5] vdi: Replace bdrv_{read, write}() with bdrv_{pread, pwrite}()

[Alberto Garcia]

There's only a couple of bdrv_read() and bdrv_write() calls left in
the vdi code, and they can be trivially replaced with the byte-based
bdrv_pread() and bdrv_pwrite().

Signed-off-by: Alberto Garcia <berto@igalia.com>
---
 block/vdi.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/block/vdi.c b/block/vdi.c
index e1c42ad732..9caeb50dd1 100644
--- a/block/vdi.c
+++ b/block/vdi.c
@@ -171,6 +171,8 @@ typedef struct {
     uint64_t unused2[7];
 } QEMU_PACKED VdiHeader;
 
+QEMU_BUILD_BUG_ON(sizeof(VdiHeader) != 512);
+
 typedef struct {
     /* The block map entries are little endian (even in memory). */
     uint32_t *bmap;
@@ -384,7 +386,7 @@ static int vdi_open(BlockDriverState *bs, QDict *options, int flags,
 
     logout("\n");
 
-    ret = bdrv_read(bs->file, 0, (uint8_t *)&header, 1);
+    ret = bdrv_pread(bs->file, 0, (uint8_t *)&header, sizeof(header));
     if (ret < 0) {
         goto fail;
     }
@@ -484,8 +486,8 @@ static int vdi_open(BlockDriverState *bs, QDict *options, int flags,
         goto fail;
     }
 
-    ret = bdrv_read(bs->file, s->bmap_sector, (uint8_t *)s->bmap,
-                    bmap_size);
+    ret = bdrv_pread(bs->file, header.offset_bmap, (uint8_t *)s->bmap,
+                     bmap_size * SECTOR_SIZE);
     if (ret < 0) {
         goto fail_free_bmap;
     }
@@ -704,7 +706,7 @@ nonallocating_write:
         assert(VDI_IS_ALLOCATED(bmap_first));
         *header = s->header;
         vdi_header_to_le(header);
-        ret = bdrv_write(bs->file, 0, block, 1);
+        ret = bdrv_pwrite(bs->file, 0, block, sizeof(VdiHeader));
         g_free(block);
         block = NULL;
 
@@ -722,10 +724,11 @@ nonallocating_write:
         base = ((uint8_t *)&s->bmap[0]) + bmap_first * SECTOR_SIZE;
         logout("will write %u block map sectors starting from entry %u\n",
                n_sectors, bmap_first);
-        ret = bdrv_write(bs->file, offset, base, n_sectors);
+        ret = bdrv_pwrite(bs->file, offset * SECTOR_SIZE, base,
+                          n_sectors * SECTOR_SIZE);
     }
 
-    return ret;
+    return ret < 0 ? ret : 0;
 }
 
 static int coroutine_fn vdi_co_do_create(BlockdevCreateOptions *create_options,
-- 
2.11.0

[Qemu-devel] [PATCH v2 2/5] vdi: Replace bdrv_{read, write}() with bdrv_{pread, pwrite}()

[Alberto Garcia]

There's only a couple of bdrv_read() and bdrv_write() calls left in
the vdi code, and they can be trivially replaced with the byte-based
bdrv_pread() and bdrv_pwrite().

Signed-off-by: Alberto Garcia <berto@igalia.com>
---
 block/vdi.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/block/vdi.c b/block/vdi.c
index e1c42ad732..9caeb50dd1 100644
--- a/block/vdi.c
+++ b/block/vdi.c
@@ -171,6 +171,8 @@ typedef struct {
     uint64_t unused2[7];
 } QEMU_PACKED VdiHeader;
 
+QEMU_BUILD_BUG_ON(sizeof(VdiHeader) != 512);
+
 typedef struct {
     /* The block map entries are little endian (even in memory). */
     uint32_t *bmap;
@@ -384,7 +386,7 @@ static int vdi_open(BlockDriverState *bs, QDict *options, int flags,
 
     logout("\n");
 
-    ret = bdrv_read(bs->file, 0, (uint8_t *)&header, 1);
+    ret = bdrv_pread(bs->file, 0, (uint8_t *)&header, sizeof(header));
     if (ret < 0) {
         goto fail;
     }
@@ -484,8 +486,8 @@ static int vdi_open(BlockDriverState *bs, QDict *options, int flags,
         goto fail;
     }
 
-    ret = bdrv_read(bs->file, s->bmap_sector, (uint8_t *)s->bmap,
-                    bmap_size);
+    ret = bdrv_pread(bs->file, header.offset_bmap, (uint8_t *)s->bmap,
+                     bmap_size * SECTOR_SIZE);
     if (ret < 0) {
         goto fail_free_bmap;
     }
@@ -704,7 +706,7 @@ nonallocating_write:
         assert(VDI_IS_ALLOCATED(bmap_first));
         *header = s->header;
         vdi_header_to_le(header);
-        ret = bdrv_write(bs->file, 0, block, 1);
+        ret = bdrv_pwrite(bs->file, 0, block, sizeof(VdiHeader));
         g_free(block);
         block = NULL;
 
@@ -722,10 +724,11 @@ nonallocating_write:
         base = ((uint8_t *)&s->bmap[0]) + bmap_first * SECTOR_SIZE;
         logout("will write %u block map sectors starting from entry %u\n",
                n_sectors, bmap_first);
-        ret = bdrv_write(bs->file, offset, base, n_sectors);
+        ret = bdrv_pwrite(bs->file, offset * SECTOR_SIZE, base,
+                          n_sectors * SECTOR_SIZE);
     }
 
-    return ret;
+    return ret < 0 ? ret : 0;
 }
 
 static int coroutine_fn vdi_co_do_create(BlockdevCreateOptions *create_options,
-- 
2.11.0

[Qemu-devel] [PATCH v2 3/5] vvfat: Replace bdrv_{read, write}() with bdrv_{pread, pwrite}()

[Alberto Garcia]

There's only a couple of bdrv_read() and bdrv_write() calls left in
the vvfat code, and they can be trivially replaced with the byte-based
bdrv_pread() and bdrv_pwrite().

Signed-off-by: Alberto Garcia <berto@igalia.com>
---
 block/vvfat.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/block/vvfat.c b/block/vvfat.c
index 5f66787890..253cc716dd 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -1494,8 +1494,8 @@ static int vvfat_read(BlockDriverState *bs, int64_t sector_num,
                 DLOG(fprintf(stderr, "sectors %" PRId64 "+%" PRId64
                              " allocated\n", sector_num,
                              n >> BDRV_SECTOR_BITS));
-                if (bdrv_read(s->qcow, sector_num, buf + i * 0x200,
-                              n >> BDRV_SECTOR_BITS)) {
+                if (bdrv_pread(s->qcow, sector_num * BDRV_SECTOR_SIZE,
+                               buf + i * 0x200, n) < 0) {
                     return -1;
                 }
                 i += (n >> BDRV_SECTOR_BITS) - 1;
@@ -1983,8 +1983,9 @@ static uint32_t get_cluster_count_for_direntry(BDRVVVFATState* s,
                         if (res) {
                             return -1;
                         }
-                        res = bdrv_write(s->qcow, offset, s->cluster_buffer, 1);
-                        if (res) {
+                        res = bdrv_pwrite(s->qcow, offset * BDRV_SECTOR_SIZE,
+                                          s->cluster_buffer, BDRV_SECTOR_SIZE);
+                        if (res < 0) {
                             return -2;
                         }
                     }
@@ -3050,7 +3051,8 @@ DLOG(checkpoint());
      * Use qcow backend. Commit later.
      */
 DLOG(fprintf(stderr, "Write to qcow backend: %d + %d\n", (int)sector_num, nb_sectors));
-    ret = bdrv_write(s->qcow, sector_num, buf, nb_sectors);
+    ret = bdrv_pwrite(s->qcow, sector_num * BDRV_SECTOR_SIZE, buf,
+                      nb_sectors * BDRV_SECTOR_SIZE);
     if (ret < 0) {
         fprintf(stderr, "Error writing to qcow backend\n");
         return ret;
-- 
2.11.0

[Qemu-devel] [PATCH v2 3/5] vvfat: Replace bdrv_{read, write}() with bdrv_{pread, pwrite}()

[Alberto Garcia]

There's only a couple of bdrv_read() and bdrv_write() calls left in
the vvfat code, and they can be trivially replaced with the byte-based
bdrv_pread() and bdrv_pwrite().

Signed-off-by: Alberto Garcia <berto@igalia.com>
---
 block/vvfat.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/block/vvfat.c b/block/vvfat.c
index 5f66787890..253cc716dd 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -1494,8 +1494,8 @@ static int vvfat_read(BlockDriverState *bs, int64_t sector_num,
                 DLOG(fprintf(stderr, "sectors %" PRId64 "+%" PRId64
                              " allocated\n", sector_num,
                              n >> BDRV_SECTOR_BITS));
-                if (bdrv_read(s->qcow, sector_num, buf + i * 0x200,
-                              n >> BDRV_SECTOR_BITS)) {
+                if (bdrv_pread(s->qcow, sector_num * BDRV_SECTOR_SIZE,
+                               buf + i * 0x200, n) < 0) {
                     return -1;
                 }
                 i += (n >> BDRV_SECTOR_BITS) - 1;
@@ -1983,8 +1983,9 @@ static uint32_t get_cluster_count_for_direntry(BDRVVVFATState* s,
                         if (res) {
                             return -1;
                         }
-                        res = bdrv_write(s->qcow, offset, s->cluster_buffer, 1);
-                        if (res) {
+                        res = bdrv_pwrite(s->qcow, offset * BDRV_SECTOR_SIZE,
+                                          s->cluster_buffer, BDRV_SECTOR_SIZE);
+                        if (res < 0) {
                             return -2;
                         }
                     }
@@ -3050,7 +3051,8 @@ DLOG(checkpoint());
      * Use qcow backend. Commit later.
      */
 DLOG(fprintf(stderr, "Write to qcow backend: %d + %d\n", (int)sector_num, nb_sectors));
-    ret = bdrv_write(s->qcow, sector_num, buf, nb_sectors);
+    ret = bdrv_pwrite(s->qcow, sector_num * BDRV_SECTOR_SIZE, buf,
+                      nb_sectors * BDRV_SECTOR_SIZE);
     if (ret < 0) {
         fprintf(stderr, "Error writing to qcow backend\n");
         return ret;
-- 
2.11.0

[Qemu-devel] [PATCH v2 4/5] block: Remove bdrv_read() and bdrv_write()

[Alberto Garcia]

No one is using these functions anymore, all callers have switched to
the byte-based bdrv_pread() and bdrv_pwrite()

Signed-off-by: Alberto Garcia <berto@igalia.com>
---
 block/io.c            | 43 +++++++------------------------------------
 include/block/block.h |  4 ----
 2 files changed, 7 insertions(+), 40 deletions(-)

diff --git a/block/io.c b/block/io.c
index dfc153b8d8..396d5364ba 100644
--- a/block/io.c
+++ b/block/io.c
@@ -837,42 +837,6 @@ static int bdrv_prwv_co(BdrvChild *child, int64_t offset,
     return rwco.ret;
 }
 
-/*
- * Process a synchronous request using coroutines
- */
-static int bdrv_rw_co(BdrvChild *child, int64_t sector_num, uint8_t *buf,
-                      int nb_sectors, bool is_write, BdrvRequestFlags flags)
-{
-    QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf,
-                                            nb_sectors * BDRV_SECTOR_SIZE);
-
-    if (nb_sectors < 0 || nb_sectors > BDRV_REQUEST_MAX_SECTORS) {
-        return -EINVAL;
-    }
-
-    return bdrv_prwv_co(child, sector_num << BDRV_SECTOR_BITS,
-                        &qiov, is_write, flags);
-}
-
-/* return < 0 if error. See bdrv_write() for the return codes */
-int bdrv_read(BdrvChild *child, int64_t sector_num,
-              uint8_t *buf, int nb_sectors)
-{
-    return bdrv_rw_co(child, sector_num, buf, nb_sectors, false, 0);
-}
-
-/* Return < 0 if error. Important errors are:
-  -EIO         generic I/O error (may happen for all errors)
-  -ENOMEDIUM   No media inserted.
-  -EINVAL      Invalid sector number or nb_sectors
-  -EACCES      Trying to write a read-only device
-*/
-int bdrv_write(BdrvChild *child, int64_t sector_num,
-               const uint8_t *buf, int nb_sectors)
-{
-    return bdrv_rw_co(child, sector_num, (uint8_t *)buf, nb_sectors, true, 0);
-}
-
 int bdrv_pwrite_zeroes(BdrvChild *child, int64_t offset,
                        int bytes, BdrvRequestFlags flags)
 {
@@ -935,6 +899,7 @@ int bdrv_preadv(BdrvChild *child, int64_t offset, QEMUIOVector *qiov)
     return qiov->size;
 }
 
+/* See bdrv_pwrite() for the return codes */
 int bdrv_pread(BdrvChild *child, int64_t offset, void *buf, int bytes)
 {
     QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes);
@@ -958,6 +923,12 @@ int bdrv_pwritev(BdrvChild *child, int64_t offset, QEMUIOVector *qiov)
     return qiov->size;
 }
 
+/* Return no. of bytes on success or < 0 on error. Important errors are:
+  -EIO         generic I/O error (may happen for all errors)
+  -ENOMEDIUM   No media inserted.
+  -EINVAL      Invalid offset or number of bytes
+  -EACCES      Trying to write a read-only device
+*/
 int bdrv_pwrite(BdrvChild *child, int64_t offset, const void *buf, int bytes)
 {
     QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes);
diff --git a/include/block/block.h b/include/block/block.h
index c7a26199aa..5e2b98b0ee 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -316,10 +316,6 @@ int bdrv_reopen_prepare(BDRVReopenState *reopen_state,
                         BlockReopenQueue *queue, Error **errp);
 void bdrv_reopen_commit(BDRVReopenState *reopen_state);
 void bdrv_reopen_abort(BDRVReopenState *reopen_state);
-int bdrv_read(BdrvChild *child, int64_t sector_num,
-              uint8_t *buf, int nb_sectors);
-int bdrv_write(BdrvChild *child, int64_t sector_num,
-               const uint8_t *buf, int nb_sectors);
 int bdrv_pwrite_zeroes(BdrvChild *child, int64_t offset,
                        int bytes, BdrvRequestFlags flags);
 int bdrv_make_zero(BdrvChild *child, BdrvRequestFlags flags);
-- 
2.11.0

[Qemu-devel] [PATCH v2 4/5] block: Remove bdrv_read() and bdrv_write()

[Alberto Garcia]

No one is using these functions anymore, all callers have switched to
the byte-based bdrv_pread() and bdrv_pwrite()

Signed-off-by: Alberto Garcia <berto@igalia.com>
---
 block/io.c            | 43 +++++++------------------------------------
 include/block/block.h |  4 ----
 2 files changed, 7 insertions(+), 40 deletions(-)

diff --git a/block/io.c b/block/io.c
index dfc153b8d8..396d5364ba 100644
--- a/block/io.c
+++ b/block/io.c
@@ -837,42 +837,6 @@ static int bdrv_prwv_co(BdrvChild *child, int64_t offset,
     return rwco.ret;
 }
 
-/*
- * Process a synchronous request using coroutines
- */
-static int bdrv_rw_co(BdrvChild *child, int64_t sector_num, uint8_t *buf,
-                      int nb_sectors, bool is_write, BdrvRequestFlags flags)
-{
-    QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf,
-                                            nb_sectors * BDRV_SECTOR_SIZE);
-
-    if (nb_sectors < 0 || nb_sectors > BDRV_REQUEST_MAX_SECTORS) {
-        return -EINVAL;
-    }
-
-    return bdrv_prwv_co(child, sector_num << BDRV_SECTOR_BITS,
-                        &qiov, is_write, flags);
-}
-
-/* return < 0 if error. See bdrv_write() for the return codes */
-int bdrv_read(BdrvChild *child, int64_t sector_num,
-              uint8_t *buf, int nb_sectors)
-{
-    return bdrv_rw_co(child, sector_num, buf, nb_sectors, false, 0);
-}
-
-/* Return < 0 if error. Important errors are:
-  -EIO         generic I/O error (may happen for all errors)
-  -ENOMEDIUM   No media inserted.
-  -EINVAL      Invalid sector number or nb_sectors
-  -EACCES      Trying to write a read-only device
-*/
-int bdrv_write(BdrvChild *child, int64_t sector_num,
-               const uint8_t *buf, int nb_sectors)
-{
-    return bdrv_rw_co(child, sector_num, (uint8_t *)buf, nb_sectors, true, 0);
-}
-
 int bdrv_pwrite_zeroes(BdrvChild *child, int64_t offset,
                        int bytes, BdrvRequestFlags flags)
 {
@@ -935,6 +899,7 @@ int bdrv_preadv(BdrvChild *child, int64_t offset, QEMUIOVector *qiov)
     return qiov->size;
 }
 
+/* See bdrv_pwrite() for the return codes */
 int bdrv_pread(BdrvChild *child, int64_t offset, void *buf, int bytes)
 {
     QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes);
@@ -958,6 +923,12 @@ int bdrv_pwritev(BdrvChild *child, int64_t offset, QEMUIOVector *qiov)
     return qiov->size;
 }
 
+/* Return no. of bytes on success or < 0 on error. Important errors are:
+  -EIO         generic I/O error (may happen for all errors)
+  -ENOMEDIUM   No media inserted.
+  -EINVAL      Invalid offset or number of bytes
+  -EACCES      Trying to write a read-only device
+*/
 int bdrv_pwrite(BdrvChild *child, int64_t offset, const void *buf, int bytes)
 {
     QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes);
diff --git a/include/block/block.h b/include/block/block.h
index c7a26199aa..5e2b98b0ee 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -316,10 +316,6 @@ int bdrv_reopen_prepare(BDRVReopenState *reopen_state,
                         BlockReopenQueue *queue, Error **errp);
 void bdrv_reopen_commit(BDRVReopenState *reopen_state);
 void bdrv_reopen_abort(BDRVReopenState *reopen_state);
-int bdrv_read(BdrvChild *child, int64_t sector_num,
-              uint8_t *buf, int nb_sectors);
-int bdrv_write(BdrvChild *child, int64_t sector_num,
-               const uint8_t *buf, int nb_sectors);
 int bdrv_pwrite_zeroes(BdrvChild *child, int64_t offset,
                        int bytes, BdrvRequestFlags flags);
 int bdrv_make_zero(BdrvChild *child, BdrvRequestFlags flags);
-- 
2.11.0

[Qemu-devel] [PATCH v2 5/5] qcow2: Remove BDRVQcow2State.cluster_sectors

[Alberto Garcia]

The last user of this field disappeared when we replace the
sector-based bdrv_write() with the byte-based bdrv_pwrite().

Signed-off-by: Alberto Garcia <berto@igalia.com>
---
 block/qcow2.c | 1 -
 block/qcow2.h | 1 -
 2 files changed, 2 deletions(-)

diff --git a/block/qcow2.c b/block/qcow2.c
index a520d116ef..8e024007db 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1259,7 +1259,6 @@ static int coroutine_fn qcow2_do_open(BlockDriverState *bs, QDict *options,
 
     s->cluster_bits = header.cluster_bits;
     s->cluster_size = 1 << s->cluster_bits;
-    s->cluster_sectors = 1 << (s->cluster_bits - BDRV_SECTOR_BITS);
 
     /* Initialise version 3 header fields */
     if (header.version == 2) {
diff --git a/block/qcow2.h b/block/qcow2.h
index fdee297f33..e62508d1ce 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -266,7 +266,6 @@ typedef struct Qcow2BitmapHeaderExt {
 typedef struct BDRVQcow2State {
     int cluster_bits;
     int cluster_size;
-    int cluster_sectors;
     int l2_slice_size;
     int l2_bits;
     int l2_size;
-- 
2.11.0

[Qemu-devel] [PATCH v2 5/5] qcow2: Remove BDRVQcow2State.cluster_sectors

[Alberto Garcia]

The last user of this field disappeared when we replace the
sector-based bdrv_write() with the byte-based bdrv_pwrite().

Signed-off-by: Alberto Garcia <berto@igalia.com>
---
 block/qcow2.c | 1 -
 block/qcow2.h | 1 -
 2 files changed, 2 deletions(-)

diff --git a/block/qcow2.c b/block/qcow2.c
index a520d116ef..8e024007db 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1259,7 +1259,6 @@ static int coroutine_fn qcow2_do_open(BlockDriverState *bs, QDict *options,
 
     s->cluster_bits = header.cluster_bits;
     s->cluster_size = 1 << s->cluster_bits;
-    s->cluster_sectors = 1 << (s->cluster_bits - BDRV_SECTOR_BITS);
 
     /* Initialise version 3 header fields */
     if (header.version == 2) {
diff --git a/block/qcow2.h b/block/qcow2.h
index fdee297f33..e62508d1ce 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -266,7 +266,6 @@ typedef struct Qcow2BitmapHeaderExt {
 typedef struct BDRVQcow2State {
     int cluster_bits;
     int cluster_size;
-    int cluster_sectors;
     int l2_slice_size;
     int l2_bits;
     int l2_size;
-- 
2.11.0

Re: [Qemu-devel] [PATCH v2 1/5] qcow2: Replace bdrv_write() with bdrv_pwrite()

[Vladimir Sementsov-Ogievskiy]

01.05.2019 21:13, Alberto Garcia wrote:
> There's only one bdrv_write() call left in the qcow2 code, and it can
> be trivially replaced with the byte-based bdrv_pwrite().
> 
> Signed-off-by: Alberto Garcia <berto@igalia.com>

Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

-- 
Best regards,
Vladimir

Re: [Qemu-devel] [PATCH v2 5/5] qcow2: Remove BDRVQcow2State.cluster_sectors

[Vladimir Sementsov-Ogievskiy]

01.05.2019 21:13, Alberto Garcia wrote:
> The last user of this field disappeared when we replace the
> sector-based bdrv_write() with the byte-based bdrv_pwrite().
> 
> Signed-off-by: Alberto Garcia <berto@igalia.com>


Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>



-- 
Best regards,
Vladimir

Re: [Qemu-devel] [PATCH v2 2/5] vdi: Replace bdrv_{read, write}() with bdrv_{pread, pwrite}()

[Vladimir Sementsov-Ogievskiy]

01.05.2019 21:13, Alberto Garcia wrote:
> There's only a couple of bdrv_read() and bdrv_write() calls left in
> the vdi code, and they can be trivially replaced with the byte-based
> bdrv_pread() and bdrv_pwrite().
> 
> Signed-off-by: Alberto Garcia <berto@igalia.com>
> ---
>   block/vdi.c | 15 +++++++++------
>   1 file changed, 9 insertions(+), 6 deletions(-)
> 
> diff --git a/block/vdi.c b/block/vdi.c
> index e1c42ad732..9caeb50dd1 100644
> --- a/block/vdi.c
> +++ b/block/vdi.c
> @@ -171,6 +171,8 @@ typedef struct {
>       uint64_t unused2[7];
>   } QEMU_PACKED VdiHeader;
>   
> +QEMU_BUILD_BUG_ON(sizeof(VdiHeader) != 512);
> +
>   typedef struct {
>       /* The block map entries are little endian (even in memory). */
>       uint32_t *bmap;
> @@ -384,7 +386,7 @@ static int vdi_open(BlockDriverState *bs, QDict *options, int flags,
>   
>       logout("\n");
>   
> -    ret = bdrv_read(bs->file, 0, (uint8_t *)&header, 1);
> +    ret = bdrv_pread(bs->file, 0, (uint8_t *)&header, sizeof(header));

bdrv_pread parameter buf parameter is void, so (uint8_t *) conversion is not needed
(and even confusing)

>       if (ret < 0) {
>           goto fail;
>       }
> @@ -484,8 +486,8 @@ static int vdi_open(BlockDriverState *bs, QDict *options, int flags,
>           goto fail;
>       }
>   
> -    ret = bdrv_read(bs->file, s->bmap_sector, (uint8_t *)s->bmap,
> -                    bmap_size);
> +    ret = bdrv_pread(bs->file, header.offset_bmap, (uint8_t *)s->bmap,
> +                     bmap_size * SECTOR_SIZE);

and here

>       if (ret < 0) {
>           goto fail_free_bmap;
>       }
> @@ -704,7 +706,7 @@ nonallocating_write:
>           assert(VDI_IS_ALLOCATED(bmap_first));
>           *header = s->header;
>           vdi_header_to_le(header);
> -        ret = bdrv_write(bs->file, 0, block, 1);
> +        ret = bdrv_pwrite(bs->file, 0, block, sizeof(VdiHeader));

maybe, more self-descriptive:
  ret = bdrv_pwrite(bs->file, 0, header, sizeof(*header));


with at least extra conversion dropped:
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

>           g_free(block);
>           block = NULL;
>   
> @@ -722,10 +724,11 @@ nonallocating_write:
>           base = ((uint8_t *)&s->bmap[0]) + bmap_first * SECTOR_SIZE;
>           logout("will write %u block map sectors starting from entry %u\n",
>                  n_sectors, bmap_first);
> -        ret = bdrv_write(bs->file, offset, base, n_sectors);
> +        ret = bdrv_pwrite(bs->file, offset * SECTOR_SIZE, base,
> +                          n_sectors * SECTOR_SIZE);
>       }
>   
> -    return ret;
> +    return ret < 0 ? ret : 0;
>   }
>   
>   static int coroutine_fn vdi_co_do_create(BlockdevCreateOptions *create_options,
> 


-- 
Best regards,
Vladimir

Re: [Qemu-devel] [PATCH v2 3/5] vvfat: Replace bdrv_{read, write}() with bdrv_{pread, pwrite}()

[Vladimir Sementsov-Ogievskiy]

01.05.2019 21:13, Alberto Garcia wrote:
> There's only a couple of bdrv_read() and bdrv_write() calls left in
> the vvfat code, and they can be trivially replaced with the byte-based
> bdrv_pread() and bdrv_pwrite().
> 
> Signed-off-by: Alberto Garcia <berto@igalia.com>
> ---
>   block/vvfat.c | 12 +++++++-----
>   1 file changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/block/vvfat.c b/block/vvfat.c
> index 5f66787890..253cc716dd 100644
> --- a/block/vvfat.c
> +++ b/block/vvfat.c
> @@ -1494,8 +1494,8 @@ static int vvfat_read(BlockDriverState *bs, int64_t sector_num,
>                   DLOG(fprintf(stderr, "sectors %" PRId64 "+%" PRId64
>                                " allocated\n", sector_num,
>                                n >> BDRV_SECTOR_BITS));
> -                if (bdrv_read(s->qcow, sector_num, buf + i * 0x200,
> -                              n >> BDRV_SECTOR_BITS)) {
> +                if (bdrv_pread(s->qcow, sector_num * BDRV_SECTOR_SIZE,
> +                               buf + i * 0x200, n) < 0) {

Shouldn't we use QEMU_ALIGN_DOWN(n, BDRV_SECTOR_SIZE) ?
Could bdrv_is_allocated give unaligned n?

>                       return -1;
>                   }
>                   i += (n >> BDRV_SECTOR_BITS) - 1;
> @@ -1983,8 +1983,9 @@ static uint32_t get_cluster_count_for_direntry(BDRVVVFATState* s,
>                           if (res) {
>                               return -1;
>                           }
> -                        res = bdrv_write(s->qcow, offset, s->cluster_buffer, 1);
> -                        if (res) {
> +                        res = bdrv_pwrite(s->qcow, offset * BDRV_SECTOR_SIZE,
> +                                          s->cluster_buffer, BDRV_SECTOR_SIZE);
> +                        if (res < 0) {
>                               return -2;
>                           }
>                       }
> @@ -3050,7 +3051,8 @@ DLOG(checkpoint());
>        * Use qcow backend. Commit later.
>        */
>   DLOG(fprintf(stderr, "Write to qcow backend: %d + %d\n", (int)sector_num, nb_sectors));
> -    ret = bdrv_write(s->qcow, sector_num, buf, nb_sectors);
> +    ret = bdrv_pwrite(s->qcow, sector_num * BDRV_SECTOR_SIZE, buf,
> +                      nb_sectors * BDRV_SECTOR_SIZE);
>       if (ret < 0) {
>           fprintf(stderr, "Error writing to qcow backend\n");
>           return ret;
> 


-- 
Best regards,
Vladimir

Re: [Qemu-devel] [PATCH v2 4/5] block: Remove bdrv_read() and bdrv_write()

[Vladimir Sementsov-Ogievskiy]

01.05.2019 21:13, Alberto Garcia wrote:
> No one is using these functions anymore, all callers have switched to
> the byte-based bdrv_pread() and bdrv_pwrite()
> 
> Signed-off-by: Alberto Garcia <berto@igalia.com>

Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

However, I doubt that we want to save error codes descriptions. On
the other hand, "Return no. of bytes on success or < 0 on error." is good
addition, but it becomes unrelated to this patch if drop error codes
description.

> ---
>   block/io.c            | 43 +++++++------------------------------------
>   include/block/block.h |  4 ----
>   2 files changed, 7 insertions(+), 40 deletions(-)
> 
> diff --git a/block/io.c b/block/io.c
> index dfc153b8d8..396d5364ba 100644
> --- a/block/io.c
> +++ b/block/io.c
> @@ -837,42 +837,6 @@ static int bdrv_prwv_co(BdrvChild *child, int64_t offset,
>       return rwco.ret;
>   }
>   
> -/*
> - * Process a synchronous request using coroutines
> - */
> -static int bdrv_rw_co(BdrvChild *child, int64_t sector_num, uint8_t *buf,
> -                      int nb_sectors, bool is_write, BdrvRequestFlags flags)
> -{
> -    QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf,
> -                                            nb_sectors * BDRV_SECTOR_SIZE);
> -
> -    if (nb_sectors < 0 || nb_sectors > BDRV_REQUEST_MAX_SECTORS) {
> -        return -EINVAL;
> -    }
> -
> -    return bdrv_prwv_co(child, sector_num << BDRV_SECTOR_BITS,
> -                        &qiov, is_write, flags);
> -}
> -
> -/* return < 0 if error. See bdrv_write() for the return codes */
> -int bdrv_read(BdrvChild *child, int64_t sector_num,
> -              uint8_t *buf, int nb_sectors)
> -{
> -    return bdrv_rw_co(child, sector_num, buf, nb_sectors, false, 0);
> -}
> -
> -/* Return < 0 if error. Important errors are:
> -  -EIO         generic I/O error (may happen for all errors)
> -  -ENOMEDIUM   No media inserted.
> -  -EINVAL      Invalid sector number or nb_sectors
> -  -EACCES      Trying to write a read-only device
> -*/
> -int bdrv_write(BdrvChild *child, int64_t sector_num,
> -               const uint8_t *buf, int nb_sectors)
> -{
> -    return bdrv_rw_co(child, sector_num, (uint8_t *)buf, nb_sectors, true, 0);
> -}
> -
>   int bdrv_pwrite_zeroes(BdrvChild *child, int64_t offset,
>                          int bytes, BdrvRequestFlags flags)
>   {
> @@ -935,6 +899,7 @@ int bdrv_preadv(BdrvChild *child, int64_t offset, QEMUIOVector *qiov)
>       return qiov->size;
>   }
>   
> +/* See bdrv_pwrite() for the return codes */
>   int bdrv_pread(BdrvChild *child, int64_t offset, void *buf, int bytes)
>   {
>       QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes);
> @@ -958,6 +923,12 @@ int bdrv_pwritev(BdrvChild *child, int64_t offset, QEMUIOVector *qiov)
>       return qiov->size;
>   }
>   
> +/* Return no. of bytes on success or < 0 on error. Important errors are:
> +  -EIO         generic I/O error (may happen for all errors)
> +  -ENOMEDIUM   No media inserted.
> +  -EINVAL      Invalid offset or number of bytes
> +  -EACCES      Trying to write a read-only device
> +*/
>   int bdrv_pwrite(BdrvChild *child, int64_t offset, const void *buf, int bytes)
>   {
>       QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes);
> diff --git a/include/block/block.h b/include/block/block.h
> index c7a26199aa..5e2b98b0ee 100644
> --- a/include/block/block.h
> +++ b/include/block/block.h
> @@ -316,10 +316,6 @@ int bdrv_reopen_prepare(BDRVReopenState *reopen_state,
>                           BlockReopenQueue *queue, Error **errp);
>   void bdrv_reopen_commit(BDRVReopenState *reopen_state);
>   void bdrv_reopen_abort(BDRVReopenState *reopen_state);
> -int bdrv_read(BdrvChild *child, int64_t sector_num,
> -              uint8_t *buf, int nb_sectors);
> -int bdrv_write(BdrvChild *child, int64_t sector_num,
> -               const uint8_t *buf, int nb_sectors);
>   int bdrv_pwrite_zeroes(BdrvChild *child, int64_t offset,
>                          int bytes, BdrvRequestFlags flags);
>   int bdrv_make_zero(BdrvChild *child, BdrvRequestFlags flags);
> 


-- 
Best regards,
Vladimir

Re: [Qemu-devel] [PATCH v2 3/5] vvfat: Replace bdrv_{read, write}() with bdrv_{pread, pwrite}()

[Eric Blake]

[-- Attachment #1: Type: text/plain, Size: 1905 bytes --]

On 5/6/19 11:47 AM, Vladimir Sementsov-Ogievskiy wrote:
> 01.05.2019 21:13, Alberto Garcia wrote:
>> There's only a couple of bdrv_read() and bdrv_write() calls left in
>> the vvfat code, and they can be trivially replaced with the byte-based
>> bdrv_pread() and bdrv_pwrite().
>>
>> Signed-off-by: Alberto Garcia <berto@igalia.com>
>> ---
>>   block/vvfat.c | 12 +++++++-----
>>   1 file changed, 7 insertions(+), 5 deletions(-)
>>
>> diff --git a/block/vvfat.c b/block/vvfat.c
>> index 5f66787890..253cc716dd 100644
>> --- a/block/vvfat.c
>> +++ b/block/vvfat.c
>> @@ -1494,8 +1494,8 @@ static int vvfat_read(BlockDriverState *bs, int64_t sector_num,
>>                   DLOG(fprintf(stderr, "sectors %" PRId64 "+%" PRId64
>>                                " allocated\n", sector_num,
>>                                n >> BDRV_SECTOR_BITS));
>> -                if (bdrv_read(s->qcow, sector_num, buf + i * 0x200,
>> -                              n >> BDRV_SECTOR_BITS)) {
>> +                if (bdrv_pread(s->qcow, sector_num * BDRV_SECTOR_SIZE,
>> +                               buf + i * 0x200, n) < 0) {
> 
> Shouldn't we use QEMU_ALIGN_DOWN(n, BDRV_SECTOR_SIZE) ?

No, n should already be aligned, which makes align_down a no-op.

> Could bdrv_is_allocated give unaligned n?
> 

Yes, bdrv_is_allocated can return unaligned n in some situations; I had
a patch that didn't make 4.0 that would add bdrv_block_status_aligned
for cases where we need to guarantee that different alignment of a
backing chain doesn't bleed through to the specified alignment of the
current layer. But those situations are rare, and I need to revisit
those and send a v2; so I don't see a problem with this one going in
during the meantime as-is.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org


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Re: [Qemu-devel] [PATCH v2 3/5] vvfat: Replace bdrv_{read, write}() with bdrv_{pread, pwrite}()

[Vladimir Sementsov-Ogievskiy]

06.05.2019 20:06, Eric Blake wrote:
> On 5/6/19 11:47 AM, Vladimir Sementsov-Ogievskiy wrote:
>> 01.05.2019 21:13, Alberto Garcia wrote:
>>> There's only a couple of bdrv_read() and bdrv_write() calls left in
>>> the vvfat code, and they can be trivially replaced with the byte-based
>>> bdrv_pread() and bdrv_pwrite().
>>>
>>> Signed-off-by: Alberto Garcia <berto@igalia.com>
>>> ---
>>>    block/vvfat.c | 12 +++++++-----
>>>    1 file changed, 7 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/block/vvfat.c b/block/vvfat.c
>>> index 5f66787890..253cc716dd 100644
>>> --- a/block/vvfat.c
>>> +++ b/block/vvfat.c
>>> @@ -1494,8 +1494,8 @@ static int vvfat_read(BlockDriverState *bs, int64_t sector_num,
>>>                    DLOG(fprintf(stderr, "sectors %" PRId64 "+%" PRId64
>>>                                 " allocated\n", sector_num,
>>>                                 n >> BDRV_SECTOR_BITS));
>>> -                if (bdrv_read(s->qcow, sector_num, buf + i * 0x200,
>>> -                              n >> BDRV_SECTOR_BITS)) {
>>> +                if (bdrv_pread(s->qcow, sector_num * BDRV_SECTOR_SIZE,
>>> +                               buf + i * 0x200, n) < 0) {
>>
>> Shouldn't we use QEMU_ALIGN_DOWN(n, BDRV_SECTOR_SIZE) ?
> 
> No, n should already be aligned, which makes align_down a no-op.
> 
>> Could bdrv_is_allocated give unaligned n?
>>
> 
> Yes, bdrv_is_allocated can return unaligned n in some situations; I had
> a patch that didn't make 4.0 that would add bdrv_block_status_aligned
> for cases where we need to guarantee that different alignment of a
> backing chain doesn't bleed through to the specified alignment of the
> current layer. But those situations are rare, and I need to revisit
> those and send a v2; so I don't see a problem with this one going in
> during the meantime as-is.
> 

Than, n is not already aligned, as it comes from bdrv_is_allocated.

-- 
Best regards,
Vladimir

Re: [Qemu-devel] [PATCH v2 3/5] vvfat: Replace bdrv_{read, write}() with bdrv_{pread, pwrite}()

[Eric Blake]

[-- Attachment #1: Type: text/plain, Size: 2339 bytes --]

On 5/6/19 12:19 PM, Vladimir Sementsov-Ogievskiy wrote:

>>>> +++ b/block/vvfat.c
>>>> @@ -1494,8 +1494,8 @@ static int vvfat_read(BlockDriverState *bs, int64_t sector_num,
>>>>                    DLOG(fprintf(stderr, "sectors %" PRId64 "+%" PRId64
>>>>                                 " allocated\n", sector_num,
>>>>                                 n >> BDRV_SECTOR_BITS));
>>>> -                if (bdrv_read(s->qcow, sector_num, buf + i * 0x200,
>>>> -                              n >> BDRV_SECTOR_BITS)) {
>>>> +                if (bdrv_pread(s->qcow, sector_num * BDRV_SECTOR_SIZE,
>>>> +                               buf + i * 0x200, n) < 0) {
>>>
>>> Shouldn't we use QEMU_ALIGN_DOWN(n, BDRV_SECTOR_SIZE) ?
>>
>> No, n should already be aligned, which makes align_down a no-op.
>>
>>> Could bdrv_is_allocated give unaligned n?
>>>
>>
>> Yes, bdrv_is_allocated can return unaligned n in some situations; I had
>> a patch that didn't make 4.0 that would add bdrv_block_status_aligned
>> for cases where we need to guarantee that different alignment of a
>> backing chain doesn't bleed through to the specified alignment of the
>> current layer. But those situations are rare, and I need to revisit
>> those and send a v2; so I don't see a problem with this one going in
>> during the meantime as-is.
>>
> 
> Than, n is not already aligned, as it comes from bdrv_is_allocated.

Note that whether bdrv_is_allocated can return data not aligned to 512
depends on the driver. It is possible when querying file-posix.c, but
only for a POSIX file that encounters EOF mid-sector. However, it is not
possible for the qcow2 driver.  The patches I need to rework are worried
more about cases where a block device with request_alignment of 4k can
still see 512-alignment leak through from a backing file.  But since
vvfat is grabbing alignment from a qcow2 image, and not a raw POSIX
file, we should never see sub-sector alignment.

So my answers above were terse but correct: bdrv_is_allocated can return
unaligned data in some cases, but vvfat should not be one of those
cases. If you'd like to add an assert instead of a QEMU_ALIGN_DOWN, that
should be reasonable.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org


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Re: [Qemu-devel] [PATCH v2 2/5] vdi: Replace bdrv_{read, write}() with bdrv_{pread, pwrite}()

[Kevin Wolf]

Am 06.05.2019 um 18:38 hat Vladimir Sementsov-Ogievskiy geschrieben:
> 01.05.2019 21:13, Alberto Garcia wrote:
> > There's only a couple of bdrv_read() and bdrv_write() calls left in
> > the vdi code, and they can be trivially replaced with the byte-based
> > bdrv_pread() and bdrv_pwrite().
> > 
> > Signed-off-by: Alberto Garcia <berto@igalia.com>
> > ---
> >   block/vdi.c | 15 +++++++++------
> >   1 file changed, 9 insertions(+), 6 deletions(-)
> > 
> > diff --git a/block/vdi.c b/block/vdi.c
> > index e1c42ad732..9caeb50dd1 100644
> > --- a/block/vdi.c
> > +++ b/block/vdi.c
> > @@ -171,6 +171,8 @@ typedef struct {
> >       uint64_t unused2[7];
> >   } QEMU_PACKED VdiHeader;
> >   
> > +QEMU_BUILD_BUG_ON(sizeof(VdiHeader) != 512);
> > +
> >   typedef struct {
> >       /* The block map entries are little endian (even in memory). */
> >       uint32_t *bmap;
> > @@ -384,7 +386,7 @@ static int vdi_open(BlockDriverState *bs, QDict *options, int flags,
> >   
> >       logout("\n");
> >   
> > -    ret = bdrv_read(bs->file, 0, (uint8_t *)&header, 1);
> > +    ret = bdrv_pread(bs->file, 0, (uint8_t *)&header, sizeof(header));
> 
> bdrv_pread parameter buf parameter is void, so (uint8_t *) conversion is not needed
> (and even confusing)
> 
> >       if (ret < 0) {
> >           goto fail;
> >       }
> > @@ -484,8 +486,8 @@ static int vdi_open(BlockDriverState *bs, QDict *options, int flags,
> >           goto fail;
> >       }
> >   
> > -    ret = bdrv_read(bs->file, s->bmap_sector, (uint8_t *)s->bmap,
> > -                    bmap_size);
> > +    ret = bdrv_pread(bs->file, header.offset_bmap, (uint8_t *)s->bmap,
> > +                     bmap_size * SECTOR_SIZE);
> 
> and here
> 
> >       if (ret < 0) {
> >           goto fail_free_bmap;
> >       }
> > @@ -704,7 +706,7 @@ nonallocating_write:
> >           assert(VDI_IS_ALLOCATED(bmap_first));
> >           *header = s->header;
> >           vdi_header_to_le(header);
> > -        ret = bdrv_write(bs->file, 0, block, 1);
> > +        ret = bdrv_pwrite(bs->file, 0, block, sizeof(VdiHeader));
> 
> maybe, more self-descriptive:
>   ret = bdrv_pwrite(bs->file, 0, header, sizeof(*header));
> 
> 
> with at least extra conversion dropped:
> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

I'll drop the casts while applying.

Kevin

Re: [Qemu-devel] [PATCH v2 0/5] Remove bdrv_read() and bdrv_write()

[Kevin Wolf]

Am 01.05.2019 um 20:13 hat Alberto Garcia geschrieben:
> Hi,
> 
> this API only had a few users left so it can be easily removed.

Thanks, applied to the block branch.

Kevin