Re: [Qemu-devel] [PATCH v2 12/17] block: Set request_alignment during .bdrv_refresh_limits()

[Fam Zheng]

On Tue, 06/14 15:30, Eric Blake wrote:
> We want to eventually stick request_alignment alongside other
> BlockLimits, but first, we must ensure it is populated at the
> same time as all other limits, rather than being a special case
> that is set only when a block is first opened.
> 
> Add a .bdrv_refresh_limits() to all four of our legacy devices
> that will always be sector-only (bochs, cloop, dmg, vvfat), in
> spite of their recent conversion to expose a byte interface.
> 
> Signed-off-by: Eric Blake 

Reviewed-by: Fam Zheng 

[Qemu-devel] [PATCH v2 12/17] block: Set request_alignment during .bdrv_refresh_limits()

[Eric Blake]

We want to eventually stick request_alignment alongside other
BlockLimits, but first, we must ensure it is populated at the
same time as all other limits, rather than being a special case
that is set only when a block is first opened.

Add a .bdrv_refresh_limits() to all four of our legacy devices
that will always be sector-only (bochs, cloop, dmg, vvfat), in
spite of their recent conversion to expose a byte interface.

Signed-off-by: Eric Blake 

---
v2: new patch
---
 block/bochs.c | 7 ++-
 block/cloop.c | 7 ++-
 block/dmg.c   | 7 ++-
 block/vvfat.c | 7 ++-
 4 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/block/bochs.c b/block/bochs.c
index 6c8d0f3..182c50b 100644
--- a/block/bochs.c
+++ b/block/bochs.c
@@ -105,7 +105,6 @@ static int bochs_open(BlockDriverState *bs, QDict *options, 
int flags,
 int ret;

 bs->read_only = 1; // no write support yet
-bs->request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O supported */

 ret = bdrv_pread(bs->file->bs, 0, , sizeof(bochs));
 if (ret < 0) {
@@ -189,6 +188,11 @@ fail:
 return ret;
 }

+static void bochs_refresh_limits(BlockDriverState *bs, Error **errp)
+{
+bs->request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O supported */
+}
+
 static int64_t seek_to_sector(BlockDriverState *bs, int64_t sector_num)
 {
 BDRVBochsState *s = bs->opaque;
@@ -283,6 +287,7 @@ static BlockDriver bdrv_bochs = {
 .instance_size = sizeof(BDRVBochsState),
 .bdrv_probe= bochs_probe,
 .bdrv_open = bochs_open,
+.bdrv_refresh_limits = bochs_refresh_limits,
 .bdrv_co_preadv = bochs_co_preadv,
 .bdrv_close= bochs_close,
 };
diff --git a/block/cloop.c b/block/cloop.c
index ea5a92b..d574003 100644
--- a/block/cloop.c
+++ b/block/cloop.c
@@ -67,7 +67,6 @@ static int cloop_open(BlockDriverState *bs, QDict *options, 
int flags,
 int ret;

 bs->read_only = 1;
-bs->request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O supported */

 /* read header */
 ret = bdrv_pread(bs->file->bs, 128, >block_size, 4);
@@ -199,6 +198,11 @@ fail:
 return ret;
 }

+static void cloop_refresh_limits(BlockDriverState *bs, Error **errp)
+{
+bs->request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O supported */
+}
+
 static inline int cloop_read_block(BlockDriverState *bs, int block_num)
 {
 BDRVCloopState *s = bs->opaque;
@@ -280,6 +284,7 @@ static BlockDriver bdrv_cloop = {
 .instance_size  = sizeof(BDRVCloopState),
 .bdrv_probe = cloop_probe,
 .bdrv_open  = cloop_open,
+.bdrv_refresh_limits = cloop_refresh_limits,
 .bdrv_co_preadv = cloop_co_preadv,
 .bdrv_close = cloop_close,
 };
diff --git a/block/dmg.c b/block/dmg.c
index 06eb513..1e53cd8 100644
--- a/block/dmg.c
+++ b/block/dmg.c
@@ -439,7 +439,6 @@ static int dmg_open(BlockDriverState *bs, QDict *options, 
int flags,
 int ret;

 bs->read_only = 1;
-bs->request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O supported */

 s->n_chunks = 0;
 s->offsets = s->lengths = s->sectors = s->sectorcounts = NULL;
@@ -547,6 +546,11 @@ fail:
 return ret;
 }

+static void dmg_refresh_limits(BlockDriverState *bs, Error **errp)
+{
+bs->request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O supported */
+}
+
 static inline int is_sector_in_chunk(BDRVDMGState* s,
 uint32_t chunk_num, uint64_t sector_num)
 {
@@ -720,6 +724,7 @@ static BlockDriver bdrv_dmg = {
 .instance_size  = sizeof(BDRVDMGState),
 .bdrv_probe = dmg_probe,
 .bdrv_open  = dmg_open,
+.bdrv_refresh_limits = dmg_refresh_limits,
 .bdrv_co_preadv = dmg_co_preadv,
 .bdrv_close = dmg_close,
 };
diff --git a/block/vvfat.c b/block/vvfat.c
index 6d2e21c..08b1aa3 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -1180,7 +1180,6 @@ static int vvfat_open(BlockDriverState *bs, QDict 
*options, int flags,
 bs->read_only = 0;
 }

-bs->request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O supported */
 bs->total_sectors = cyls * heads * secs;

 if (init_directories(s, dirname, heads, secs, errp)) {
@@ -1212,6 +1211,11 @@ fail:
 return ret;
 }

+static void vvfat_refresh_limits(BlockDriverState *bs, Error **errp)
+{
+bs->request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O supported */
+}
+
 static inline void vvfat_close_current_file(BDRVVVFATState *s)
 {
 if(s->current_mapping) {
@@ -3049,6 +3053,7 @@ static BlockDriver bdrv_vvfat = {

 .bdrv_parse_filename= vvfat_parse_filename,
 .bdrv_file_open = vvfat_open,
+.bdrv_refresh_limits= vvfat_refresh_limits,
 .bdrv_close = vvfat_close,

 .bdrv_co_preadv = vvfat_co_preadv,
-- 
2.5.5