Re: [Qemu-devel] [PATCH 3/3] cow: use qemu block API

2010-06-08 Thread Christoph Hellwig 
On Mon, Jun 07, 2010 at 02:27:40PM +0200, Markus Armbruster wrote:
 Christoph Hellwig h...@lst.de writes:
 
  Use bdrv_pwrite to access the backing device instead of pread, and
  convert the driver to implementing the bdrv_open method which gives
  it an already opened BlockDriverState for the underlying device.
 
  Signed-off-by: Christoph Hellwig h...@lst.de
 
 In my (admittedly limited) understanding, we need this for sane protocol
 handling in -blockdev  friends.

Yes - not just in -blockdev but also in general.

Re: [Qemu-devel] [PATCH 3/3] cow: use qemu block API

2010-06-08 Thread Kevin Wolf 
Am 07.06.2010 12:06, schrieb Christoph Hellwig:
 Use bdrv_pwrite to access the backing device instead of pread, and
 convert the driver to implementing the bdrv_open method which gives
 it an already opened BlockDriverState for the underlying device.
 
 Signed-off-by: Christoph Hellwig h...@lst.de

Thanks, applied all to the block branch.

Kevin

[Qemu-devel] [PATCH 3/3] cow: use qemu block API

2010-06-07 Thread Christoph Hellwig 
Use bdrv_pwrite to access the backing device instead of pread, and
convert the driver to implementing the bdrv_open method which gives
it an already opened BlockDriverState for the underlying device.

Signed-off-by: Christoph Hellwig h...@lst.de

Index: qemu/block/cow.c
===
--- qemu.orig/block/cow.c   2010-05-07 17:07:56.0 +0200
+++ qemu/block/cow.c2010-05-07 17:11:11.498255489 +0200
@@ -42,7 +42,6 @@ struct cow_header_v2 {
 };
 
 typedef struct BDRVCowState {
-int fd;
 int64_t cow_sectors_offset;
 } BDRVCowState;
 
@@ -58,23 +57,16 @@ static int cow_probe(const uint8_t *buf,
 return 0;
 }
 
-static int cow_open(BlockDriverState *bs, const char *filename, int flags)
+static int cow_open(BlockDriverState *bs, int flags)
 {
 BDRVCowState *s = bs-opaque;
-int fd;
 struct cow_header_v2 cow_header;
 int bitmap_size;
 int64_t size;
 
-fd = open(filename, O_RDWR | O_BINARY | O_LARGEFILE);
-if (fd  0) {
-fd = open(filename, O_RDONLY | O_BINARY | O_LARGEFILE);
-if (fd  0)
-return -1;
-}
-s-fd = fd;
 /* see if it is a cow image */
-if (pread(fd, cow_header, sizeof(cow_header), 0) != sizeof(cow_header)) {
+if (bdrv_pread(bs-file, 0, cow_header, sizeof(cow_header)) !=
+sizeof(cow_header)) {
 goto fail;
 }
 
@@ -94,7 +86,6 @@ static int cow_open(BlockDriverState *bs
 s-cow_sectors_offset = (bitmap_size + 511)  ~511;
 return 0;
  fail:
-close(fd);
 return -1;
 }
 
@@ -104,18 +95,17 @@ static int cow_open(BlockDriverState *bs
  */
 static inline int cow_set_bit(BlockDriverState *bs, int64_t bitnum)
 {
-BDRVCowState *s = bs-opaque;
 uint64_t offset = sizeof(struct cow_header_v2) + bitnum / 8;
 uint8_t bitmap;
 
-if (pread(s-fd, bitmap, sizeof(bitmap), offset) !=
+if (bdrv_pread(bs-file, offset, bitmap, sizeof(bitmap)) !=
sizeof(bitmap)) {
return -errno;
 }
 
 bitmap |= (1  (bitnum % 8));
 
-if (pwrite(s-fd, bitmap, sizeof(bitmap), offset) !=
+if (bdrv_pwrite(bs-file, offset, bitmap, sizeof(bitmap)) !=
sizeof(bitmap)) {
return -errno;
 }
@@ -124,11 +114,10 @@ static inline int cow_set_bit(BlockDrive
 
 static inline int is_bit_set(BlockDriverState *bs, int64_t bitnum)
 {
-BDRVCowState *s = bs-opaque;
 uint64_t offset = sizeof(struct cow_header_v2) + bitnum / 8;
 uint8_t bitmap;
 
-if (pread(s-fd, bitmap, sizeof(bitmap), offset) !=
+if (bdrv_pread(bs-file, offset, bitmap, sizeof(bitmap)) !=
sizeof(bitmap)) {
return -errno;
 }
@@ -186,8 +175,9 @@ static int cow_read(BlockDriverState *bs
 
 while (nb_sectors  0) {
 if (cow_is_allocated(bs, sector_num, nb_sectors, n)) {
-ret = pread(s-fd, buf, n * 512,
-s-cow_sectors_offset + sector_num * 512);
+ret = bdrv_pread(bs-file,
+s-cow_sectors_offset + sector_num * 512,
+buf, n * 512);
 if (ret != n * 512)
 return -1;
 } else {
@@ -213,8 +203,8 @@ static int cow_write(BlockDriverState *b
 BDRVCowState *s = bs-opaque;
 int ret;
 
-ret = pwrite(s-fd, buf, nb_sectors * 512,
- s-cow_sectors_offset + sector_num * 512);
+ret = bdrv_pwrite(bs-file, s-cow_sectors_offset + sector_num * 512,
+  buf, nb_sectors * 512);
 if (ret != nb_sectors * 512)
 return -1;
 
@@ -223,8 +213,6 @@ static int cow_write(BlockDriverState *b
 
 static void cow_close(BlockDriverState *bs)
 {
-BDRVCowState *s = bs-opaque;
-close(s-fd);
 }
 
 static int cow_create(const char *filename, QEMUOptionParameter *options)
@@ -294,8 +282,7 @@ exit:
 
 static void cow_flush(BlockDriverState *bs)
 {
-BDRVCowState *s = bs-opaque;
-qemu_fdatasync(s-fd);
+bdrv_flush(bs-file);
 }
 
 static QEMUOptionParameter cow_create_options[] = {
@@ -316,7 +303,7 @@ static BlockDriver bdrv_cow = {
 .format_name   = cow,
 .instance_size = sizeof(BDRVCowState),
 .bdrv_probe= cow_probe,
-.bdrv_file_open= cow_open,
+.bdrv_open = cow_open,
 .bdrv_read = cow_read,
 .bdrv_write= cow_write,
 .bdrv_close= cow_close,

Re: [Qemu-devel] [PATCH 3/3] cow: use qemu block API

2010-06-07 Thread Markus Armbruster 
Christoph Hellwig h...@lst.de writes:

 Use bdrv_pwrite to access the backing device instead of pread, and
 convert the driver to implementing the bdrv_open method which gives
 it an already opened BlockDriverState for the underlying device.

 Signed-off-by: Christoph Hellwig h...@lst.de

In my (admittedly limited) understanding, we need this for sane protocol
handling in -blockdev  friends.

[Qemu-devel] [PATCH 3/3] cow: use qemu block API

2010-05-07 Thread Christoph Hellwig 
Use bdrv_pwrite to access the backing device instead of pread, and
convert the driver to implementing the bdrv_open method which gives
it an already opened BlockDriverState for the underlying device.

Signed-off-by: Christoph Hellwig h...@lst.de

Index: qemu/block/cow.c
===
--- qemu.orig/block/cow.c   2010-05-07 17:07:56.0 +0200
+++ qemu/block/cow.c2010-05-07 17:11:11.498255489 +0200
@@ -42,7 +42,6 @@ struct cow_header_v2 {
 };
 
 typedef struct BDRVCowState {
-int fd;
 int64_t cow_sectors_offset;
 } BDRVCowState;
 
@@ -58,23 +57,16 @@ static int cow_probe(const uint8_t *buf,
 return 0;
 }
 
-static int cow_open(BlockDriverState *bs, const char *filename, int flags)
+static int cow_open(BlockDriverState *bs, int flags)
 {
 BDRVCowState *s = bs-opaque;
-int fd;
 struct cow_header_v2 cow_header;
 int bitmap_size;
 int64_t size;
 
-fd = open(filename, O_RDWR | O_BINARY | O_LARGEFILE);
-if (fd  0) {
-fd = open(filename, O_RDONLY | O_BINARY | O_LARGEFILE);
-if (fd  0)
-return -1;
-}
-s-fd = fd;
 /* see if it is a cow image */
-if (pread(fd, cow_header, sizeof(cow_header), 0) != sizeof(cow_header)) {
+if (bdrv_pread(bs-file, 0, cow_header, sizeof(cow_header)) !=
+sizeof(cow_header)) {
 goto fail;
 }
 
@@ -94,7 +86,6 @@ static int cow_open(BlockDriverState *bs
 s-cow_sectors_offset = (bitmap_size + 511)  ~511;
 return 0;
  fail:
-close(fd);
 return -1;
 }
 
@@ -104,18 +95,17 @@ static int cow_open(BlockDriverState *bs
  */
 static inline int cow_set_bit(BlockDriverState *bs, int64_t bitnum)
 {
-BDRVCowState *s = bs-opaque;
 uint64_t offset = sizeof(struct cow_header_v2) + bitnum / 8;
 uint8_t bitmap;
 
-if (pread(s-fd, bitmap, sizeof(bitmap), offset) !=
+if (bdrv_pread(bs-file, offset, bitmap, sizeof(bitmap)) !=
sizeof(bitmap)) {
return -errno;
 }
 
 bitmap |= (1  (bitnum % 8));
 
-if (pwrite(s-fd, bitmap, sizeof(bitmap), offset) !=
+if (bdrv_pwrite(bs-file, offset, bitmap, sizeof(bitmap)) !=
sizeof(bitmap)) {
return -errno;
 }
@@ -124,11 +114,10 @@ static inline int cow_set_bit(BlockDrive
 
 static inline int is_bit_set(BlockDriverState *bs, int64_t bitnum)
 {
-BDRVCowState *s = bs-opaque;
 uint64_t offset = sizeof(struct cow_header_v2) + bitnum / 8;
 uint8_t bitmap;
 
-if (pread(s-fd, bitmap, sizeof(bitmap), offset) !=
+if (bdrv_pread(bs-file, offset, bitmap, sizeof(bitmap)) !=
sizeof(bitmap)) {
return -errno;
 }
@@ -186,8 +175,9 @@ static int cow_read(BlockDriverState *bs
 
 while (nb_sectors  0) {
 if (cow_is_allocated(bs, sector_num, nb_sectors, n)) {
-ret = pread(s-fd, buf, n * 512,
-s-cow_sectors_offset + sector_num * 512);
+ret = bdrv_pread(bs-file,
+s-cow_sectors_offset + sector_num * 512,
+buf, n * 512);
 if (ret != n * 512)
 return -1;
 } else {
@@ -213,8 +203,8 @@ static int cow_write(BlockDriverState *b
 BDRVCowState *s = bs-opaque;
 int ret;
 
-ret = pwrite(s-fd, buf, nb_sectors * 512,
- s-cow_sectors_offset + sector_num * 512);
+ret = bdrv_pwrite(bs-file, s-cow_sectors_offset + sector_num * 512,
+  buf, nb_sectors * 512);
 if (ret != nb_sectors * 512)
 return -1;
 
@@ -223,8 +213,6 @@ static int cow_write(BlockDriverState *b
 
 static void cow_close(BlockDriverState *bs)
 {
-BDRVCowState *s = bs-opaque;
-close(s-fd);
 }
 
 static int cow_create(const char *filename, QEMUOptionParameter *options)
@@ -294,8 +282,7 @@ exit:
 
 static void cow_flush(BlockDriverState *bs)
 {
-BDRVCowState *s = bs-opaque;
-qemu_fdatasync(s-fd);
+bdrv_flush(bs-file);
 }
 
 static QEMUOptionParameter cow_create_options[] = {
@@ -316,7 +303,7 @@ static BlockDriver bdrv_cow = {
 .format_name   = cow,
 .instance_size = sizeof(BDRVCowState),
 .bdrv_probe= cow_probe,
-.bdrv_file_open= cow_open,
+.bdrv_open = cow_open,
 .bdrv_read = cow_read,
 .bdrv_write= cow_write,
 .bdrv_close= cow_close,