* [Qemu-devel] [PATCH v2 2/2] block: Avoid second open for format probing
2012-11-15 12:57 [Qemu-devel] [PATCH v2 0/2] block: Avoid second open for format probing Kevin Wolf
2012-11-15 12:57 ` [Qemu-devel] [PATCH v2 1/2] block: Factor out bdrv_open_flags Kevin Wolf
@ 2012-11-15 12:57 ` Kevin Wolf
2012-11-16 12:32 ` Stefan Hajnoczi
1 sibling, 1 reply; 4+ messages in thread
From: Kevin Wolf @ 2012-11-15 12:57 UTC (permalink / raw)
To: qemu-devel; +Cc: kwolf
This fixes problems that are caused by the additional open/close cycle
of the existing format probing, for example related to qemu-nbd without
-t option or file descriptor passing.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
block.c | 66 ++++++++++++++++++++++++++++++++++++--------------------------
1 files changed, 38 insertions(+), 28 deletions(-)
diff --git a/block.c b/block.c
index 95fd00e..1be667f 100644
--- a/block.c
+++ b/block.c
@@ -518,22 +518,16 @@ BlockDriver *bdrv_find_protocol(const char *filename)
return NULL;
}
-static int find_image_format(const char *filename, BlockDriver **pdrv)
+static int find_image_format(BlockDriverState *bs, const char *filename,
+ BlockDriver **pdrv)
{
- int ret, score, score_max;
+ int score, score_max;
BlockDriver *drv1, *drv;
uint8_t buf[2048];
- BlockDriverState *bs;
-
- ret = bdrv_file_open(&bs, filename, 0);
- if (ret < 0) {
- *pdrv = NULL;
- return ret;
- }
+ int ret = 0;
/* Return the raw BlockDriver * to scsi-generic devices or empty drives */
if (bs->sg || !bdrv_is_inserted(bs)) {
- bdrv_delete(bs);
drv = bdrv_find_format("raw");
if (!drv) {
ret = -ENOENT;
@@ -543,7 +537,6 @@ static int find_image_format(const char *filename, BlockDriver **pdrv)
}
ret = bdrv_pread(bs, 0, buf, sizeof(buf));
- bdrv_delete(bs);
if (ret < 0) {
*pdrv = NULL;
return ret;
@@ -657,7 +650,8 @@ static int bdrv_open_flags(BlockDriverState *bs, int flags)
/*
* Common part for opening disk images and files
*/
-static int bdrv_open_common(BlockDriverState *bs, const char *filename,
+static int bdrv_open_common(BlockDriverState *bs, BlockDriverState *file,
+ const char *filename,
int flags, BlockDriver *drv)
{
int ret, open_flags;
@@ -691,12 +685,16 @@ static int bdrv_open_common(BlockDriverState *bs, const char *filename,
/* Open the image, either directly or using a protocol */
if (drv->bdrv_file_open) {
- ret = drv->bdrv_file_open(bs, filename, open_flags);
- } else {
- ret = bdrv_file_open(&bs->file, filename, open_flags);
- if (ret >= 0) {
- ret = drv->bdrv_open(bs, open_flags);
+ if (file != NULL) {
+ bdrv_swap(file, bs);
+ ret = 0;
+ } else {
+ ret = drv->bdrv_file_open(bs, filename, open_flags);
}
+ } else {
+ assert(file != NULL);
+ bs->file = file;
+ ret = drv->bdrv_open(bs, open_flags);
}
if (ret < 0) {
@@ -716,10 +714,7 @@ static int bdrv_open_common(BlockDriverState *bs, const char *filename,
return 0;
free_and_fail:
- if (bs->file) {
- bdrv_delete(bs->file);
- bs->file = NULL;
- }
+ bs->file = NULL;
g_free(bs->opaque);
bs->opaque = NULL;
bs->drv = NULL;
@@ -741,7 +736,7 @@ int bdrv_file_open(BlockDriverState **pbs, const char *filename, int flags)
}
bs = bdrv_new("");
- ret = bdrv_open_common(bs, filename, flags, drv);
+ ret = bdrv_open_common(bs, NULL, filename, flags, drv);
if (ret < 0) {
bdrv_delete(bs);
return ret;
@@ -795,6 +790,7 @@ int bdrv_open(BlockDriverState *bs, const char *filename, int flags,
{
int ret;
char tmp_filename[PATH_MAX];
+ BlockDriverState *file = NULL;
if (flags & BDRV_O_SNAPSHOT) {
BlockDriverState *bs1;
@@ -854,25 +850,36 @@ int bdrv_open(BlockDriverState *bs, const char *filename, int flags,
bs->is_temporary = 1;
}
+ /* Open image file without format layer */
+ if (flags & BDRV_O_RDWR) {
+ flags |= BDRV_O_ALLOW_RDWR;
+ }
+
+ ret = bdrv_file_open(&file, filename, bdrv_open_flags(bs, flags));
+ if (ret < 0) {
+ return ret;
+ }
+
/* Find the right image format driver */
if (!drv) {
- ret = find_image_format(filename, &drv);
+ ret = find_image_format(file, filename, &drv);
}
if (!drv) {
goto unlink_and_fail;
}
- if (flags & BDRV_O_RDWR) {
- flags |= BDRV_O_ALLOW_RDWR;
- }
-
/* Open the image */
- ret = bdrv_open_common(bs, filename, flags, drv);
+ ret = bdrv_open_common(bs, file, filename, flags, drv);
if (ret < 0) {
goto unlink_and_fail;
}
+ if (bs->file != file) {
+ bdrv_delete(file);
+ file = NULL;
+ }
+
/* If there is a backing file, use it */
if ((flags & BDRV_O_NO_BACKING) == 0) {
ret = bdrv_open_backing_file(bs);
@@ -894,6 +901,9 @@ int bdrv_open(BlockDriverState *bs, const char *filename, int flags,
return 0;
unlink_and_fail:
+ if (file != NULL) {
+ bdrv_delete(file);
+ }
if (bs->is_temporary) {
unlink(filename);
}
--
1.7.6.5
^ permalink raw reply related [flat|nested] 4+ messages in thread