mirror of https://gitee.com/openkylin/qemu.git
block: Avoid second open for format probing
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>
This commit is contained in:
Kevin Wolf
parent
7b27245239
commit
f500a6d3c2
74
block.c
74
block.c
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@ -518,22 +518,16 @@ BlockDriver *bdrv_find_protocol(const char *filename)
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return NULL;
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}
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static int find_image_format(const char *filename, BlockDriver **pdrv)
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static int find_image_format(BlockDriverState *bs, const char *filename,
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BlockDriver **pdrv)
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{
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int ret, score, score_max;
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int score, score_max;
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BlockDriver *drv1, *drv;
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uint8_t buf[2048];
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BlockDriverState *bs;
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ret = bdrv_file_open(&bs, filename, 0);
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if (ret < 0) {
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*pdrv = NULL;
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return ret;
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}
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int ret = 0;
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/* Return the raw BlockDriver * to scsi-generic devices or empty drives */
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if (bs->sg || !bdrv_is_inserted(bs)) {
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bdrv_delete(bs);
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drv = bdrv_find_format("raw");
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if (!drv) {
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ret = -ENOENT;
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@ -543,7 +537,6 @@ static int find_image_format(const char *filename, BlockDriver **pdrv)
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}
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ret = bdrv_pread(bs, 0, buf, sizeof(buf));
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bdrv_delete(bs);
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if (ret < 0) {
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*pdrv = NULL;
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return ret;
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@ -657,7 +650,8 @@ static int bdrv_open_flags(BlockDriverState *bs, int flags)
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/*
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* Common part for opening disk images and files
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*/
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static int bdrv_open_common(BlockDriverState *bs, const char *filename,
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static int bdrv_open_common(BlockDriverState *bs, BlockDriverState *file,
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const char *filename,
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int flags, BlockDriver *drv)
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{
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int ret, open_flags;
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@ -691,12 +685,16 @@ static int bdrv_open_common(BlockDriverState *bs, const char *filename,
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/* Open the image, either directly or using a protocol */
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if (drv->bdrv_file_open) {
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ret = drv->bdrv_file_open(bs, filename, open_flags);
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} else {
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ret = bdrv_file_open(&bs->file, filename, open_flags);
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if (ret >= 0) {
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ret = drv->bdrv_open(bs, open_flags);
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if (file != NULL) {
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bdrv_swap(file, bs);
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ret = 0;
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} else {
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ret = drv->bdrv_file_open(bs, filename, open_flags);
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}
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} else {
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assert(file != NULL);
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bs->file = file;
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ret = drv->bdrv_open(bs, open_flags);
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}
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if (ret < 0) {
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@ -716,10 +714,7 @@ static int bdrv_open_common(BlockDriverState *bs, const char *filename,
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return 0;
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free_and_fail:
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if (bs->file) {
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bdrv_delete(bs->file);
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bs->file = NULL;
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}
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bs->file = NULL;
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g_free(bs->opaque);
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bs->opaque = NULL;
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bs->drv = NULL;
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@ -741,7 +736,7 @@ int bdrv_file_open(BlockDriverState **pbs, const char *filename, int flags)
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}
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bs = bdrv_new("");
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ret = bdrv_open_common(bs, filename, flags, drv);
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ret = bdrv_open_common(bs, NULL, filename, flags, drv);
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if (ret < 0) {
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bdrv_delete(bs);
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return ret;
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@ -796,6 +791,7 @@ int bdrv_open(BlockDriverState *bs, const char *filename, int flags,
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int ret;
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/* TODO: extra byte is a hack to ensure MAX_PATH space on Windows. */
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char tmp_filename[PATH_MAX + 1];
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BlockDriverState *file = NULL;
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if (flags & BDRV_O_SNAPSHOT) {
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BlockDriverState *bs1;
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@ -855,25 +851,36 @@ int bdrv_open(BlockDriverState *bs, const char *filename, int flags,
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bs->is_temporary = 1;
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}
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/* Find the right image format driver */
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if (!drv) {
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ret = find_image_format(filename, &drv);
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}
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if (!drv) {
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goto unlink_and_fail;
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}
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/* Open image file without format layer */
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if (flags & BDRV_O_RDWR) {
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flags |= BDRV_O_ALLOW_RDWR;
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}
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ret = bdrv_file_open(&file, filename, bdrv_open_flags(bs, flags));
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if (ret < 0) {
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return ret;
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}
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/* Find the right image format driver */
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if (!drv) {
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ret = find_image_format(file, filename, &drv);
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}
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if (!drv) {
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goto unlink_and_fail;
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}
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/* Open the image */
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ret = bdrv_open_common(bs, filename, flags, drv);
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ret = bdrv_open_common(bs, file, filename, flags, drv);
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if (ret < 0) {
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goto unlink_and_fail;
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}
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if (bs->file != file) {
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bdrv_delete(file);
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file = NULL;
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}
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/* If there is a backing file, use it */
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if ((flags & BDRV_O_NO_BACKING) == 0) {
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ret = bdrv_open_backing_file(bs);
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@ -895,6 +902,9 @@ int bdrv_open(BlockDriverState *bs, const char *filename, int flags,
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return 0;
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unlink_and_fail:
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if (file != NULL) {
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bdrv_delete(file);
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}
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if (bs->is_temporary) {
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unlink(filename);
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}
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