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block: Introduce BDRV_O_NO_BACKING

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If an image references a backing file that doesn't exist, qemu-img info fails
to open this image. Exactly in this case the info would be valuable, though:
the user might want to find out which file is missing.

This patch introduces a BDRV_O_NO_BACKING flag to ignore the backing file when
opening the image. qemu-img info is the first user and provides info now even
if the backing file is invalid.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This commit is contained in:
Kevin Wolf 2010-01-12 12:55:16 +01:00 committed by Anthony Liguori
parent 8f0056b763
commit b783e409bf
3 changed files with 4 additions and 3 deletions
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4
block.c
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@ -477,7 +477,7 @@ int bdrv_open2(BlockDriverState *bs, const char *filename, int flags,
unlink(filename); unlink(filename);
} }
#endif #endif
if (bs->backing_file[0] != '\0') { if ((flags & BDRV_O_NO_BACKING) == 0 && bs->backing_file[0] != '\0') {
/* if there is a backing file, use it */ /* if there is a backing file, use it */
BlockDriver *back_drv = NULL; BlockDriver *back_drv = NULL;
bs->backing_hd = bdrv_new(""); bs->backing_hd = bdrv_new("");
@ -1352,7 +1352,7 @@ const char *bdrv_get_encrypted_filename(BlockDriverState *bs)
void bdrv_get_backing_filename(BlockDriverState *bs, void bdrv_get_backing_filename(BlockDriverState *bs,
char *filename, int filename_size) char *filename, int filename_size)
{ {
if (!bs->backing_hd) { if (!bs->backing_file) {
pstrcpy(filename, filename_size, ""); pstrcpy(filename, filename_size, "");
} else { } else {
pstrcpy(filename, filename_size, bs->backing_file); pstrcpy(filename, filename_size, bs->backing_file);

1
block.h
View File

@ -39,6 +39,7 @@ typedef struct QEMUSnapshotInfo {
#define BDRV_O_NOCACHE 0x0020 /* do not use the host page cache */ #define BDRV_O_NOCACHE 0x0020 /* do not use the host page cache */
#define BDRV_O_CACHE_WB 0x0040 /* use write-back caching */ #define BDRV_O_CACHE_WB 0x0040 /* use write-back caching */
#define BDRV_O_NATIVE_AIO 0x0080 /* use native AIO instead of the thread pool */ #define BDRV_O_NATIVE_AIO 0x0080 /* use native AIO instead of the thread pool */
#define BDRV_O_NO_BACKING 0x0100 /* don't open the backing file */
#define BDRV_O_CACHE_MASK (BDRV_O_NOCACHE | BDRV_O_CACHE_WB) #define BDRV_O_CACHE_MASK (BDRV_O_NOCACHE | BDRV_O_CACHE_WB)

2
qemu-img.c
View File

@ -884,7 +884,7 @@ static int img_info(int argc, char **argv)
} else { } else {
drv = NULL; drv = NULL;
} }
if (bdrv_open2(bs, filename, BRDV_O_FLAGS, drv) < 0) { if (bdrv_open2(bs, filename, BRDV_O_FLAGS | BDRV_O_NO_BACKING, drv) < 0) {
error("Could not open '%s'", filename); error("Could not open '%s'", filename);
} }
bdrv_get_format(bs, fmt_name, sizeof(fmt_name)); bdrv_get_format(bs, fmt_name, sizeof(fmt_name));