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block: correctly set the keep_read_only flag

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I believe the bs->keep_read_only flag is supposed to reflect
the initial open state of the device. If the device is initially
opened R/O, then commit operations, or reopen operations changing
to R/W, are prohibited.

Currently, the keep_read_only flag is only accurate for the active
layer, and its backing file. Subsequent images end up always having
the keep_read_only flag set.

For instance, what happens now:

[  base  ]  kro = 1, ro = 1
    |
    v
[ snap-1 ]  kro = 1, ro = 1
    |
    v
[ snap-2 ]  kro = 0, ro = 1
    |
    v
[ active ]  kro = 0, ro = 0

What we want:

[  base  ]  kro = 0, ro = 1
    |
    v
[ snap-1 ]  kro = 0, ro = 1
    |
    v
[ snap-2 ]  kro = 0, ro = 1
    |
    v
[ active ]  kro = 0, ro = 0

Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Jeff Cody 2012-09-20 15:13:17 -04:00 committed by Kevin Wolf
parent 80dd1aae36
commit be028adced
2 changed files with 8 additions and 7 deletions
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14
block.c
View file

@ -668,7 +668,7 @@ static int bdrv_open_common(BlockDriverState *bs, const char *filename,
open_flags |= BDRV_O_RDWR;
}
bs->keep_read_only = bs->read_only = !(open_flags & BDRV_O_RDWR);
bs->read_only = !(open_flags & BDRV_O_RDWR);
/* Open the image, either directly or using a protocol */
if (drv->bdrv_file_open) {
@ -808,6 +808,12 @@ int bdrv_open(BlockDriverState *bs, const char *filename, int flags,
goto unlink_and_fail;
}
if (flags & BDRV_O_RDWR) {
flags |= BDRV_O_ALLOW_RDWR;
}
bs->keep_read_only = !(flags & BDRV_O_ALLOW_RDWR);
/* Open the image */
ret = bdrv_open_common(bs, filename, flags, drv);
if (ret < 0) {
@ -837,12 +843,6 @@ int bdrv_open(BlockDriverState *bs, const char *filename, int flags,
bdrv_close(bs);
return ret;
}
if (bs->is_temporary) {
bs->backing_hd->keep_read_only = !(flags & BDRV_O_RDWR);
} else {
/* base image inherits from "parent" */
bs->backing_hd->keep_read_only = bs->keep_read_only;
}
}
if (!bdrv_key_required(bs)) {

1
block.h
View file

@ -80,6 +80,7 @@ typedef struct BlockDevOps {
#define BDRV_O_COPY_ON_READ 0x0400 /* copy read backing sectors into image */
#define BDRV_O_INCOMING 0x0800 /* consistency hint for incoming migration */
#define BDRV_O_CHECK 0x1000 /* open solely for consistency check */
#define BDRV_O_ALLOW_RDWR 0x2000 /* allow reopen to change from r/o to r/w */
#define BDRV_O_CACHE_MASK (BDRV_O_NOCACHE | BDRV_O_CACHE_WB | BDRV_O_NO_FLUSH)