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block: driver should override flags in bdrv_open()

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The BDRV_O_PROTOCOL flag should have an impact only if no driver is
specified explicitly. Therefore, if bdrv_open() is called with an
explicit block driver argument (either through the options QDict or
through the drv parameter) and that block driver is a protocol block
driver, BDRV_O_PROTOCOL should be set; if it is a format block driver,
BDRV_O_PROTOCOL should be unset.

While there was code to unset the flag in case a format block driver
has been selected, it only followed the bdrv_fill_options() function
call whereas the flag in fact needs to be adjusted before it is used
there.

With that change, BDRV_O_PROTOCOL will always be set if the BDS should
be a protocol driver; if the driver has been specified explicitly, the
new code will set it; and bdrv_fill_options() will only "probe" a
protocol driver if BDRV_O_PROTOCOL is set. The probing after
bdrv_fill_options() cannot select a protocol driver.

Thus, bdrv_open_image() to open BDS.file is never called if a protocol
BDS is about to be created. With that change in turn it is impossible to
call bdrv_open_common() with a protocol drv and file != NULL, which
allows us to remove the bdrv_swap() call.

This change breaks a test case in qemu-iotest 051:
"-drive file=t.qcow2,file.driver=qcow2" now works because the explicitly
specified "qcow2" overrides the BDRV_O_PROTOCOL which is automatically
set for the "file" BDS (and the filename is just passed down).
Therefore, this patch removes that test case.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Max Reitz 2015-03-19 14:53:16 -04:00 committed by Kevin Wolf
parent 06207b0ff5
commit 53a2951312
3 changed files with 31 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

49
block.c
View File

@ -806,14 +806,6 @@ static int bdrv_open_common(BlockDriverState *bs, BlockDriverState *file,
}
qdict_del(options, "node-name");
/* bdrv_open() with directly using a protocol as drv. This layer is already
* opened, so assign it to bs (while file becomes a closed BlockDriverState)
* and return immediately. */
if (file != NULL && drv->bdrv_file_open) {
bdrv_swap(file, bs);
return 0;
}
bs->open_flags = flags;
bs->guest_block_size = 512;
bs->request_alignment = 512;
@ -942,14 +934,17 @@ static QDict *parse_json_filename(const char *filename, Error **errp)
/*
* Fills in default options for opening images and converts the legacy
* filename/flags pair to option QDict entries.
* The BDRV_O_PROTOCOL flag in *flags will be set or cleared accordingly if a
* block driver has been specified explicitly.
*/
static int bdrv_fill_options(QDict **options, const char **pfilename, int flags,
BlockDriver *drv, Error **errp)
static int bdrv_fill_options(QDict **options, const char **pfilename,
int *flags, BlockDriver *drv, Error **errp)
{
const char *filename = *pfilename;
const char *drvname;
bool protocol = flags & BDRV_O_PROTOCOL;
bool protocol = *flags & BDRV_O_PROTOCOL;
bool parse_filename = false;
BlockDriver *tmp_drv;
Error *local_err = NULL;
/* Parse json: pseudo-protocol */
@ -967,6 +962,24 @@ static int bdrv_fill_options(QDict **options, const char **pfilename, int flags,
*pfilename = filename = NULL;
}
drvname = qdict_get_try_str(*options, "driver");
/* If the user has explicitly specified the driver, this choice should
* override the BDRV_O_PROTOCOL flag */
tmp_drv = drv;
if (!tmp_drv && drvname) {
tmp_drv = bdrv_find_format(drvname);
}
if (tmp_drv) {
protocol = tmp_drv->bdrv_file_open;
}
if (protocol) {
*flags |= BDRV_O_PROTOCOL;
} else {
*flags &= ~BDRV_O_PROTOCOL;
}
/* Fetch the file name from the options QDict if necessary */
if (protocol && filename) {
if (!qdict_haskey(*options, "filename")) {
@ -981,7 +994,6 @@ static int bdrv_fill_options(QDict **options, const char **pfilename, int flags,
/* Find the right block driver */
filename = qdict_get_try_str(*options, "filename");
drvname = qdict_get_try_str(*options, "driver");
if (drv) {
if (drvname) {
@ -1317,7 +1329,7 @@ int bdrv_open(BlockDriverState **pbs, const char *filename,
options = qdict_new();
}
ret = bdrv_fill_options(&options, &filename, flags, drv, &local_err);
ret = bdrv_fill_options(&options, &filename, &flags, drv, &local_err);
if (local_err) {
goto fail;
}
@ -1336,11 +1348,6 @@ int bdrv_open(BlockDriverState **pbs, const char *filename,
}
assert(drvname || !(flags & BDRV_O_PROTOCOL));
if (drv && !drv->bdrv_file_open) {
/* If the user explicitly wants a format driver here, we'll need to add
* another layer for the protocol in bs->file */
flags &= ~BDRV_O_PROTOCOL;
}
bs->options = options;
options = qdict_clone_shallow(options);
@ -1377,6 +1384,12 @@ int bdrv_open(BlockDriverState **pbs, const char *filename,
goto fail;
}
/* BDRV_O_PROTOCOL must be set iff a protocol BDS is about to be created */
assert(!!(flags & BDRV_O_PROTOCOL) == !!drv->bdrv_file_open);
/* file must be NULL if a protocol BDS is about to be created
* (the inverse results in an error message from bdrv_open_common()) */
assert(!(flags & BDRV_O_PROTOCOL) || !file);
/* Open the image */
ret = bdrv_open_common(bs, file, options, flags, drv, &local_err);
if (ret < 0) {

1
tests/qemu-iotests/051
View File

@ -194,7 +194,6 @@ echo === Specifying the protocol layer ===
echo
run_qemu -drive file="$TEST_IMG",file.driver=file
run_qemu -drive file="$TEST_IMG",file.driver=qcow2
echo
echo === Leaving out required options ===

3
tests/qemu-iotests/051.out
View File

@ -253,9 +253,6 @@ Testing: -drive file=TEST_DIR/t.qcow2,file.driver=file
QEMU X.Y.Z monitor - type 'help' for more information
(qemu) qququiquit
Testing: -drive file=TEST_DIR/t.qcow2,file.driver=qcow2
QEMU_PROG: -drive file=TEST_DIR/t.qcow2,file.driver=qcow2: Block format 'qcow2' used by device '' doesn't support the option 'filename'
=== Leaving out required options ===