From 53a295131274c87914c97053e2ca00f19a9c2efa Mon Sep 17 00:00:00 2001 From: Max Reitz Date: Thu, 19 Mar 2015 14:53:16 -0400 Subject: block: driver should override flags in bdrv_open() 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 Signed-off-by: Kevin Wolf --- block.c | 49 +++++++++++++++++++++++++++++++------------------ 1 file changed, 31 insertions(+), 18 deletions(-) (limited to 'block.c') diff --git a/block.c b/block.c index 4ea2c4f5c8..b2e784e3ff 100644 --- a/block.c +++ b/block.c @@ -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) { -- cgit v1.2.3