|
| From: | Max Reitz |
| Subject: | Re: [Qemu-devel] [PATCH 01/10] block: Change BDS parameter of bdrv_open() to ** |
| Date: | Mon, 27 Jan 2014 19:51:59 +0100 |
| User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 |
On 27.01.2014 03:38, Benoît Canet wrote:
Le Sunday 26 Jan 2014 à 20:02:34 (+0100), Max Reitz a écrit :Make bdrv_open() take a pointer to a BDS pointer, similarly to bdrv_file_open(). If a pointer to a NULL pointer is given, bdrv_open() will create a new BDS with an empty name; if the BDS pointer is not NULL, that existing BDS will be reused (in the same way as bdrv_open() already did). Signed-off-by: Max Reitz <address@hidden> --- block.c | 53 ++++++++++++++++++++++++++------------------------- block/qcow2.c | 14 +++++++++----- block/vmdk.c | 5 ++--- block/vvfat.c | 6 ++---- blockdev.c | 21 ++++++++------------ hw/block/xen_disk.c | 2 +- include/block/block.h | 2 +- qemu-img.c | 6 +++--- qemu-io.c | 2 +- qemu-nbd.c | 2 +- 10 files changed, 55 insertions(+), 58 deletions(-) diff --git a/block.c b/block.c index cb21a5f..c660609 100644 --- a/block.c +++ b/block.c @@ -1039,7 +1039,7 @@ int bdrv_file_open(BlockDriverState **pbs, const char *filename, }if (!drv->bdrv_file_open) {- ret = bdrv_open(bs, filename, options, flags, drv, &local_err); + ret = bdrv_open(&bs, filename, options, flags, drv, &local_err); options = NULL; } else { ret = bdrv_open_common(bs, NULL, options, flags, drv, &local_err); @@ -1108,8 +1108,6 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp) sizeof(backing_filename)); }- bs->backing_hd = bdrv_new("");- if (bs->backing_format[0] != '\0') { back_drv = bdrv_find_format(bs->backing_format); } @@ -1118,11 +1116,10 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp) back_flags = bs->open_flags & ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT | BDRV_O_COPY_ON_READ);- ret = bdrv_open(bs->backing_hd,+ ret = bdrv_open(&bs->backing_hd, *backing_filename ? backing_filename : NULL, options, back_flags, back_drv, &local_err); if (ret < 0) { - bdrv_unref(bs->backing_hd); bs->backing_hd = NULL; bs->open_flags |= BDRV_O_NO_BACKING; error_setg(errp, "Could not open backing file: %s", @@ -1189,8 +1186,6 @@ int bdrv_open_image(BlockDriverState **pbs, const char *filename, /* If a filename is given and the block driver should be detected automatically (instead of using none), use bdrv_open() in order to do that auto-detection. */ - BlockDriverState *bs; - if (reference) { error_setg(errp, "Cannot reference an existing block device while " "giving a filename"); @@ -1198,13 +1193,8 @@ int bdrv_open_image(BlockDriverState **pbs, const char *filename, goto done; }- bs = bdrv_new("");- ret = bdrv_open(bs, filename, image_options, flags, NULL, errp); - if (ret < 0) { - bdrv_unref(bs); - } else { - *pbs = bs; - } + *pbs = NULL;bdrv_open set *file = NULL before calling bdrv_open_image so this is redundant. What would be the correct behavior if the caller was giving *pbs != NULL ? Is loosing the reference to a previously existing bds right ?
I thought about that, too. But it would have to be a pretty broken caller to rely on this function to preserve *pbs if it fails and to overwrite it otherwise. But you're right, to conform with the behavior of bdrv_open/bdrv_file_open, it would probably make more sense not to overwrite *pbs.
+ ret = bdrv_open(pbs, filename, image_options, flags, NULL, errp); } else { ret = bdrv_file_open(pbs, filename, reference, image_options, flags, errp); @@ -1222,14 +1212,17 @@ done: * empty set of options. The reference to the QDict belongs to the block layer * after the call (even on failure), so if the caller intends to reuse the * dictionary, it needs to use QINCREF() before calling bdrv_open. + * + * If *pbs is NULL, a new BDS will be created with a pointer to it stored there. + * If it is not NULL, the referenced BDS will be reused. */ -int bdrv_open(BlockDriverState *bs, const char *filename, QDict *options, +int bdrv_open(BlockDriverState **pbs, const char *filename, QDict *options, int flags, BlockDriver *drv, Error **errp) { int ret; /* TODO: extra byte is a hack to ensure MAX_PATH space on Windows. */ char tmp_filename[PATH_MAX + 1]; - BlockDriverState *file = NULL; + BlockDriverState *file = NULL, *bs = NULL; const char *drvname; Error *local_err = NULL;@@ -1238,12 +1231,17 @@ int bdrv_open(BlockDriverState *bs, const char *filename, QDict *options,options = qdict_new(); }+ if (*pbs) {+ bs = *pbs; + } else { + bs = bdrv_new(""); + } bs->options = options; options = qdict_clone_shallow(options);/* For snapshot=on, create a temporary qcow2 overlay */if (flags & BDRV_O_SNAPSHOT) { - BlockDriverState *bs1; + BlockDriverState *bs1 = NULL; int64_t total_size; BlockDriver *bdrv_qcow2; QEMUOptionParameter *create_options; @@ -1253,12 +1251,10 @@ int bdrv_open(BlockDriverState *bs, const char *filename, QDict *options, instead of opening 'filename' directly *//* Get the required size from the image */- bs1 = bdrv_new(""); QINCREF(options); - ret = bdrv_open(bs1, filename, options, BDRV_O_NO_BACKING, + ret = bdrv_open(&bs1, filename, options, BDRV_O_NO_BACKING, drv, &local_err); if (ret < 0) { - bdrv_unref(bs1); goto fail; } total_size = bdrv_getlength(bs1) & BDRV_SECTOR_MASK; @@ -1386,6 +1382,7 @@ int bdrv_open(BlockDriverState *bs, const char *filename, QDict *options, bdrv_dev_change_media_cb(bs, true); }+ *pbs = bs;return 0;unlink_and_fail:The goto chain is different on Kevin qemu.git block; there is an additional fail label ? On which tree and branch are these patches based ?
They are based on Kevin's (current) block branch (at least, that's what my git log says ;-)).
@@ -1399,13 +1396,20 @@ fail: QDECREF(bs->options); QDECREF(options); bs->options = NULL; + if (!*pbs) { + bdrv_unref(bs); + } if (error_is_set(&local_err)) { error_propagate(errp, local_err); } return ret;close_and_fail:- bdrv_close(bs); + if (*pbs) { + bdrv_close(bs); + } else { + bdrv_unref(bs); + } QDECREF(options); if (error_is_set(&local_err)) { error_propagate(errp, local_err); @@ -5276,7 +5280,7 @@ void bdrv_img_create(const char *filename, const char *fmt, size = get_option_parameter(param, BLOCK_OPT_SIZE); if (size && size->value.n == -1) { if (backing_file && backing_file->value.s) { - BlockDriverState *bs; + BlockDriverState *bs = NULL; uint64_t size; char buf[32]; int back_flags; @@ -5285,9 +5289,7 @@ void bdrv_img_create(const char *filename, const char *fmt, back_flags = flags & ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING);- bs = bdrv_new("");- - ret = bdrv_open(bs, backing_file->value.s, NULL, back_flags, + ret = bdrv_open(&bs, backing_file->value.s, NULL, back_flags, backing_drv, &local_err); if (ret < 0) { error_setg_errno(errp, -ret, "Could not open '%s': %s", @@ -5295,7 +5297,6 @@ void bdrv_img_create(const char *filename, const char *fmt, error_get_pretty(local_err)); error_free(local_err); local_err = NULL; - bdrv_unref(bs); goto out; } bdrv_get_geometry(bs, &size); diff --git a/block/qcow2.c b/block/qcow2.c index 2da62b8..9a25fbd 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -1541,7 +1541,8 @@ static int qcow2_create2(const char *filename, int64_t total_size, goto out; }- bdrv_close(bs);+ bdrv_unref(bs); + bs = NULL;/** And now open the image and make it consistent first (i.e. increase the @@ -1550,7 +1551,7 @@ static int qcow2_create2(const char *filename, int64_t total_size, */ BlockDriver* drv = bdrv_find_format("qcow2"); assert(drv != NULL); - ret = bdrv_open(bs, filename, NULL, + ret = bdrv_open(&bs, filename, NULL, BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_NO_FLUSH, drv, &local_err); if (ret < 0) { error_propagate(errp, local_err); @@ -1597,10 +1598,11 @@ static int qcow2_create2(const char *filename, int64_t total_size, } }- bdrv_close(bs);+ bdrv_unref(bs); + bs = NULL;/* Reopen the image without BDRV_O_NO_FLUSH to flush it before returning */- ret = bdrv_open(bs, filename, NULL, + ret = bdrv_open(&bs, filename, NULL, BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_NO_BACKING, drv, &local_err); if (error_is_set(&local_err)) { @@ -1610,7 +1612,9 @@ static int qcow2_create2(const char *filename, int64_t total_size,ret = 0;out: - bdrv_unref(bs); + if (bs) { + bdrv_unref(bs); + } return ret; }diff --git a/block/vmdk.c b/block/vmdk.cindex 99ca60f..0fbf230 100644 --- a/block/vmdk.c +++ b/block/vmdk.c @@ -1755,10 +1755,9 @@ static int vmdk_create(const char *filename, QEMUOptionParameter *options, goto exit; } if (backing_file) { - BlockDriverState *bs = bdrv_new(""); - ret = bdrv_open(bs, backing_file, NULL, BDRV_O_NO_BACKING, NULL, errp); + BlockDriverState *bs = NULL; + ret = bdrv_open(&bs, backing_file, NULL, BDRV_O_NO_BACKING, NULL, errp); if (ret != 0) { - bdrv_unref(bs); goto exit; } if (strcmp(bs->drv->format_name, "vmdk")) { diff --git a/block/vvfat.c b/block/vvfat.c index 664941c..ae7bc6f 100644 --- a/block/vvfat.c +++ b/block/vvfat.c @@ -2936,15 +2936,13 @@ static int enable_write_target(BDRVVVFATState *s) goto err; }- s->qcow = bdrv_new("");- - ret = bdrv_open(s->qcow, s->qcow_filename, NULL, + s->qcow = NULL; + ret = bdrv_open(&s->qcow, s->qcow_filename, NULL, BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_NO_FLUSH, bdrv_qcow, &local_err); if (ret < 0) { qerror_report_err(local_err); error_free(local_err); - bdrv_unref(s->qcow); goto err; }diff --git a/blockdev.c b/blockdev.cindex 36ceece..42163f8 100644 --- a/blockdev.c +++ b/blockdev.c @@ -510,7 +510,7 @@ static DriveInfo *blockdev_init(const char *file, QDict *bs_opts, bdrv_flags |= ro ? 0 : BDRV_O_RDWR;QINCREF(bs_opts);- ret = bdrv_open(dinfo->bdrv, file, bs_opts, bdrv_flags, drv, &error); + ret = bdrv_open(&dinfo->bdrv, file, bs_opts, bdrv_flags, drv, &error);if (ret < 0) {error_setg(errp, "could not open disk image %s: %s", @@ -1301,12 +1301,11 @@ static void external_snapshot_prepare(BlkTransactionState *common, qstring_from_str(snapshot_node_name)); }- /* We will manually add the backing_hd field to the bs later */- state->new_bs = bdrv_new(""); /* TODO Inherit bs->options or only take explicit options with an * extended QMP command? */The state has been g_malloc0 so ok.- ret = bdrv_open(state->new_bs, new_image_file, options, + ret = bdrv_open(&state->new_bs, new_image_file, options, flags | BDRV_O_NO_BACKING, drv, &local_err); + /* We will manually add the backing_hd field to the bs later */ if (ret != 0) { error_propagate(errp, local_err); } @@ -1555,7 +1554,7 @@ static void qmp_bdrv_open_encrypted(BlockDriverState *bs, const char *filename, Error *local_err = NULL; int ret;- ret = bdrv_open(bs, filename, NULL, bdrv_flags, drv, &local_err);It already open here so ok.+ ret = bdrv_open(&bs, filename, NULL, bdrv_flags, drv, &local_err); if (ret < 0) { error_propagate(errp, local_err); return; @@ -1906,7 +1905,7 @@ void qmp_drive_backup(const char *device, const char *target, Error **errp) { BlockDriverState *bs; - BlockDriverState *target_bs; + BlockDriverState *target_bs = NULL; BlockDriverState *source = NULL; BlockDriver *drv = NULL; Error *local_err = NULL; @@ -1991,10 +1990,8 @@ void qmp_drive_backup(const char *device, const char *target, return; }- target_bs = bdrv_new("");- ret = bdrv_open(target_bs, target, NULL, flags, drv, &local_err); + ret = bdrv_open(&target_bs, target, NULL, flags, drv, &local_err); if (ret < 0) { - bdrv_unref(target_bs); error_propagate(errp, local_err); return; } @@ -2027,7 +2024,7 @@ void qmp_drive_mirror(const char *device, const char *target, Error **errp) { BlockDriverState *bs; - BlockDriverState *source, *target_bs; + BlockDriverState *source, *target_bs = NULL; BlockDriver *drv = NULL; Error *local_err = NULL; int flags; @@ -2135,11 +2132,9 @@ void qmp_drive_mirror(const char *device, const char *target, /* Mirroring takes care of copy-on-write using the source's backing * file. */ - target_bs = bdrv_new(""); - ret = bdrv_open(target_bs, target, NULL, flags | BDRV_O_NO_BACKING, drv, + ret = bdrv_open(&target_bs, target, NULL, flags | BDRV_O_NO_BACKING, drv, &local_err); if (ret < 0) { - bdrv_unref(target_bs); error_propagate(errp, local_err); return; } diff --git a/hw/block/xen_disk.c b/hw/block/xen_disk.c index 098f6c6..14e6d0b 100644 --- a/hw/block/xen_disk.c +++ b/hw/block/xen_disk.c @@ -813,7 +813,7 @@ static int blk_connect(struct XenDevice *xendev) Error *local_err = NULL; BlockDriver *drv = bdrv_find_whitelisted_format(blkdev->fileproto, readonly); - if (bdrv_open(blkdev->bs, + if (bdrv_open(&blkdev->bs, blkdev->filename, NULL, qflags, drv, &local_err) != 0) { xen_be_printf(&blkdev->xendev, 0, "error: %s\n", diff --git a/include/block/block.h b/include/block/block.h index 963a61f..980869d 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -190,7 +190,7 @@ int bdrv_open_image(BlockDriverState **pbs, const char *filename, QDict *options, const char *bdref_key, int flags, bool force_raw, bool allow_none, Error **errp); int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp); -int bdrv_open(BlockDriverState *bs, const char *filename, QDict *options, +int bdrv_open(BlockDriverState **pbs, const char *filename, QDict *options, int flags, BlockDriver *drv, Error **errp); BlockReopenQueue *bdrv_reopen_queue(BlockReopenQueue *bs_queue, BlockDriverState *bs, int flags); diff --git a/qemu-img.c b/qemu-img.c index c989850..c39d486 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -289,7 +289,7 @@ static BlockDriverState *bdrv_new_open(const char *filename, drv = NULL; }- ret = bdrv_open(bs, filename, NULL, flags, drv, &local_err);+ ret = bdrv_open(&bs, filename, NULL, flags, drv, &local_err);I wonder if the if(bs) test in the fail label is dead code. The bdrv_unref in the test branch is not. I don't see how bs could be NULL.
Oh, yes, you're right. I'll remove it.
if (ret < 0) { error_report("Could not open '%s': %s", filename, error_get_pretty(local_err)); @@ -2314,7 +2314,7 @@ static int img_rebase(int argc, char **argv)bs_old_backing = bdrv_new("old_backing");bdrv_get_backing_filename(bs, backing_name, sizeof(backing_name)); - ret = bdrv_open(bs_old_backing, backing_name, NULL, BDRV_O_FLAGS, + ret = bdrv_open(&bs_old_backing, backing_name, NULL, BDRV_O_FLAGS, old_backing_drv, &local_err); if (ret) { error_report("Could not open old backing file '%s': %s", @@ -2324,7 +2324,7 @@ static int img_rebase(int argc, char **argv) } if (out_baseimg[0]) { bs_new_backing = bdrv_new("new_backing"); - ret = bdrv_open(bs_new_backing, out_baseimg, NULL, BDRV_O_FLAGS, + ret = bdrv_open(&bs_new_backing, out_baseimg, NULL, BDRV_O_FLAGS, new_backing_drv, &local_err); if (ret) { error_report("Could not open new backing file '%s': %s", diff --git a/qemu-io.c b/qemu-io.c index d669028..2f06dc6 100644 --- a/qemu-io.c +++ b/qemu-io.c @@ -68,7 +68,7 @@ static int openfile(char *name, int flags, int growable, QDict *opts) } else { qemuio_bs = bdrv_new("hda");- if (bdrv_open(qemuio_bs, name, opts, flags, NULL, &local_err) < 0) {+ if (bdrv_open(&qemuio_bs, name, opts, flags, NULL, &local_err) < 0) { fprintf(stderr, "%s: can't open device %s: %s\n", progname, name, error_get_pretty(local_err)); error_free(local_err); diff --git a/qemu-nbd.c b/qemu-nbd.c index 136e8c9..0cf123c 100644 --- a/qemu-nbd.c +++ b/qemu-nbd.c @@ -597,7 +597,7 @@ int main(int argc, char **argv)bs = bdrv_new("hda");srcpath = argv[optind]; - ret = bdrv_open(bs, srcpath, NULL, flags, drv, &local_err); + ret = bdrv_open(&bs, srcpath, NULL, flags, drv, &local_err); if (ret < 0) { errno = -ret; err(EXIT_FAILURE, "Failed to bdrv_open '%s': %s", argv[optind], -- 1.8.5.3
Thanks for reviewing! Max
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