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bh=CLXSn/nyPMG0gDDfnhgpYQX85htiZ5wnoZj7/jcHbL4=; b=eFX5A9Ur7S0I8UjwtOwAiYQ8+8RyJrWEqdyDRZkXyRpKtSykBB4KJPbIYAVDGTo7VUpWKq sJFL2y/kkxMic/ZfpltuosfyuWXt9NTM7e2p6JwUDvdgjk7asch97/eo4dZF5GuRHPIcdY BqRVoEpzV0GwZc5UnslzoGJUfHUcEc0= X-MC-Unique: QHsH3zQ5N5OG7uF10SA22g-1 From: Kevin Wolf To: qemu-block@nongnu.org Cc: kwolf@redhat.com, qemu-devel@nongnu.org Subject: [PULL 06/13] qcow2: Do not reopen data_file in invalidate_cache Date: Wed, 4 May 2022 16:25:15 +0200 Message-Id: <20220504142522.167506-7-kwolf@redhat.com> In-Reply-To: <20220504142522.167506-1-kwolf@redhat.com> References: <20220504142522.167506-1-kwolf@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 2.85 on 10.11.54.9 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.129.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1651674854884100001 Content-Type: text/plain; charset="utf-8" From: Hanna Reitz qcow2_co_invalidate_cache() closes and opens the qcow2 file, by calling qcow2_close() and qcow2_do_open(). These two functions must thus be usable from both a global-state and an I/O context. As they are, they are not safe to call in an I/O context, because they use bdrv_unref_child() and bdrv_open_child() to close/open the data_file child, respectively, both of which are global-state functions. When used from qcow2_co_invalidate_cache(), we do not need to close/open the data_file child, though (we do not do this for bs->file or bs->backing either), and so we should skip it in the qcow2_co_invalidate_cache() path. To do so, add a parameter to qcow2_do_open() and qcow2_close() to make them skip handling s->data_file, and have qcow2_co_invalidate_cache() exempt it from the memset() on the BDRVQcow2State. (Note that the QED driver similarly closes/opens the QED image by invoking bdrv_qed_close()+bdrv_qed_do_open(), but both functions seem safe to use in an I/O context.) Fixes: https://gitlab.com/qemu-project/qemu/-/issues/945 Signed-off-by: Hanna Reitz Message-Id: <20220427114057.36651-3-hreitz@redhat.com> Reviewed-by: Eric Blake Signed-off-by: Kevin Wolf --- block/qcow2.c | 104 ++++++++++++++++++++++++++++++-------------------- 1 file changed, 62 insertions(+), 42 deletions(-) diff --git a/block/qcow2.c b/block/qcow2.c index b5c47931ef..4f5e6440fb 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -1296,7 +1296,8 @@ static int validate_compression_type(BDRVQcow2State *= s, Error **errp) =20 /* Called with s->lock held. */ static int coroutine_fn qcow2_do_open(BlockDriverState *bs, QDict *options, - int flags, Error **errp) + int flags, bool open_data_file, + Error **errp) { ERRP_GUARD(); BDRVQcow2State *s =3D bs->opaque; @@ -1614,50 +1615,52 @@ static int coroutine_fn qcow2_do_open(BlockDriverSt= ate *bs, QDict *options, goto fail; } =20 - /* Open external data file */ - s->data_file =3D bdrv_open_child(NULL, options, "data-file", bs, - &child_of_bds, BDRV_CHILD_DATA, - true, errp); - if (*errp) { - ret =3D -EINVAL; - goto fail; - } + if (open_data_file) { + /* Open external data file */ + s->data_file =3D bdrv_open_child(NULL, options, "data-file", bs, + &child_of_bds, BDRV_CHILD_DATA, + true, errp); + if (*errp) { + ret =3D -EINVAL; + goto fail; + } =20 - if (s->incompatible_features & QCOW2_INCOMPAT_DATA_FILE) { - if (!s->data_file && s->image_data_file) { - s->data_file =3D bdrv_open_child(s->image_data_file, options, - "data-file", bs, &child_of_bds, - BDRV_CHILD_DATA, false, errp); + if (s->incompatible_features & QCOW2_INCOMPAT_DATA_FILE) { + if (!s->data_file && s->image_data_file) { + s->data_file =3D bdrv_open_child(s->image_data_file, optio= ns, + "data-file", bs, &child_of_= bds, + BDRV_CHILD_DATA, false, err= p); + if (!s->data_file) { + ret =3D -EINVAL; + goto fail; + } + } if (!s->data_file) { + error_setg(errp, "'data-file' is required for this image"); ret =3D -EINVAL; goto fail; } - } - if (!s->data_file) { - error_setg(errp, "'data-file' is required for this image"); - ret =3D -EINVAL; - goto fail; - } =20 - /* No data here */ - bs->file->role &=3D ~BDRV_CHILD_DATA; + /* No data here */ + bs->file->role &=3D ~BDRV_CHILD_DATA; =20 - /* Must succeed because we have given up permissions if anything */ - bdrv_child_refresh_perms(bs, bs->file, &error_abort); - } else { - if (s->data_file) { - error_setg(errp, "'data-file' can only be set for images with = an " - "external data file"); - ret =3D -EINVAL; - goto fail; - } + /* Must succeed because we have given up permissions if anythi= ng */ + bdrv_child_refresh_perms(bs, bs->file, &error_abort); + } else { + if (s->data_file) { + error_setg(errp, "'data-file' can only be set for images w= ith " + "an external data file"); + ret =3D -EINVAL; + goto fail; + } =20 - s->data_file =3D bs->file; + s->data_file =3D bs->file; =20 - if (data_file_is_raw(bs)) { - error_setg(errp, "data-file-raw requires a data file"); - ret =3D -EINVAL; - goto fail; + if (data_file_is_raw(bs)) { + error_setg(errp, "data-file-raw requires a data file"); + ret =3D -EINVAL; + goto fail; + } } } =20 @@ -1839,7 +1842,7 @@ static int coroutine_fn qcow2_do_open(BlockDriverStat= e *bs, QDict *options, =20 fail: g_free(s->image_data_file); - if (has_data_file(bs)) { + if (open_data_file && has_data_file(bs)) { bdrv_unref_child(bs, s->data_file); s->data_file =3D NULL; } @@ -1876,7 +1879,8 @@ static void coroutine_fn qcow2_open_entry(void *opaqu= e) BDRVQcow2State *s =3D qoc->bs->opaque; =20 qemu_co_mutex_lock(&s->lock); - qoc->ret =3D qcow2_do_open(qoc->bs, qoc->options, qoc->flags, qoc->err= p); + qoc->ret =3D qcow2_do_open(qoc->bs, qoc->options, qoc->flags, true, + qoc->errp); qemu_co_mutex_unlock(&s->lock); } =20 @@ -2714,7 +2718,7 @@ static int qcow2_inactivate(BlockDriverState *bs) return result; } =20 -static void qcow2_close(BlockDriverState *bs) +static void qcow2_do_close(BlockDriverState *bs, bool close_data_file) { BDRVQcow2State *s =3D bs->opaque; qemu_vfree(s->l1_table); @@ -2740,7 +2744,7 @@ static void qcow2_close(BlockDriverState *bs) g_free(s->image_backing_file); g_free(s->image_backing_format); =20 - if (has_data_file(bs)) { + if (close_data_file && has_data_file(bs)) { bdrv_unref_child(bs, s->data_file); s->data_file =3D NULL; } @@ -2749,11 +2753,17 @@ static void qcow2_close(BlockDriverState *bs) qcow2_free_snapshots(bs); } =20 +static void qcow2_close(BlockDriverState *bs) +{ + qcow2_do_close(bs, true); +} + static void coroutine_fn qcow2_co_invalidate_cache(BlockDriverState *bs, Error **errp) { ERRP_GUARD(); BDRVQcow2State *s =3D bs->opaque; + BdrvChild *data_file; int flags =3D s->flags; QCryptoBlock *crypto =3D NULL; QDict *options; @@ -2767,14 +2777,24 @@ static void coroutine_fn qcow2_co_invalidate_cache(= BlockDriverState *bs, crypto =3D s->crypto; s->crypto =3D NULL; =20 - qcow2_close(bs); + /* + * Do not reopen s->data_file (i.e., have qcow2_do_close() not close i= t, + * and then prevent qcow2_do_open() from opening it), because this fun= ction + * runs in the I/O path and as such we must not invoke global-state + * functions like bdrv_unref_child() and bdrv_open_child(). + */ =20 + qcow2_do_close(bs, false); + + data_file =3D s->data_file; memset(s, 0, sizeof(BDRVQcow2State)); + s->data_file =3D data_file; + options =3D qdict_clone_shallow(bs->options); =20 flags &=3D ~BDRV_O_INACTIVE; qemu_co_mutex_lock(&s->lock); - ret =3D qcow2_do_open(bs, options, flags, errp); + ret =3D qcow2_do_open(bs, options, flags, false, errp); qemu_co_mutex_unlock(&s->lock); qobject_unref(options); if (ret < 0) { --=20 2.35.1