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bh=2RitocbdoLpW1Xp/b3/4Z4VLVmr1YkektDJZ1jjja9s=; b=Xr7qVs5tQo8ZFIOQujRCyshpswBf8ydxuv/x1V3T/FPHNQMXrC1TLorV9H+lTI2/3/+d99 EWoOWqbsX7kNDXytZ7Vuk5aVAcSrpRBWM0BHFgSGKJ1NhVah2Mg5l4nU73QUZgf0I6vnZ7 zHS6UXaK2ivTpP7IFJzttwcyl9CH4Vk= X-MC-Unique: 8R7yW-RaM5OrbBKbmxelcQ-1 From: Kevin Wolf To: qemu-block@nongnu.org Cc: kwolf@redhat.com, peter.maydell@linaro.org, qemu-devel@nongnu.org Subject: [PULL 1/3] block/fuse: Let PUNCH_HOLE write zeroes Date: Fri, 10 Mar 2023 18:55:27 +0100 Message-Id: <20230310175529.240379-2-kwolf@redhat.com> In-Reply-To: <20230310175529.240379-1-kwolf@redhat.com> References: <20230310175529.240379-1-kwolf@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.3 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: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham 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-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1678471011286100005 Content-Type: text/plain; charset="utf-8" From: Hanna Czenczek fallocate(2) says about PUNCH_HOLE: "After a successful call, subsequent reads from this range will return zeros." As it is, PUNCH_HOLE is implemented as a call to blk_pdiscard(), which does not guarantee this. We must call blk_pwrite_zeroes() instead. The difference to ZERO_RANGE is that we pass the `BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK` flags to the call -- the storage is supposed to be unmapped, and a slow fallback by actually writing zeroes as data is not allowed. Closes: https://gitlab.com/qemu-project/qemu/-/issues/1507 Signed-off-by: Hanna Czenczek Message-Id: <20230227104725.33511-2-hreitz@redhat.com> Reviewed-by: Kevin Wolf Signed-off-by: Kevin Wolf --- block/export/fuse.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/block/export/fuse.c b/block/export/fuse.c index e5fc4af165..06fa41079e 100644 --- a/block/export/fuse.c +++ b/block/export/fuse.c @@ -673,7 +673,16 @@ static void fuse_fallocate(fuse_req_t req, fuse_ino_t = inode, int mode, do { int size =3D MIN(length, BDRV_REQUEST_MAX_BYTES); =20 - ret =3D blk_pdiscard(exp->common.blk, offset, size); + ret =3D blk_pwrite_zeroes(exp->common.blk, offset, size, + BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLB= ACK); + if (ret =3D=3D -ENOTSUP) { + /* + * fallocate() specifies to return EOPNOTSUPP for unsuppor= ted + * operations + */ + ret =3D -EOPNOTSUPP; + } + offset +=3D size; length -=3D size; } while (ret =3D=3D 0 && length > 0); --=20 2.39.2