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Mon, 24 May 2021 09:36:48 -0700 (PDT) Received: from avogadro.redhat.com ([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id n8sm7967684ejl.0.2021.05.24.09.36.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 24 May 2021 09:36:47 -0700 (PDT) From: Paolo Bonzini To: qemu-devel@nongnu.org Subject: [PATCH v2 2/6] file-posix: try BLKSECTGET on block devices too, do not round to power of 2 Date: Mon, 24 May 2021 18:36:41 +0200 Message-Id: <20210524163645.382940-3-pbonzini@redhat.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210524163645.382940-1-pbonzini@redhat.com> References: <20210524163645.382940-1-pbonzini@redhat.com> MIME-Version: 1.0 Received-SPF: pass client-ip=2a00:1450:4864:20::52a; envelope-from=paolo.bonzini@gmail.com; helo=mail-ed1-x52a.google.com X-Spam_score_int: -14 X-Spam_score: -1.5 X-Spam_bar: - X-Spam_report: (-1.5 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FORGED_FROMDOMAIN=0.249, FREEMAIL_FROM=0.001, HEADER_FROM_DIFFERENT_DOMAINS=0.249, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-block@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" bs->sg is only true for character devices, but block devices can also be used with scsi-block and scsi-generic. Unfortunately BLKSECTGET returns bytes in an int for /dev/sgN devices, and sectors in a short for block devices, so account for that in the code. The maximum transfer also need not be a power of 2 (for example I have seen disks with 1280 KiB maximum transfer) so there's no need to pass the result through pow2floor. Signed-off-by: Paolo Bonzini --- block/file-posix.c | 40 ++++++++++++++++++++++------------------ 1 file changed, 22 insertions(+), 18 deletions(-) diff --git a/block/file-posix.c b/block/file-posix.c index 59c889d5a7..e5ef006aee 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -1149,22 +1149,27 @@ static void raw_reopen_abort(BDRVReopenState *state) s->reopen_state = NULL; } -static int sg_get_max_transfer_length(int fd) +static int sg_get_max_transfer_length(int fd, struct stat *st) { #ifdef BLKSECTGET - int max_bytes = 0; - - if (ioctl(fd, BLKSECTGET, &max_bytes) == 0) { - return max_bytes; + if (S_ISBLK(st->st_mode)) { + unsigned short max_sectors = 0; + if (ioctl(fd, BLKSECTGET, &max_sectors) == 0) { + return max_sectors * 512; + } } else { - return -errno; + int max_bytes = 0; + if (ioctl(fd, BLKSECTGET, &max_bytes) == 0) { + return max_bytes; + } } + return -errno; #else return -ENOSYS; #endif } -static int sg_get_max_segments(int fd) +static int sg_get_max_segments(int fd, struct stat *st) { #ifdef CONFIG_LINUX char buf[32]; @@ -1173,15 +1178,9 @@ static int sg_get_max_segments(int fd) int ret; int sysfd = -1; long max_segments; - struct stat st; - - if (fstat(fd, &st)) { - ret = -errno; - goto out; - } sysfspath = g_strdup_printf("/sys/dev/block/%u:%u/queue/max_segments", - major(st.st_rdev), minor(st.st_rdev)); + major(st->st_rdev), minor(st->st_rdev)); sysfd = open(sysfspath, O_RDONLY); if (sysfd == -1) { ret = -errno; @@ -1218,15 +1217,20 @@ out: static void raw_refresh_limits(BlockDriverState *bs, Error **errp) { BDRVRawState *s = bs->opaque; + struct stat st; + + if (fstat(s->fd, &st)) { + return; + } - if (bs->sg) { - int ret = sg_get_max_transfer_length(s->fd); + if (bs->sg || S_ISBLK(st.st_mode)) { + int ret = sg_get_max_transfer_length(s->fd, &st); if (ret > 0 && ret <= BDRV_REQUEST_MAX_BYTES) { - bs->bl.max_transfer = pow2floor(ret); + bs->bl.max_transfer = ret; } - ret = sg_get_max_segments(s->fd); + ret = sg_get_max_segments(s->fd, &st); if (ret > 0) { bs->bl.max_iov = ret; }