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c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1773160022; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=j1zNq0gkwMJJa9HJNegRdCHxMB46SL9Pee5peNOWcGg=; b=H4IUpRqMrpDNZZwkEO0u67TQMFUkevE5H2mb+5r520wrN7CcxMpZERCFwWLQkFeT4c94s8 KFTZkfRKS4lURUrt45ei+HpP/mQvyS2X2kg5a0AWejAAPPfdgvsdfybbCdineW8s8//mQM UezhbwBtMlyiGXy0aN5d5XEuv2gvtAA= X-MC-Unique: V7dINj91MX6NnbDt8k3BxA-1 X-Mimecast-MFC-AGG-ID: V7dINj91MX6NnbDt8k3BxA_1773160019 From: Kevin Wolf To: qemu-block@nongnu.org Cc: kwolf@redhat.com, qemu-devel@nongnu.org Subject: [PULL 18/28] fuse: Reduce max read size Date: Tue, 10 Mar 2026 17:26:12 +0100 Message-ID: <20260310162622.333137-19-kwolf@redhat.com> In-Reply-To: <20260310162622.333137-1-kwolf@redhat.com> References: <20260310162622.333137-1-kwolf@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; 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charset="utf-8" From: Hanna Czenczek We are going to introduce parallel processing via coroutines, a maximum read size of 64 MB may be problematic, allowing users of the export to force us to allocate quite large amounts of memory with just a few requests. At least tone it down to 1 MB, which is still probably far more than enough. (Larger requests are split automatically by the FUSE kernel driver anyway.) (Yes, we inadvertently already had parallel request processing due to nested polling before. Better to fix this late than never.) Reviewed-by: Stefan Hajnoczi Signed-off-by: Hanna Czenczek Message-ID: <20260309150856.26800-19-hreitz@redhat.com> Reviewed-by: Kevin Wolf Signed-off-by: Kevin Wolf --- block/export/fuse.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/block/export/fuse.c b/block/export/fuse.c index bd099d12911..f32e74f39dd 100644 --- a/block/export/fuse.c +++ b/block/export/fuse.c @@ -45,7 +45,7 @@ #endif =20 /* Prevent overly long bounce buffer allocations */ -#define FUSE_MAX_READ_BYTES (MIN(BDRV_REQUEST_MAX_BYTES, 64 * 1024 * 1024)) +#define FUSE_MAX_READ_BYTES (MIN(BDRV_REQUEST_MAX_BYTES, 1 * 1024 * 1024)) #define FUSE_MAX_WRITE_BYTES (64 * 1024) =20 /* --=20 2.53.0