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[209.85.218.52]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-639d4a67888sm736974a12.1.2025.10.07.15.54.37 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 07 Oct 2025 15:54:39 -0700 (PDT) Received: by mail-ej1-f52.google.com with SMTP id a640c23a62f3a-b00a9989633so81196166b.0 for ; Tue, 07 Oct 2025 15:54:37 -0700 (PDT) X-Forwarded-Encrypted: i=1; AJvYcCUOZQkk3QAf+duc4TnpsVRwfFrmlWyRR5K+2vkpmHaUuPd/BWcBMHMibj48seeuutkFXT70jBWDJg==@kvack.org X-Received: by 2002:a17:907:a70d:b0:b4a:e7fa:3196 with SMTP id a640c23a62f3a-b4f429efe15mr563250766b.20.1759877677521; Tue, 07 Oct 2025 15:54:37 -0700 (PDT) MIME-Version: 1.0 References: <4bjh23pk56gtnhutt4i46magq74zx3nlkuo4ym2tkn54rv4gjl@rhxb6t6ncewp> <5zq4qlllkr7zlif3dohwuraa7rukykkuu6khifumnwoltcijfc@po27djfyqbka> In-Reply-To: From: Linus Torvalds Date: Tue, 7 Oct 2025 15:54:19 -0700 X-Gmail-Original-Message-ID: X-Gm-Features: AS18NWCjiZmGz9lB5bT-2RpXXU6lsyJbiuU0NDcMLPnF_ouVHC3HSZomRtmlOeE Message-ID: Subject: Re: Optimizing small reads To: Kiryl Shutsemau Cc: Matthew Wilcox , Luis Chamberlain , Linux-MM , linux-fsdevel@vger.kernel.org Content-Type: multipart/mixed; boundary="000000000000d19e860640997327" X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 97DF414000E X-Stat-Signature: ay3yecz6rnoh771fjigoyeakdxcm5aww X-HE-Tag: 1759877681-349935 X-HE-Meta: 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 evOy4Foi bXJbMfcGWkg91EeDV6PgkHRsN1vpHM1XJaQFzkMWe9xWDuRU7r6IQh+llwyTB4jvzlVcHvjhzmO2bHUYFY0ZHQQJBqk0QlCo0iiOGZ0b633T9KwSLJWTzSEh1p6lX7lxppME85XvOjL+zUgnwwrqlnIMsqHe/VbIEKW7LTvmclnolWTJh7wYzusZGaU3ectA8O/S/pZhjVngIToJp5ucG1CNRCfNr1G6wHXjffRLnmDfR0sD4NuX+6YTX+2JUPrC5Dukx/7gWDE9A3eBOrbUQMlRq8ms2h5wr2dsTAK5xudg0pxms/4RKS0Yd5VwChWc1gSmTqu6okHxN2ZjI965aC7k/DILkL6G5d1h9 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: --000000000000d19e860640997327 Content-Type: text/plain; charset="UTF-8" On Tue, 7 Oct 2025 at 15:35, Linus Torvalds wrote: > > But I think I'll try to boot it next. Wish me luck. Bah. It boots - after you fix the stupid double increment of 'already_copied'. I didn't remove the update inside the loop when I made it update it after the loop. So here's the slightly fixed patch that actually does boot - and that I'm running right now. But I wouldn't call it exactly "tested". Caveat patchor. Linus --000000000000d19e860640997327 Content-Type: text/x-patch; charset="US-ASCII"; name="patch.diff" Content-Disposition: attachment; filename="patch.diff" Content-Transfer-Encoding: base64 Content-ID: X-Attachment-Id: f_mgh5pv7k0 CiBtbS9maWxlbWFwLmMgfCAzMyArKysrKysrKysrKysrKysrKysrKysrKysrLS0tLS0tLS0KIDEg ZmlsZSBjaGFuZ2VkLCAyNSBpbnNlcnRpb25zKCspLCA4IGRlbGV0aW9ucygtKQoKZGlmZiAtLWdp dCBhL21tL2ZpbGVtYXAuYyBiL21tL2ZpbGVtYXAuYwppbmRleCA2MGE3YjkyNzU3NDEuLmJhMTFm MDE4Y2E2YiAxMDA2NDQKLS0tIGEvbW0vZmlsZW1hcC5jCisrKyBiL21tL2ZpbGVtYXAuYwpAQCAt Mjc5MiwyMCArMjc5MiwzNyBAQCBzc2l6ZV90IGZpbGVtYXBfcmVhZChzdHJ1Y3Qga2lvY2IgKmlv Y2IsIHN0cnVjdCBpb3ZfaXRlciAqaXRlciwKIAkgKiBhbnkgY29tcGlsZXIgaW5pdGlhbGl6YXRp b24gd291bGQgYmUgcG9pbnRsZXNzIHNpbmNlIHRoaXMKIAkgKiBjYW4gZmlsbCBpdCB3aWxsIGdh cmJhZ2UuCiAJICovCi0JaWYgKGlvdl9pdGVyX2NvdW50KGl0ZXIpIDw9IHNpemVvZihhcmVhKSkg eworCWlmIChpb3ZfaXRlcl9jb3VudChpdGVyKSA8PSBQQUdFX1NJWkUpIHsKIAkJc2l6ZV90IGNv dW50ID0gaW92X2l0ZXJfY291bnQoaXRlcik7CisJCXNpemVfdCBmYXN0X3JlYWQgPSAwOwogCiAJ CS8qIExldCdzIHNlZSBpZiB3ZSBjYW4ganVzdCBkbyB0aGUgcmVhZCB1bmRlciBSQ1UgKi8KIAkJ cmN1X3JlYWRfbG9jaygpOwotCQljb3VudCA9IGZpbGVtYXBfZmFzdF9yZWFkKG1hcHBpbmcsIGlv Y2ItPmtpX3BvcywgYXJlYS5idWZmZXIsIGNvdW50KTsKKwkJcGFnZWZhdWx0X2Rpc2FibGUoKTsK KwkJZG8geworCQkJc2l6ZV90IGNvcGllZCA9IG1pbihjb3VudCwgc2l6ZW9mKGFyZWEpKTsKKwor CQkJY29waWVkID0gZmlsZW1hcF9mYXN0X3JlYWQobWFwcGluZywgaW9jYi0+a2lfcG9zLCBhcmVh LmJ1ZmZlciwgY29waWVkKTsKKwkJCWlmICghY29waWVkKQorCQkJCWJyZWFrOworCQkJY29waWVk ID0gY29weV90b19pdGVyKGFyZWEuYnVmZmVyLCBjb3BpZWQsIGl0ZXIpOworCQkJaWYgKCFjb3Bp ZWQpCisJCQkJYnJlYWs7CisJCQlmYXN0X3JlYWQgKz0gY29waWVkOworCQkJaW9jYi0+a2lfcG9z ICs9IGNvcGllZDsKKwkJCWNvdW50IC09IGNvcGllZDsKKwkJfSB3aGlsZSAoY291bnQpOworCQlw YWdlZmF1bHRfZW5hYmxlKCk7CiAJCXJjdV9yZWFkX3VubG9jaygpOwotCQlpZiAoY291bnQpIHsK LQkJCXNpemVfdCBjb3BpZWQgPSBjb3B5X3RvX2l0ZXIoYXJlYS5idWZmZXIsIGNvdW50LCBpdGVy KTsKLQkJCWlmICh1bmxpa2VseSghY29waWVkKSkKLQkJCQlyZXR1cm4gYWxyZWFkeV9yZWFkID8g YWxyZWFkeV9yZWFkIDogLUVGQVVMVDsKLQkJCXJhLT5wcmV2X3BvcyA9IGlvY2ItPmtpX3BvcyAr PSBjb3BpZWQ7CisKKwkJaWYgKGZhc3RfcmVhZCkgeworCQkJcmEtPnByZXZfcG9zICs9IGZhc3Rf cmVhZDsKKwkJCWFscmVhZHlfcmVhZCArPSBmYXN0X3JlYWQ7CiAJCQlmaWxlX2FjY2Vzc2VkKGZp bHApOwotCQkJcmV0dXJuIGNvcGllZCArIGFscmVhZHlfcmVhZDsKKworCQkJLyogQWxsIGRvbmU/ ICovCisJCQlpZiAoIWNvdW50KQorCQkJCXJldHVybiBhbHJlYWR5X3JlYWQ7CiAJCX0KIAl9CiAK --000000000000d19e860640997327--