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Wed, 28 Apr 2021 02:54:37 -0700 (PDT) Received: from localhost.localdomain ([139.177.225.233]) by smtp.gmail.com with ESMTPSA id x77sm4902365pfc.19.2021.04.28.02.54.32 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 28 Apr 2021 02:54:36 -0700 (PDT) From: Muchun Song To: willy@infradead.org, akpm@linux-foundation.org, hannes@cmpxchg.org, mhocko@kernel.org, vdavydov.dev@gmail.com, shakeelb@google.com, guro@fb.com, shy828301@gmail.com, alexs@kernel.org, alexander.h.duyck@linux.intel.com, richard.weiyang@gmail.com Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Muchun Song Subject: [PATCH 7/9] ida: introduce ida_max() to return the maximum allocated ID Date: Wed, 28 Apr 2021 17:49:47 +0800 Message-Id: <20210428094949.43579-8-songmuchun@bytedance.com> X-Mailer: git-send-email 2.21.0 (Apple Git-122) In-Reply-To: <20210428094949.43579-1-songmuchun@bytedance.com> References: <20210428094949.43579-1-songmuchun@bytedance.com> MIME-Version: 1.0 X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: EFEA2E000111 X-Stat-Signature: 8kgcsnbxym4qecznmab77zpkp43udid3 Received-SPF: none (bytedance.com>: No applicable sender policy available) receiver=imf13; identity=mailfrom; envelope-from=""; helo=mail-pl1-f179.google.com; client-ip=209.85.214.179 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1619603669-790969 Content-Transfer-Encoding: quoted-printable 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: Introduce ida_max() to return the maximum allocated ID. This will be used by memory cgroup in the later patch. Signed-off-by: Muchun Song --- include/linux/idr.h | 1 + lib/idr.c | 40 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 41 insertions(+) diff --git a/include/linux/idr.h b/include/linux/idr.h index a0dce14090a9..c3968a6348d1 100644 --- a/include/linux/idr.h +++ b/include/linux/idr.h @@ -255,6 +255,7 @@ struct ida { int ida_alloc_range(struct ida *, unsigned int min, unsigned int max, gf= p_t); void ida_free(struct ida *, unsigned int id); void ida_destroy(struct ida *ida); +int ida_max(struct ida *ida); =20 /** * ida_alloc() - Allocate an unused ID. diff --git a/lib/idr.c b/lib/idr.c index f4ab4f4aa3c7..bcfcaae89aa7 100644 --- a/lib/idr.c +++ b/lib/idr.c @@ -553,6 +553,46 @@ void ida_destroy(struct ida *ida) } EXPORT_SYMBOL(ida_destroy); =20 +/** + * ida_max() - Return the maximum allocated ID. + * @ida: IDA handle. + * + * Context: Any context. It is safe to call this function without + * locking in your code. + * + * Return: The maximum allocated ID, or %-ENOSPC if the @ida is empty + */ +int ida_max(struct ida *ida) +{ + XA_STATE(xas, &ida->xa, 0); + struct ida_bitmap *curr, *prev; + unsigned long flags; + unsigned int bit, index; + + xas_lock_irqsave(&xas, flags); + if (ida_is_empty(ida)) { + xas_unlock_irqrestore(&xas, flags); + return -ENOSPC; + } + + xas_for_each(&xas, curr, ULONG_MAX) { + prev =3D curr; + index =3D xas.xa_index; + } + + if (xa_is_value(prev)) { + unsigned long val =3D xa_to_value(prev); + + bit =3D find_last_bit(&val, BITS_PER_XA_VALUE); + } else { + bit =3D find_last_bit(prev->bitmap, IDA_BITMAP_BITS); + } + + xas_unlock_irqrestore(&xas, flags); + + return index * IDA_BITMAP_BITS + bit; +} + #ifndef __KERNEL__ extern void xa_dump_index(unsigned long index, unsigned int shift); #define IDA_CHUNK_SHIFT ilog2(IDA_BITMAP_BITS) --=20 2.11.0