From patchwork Fri Mar 28 16:15:57 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 14032232 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 92B9F1DA0E0; Fri, 28 Mar 2025 16:16:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743178593; cv=none; b=YzltDuc9FHcKt8UCtVTZtecxCMJ0BBY9yK/yLgYW2KHhdOElUzPrm1s7sRjjNm9jOzZVzX6ELUnfIFFaB/8VYaXOXoS11kch5t8tj6j1/5oZOKanXo+SjXC5MdLm9mIVK79TrZIdllkzMvMJ8HIk1vNmBUoytFDSIM2N9NZSjHY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743178593; c=relaxed/simple; bh=lt6u0j7G8M4UVt/q9RdtvvmlEwoeC1nsKag6HYnxJkE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=FgsZrJxRDckP+9Y0iLXUvpBqScR+G1n6IX2GTUGIeG91s/q+oXH9w5NfQBDVnZJFtmePJ+lk1JjLcP5UnLb/d5zWjIX0a7XfGqain3D06ZiuoH/N30uSAIsusQxKMvqlZ+8GC75NAymdv+47Z8yNcN+AX0Y3ytjQdcYmscKJVSQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LnQiU3D1; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="LnQiU3D1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C3AF0C4CEE9; Fri, 28 Mar 2025 16:16:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1743178593; bh=lt6u0j7G8M4UVt/q9RdtvvmlEwoeC1nsKag6HYnxJkE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LnQiU3D1umTaR/AAcrsZckyuXz/ZLIdk0NEsccP2UgAsaV9Kgl2f4oYsIBSje7waC 6uUDTdnftl0tNa4BlJu7qWhTVdusA93CNa6Yh5EekUDHkgl3htqMoMqKJBemrxGSTf /19CqRGmrf16ssQYXAWrZ+lKZEFrvLvNdNF11J13MYQOGO16f8FHigZC0QM1yvV97p JUWeyibTdPnluBfPIrgav1merQK1oS6kx3icGeDbDSQQ+7Kq5ntQsztzlu/lgMi9ic FtDPlkjTYwRFYpctBhT/7enrGsloZ5pYOR3znq5IM5tJTqmNXJ2SVwhCgEXTFBhaV7 utTqgN144vRlw== From: Christian Brauner To: linux-fsdevel@vger.kernel.org, jack@suse.cz Cc: Christian Brauner , linux-kernel@vger.kernel.org, James Bottomley , mcgrof@kernel.org, hch@infradead.org, david@fromorbit.com, rafael@kernel.org, djwong@kernel.org, pavel@kernel.org, peterz@infradead.org, mingo@redhat.com, will@kernel.org, boqun.feng@gmail.com Subject: [PATCH 5/6] super: use common iterator (Part 2) Date: Fri, 28 Mar 2025 17:15:57 +0100 Message-ID: <20250328-work-freeze-v1-5-a2c3a6b0e7a6@kernel.org> X-Mailer: git-send-email 2.47.2 In-Reply-To: <20250328-work-freeze-v1-0-a2c3a6b0e7a6@kernel.org> References: <20250328-work-freeze-v1-0-a2c3a6b0e7a6@kernel.org> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Mailer: b4 0.15-dev-42535 X-Developer-Signature: v=1; a=openpgp-sha256; l=4796; i=brauner@kernel.org; h=from:subject:message-id; bh=lt6u0j7G8M4UVt/q9RdtvvmlEwoeC1nsKag6HYnxJkE=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMaQ/O+18+tS7+hNWlydoXr96tpujxqRXytPGve9aBU/Nq aK2P4YpHaUsDGJcDLJiiiwO7Sbhcst5KjYbZWrAzGFlAhnCwMUpABM5O5WRYcbt6OJUawk7EfGr p7pTE+cuSbwWVjVXbefMrlXM825dnMzw3+GgePTH/ueeNjWd98IzbvKb3Zi0I50hLsZCUTPyduJ rVgA= X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Use a common iterator for all callbacks. We could go for something even more elaborate (advance step-by-step similar to iov_iter) but I really don't think this is warranted. Signed-off-by: Christian Brauner --- fs/super.c | 76 +++++++++++++++++++++++++++++++++++++++++++++--------- include/linux/fs.h | 6 +---- 2 files changed, 65 insertions(+), 17 deletions(-) diff --git a/fs/super.c b/fs/super.c index 0dd208804a74..58c95210e66c 100644 --- a/fs/super.c +++ b/fs/super.c @@ -887,24 +887,71 @@ void drop_super_exclusive(struct super_block *sb) } EXPORT_SYMBOL(drop_super_exclusive); -void __iterate_supers(void (*f)(struct super_block *, void *), void *arg, bool excl) +enum super_iter_flags_t { + SUPER_ITER_EXCL = (1U << 0), + SUPER_ITER_GRAB = (1U << 1) | SUPER_ITER_EXCL, + SUPER_ITER_REVERSE = (1U << 2), +}; + +static inline struct super_block *first_super(enum super_iter_flags_t flags) +{ + if (flags & SUPER_ITER_REVERSE) + return list_last_entry(&super_blocks, struct super_block, s_list); + return list_first_entry(&super_blocks, struct super_block, s_list); +} + +static inline struct super_block *next_super(struct super_block *sb, + enum super_iter_flags_t flags) +{ + if (flags & SUPER_ITER_REVERSE) + return list_prev_entry(sb, s_list); + return list_next_entry(sb, s_list); +} + +static inline void super_cb_locked(struct super_block *sb, + void (*f)(struct super_block *, void *), + void *arg, bool excl) +{ + if (super_lock(sb, excl)) { + f(sb, arg); + super_unlock(sb, excl); + } +} + +static inline void super_cb_grabbed(struct super_block *sb, + void (*f)(struct super_block *, void *), + void *arg) +{ + if (super_lock_excl(sb)) { + bool active = atomic_inc_not_zero(&sb->s_active); + super_unlock_excl(sb); + if (active) + f(sb, arg); + deactivate_super(sb); + } +} + +#define invalid_super list_entry_is_head + +static void __iterate_supers(void (*f)(struct super_block *, void *), void *arg, + enum super_iter_flags_t flags) { struct super_block *sb, *p = NULL; + bool excl = flags & SUPER_ITER_EXCL; - spin_lock(&sb_lock); - list_for_each_entry(sb, &super_blocks, s_list) { - bool locked; + guard(spinlock)(&sb_lock); + for (sb = first_super(flags); !invalid_super(sb, &super_blocks, s_list); + sb = next_super(sb, flags)) { if (super_flags(sb, SB_DYING)) continue; sb->s_count++; spin_unlock(&sb_lock); - locked = super_lock(sb, excl); - if (locked) { - f(sb, arg); - super_unlock(sb, excl); - } + if (flags & SUPER_ITER_GRAB) + super_cb_grabbed(sb, f, arg); + else + super_cb_locked(sb, f, arg, excl); spin_lock(&sb_lock); if (p) @@ -913,7 +960,11 @@ void __iterate_supers(void (*f)(struct super_block *, void *), void *arg, bool e } if (p) __put_super(p); - spin_unlock(&sb_lock); +} + +void iterate_supers(void (*f)(struct super_block *, void *), void *arg) +{ + __iterate_supers(f, arg, 0); } /** @@ -1097,7 +1148,8 @@ static void do_emergency_remount_callback(struct super_block *sb, void *unused) static void do_emergency_remount(struct work_struct *work) { - __iterate_supers(do_emergency_remount_callback, NULL, true); + __iterate_supers(do_emergency_remount_callback, NULL, + SUPER_ITER_EXCL | SUPER_ITER_REVERSE); kfree(work); printk("Emergency Remount complete\n"); } @@ -1124,7 +1176,7 @@ static void do_thaw_all_callback(struct super_block *sb, void *unused) static void do_thaw_all(struct work_struct *work) { - __iterate_supers(do_thaw_all_callback, NULL, true); + __iterate_supers(do_thaw_all_callback, NULL, SUPER_ITER_EXCL); kfree(work); printk(KERN_WARNING "Emergency Thaw complete\n"); } diff --git a/include/linux/fs.h b/include/linux/fs.h index 0351500b71d2..c475fa874055 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -3515,11 +3515,7 @@ extern void put_filesystem(struct file_system_type *fs); extern struct file_system_type *get_fs_type(const char *name); extern void drop_super(struct super_block *sb); extern void drop_super_exclusive(struct super_block *sb); -void __iterate_supers(void (*f)(struct super_block *, void *), void *arg, bool excl); -static inline void iterate_supers(void (*f)(struct super_block *, void *), void *arg) -{ - __iterate_supers(f, arg, false); -} +extern void iterate_supers(void (*f)(struct super_block *, void *), void *arg); extern void iterate_supers_type(struct file_system_type *, void (*)(struct super_block *, void *), void *);