From nobody Wed Dec 24 16:04:26 2025 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.8]) (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 D49961B59A; Thu, 25 Jan 2024 23:57:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.8 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706227061; cv=none; b=hw6tyITyJuZdixd6k3mhaGYCovw500s47eMdh11J8jHPCjiVIfhi+k/HGD0a+uCKt2G8y2KCndy8soEQPaMZ6BDrDep3PH/zZfRbBLp1hH1MHnypFrVbiqToVHjQc2t7igbpb/wb2F2olJ7qUtujJNwKVvM3e4IjE9bYhHLaOCw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706227061; c=relaxed/simple; bh=FKBREtj8gYP8EY7HfUrJK9Zp1Jdp/dowThfEAGkB4+4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=I0fpifCzue4hGDGr4o3fduWoYEDAzvrersN9EYyCtZdZZo+WVLwgItNFIwhkV9xLsANUAPxfGCPmLuTHrtEBkqqwN0F7sBo7qM85WhkLgooH5cSvoA16+b2m1EVWW7jmLrxPRiGzhafaVvPG1aQqLRcFFyF6yb342UOsiV/cMP8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=Rg6zDdom; arc=none smtp.client-ip=192.198.163.8 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="Rg6zDdom" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1706227059; x=1737763059; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=FKBREtj8gYP8EY7HfUrJK9Zp1Jdp/dowThfEAGkB4+4=; b=Rg6zDdomHb701a52Ibx9TbYZRCiwRVHbp67jgaYQks4Ig5lW0yVTqj0P 8CfqWC/bPJ/PIhMrTYjqaYqqE2x4l8lSnSK9UySwegQTiL+mFGAskFeTJ 6dUQGlVNSs3WPBPuGGv66qE4ZQ7OJ1400S4DLrFBNakHum3U2oBS9IhMl kqbp+sEzQEn4fhMCprQqnQ+/oxzRUdUsYQ00IxOHZcmVKW/r6awtEov6m 4nIOROjEo2Tf0OdwSBW8W+PylP807uOAi+XjPmdKrJyqizhAgPj20FoFb V8wNv33LiV34pVi90EfxtYLFlQCaqYfDSiuxnRCZtjGqaYbYkiBeIu+or Q==; X-IronPort-AV: E=McAfee;i="6600,9927,10964"; a="15867575" X-IronPort-AV: E=Sophos;i="6.05,216,1701158400"; d="scan'208";a="15867575" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmvoesa102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Jan 2024 15:57:37 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10964"; a="930191107" X-IronPort-AV: E=Sophos;i="6.05,216,1701158400"; d="scan'208";a="930191107" Received: from vcostago-mobl3.jf.intel.com ([10.24.14.99]) by fmsmga001-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Jan 2024 15:57:36 -0800 From: Vinicius Costa Gomes To: brauner@kernel.org, amir73il@gmail.com, hu1.chen@intel.com Cc: miklos@szeredi.hu, malini.bhandaru@intel.com, tim.c.chen@intel.com, mikko.ylinen@intel.com, lizhen.you@intel.com, linux-unionfs@vger.kernel.org, linux-kernel@vger.kernel.org, Vinicius Costa Gomes Subject: [RFC v2 4/4] fs: Optimize credentials reference count for backing file ops Date: Thu, 25 Jan 2024 15:57:23 -0800 Message-ID: <20240125235723.39507-5-vinicius.gomes@intel.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240125235723.39507-1-vinicius.gomes@intel.com> References: <20240125235723.39507-1-vinicius.gomes@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" For backing file operations, users are expected to pass credentials that will outlive the backing file common operations. Use the specialized guard statements to override/revert the credentials. Signed-off-by: Vinicius Costa Gomes --- fs/backing-file.c | 124 ++++++++++++++++++++++------------------------ 1 file changed, 60 insertions(+), 64 deletions(-) diff --git a/fs/backing-file.c b/fs/backing-file.c index a681f38d84d8..9874f09f860f 100644 --- a/fs/backing-file.c +++ b/fs/backing-file.c @@ -140,7 +140,7 @@ ssize_t backing_file_read_iter(struct file *file, struc= t iov_iter *iter, struct backing_file_ctx *ctx) { struct backing_aio *aio =3D NULL; - const struct cred *old_cred; + const struct cred *old_cred =3D ctx->cred; ssize_t ret; =20 if (WARN_ON_ONCE(!(file->f_mode & FMODE_BACKING))) @@ -153,29 +153,28 @@ ssize_t backing_file_read_iter(struct file *file, str= uct iov_iter *iter, !(file->f_mode & FMODE_CAN_ODIRECT)) return -EINVAL; =20 - old_cred =3D override_creds(ctx->cred); - if (is_sync_kiocb(iocb)) { - rwf_t rwf =3D iocb_to_rw_flags(flags); + scoped_guard(cred, old_cred) { + if (is_sync_kiocb(iocb)) { + rwf_t rwf =3D iocb_to_rw_flags(flags); =20 - ret =3D vfs_iter_read(file, iter, &iocb->ki_pos, rwf); - } else { - ret =3D -ENOMEM; - aio =3D kmem_cache_zalloc(backing_aio_cachep, GFP_KERNEL); - if (!aio) - goto out; + ret =3D vfs_iter_read(file, iter, &iocb->ki_pos, rwf); + } else { + ret =3D -ENOMEM; + aio =3D kmem_cache_zalloc(backing_aio_cachep, GFP_KERNEL); + if (!aio) + goto out; =20 - aio->orig_iocb =3D iocb; - kiocb_clone(&aio->iocb, iocb, get_file(file)); - aio->iocb.ki_complete =3D backing_aio_rw_complete; - refcount_set(&aio->ref, 2); - ret =3D vfs_iocb_iter_read(file, &aio->iocb, iter); - backing_aio_put(aio); - if (ret !=3D -EIOCBQUEUED) - backing_aio_cleanup(aio, ret); + aio->orig_iocb =3D iocb; + kiocb_clone(&aio->iocb, iocb, get_file(file)); + aio->iocb.ki_complete =3D backing_aio_rw_complete; + refcount_set(&aio->ref, 2); + ret =3D vfs_iocb_iter_read(file, &aio->iocb, iter); + backing_aio_put(aio); + if (ret !=3D -EIOCBQUEUED) + backing_aio_cleanup(aio, ret); + } } out: - revert_creds(old_cred); - if (ctx->accessed) ctx->accessed(ctx->user_file); =20 @@ -187,7 +186,7 @@ ssize_t backing_file_write_iter(struct file *file, stru= ct iov_iter *iter, struct kiocb *iocb, int flags, struct backing_file_ctx *ctx) { - const struct cred *old_cred; + const struct cred *old_cred =3D ctx->cred; ssize_t ret; =20 if (WARN_ON_ONCE(!(file->f_mode & FMODE_BACKING))) @@ -210,39 +209,37 @@ ssize_t backing_file_write_iter(struct file *file, st= ruct iov_iter *iter, */ flags &=3D ~IOCB_DIO_CALLER_COMP; =20 - old_cred =3D override_creds(ctx->cred); - if (is_sync_kiocb(iocb)) { - rwf_t rwf =3D iocb_to_rw_flags(flags); + scoped_guard(cred, old_cred) { + if (is_sync_kiocb(iocb)) { + rwf_t rwf =3D iocb_to_rw_flags(flags); =20 - ret =3D vfs_iter_write(file, iter, &iocb->ki_pos, rwf); - if (ctx->end_write) - ctx->end_write(ctx->user_file); - } else { - struct backing_aio *aio; + ret =3D vfs_iter_write(file, iter, &iocb->ki_pos, rwf); + if (ctx->end_write) + ctx->end_write(ctx->user_file); + } else { + struct backing_aio *aio; =20 - ret =3D backing_aio_init_wq(iocb); - if (ret) - goto out; + ret =3D backing_aio_init_wq(iocb); + if (ret) + return ret; =20 - ret =3D -ENOMEM; - aio =3D kmem_cache_zalloc(backing_aio_cachep, GFP_KERNEL); - if (!aio) - goto out; + ret =3D -ENOMEM; + aio =3D kmem_cache_zalloc(backing_aio_cachep, GFP_KERNEL); + if (!aio) + return ret; =20 - aio->orig_iocb =3D iocb; - aio->end_write =3D ctx->end_write; - kiocb_clone(&aio->iocb, iocb, get_file(file)); - aio->iocb.ki_flags =3D flags; - aio->iocb.ki_complete =3D backing_aio_queue_completion; - refcount_set(&aio->ref, 2); - ret =3D vfs_iocb_iter_write(file, &aio->iocb, iter); - backing_aio_put(aio); - if (ret !=3D -EIOCBQUEUED) - backing_aio_cleanup(aio, ret); + aio->orig_iocb =3D iocb; + aio->end_write =3D ctx->end_write; + kiocb_clone(&aio->iocb, iocb, get_file(file)); + aio->iocb.ki_flags =3D flags; + aio->iocb.ki_complete =3D backing_aio_queue_completion; + refcount_set(&aio->ref, 2); + ret =3D vfs_iocb_iter_write(file, &aio->iocb, iter); + backing_aio_put(aio); + if (ret !=3D -EIOCBQUEUED) + backing_aio_cleanup(aio, ret); + } } -out: - revert_creds(old_cred); - return ret; } EXPORT_SYMBOL_GPL(backing_file_write_iter); @@ -252,15 +249,15 @@ ssize_t backing_file_splice_read(struct file *in, lof= f_t *ppos, unsigned int flags, struct backing_file_ctx *ctx) { - const struct cred *old_cred; + const struct cred *old_cred =3D ctx->cred; ssize_t ret; =20 if (WARN_ON_ONCE(!(in->f_mode & FMODE_BACKING))) return -EIO; =20 - old_cred =3D override_creds(ctx->cred); - ret =3D vfs_splice_read(in, ppos, pipe, len, flags); - revert_creds(old_cred); + scoped_guard(cred, old_cred) { + ret =3D vfs_splice_read(in, ppos, pipe, len, flags); + } =20 if (ctx->accessed) ctx->accessed(ctx->user_file); @@ -274,7 +271,7 @@ ssize_t backing_file_splice_write(struct pipe_inode_inf= o *pipe, unsigned int flags, struct backing_file_ctx *ctx) { - const struct cred *old_cred; + const struct cred *old_cred =3D ctx->cred; ssize_t ret; =20 if (WARN_ON_ONCE(!(out->f_mode & FMODE_BACKING))) @@ -284,12 +281,11 @@ ssize_t backing_file_splice_write(struct pipe_inode_i= nfo *pipe, if (ret) return ret; =20 - old_cred =3D override_creds(ctx->cred); - file_start_write(out); - ret =3D iter_file_splice_write(pipe, out, ppos, len, flags); - file_end_write(out); - revert_creds(old_cred); - + scoped_guard(cred, old_cred) { + file_start_write(out); + ret =3D iter_file_splice_write(pipe, out, ppos, len, flags); + file_end_write(out); + } if (ctx->end_write) ctx->end_write(ctx->user_file); =20 @@ -300,7 +296,7 @@ EXPORT_SYMBOL_GPL(backing_file_splice_write); int backing_file_mmap(struct file *file, struct vm_area_struct *vma, struct backing_file_ctx *ctx) { - const struct cred *old_cred; + const struct cred *old_cred =3D ctx->cred; int ret; =20 if (WARN_ON_ONCE(!(file->f_mode & FMODE_BACKING)) || @@ -312,9 +308,9 @@ int backing_file_mmap(struct file *file, struct vm_area= _struct *vma, =20 vma_set_file(vma, file); =20 - old_cred =3D override_creds(ctx->cred); - ret =3D call_mmap(vma->vm_file, vma); - revert_creds(old_cred); + scoped_guard(cred, old_cred) { + ret =3D call_mmap(vma->vm_file, vma); + } =20 if (ctx->accessed) ctx->accessed(ctx->user_file); --=20 2.43.0