From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 6C382347FD0 for ; Mon, 27 Apr 2026 15:30:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777303839; cv=none; b=uWfzFA3SejC1RE+esPCR3RdiZt61p4PiHy2XVYpyaWOhq/PFmeKFwbyPqzskkMQWuyK15SmWdZ2EJ/NL3esIg6sb0VfaDftXUr9/Jnlg6xkvRH+jviVIwhQROcgGI06yda4Q/Prq8DmiBdJk0Uciu+H0B85XneLRagvAqS/M/TQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777303839; c=relaxed/simple; bh=o05Io1xRtBayWGYR2oc3Xg7A3FtUEcWOi0kE+EBlUgg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=SwOjCTxbu8b8KEj9B2HRpU/Fq0NGb9YivkwLsS0ItuyvHKmZ6K9RdMnxX2tsm4wbw38h86lcxPPoCgUjeTZxz7pYF+shWtj4Ik8vXi+Jams/A/BTAd6tUTL7LQKmqAlyPfqchRFB3B9dgPULgNz+LQ84jktVePb+7+/0bLZ0qHM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=M6pEI3+L; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="M6pEI3+L" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1777303837; 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=47TW6xAuGaXgyo+FT4sWhE5OZ+F3gm9XYQOGltuTIYQ=; b=M6pEI3+Lmu3pNMRKWsXJxionYDj7D3IAiHXf4cuFVNE0XULKGhobhrTnDTCZkJezsKHsnv 52IlYjPPm3L3gNqaxgcAFAOo5o5lxQnOrX/CbsT9UhUqJeB1cls2ROP/AWw/BFDnnZOQAz QW6Mer09uSTURXipbmBIEk7eSK2xuUQ= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-647-fGjFsSZnM_6IA_Ug3IaImg-1; Mon, 27 Apr 2026 11:30:35 -0400 X-MC-Unique: fGjFsSZnM_6IA_Ug3IaImg-1 X-Mimecast-MFC-AGG-ID: fGjFsSZnM_6IA_Ug3IaImg_1777303830 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 9ADD31800464; Mon, 27 Apr 2026 15:30:30 +0000 (UTC) Received: from warthog.procyon.org.com (unknown [10.44.32.126]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id C698A19560AB; Mon, 27 Apr 2026 15:30:26 +0000 (UTC) From: David Howells To: Christian Brauner Cc: David Howells , Paulo Alcantara , netfs@lists.linux.dev, linux-afs@lists.infradead.org, linux-cifs@vger.kernel.org, ceph-devel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Matthew Wilcox Subject: [PATCH v4 06/22] netfs: Fix zeropoint update where i_size > remote_i_size Date: Mon, 27 Apr 2026 16:29:33 +0100 Message-ID: <20260427152953.180038-7-dhowells@redhat.com> In-Reply-To: <20260427152953.180038-1-dhowells@redhat.com> References: <20260427152953.180038-1-dhowells@redhat.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Fix the update of the zero point[*] by netfs_release_folio() when there is uncommitted data in the pagecache beyond the folio being released but the on-server EOF is in this folio (ie. i_size > remote_i_size). The update needs to limit zero_point to remote_i_size, not i_size as i_size is a local phenomenon reflecting updates made locally to the pagecache, not stuff written to the server. remote_i_size tracks the server's i_size. [*] The zero point is the file position from which we can assume that the server will just return zeros, so we can avoid generating reads. Note that netfs_invalidate_folio() probably doesn't need fixing as zero_point should be updated by setattr after truncation or fallocate. Found with: fsx -q -N 1000000 -p 10000 -o 128000 -l 600000 \ /xfstest.test/junk --replay-ops=junk.fsxops using the following as junk.fsxops: truncate 0x0 0x1bbae 0x82864 write 0x3ef2e 0xf9c8 0x1bbae write 0x67e05 0xcb5a 0x4e8f6 mapread 0x57781 0x85b6 0x7495f copy_range 0x5d3d 0x10329 0x54fac 0x7495f write 0x64710 0x1c2b 0x7495f mapread 0x64000 0x1000 0x7495f on cifs with the default cache option. It shows read-gaps on folio 0x64 failing with a short read (ie. it hits EOF) if the FMODE_READ check is commented out in netfs_perform_write(): if (//(file->f_mode & FMODE_READ) || netfs_is_cache_enabled(ctx)) { and no fscache. This was initially found with the generic/522 xfstest. Fixes: cce6bfa6ca0e ("netfs: Fix trimming of streaming-write folios in netfs_inval_folio()") Signed-off-by: David Howells cc: Paulo Alcantara cc: Matthew Wilcox cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org --- fs/netfs/misc.c | 4 ++-- include/linux/netfs.h | 35 +++++++++++++++++++++++++++-------- 2 files changed, 29 insertions(+), 10 deletions(-) diff --git a/fs/netfs/misc.c b/fs/netfs/misc.c index 9d92d068f1da..37d9651078e6 100644 --- a/fs/netfs/misc.c +++ b/fs/netfs/misc.c @@ -299,9 +299,9 @@ bool netfs_release_folio(struct folio *folio, gfp_t gfp) return false; netfs_read_sizes(ctx, &i_size, &remote_i_size, &zero_point); - end = umin(folio_next_pos(folio), i_size); + end = folio_next_pos(folio); if (end > zero_point) - netfs_write_zero_point(ctx, end); + netfs_push_back_zero_point(ctx, umin(end, remote_i_size)); if (folio_test_private(folio)) return false; diff --git a/include/linux/netfs.h b/include/linux/netfs.h index 90e061e444ce..59f35d2eeb2e 100644 --- a/include/linux/netfs.h +++ b/include/linux/netfs.h @@ -530,11 +530,11 @@ static inline void netfs_write_remote_i_size(struct netfs_inode *ictx, #if BITS_PER_LONG==32 && defined(CONFIG_SMP) struct inode *inode = &ictx->inode; - preempt_disable(); + spin_lock(&inode->i_lock); write_seqcount_begin(&inode->i_size_seqcount); ictx->_remote_i_size = remote_i_size; write_seqcount_end(&inode->i_size_seqcount); - preempt_enable(); + spin_unlock(&inode->i_lock); #elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION) preempt_disable(); ictx->_remote_i_size = remote_i_size; @@ -605,11 +605,11 @@ static inline void netfs_write_zero_point(struct netfs_inode *ictx, #if BITS_PER_LONG==32 && defined(CONFIG_SMP) struct inode *inode = &ictx->inode; - preempt_disable(); + spin_lock(&inode->i_lock); write_seqcount_begin(&inode->i_size_seqcount); ictx->_zero_point = zero_point; write_seqcount_end(&inode->i_size_seqcount); - preempt_enable(); + spin_unlock(&inode->i_lock); #elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION) preempt_disable(); ictx->_zero_point = zero_point; @@ -635,8 +635,27 @@ static inline void netfs_write_zero_point(struct netfs_inode *ictx, static inline void netfs_push_back_zero_point(struct netfs_inode *ictx, unsigned long long to) { - if (to > netfs_read_zero_point(ictx)) - netfs_write_zero_point(ictx, to); +#if BITS_PER_LONG==32 && defined(CONFIG_SMP) + struct inode *inode = &ictx->inode; + + spin_lock(&inode->i_lock); + write_seqcount_begin(&inode->i_size_seqcount); + if (to > ictx->_zero_point) + ictx->_zero_point = to; + write_seqcount_end(&inode->i_size_seqcount); + spin_unlock(&inode->i_lock); +#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION) + preempt_disable(); + if (to > ictx->_zero_point) + ictx->_zero_point = to; + preempt_enable(); +#else + unsigned long long old = ictx->_zero_point; + + while (to > old) { + old = cmpxchg_release(&ictx->_zero_point, old, to); + } +#endif } /** @@ -709,12 +728,12 @@ static inline void netfs_write_sizes(struct netfs_inode *ictx, #if BITS_PER_LONG==32 && defined(CONFIG_SMP) struct inode *inode = &ictx->inode; - preempt_disable(); + spin_lock(&inode->i_lock); write_seqcount_begin(&inode->i_size_seqcount); ictx->_remote_i_size = remote_i_size; ictx->_zero_point = zero_point; write_seqcount_end(&inode->i_size_seqcount); - preempt_enable(); + spin_unlock(&inode->i_lock); #elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION) preempt_disable(); ictx->_remote_i_size = remote_i_size;