{"id":2228989,"url":"http://patchwork.ozlabs.org/api/1.1/patches/2228989/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-cifs-client/patch/20260427152953.180038-7-dhowells@redhat.com/","project":{"id":12,"url":"http://patchwork.ozlabs.org/api/1.1/projects/12/?format=json","name":"Linux CIFS Client","link_name":"linux-cifs-client","list_id":"linux-cifs.vger.kernel.org","list_email":"linux-cifs@vger.kernel.org","web_url":"","scm_url":"","webscm_url":""},"msgid":"<20260427152953.180038-7-dhowells@redhat.com>","date":"2026-04-27T15:29:33","name":"[v4,06/22] netfs: Fix zeropoint update where i_size > remote_i_size","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"402f8a47f538dc9ea2ef50eff01841489e5008f2","submitter":{"id":59,"url":"http://patchwork.ozlabs.org/api/1.1/people/59/?format=json","name":"David Howells","email":"dhowells@redhat.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/linux-cifs-client/patch/20260427152953.180038-7-dhowells@redhat.com/mbox/","series":[{"id":501677,"url":"http://patchwork.ozlabs.org/api/1.1/series/501677/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-cifs-client/list/?series=501677","date":"2026-04-27T15:29:27","name":"netfs: Miscellaneous fixes","version":4,"mbox":"http://patchwork.ozlabs.org/series/501677/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2228989/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2228989/checks/","tags":{},"headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linux-cifs@vger.kernel.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256\n header.s=mimecast20190719 header.b=TtibyKQa;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=2600:3c0a:e001:db::12fc:5321; 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c=relaxed/relaxed; d=redhat.com;\n\ts=mimecast20190719; t=1777303840;\n\th=from:from:reply-to:subject:subject:date:date:message-id:message-id:\n\t to:to:cc:cc:mime-version:mime-version:\n\t content-transfer-encoding:content-transfer-encoding:\n\t in-reply-to:in-reply-to:references:references;\n\tbh=47TW6xAuGaXgyo+FT4sWhE5OZ+F3gm9XYQOGltuTIYQ=;\n\tb=TtibyKQacpyqnurVak8k+SJ2yvToKr/eBg29DVfO7RFAPvFgnYe+IEqE5yspyNplyTegEq\n\tylycGDvXxMhqjj7IEPPOV+ChVRkq4Xw9D/5Z+LObce19RX1zkB16kVcyyfdcUkeJxD4F6r\n\tBI1hrRcEh/CAk7eaKo/UkS/rA7SvRTU=","X-MC-Unique":"fGjFsSZnM_6IA_Ug3IaImg-1","X-Mimecast-MFC-AGG-ID":"fGjFsSZnM_6IA_Ug3IaImg_1777303830","From":"David Howells ","To":"Christian Brauner ","Cc":"David Howells ,\n\tPaulo Alcantara ,\n\tnetfs@lists.linux.dev,\n\tlinux-afs@lists.infradead.org,\n\tlinux-cifs@vger.kernel.org,\n\tceph-devel@vger.kernel.org,\n\tlinux-fsdevel@vger.kernel.org,\n\tlinux-kernel@vger.kernel.org,\n\tMatthew Wilcox ","Subject":"[PATCH v4 06/22] netfs: Fix zeropoint update where i_size >\n 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-cifs@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"},"content":"Fix the update of the zero point[*] by netfs_release_folio() when there is\nuncommitted data in the pagecache beyond the folio being released but the\non-server EOF is in this folio (ie. i_size > remote_i_size). The update\nneeds to limit zero_point to remote_i_size, not i_size as i_size is a local\nphenomenon reflecting updates made locally to the pagecache, not stuff\nwritten to the server. remote_i_size tracks the server's i_size.\n\n[*] The zero point is the file position from which we can assume that the\n server will just return zeros, so we can avoid generating reads.\n\nNote that netfs_invalidate_folio() probably doesn't need fixing as\nzero_point should be updated by setattr after truncation or fallocate.\n\nFound with:\n\n fsx -q -N 1000000 -p 10000 -o 128000 -l 600000 \\\n /xfstest.test/junk --replay-ops=junk.fsxops\n\nusing the following as junk.fsxops:\n\n truncate 0x0 0x1bbae 0x82864\n write 0x3ef2e 0xf9c8 0x1bbae\n write 0x67e05 0xcb5a 0x4e8f6\n mapread 0x57781 0x85b6 0x7495f\n copy_range 0x5d3d 0x10329 0x54fac 0x7495f\n write 0x64710 0x1c2b 0x7495f\n mapread 0x64000 0x1000 0x7495f\n\non cifs with the default cache option.\n\nIt shows read-gaps on folio 0x64 failing with a short read (ie. it hits\nEOF) if the FMODE_READ check is commented out in netfs_perform_write():\n\n if (//(file->f_mode & FMODE_READ) ||\n netfs_is_cache_enabled(ctx)) {\n\nand no fscache. This was initially found with the generic/522 xfstest.\n\nFixes: cce6bfa6ca0e (\"netfs: Fix trimming of streaming-write folios in netfs_inval_folio()\")\nSigned-off-by: David Howells \ncc: Paulo Alcantara \ncc: Matthew Wilcox \ncc: netfs@lists.linux.dev\ncc: linux-fsdevel@vger.kernel.org\n---\n fs/netfs/misc.c | 4 ++--\n include/linux/netfs.h | 35 +++++++++++++++++++++++++++--------\n 2 files changed, 29 insertions(+), 10 deletions(-)","diff":"diff --git a/fs/netfs/misc.c b/fs/netfs/misc.c\nindex 9d92d068f1da..37d9651078e6 100644\n--- a/fs/netfs/misc.c\n+++ b/fs/netfs/misc.c\n@@ -299,9 +299,9 @@ bool netfs_release_folio(struct folio *folio, gfp_t gfp)\n \t\treturn false;\n \n \tnetfs_read_sizes(ctx, &i_size, &remote_i_size, &zero_point);\n-\tend = umin(folio_next_pos(folio), i_size);\n+\tend = folio_next_pos(folio);\n \tif (end > zero_point)\n-\t\tnetfs_write_zero_point(ctx, end);\n+\t\tnetfs_push_back_zero_point(ctx, umin(end, remote_i_size));\n \n \tif (folio_test_private(folio))\n \t\treturn false;\ndiff --git a/include/linux/netfs.h b/include/linux/netfs.h\nindex 90e061e444ce..59f35d2eeb2e 100644\n--- a/include/linux/netfs.h\n+++ b/include/linux/netfs.h\n@@ -530,11 +530,11 @@ static inline void netfs_write_remote_i_size(struct netfs_inode *ictx,\n #if BITS_PER_LONG==32 && defined(CONFIG_SMP)\n \tstruct inode *inode = &ictx->inode;\n \n-\tpreempt_disable();\n+\tspin_lock(&inode->i_lock);\n \twrite_seqcount_begin(&inode->i_size_seqcount);\n \tictx->_remote_i_size = remote_i_size;\n \twrite_seqcount_end(&inode->i_size_seqcount);\n-\tpreempt_enable();\n+\tspin_unlock(&inode->i_lock);\n #elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION)\n \tpreempt_disable();\n \tictx->_remote_i_size = remote_i_size;\n@@ -605,11 +605,11 @@ static inline void netfs_write_zero_point(struct netfs_inode *ictx,\n #if BITS_PER_LONG==32 && defined(CONFIG_SMP)\n \tstruct inode *inode = &ictx->inode;\n \n-\tpreempt_disable();\n+\tspin_lock(&inode->i_lock);\n \twrite_seqcount_begin(&inode->i_size_seqcount);\n \tictx->_zero_point = zero_point;\n \twrite_seqcount_end(&inode->i_size_seqcount);\n-\tpreempt_enable();\n+\tspin_unlock(&inode->i_lock);\n #elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION)\n \tpreempt_disable();\n \tictx->_zero_point = zero_point;\n@@ -635,8 +635,27 @@ static inline void netfs_write_zero_point(struct netfs_inode *ictx,\n static inline void netfs_push_back_zero_point(struct netfs_inode *ictx,\n \t\t\t\t\t unsigned long long to)\n {\n-\tif (to > netfs_read_zero_point(ictx))\n-\t\tnetfs_write_zero_point(ictx, to);\n+#if BITS_PER_LONG==32 && defined(CONFIG_SMP)\n+\tstruct inode *inode = &ictx->inode;\n+\n+\tspin_lock(&inode->i_lock);\n+\twrite_seqcount_begin(&inode->i_size_seqcount);\n+\tif (to > ictx->_zero_point)\n+\t\tictx->_zero_point = to;\n+\twrite_seqcount_end(&inode->i_size_seqcount);\n+\tspin_unlock(&inode->i_lock);\n+#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION)\n+\tpreempt_disable();\n+\tif (to > ictx->_zero_point)\n+\t\tictx->_zero_point = to;\n+\tpreempt_enable();\n+#else\n+\tunsigned long long old = ictx->_zero_point;\n+\n+\twhile (to > old) {\n+\t\told = cmpxchg_release(&ictx->_zero_point, old, to);\n+\t}\n+#endif\n }\n \n /**\n@@ -709,12 +728,12 @@ static inline void netfs_write_sizes(struct netfs_inode *ictx,\n #if BITS_PER_LONG==32 && defined(CONFIG_SMP)\n \tstruct inode *inode = &ictx->inode;\n \n-\tpreempt_disable();\n+\tspin_lock(&inode->i_lock);\n \twrite_seqcount_begin(&inode->i_size_seqcount);\n \tictx->_remote_i_size = remote_i_size;\n \tictx->_zero_point = zero_point;\n \twrite_seqcount_end(&inode->i_size_seqcount);\n-\tpreempt_enable();\n+\tspin_unlock(&inode->i_lock);\n #elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION)\n \tpreempt_disable();\n \tictx->_remote_i_size = remote_i_size;\n","prefixes":["v4","06/22"]}