{"id":2226961,"url":"http://patchwork.ozlabs.org/api/patches/2226961/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-ext4/patch/177689989365.3821152.8925862475853227905.stgit@frogsfrogsfrogs/","project":{"id":8,"url":"http://patchwork.ozlabs.org/api/projects/8/?format=json","name":"Linux ext4 filesystem development","link_name":"linux-ext4","list_id":"linux-ext4.vger.kernel.org","list_email":"linux-ext4@vger.kernel.org","web_url":null,"scm_url":null,"webscm_url":null,"list_archive_url":"","list_archive_url_format":"","commit_url_format":""},"msgid":"<177689989365.3821152.8925862475853227905.stgit@frogsfrogsfrogs>","list_archive_url":null,"date":"2026-04-22T23:23:31","name":"[3/3] libext2fs: only fsync the unix fd if we wrote to the device","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"f2984bf95379f5137aa57bb8dbbff9b25adb990e","submitter":{"id":77032,"url":"http://patchwork.ozlabs.org/api/people/77032/?format=json","name":"Darrick J. Wong","email":"djwong@kernel.org"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/linux-ext4/patch/177689989365.3821152.8925862475853227905.stgit@frogsfrogsfrogs/mbox/","series":[{"id":501126,"url":"http://patchwork.ozlabs.org/api/series/501126/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-ext4/list/?series=501126","date":"2026-04-22T23:23:00","name":"[1/3] libext2fs: always fsync the device when flushing the cache","version":1,"mbox":"http://patchwork.ozlabs.org/series/501126/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2226961/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2226961/checks/","tags":{},"related":[],"headers":{"Return-Path":"\n <SRS0=Oiuj=CV=vger.kernel.org=linux-ext4+bounces-16004-patchwork-incoming=ozlabs.org@ozlabs.org>","X-Original-To":["incoming@patchwork.ozlabs.org","linux-ext4@vger.kernel.org"],"Delivered-To":["patchwork-incoming@legolas.ozlabs.org","patchwork-incoming@ozlabs.org"],"Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256\n header.s=k20201202 header.b=CAKqxZZO;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=ozlabs.org\n (client-ip=2404:9400:2221:ea00::3; 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arc=none smtp.client-ip=10.30.226.201"],"DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org;\n\ts=k20201202; t=1776900212;\n\tbh=Pk02YPuTUdweloGaaOW78g5tl702ky76X/Wu667Tbb8=;\n\th=Date:Subject:From:To:Cc:In-Reply-To:References:From;\n\tb=CAKqxZZOz/8Xkou8qH4qP3z3dHT2rYtGWMXXaGVJ5ouqmQ7/YWQw50CGl89K6q6Xp\n\t cAS34sXqZXO8ORNYyAg7fRoS4tdPJ89cE//owq8/pLSMRzVTLJMSJ8plRG9PI+3VWh\n\t 2WFo1cMPKHHlwBYaSMhnrSKGe0T1cPsMyIBRQQCqK8a9hPf0HWTHw4Fyio6gOtREhg\n\t z0jlsUkm6ThQTORkG5fkP0E5u+p09mgonnkmyT8O769R7drQcbCeK7XclghxrnWl0D\n\t P4otuzrOfZ+vLK491KGktERgpA54uR7MHvQVVw2PFim0rPPFFtBoMKkPF8fJZbVcpl\n\t 1L0TbeL/IoHjg==","Date":"Wed, 22 Apr 2026 16:23:31 -0700","Subject":"[PATCH 3/3] libext2fs: only fsync the unix fd if we wrote to the\n device","From":"\"Darrick J. Wong\" <djwong@kernel.org>","To":"tytso@mit.edu","Cc":"linux-ext4@vger.kernel.org","Message-ID":"<177689989365.3821152.8925862475853227905.stgit@frogsfrogsfrogs>","In-Reply-To":"<177689989303.3821152.12873703999139555043.stgit@frogsfrogsfrogs>","References":"<177689989303.3821152.12873703999139555043.stgit@frogsfrogsfrogs>","Precedence":"bulk","X-Mailing-List":"linux-ext4@vger.kernel.org","List-Id":"<linux-ext4.vger.kernel.org>","List-Subscribe":"<mailto:linux-ext4+subscribe@vger.kernel.org>","List-Unsubscribe":"<mailto:linux-ext4+unsubscribe@vger.kernel.org>","MIME-Version":"1.0","Content-Type":"text/plain; charset=\"utf-8\"","Content-Transfer-Encoding":"7bit","X-Spam-Status":"No, score=-1.2 required=5.0 tests=ARC_SIGNED,ARC_VALID,\n\tDKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DMARC_PASS,\n\tMAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=disabled\n\tversion=4.0.1","X-Spam-Checker-Version":"SpamAssassin 4.0.1 (2024-03-25) on gandalf.ozlabs.org"},"content":"From: Darrick J. Wong <djwong@kernel.org>\n\nAs an optimization, only fsync the block device fd if we tried to write\nto the io channel.\n\nSigned-off-by: \"Darrick J. Wong\" <djwong@kernel.org>\n---\n lib/ext2fs/unix_io.c |   86 +++++++++++++++++++++++++++++++++++++++-----------\n 1 file changed, 67 insertions(+), 19 deletions(-)","diff":"diff --git a/lib/ext2fs/unix_io.c b/lib/ext2fs/unix_io.c\nindex 15d6d55ff7fdd4..f4307db0fb2b05 100644\n--- a/lib/ext2fs/unix_io.c\n+++ b/lib/ext2fs/unix_io.c\n@@ -132,10 +132,13 @@ struct unix_cache {\n #define WRITE_DIRECT_SIZE 4\t/* Must be smaller than CACHE_SIZE */\n #define READ_DIRECT_SIZE 4\t/* Should be smaller than CACHE_SIZE */\n \n+#define UNIX_STATE_DIRTY\t(1U << 0) /* device needs fsyncing */\n+\n struct unix_private_data {\n \tint\tmagic;\n \tint\tdev;\n \tint\tflags;\n+\tunsigned int\tstate; /* UNIX_STATE_* */\n \tint\talign;\n \tint\taccess_time;\n \tint\tunix_flock_flags;\n@@ -1198,10 +1201,65 @@ static errcode_t unix_open(const char *name, int flags,\n \treturn unix_open_channel(name, fd, flags, channel, unix_io_manager);\n }\n \n+#ifdef HAVE_FSYNC\n+static void mark_dirty(io_channel channel)\n+{\n+\tstruct unix_private_data *data =\n+\t\t(struct unix_private_data *) channel->private_data;\n+\n+\tmutex_lock(data, CACHE_MTX);\n+\tdata->state |= UNIX_STATE_DIRTY;\n+\tmutex_unlock(data, CACHE_MTX);\n+}\n+\n+static errcode_t maybe_fsync(io_channel channel, int force_fsync)\n+{\n+\tstruct unix_private_data *data =\n+\t\t(struct unix_private_data *) channel->private_data;\n+\tint need_fsync;\n+\terrcode_t retval = 0;\n+\n+#ifndef NO_IO_CACHE\n+\tretval = flush_cached_blocks(channel, data, 0);\n+#endif\n+\n+\tmutex_lock(data, CACHE_MTX);\n+\tneed_fsync = force_fsync || (data->state & UNIX_STATE_DIRTY);\n+\tdata->state &= ~UNIX_STATE_DIRTY;\n+\tmutex_unlock(data, CACHE_MTX);\n+\n+\tif (need_fsync && fsync(data->dev) != 0) {\n+\t\tif (!retval)\n+\t\t\tretval = errno;\n+\t}\n+\tif (retval) {\n+\t\t/* redirty because writeback failed */\n+\t\tmark_dirty(channel);\n+\t\treturn retval;\n+\t}\n+\n+\treturn 0;\n+}\n+#else\n+# define mark_dirty(...)\t\t((void)0)\n+\n+static errcode_t maybe_fsync(io_channel channel, int force_fsync)\n+{\n+\tstruct unix_private_data *data =\n+\t\t(struct unix_private_data *) channel->private_data;\n+\terrcode_t retval = 0;\n+\n+#ifndef NO_IO_CACHE\n+\tretval = flush_cached_blocks(channel, data, 0);\n+#endif\n+\treturn retval;\n+}\n+#endif\n+\n static errcode_t unix_close(io_channel channel)\n {\n \tstruct unix_private_data *data;\n-\terrcode_t\tretval = 0;\n+\terrcode_t\tretval;\n \n \tEXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);\n \tdata = (struct unix_private_data *) channel->private_data;\n@@ -1210,14 +1268,7 @@ static errcode_t unix_close(io_channel channel)\n \tif (--channel->refcount > 0)\n \t\treturn 0;\n \n-#ifndef NO_IO_CACHE\n-\tretval = flush_cached_blocks(channel, data, 0);\n-#endif\n-#ifdef HAVE_FSYNC\n-\t/* always fsync the device, even if flushing our own cache failed */\n-\tif (fsync(data->dev) != 0 && !retval)\n-\t\tretval = errno;\n-#endif\n+\tretval = maybe_fsync(channel, 1);\n \n \tunix_funlock(channel);\n \n@@ -1388,6 +1439,8 @@ static errcode_t unix_write_blk64(io_channel channel, unsigned long long block,\n \tdata = (struct unix_private_data *) channel->private_data;\n \tEXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);\n \n+\tmark_dirty(channel);\n+\n #ifdef NO_IO_CACHE\n \treturn raw_write_blk(channel, data, block, count, buf, 0);\n #else\n@@ -1512,6 +1565,8 @@ static errcode_t unix_write_byte(io_channel channel, unsigned long offset,\n \tif (lseek(data->dev, offset + data->offset, SEEK_SET) < 0)\n \t\treturn errno;\n \n+\tmark_dirty(channel);\n+\n \tactual = write(data->dev, buf, size);\n \tif (actual < 0)\n \t\treturn errno;\n@@ -1527,21 +1582,12 @@ static errcode_t unix_write_byte(io_channel channel, unsigned long offset,\n static errcode_t unix_flush(io_channel channel)\n {\n \tstruct unix_private_data *data;\n-\terrcode_t retval = 0;\n \n \tEXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);\n \tdata = (struct unix_private_data *) channel->private_data;\n \tEXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);\n \n-#ifndef NO_IO_CACHE\n-\tretval = flush_cached_blocks(channel, data, 0);\n-#endif\n-#ifdef HAVE_FSYNC\n-\t/* always fsync the device, even if flushing our own cache failed */\n-\tif (fsync(data->dev) != 0 && !retval)\n-\t\treturn errno;\n-#endif\n-\treturn retval;\n+\treturn maybe_fsync(channel, 0);\n }\n \n static errcode_t unix_set_option(io_channel channel, const char *option,\n@@ -1653,6 +1699,7 @@ static errcode_t unix_discard(io_channel channel, unsigned long long block,\n \t\t}\n \t\treturn errno;\n \t}\n+\tmark_dirty(channel);\n \treturn 0;\n unimplemented:\n \treturn EXT2_ET_UNIMPLEMENTED;\n@@ -1734,6 +1781,7 @@ static errcode_t unix_zeroout(io_channel channel, unsigned long long block,\n \t\t}\n \t\treturn errno;\n \t}\n+\tmark_dirty(channel);\n \treturn 0;\n unimplemented:\n \treturn EXT2_ET_UNIMPLEMENTED;\n","prefixes":["3/3"]}