{"id":2226963,"url":"http://patchwork.ozlabs.org/api/patches/2226963/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-ext4/patch/177689989593.3821326.8030762717050212953.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":"<177689989593.3821326.8030762717050212953.stgit@frogsfrogsfrogs>","list_archive_url":null,"date":"2026-04-22T23:24:19","name":"[03/10] unix_io: allow passing /dev/fd/XXX paths to the unixfd IO manager","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"d6992abcc26f0b7888b93922679b097829f1ba5c","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/177689989593.3821326.8030762717050212953.stgit@frogsfrogsfrogs/mbox/","series":[{"id":501127,"url":"http://patchwork.ozlabs.org/api/series/501127/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-ext4/list/?series=501127","date":"2026-04-22T23:23:47","name":"[01/10] libext2fs: make it possible to extract the fd from an IO manager","version":1,"mbox":"http://patchwork.ozlabs.org/series/501127/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2226963/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2226963/checks/","tags":{},"related":[],"headers":{"Return-Path":"\n ","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=odUyoTq7;\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=1776900259;\n\tbh=NkhOfkyKeLlFOmxSWSlGf6xb4M1S8YLYljkVdi3MaHo=;\n\th=Date:Subject:From:To:Cc:In-Reply-To:References:From;\n\tb=odUyoTq7Vp2S9mBWvbF5qFoaOAgbteZHoTrVx5PVBIawj82FhrXenru3gif6sFq6z\n\t 94zBP8JnIo+J9nHjwo9zz2fjgNYVsguByZ2KQgKZ8XMyquvgVY0Zlpm4WxpBhLM7HA\n\t K3XOwgHyFuA1pzMqC44uXhZ+JM8AYmwLVYRJJtBoEja69GaduWY4k5cuNyQzCbIh/v\n\t A0kd22K5+OGZM6NHfeAS1+LOzz8asjECepWOSRYLC5jso0QV0TtRiXe2zpiK4684Mn\n\t lJPaALs/x3+pruq6SFHFUDKLoEHSS9q4+bqmlkR3pE9KrKWP49pHUL9jLS/sVUYUFg\n\t fVVSLyyllapeg==","Date":"Wed, 22 Apr 2026 16:24:19 -0700","Subject":"[PATCH 03/10] unix_io: allow passing /dev/fd/XXX paths to the unixfd\n IO manager","From":"\"Darrick J. Wong\" ","To":"tytso@mit.edu","Cc":"linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org,\n fuse-devel@lists.linux.dev, linux-ext4@vger.kernel.org, neal@gompa.dev,\n joannelkoong@gmail.com, miklos@szeredi.hu, bernd@bsbernd.com","Message-ID":"<177689989593.3821326.8030762717050212953.stgit@frogsfrogsfrogs>","In-Reply-To":"<177689989498.3821326.15497525132012299039.stgit@frogsfrogsfrogs>","References":"<177689989498.3821326.15497525132012299039.stgit@frogsfrogsfrogs>","Precedence":"bulk","X-Mailing-List":"linux-ext4@vger.kernel.org","List-Id":"","List-Subscribe":"","List-Unsubscribe":"","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 \n\nCommit 4ccf9e4fe165cf created a \"unixfd\" IO manager that allows someone\nto choose the unixfd IO manager and then mount a filesystem from an\nexisting file descriptor by passing a string with the fd number as the\n\"device\" name to ext2fs_open().\n\nThat was an unfortunate choice of naming, however, because that could\nbe mistaken for a relative path to a file whose name is an integer\nnumber. Let's improve this by allowing callers to pass /dev/fd/XX\nas the filesystem device name. The upcoming fuse4fs service patches\nwill employ this method to open a filesystem on a block device fd passed\ninto the secure container from a mount helper.\n\nCc: # v1.43.2\nFixes: 4ccf9e4fe165cf (\"libext2fs: add unixfd_io_manager\")\nSigned-off-by: \"Darrick J. Wong\" \n---\n lib/ext2fs/unix_io.c | 30 +++++++++++++++++++++++++++++-\n 1 file changed, 29 insertions(+), 1 deletion(-)","diff":"diff --git a/lib/ext2fs/unix_io.c b/lib/ext2fs/unix_io.c\nindex 79bc9219f9515b..a9b1fac62a0250 100644\n--- a/lib/ext2fs/unix_io.c\n+++ b/lib/ext2fs/unix_io.c\n@@ -67,6 +67,7 @@\n #ifdef HAVE_SYS_FILE_H\n #include \n #endif\n+#include \n \n #if defined(__linux__) && defined(_IO) && !defined(BLKROGET)\n #define BLKROGET _IO(0x12, 94) /* Get read-only status (0 = read_write). */\n@@ -1148,13 +1149,40 @@ static errcode_t unix_open_channel(const char *name, int fd,\n \treturn retval;\n }\n \n+#define DEV_FD_PATH\t\"/dev/fd/\"\n+#define DEV_FD_PATHLEN\t(sizeof(DEV_FD_PATH) - 1)\n+\n+static int possible_unixfd_pathname(const char *path)\n+{\n+\treturn strncmp(DEV_FD_PATH, path, DEV_FD_PATHLEN) == 0;\n+}\n+\n static errcode_t unixfd_open(const char *str_fd, int flags,\n \t\t\t io_channel *channel)\n {\n \tint fd;\n \tint fd_flags;\n \n-\tfd = atoi(str_fd);\n+\t/*\n+\t * The caller should provide a path in the form \"/dev/fd/XX\",\n+\t * but the shorthand form \"XX\" is allowed for legacy reasons.\n+\t */\n+\tif (possible_unixfd_pathname(str_fd)) {\n+\t\tchar *endptr;\n+\t\tlong maybe_fd;\n+\n+\t\terrno = 0;\n+\t\tmaybe_fd = strtol(str_fd + DEV_FD_PATHLEN, &endptr, 10);\n+\t\tif (errno)\n+\t\t\treturn errno;\n+\t\tif (*endptr != 0)\n+\t\t\treturn EINVAL;\n+\t\tif (maybe_fd < 0 || maybe_fd > INT_MAX)\n+\t\t\treturn EINVAL;\n+\t\tfd = maybe_fd;\n+\t} else {\n+\t\tfd = atoi(str_fd);\n+\t}\n #if defined(HAVE_FCNTL)\n \tfd_flags = fcntl(fd, F_GETFL);\n \tif (fd_flags == -1)\n","prefixes":["03/10"]}