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Wed, 07 Oct 2026 09:03:57 -0700 (PDT) From: Adarsh Das To: johannes.thumshirn@wdc.com Cc: adarshdas950@gmail.com, dsterba@suse.com, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, mason@kernel.org, syzbot+3bf3e110b2d406b8166c@syzkaller.appspotmail.com Subject: [PATCH v2] btrfs: unwind device add when sysfs registration fails Date: Wed, 7 Oct 2026 21:33:49 +0530 Message-ID: <20261007160349.22411-1-adarshdas950@gmail.com> X-Mailer: git-send-email 2.56.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit btrfs_init_new_device() ignored the return value of btrfs_sysfs_add_device(). When sysfs link creation failed (e.g. -EEXIST), the add path continued, aborted the transaction with the same errno, and tripped WARN_ON(btrfs_abort_should_print_stack()) while leaving the device half-registered in memory. Check the return value and unwind when registration fails, without aborting the filesystem for errnos like -EEXIST. If add failed before anything was published in sysfs, tear down the in-memory device state only and do not call btrfs_sysfs_remove_device(). When the block-device link was created but devid kobject registration fails, drop the link inside btrfs_sysfs_add_device() before returning the error. Reported-by: syzbot+3bf3e110b2d406b8166c@syzkaller.appspotmail.com Link: https://lore.kernel.org/all/6a791c94.01d0871a.3a0d52.0099.GAE@google.com Tested-by: syzbot+3bf3e110b2d406b8166c@syzkaller.appspotmail.com Assisted-by: LLM Signed-off-by: Adarsh Das --- v2: - Unwind without sysfs remove when add failed (review on v1) - Roll back block-device link if devid kobject add fails v1: https://lore.kernel.org/all/20261003111951.24527-1-adarshdas950@gmail.com/ --- fs/btrfs/sysfs.c | 3 +++ fs/btrfs/volumes.c | 7 ++++++- 2 files changed, 9 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c index 39cb01ee441a..2f034689e71b 100644 --- a/fs/btrfs/sysfs.c +++ b/fs/btrfs/sysfs.c @@ -2165,6 +2165,9 @@ int btrfs_sysfs_add_device(struct btrfs_device *device) ret = kobject_init_and_add(&device->devid_kobj, &devid_ktype, devinfo_kobj, "%llu", device->devid); if (ret) { + if (device->bdev) + sysfs_remove_link(devices_kobj, + bdev_kobj(device->bdev)->name); kobject_put(&device->devid_kobj); btrfs_warn(device->fs_info, "devinfo init for devid %llu failed: %d", diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 85ea9c5d4536..56b38f012093 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -3066,7 +3066,11 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path mutex_unlock(&fs_info->chunk_mutex); /* Add sysfs device entry */ - btrfs_sysfs_add_device(device); + ret = btrfs_sysfs_add_device(device); + if (ret) { + mutex_unlock(&fs_devices->device_list_mutex); + goto error_unwind_device; + } mutex_unlock(&fs_devices->device_list_mutex); @@ -3147,6 +3151,7 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path error_sysfs: btrfs_sysfs_remove_device(device); +error_unwind_device: mutex_lock(&fs_info->fs_devices->device_list_mutex); if (seeding_dev) btrfs_assign_next_active_device(device, seed_devices->latest_dev);