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[83.162.234.235]) by smtp.gmail.com with ESMTPSA id a67sm335827wmc.30.2020.04.20.01.04.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 20 Apr 2020 01:04:43 -0700 (PDT) From: Martijn Coenen To: axboe@kernel.dk, hch@lst.de, ming.lei@redhat.com Cc: narayan@google.com, zezeozue@google.com, kernel-team@android.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, maco@google.com, bvanassche@acm.org, Chaitanya.Kulkarni@wdc.com, Martijn Coenen Subject: [PATCH 1/4] loop: Refactor size calculation. Date: Mon, 20 Apr 2020 10:04:06 +0200 Message-Id: <20200420080409.111693-2-maco@android.com> X-Mailer: git-send-email 2.26.1.301.g55bc3eb7cb9-goog In-Reply-To: <20200420080409.111693-1-maco@android.com> References: <20200420080409.111693-1-maco@android.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org figure_loop_size() calculates the loop size based on the passed in parameters, but at the same time it updates the offset and sizelimit parameters in the loop device configuration. That is a somewhat unexpected side effect of a function with this name, and it is only only needed by one of the two callers of this function - loop_set_status(). Move the lo_offset and lo_sizelimit assignment back into loop_set_status(), and factor out a new function (loop_set_size()) to apply a newly calculated size that has been validated to fit in sector_t, and notify user-space. loop_update_size() is now solely used by loop_set_capacity to compute an updated size, and loop_set_status() uses a combination of functions to validate the loop size, and only apply it later. Signed-off-by: Martijn Coenen --- drivers/block/loop.c | 88 ++++++++++++++++++++++++++++---------------- 1 file changed, 56 insertions(+), 32 deletions(-) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index f1754262fc94..d934d65dbe92 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -228,23 +228,42 @@ static void __loop_update_dio(struct loop_device *lo, bool dio) blk_mq_unfreeze_queue(lo->lo_queue); } +/** + * loop_set_size - sets device size and notifies userspace + * @lo: struct loop_device to set the size for + * @size: new size of the loop device + * + * Callers must validate that the size passed into this function fits into + * a sector_t. + */ +static void loop_set_size(struct loop_device *lo, loff_t size) +{ + struct block_device *bdev = lo->lo_device; + + set_capacity(lo->lo_disk, size); + bd_set_size(bdev, size << 9); + /* let user-space know about the new size */ + kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE); +} + +/** + * loop_update_size - updates device size from the backing file + * @lo: struct loop_device to update the size for + * + * Recomputes the device size from the backing file, and updates the device + * with the new size. + */ static int -figure_loop_size(struct loop_device *lo, loff_t offset, loff_t sizelimit) +loop_update_size(struct loop_device *lo) { - loff_t size = get_size(offset, sizelimit, lo->lo_backing_file); + loff_t size = get_loop_size(lo, lo->lo_backing_file); sector_t x = (sector_t)size; - struct block_device *bdev = lo->lo_device; if (unlikely((loff_t)x != size)) return -EFBIG; - if (lo->lo_offset != offset) - lo->lo_offset = offset; - if (lo->lo_sizelimit != sizelimit) - lo->lo_sizelimit = sizelimit; - set_capacity(lo->lo_disk, x); - bd_set_size(bdev, (loff_t)get_capacity(bdev->bd_disk) << 9); - /* let user-space know about the new size */ - kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE); + + loop_set_size(lo, size); + return 0; } @@ -1040,11 +1059,8 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode, loop_update_rotational(lo); loop_update_dio(lo); - set_capacity(lo->lo_disk, size); - bd_set_size(bdev, size << 9); loop_sysfs_init(lo); - /* let user-space know about the new size */ - kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE); + loop_set_size(lo, size); set_blocksize(bdev, S_ISBLK(inode->i_mode) ? block_size(inode->i_bdev) : PAGE_SIZE); @@ -1267,6 +1283,8 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info) kuid_t uid = current_uid(); struct block_device *bdev; bool partscan = false; + bool size_changed = false; + loff_t validated_size; err = mutex_lock_killable(&loop_ctl_mutex); if (err) @@ -1288,6 +1306,14 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info) if (lo->lo_offset != info->lo_offset || lo->lo_sizelimit != info->lo_sizelimit) { + size_t size = get_size(info->lo_offset, info->lo_sizelimit, + lo->lo_backing_file); + if ((loff_t)(sector_t)size != size) { + err = -EFBIG; + goto out_unlock; + } + size_changed = true; + validated_size = size; sync_blockdev(lo->lo_device); kill_bdev(lo->lo_device); } @@ -1295,6 +1321,15 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info) /* I/O need to be drained during transfer transition */ blk_mq_freeze_queue(lo->lo_queue); + if (size_changed && lo->lo_device->bd_inode->i_mapping->nrpages) { + /* kill_bdev should have truncated all the pages */ + err = -EAGAIN; + pr_warn("%s: loop%d (%s) has still dirty pages (nrpages=%lu)\n", + __func__, lo->lo_number, lo->lo_file_name, + lo->lo_device->bd_inode->i_mapping->nrpages); + goto out_unfreeze; + } + err = loop_release_xfer(lo); if (err) goto out_unfreeze; @@ -1318,22 +1353,8 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info) if (err) goto out_unfreeze; - if (lo->lo_offset != info->lo_offset || - lo->lo_sizelimit != info->lo_sizelimit) { - /* kill_bdev should have truncated all the pages */ - if (lo->lo_device->bd_inode->i_mapping->nrpages) { - err = -EAGAIN; - pr_warn("%s: loop%d (%s) has still dirty pages (nrpages=%lu)\n", - __func__, lo->lo_number, lo->lo_file_name, - lo->lo_device->bd_inode->i_mapping->nrpages); - goto out_unfreeze; - } - if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit)) { - err = -EFBIG; - goto out_unfreeze; - } - } - + lo->lo_offset = info->lo_offset; + lo->lo_sizelimit = info->lo_sizelimit; memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE); memcpy(lo->lo_crypt_name, info->lo_crypt_name, LO_NAME_SIZE); lo->lo_file_name[LO_NAME_SIZE-1] = 0; @@ -1357,6 +1378,9 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info) lo->lo_key_owner = uid; } + if (size_changed) + loop_set_size(lo, validated_size); + loop_config_discard(lo); /* update dio if lo_offset or transfer is changed */ @@ -1534,7 +1558,7 @@ static int loop_set_capacity(struct loop_device *lo) if (unlikely(lo->lo_state != Lo_bound)) return -ENXIO; - return figure_loop_size(lo, lo->lo_offset, lo->lo_sizelimit); + return loop_update_size(lo); } static int loop_set_dio(struct loop_device *lo, unsigned long arg) -- 2.26.1.301.g55bc3eb7cb9-goog