user/sven/linux.git/include/linux/genhd.h, branch v3.0.46

block: fix buffer overflow when printing partition UUIDs

2012-06-01T07:12:52Z

commit 05c69d298c96703741cac9a5cbbf6c53bd55a6e2 upstream. 6d1d8050b4bc8 "block, partition: add partition_meta_info to hd_struct" added part_unpack_uuid() which assumes that the passed in buffer has enough space for sprintfing "%pU" - 37 characters including '\0'. Unfortunately, b5af921ec0233 "init: add support for root devices specified by partition UUID" supplied 33 bytes buffer to the function leading to the following panic with stackprotector enabled. Kernel panic - not syncing: stack-protector: Kernel stack corrupted in: ffffffff81b14c7e [] panic+0xba/0x1c6 [] ? printk_all_partitions+0x259/0x26xb [] __stack_chk_fail+0x1b/0x20 [] printk_all_paritions+0x259/0x26xb [] mount_block_root+0x1bc/0x27f [] mount_root+0x57/0x5b [] prepare_namespace+0x13d/0x176 [] ? release_tgcred.isra.4+0x330/0x30 [] kernel_init+0x155/0x15a [] ? schedule_tail+0x27/0xb0 [] kernel_thread_helper+0x5/0x10 [] ? start_kernel+0x3c5/0x3c5 [] ? gs_change+0x13/0x13 Increase the buffer size, remove the dangerous part_unpack_uuid() and use snprintf() directly from printk_all_partitions(). Signed-off-by: Tejun Heo Reported-by: Szymon Gruszczynski Cc: Will Drewry Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

block: Fix NULL pointer dereference in sd_revalidate_disk

2012-03-19T15:57:58Z

commit fe316bf2d5847bc5dd975668671a7b1067603bc7 upstream. Since 2.6.39 (1196f8b), when a driver returns -ENOMEDIUM for open(), __blkdev_get() calls rescan_partitions() to remove in-kernel partition structures and raise KOBJ_CHANGE uevent. However it ends up calling driver's revalidate_disk without open and could cause oops. In the case of SCSI: process A process B ---------------------------------------------- sys_open __blkdev_get sd_open returns -ENOMEDIUM scsi_remove_device rescan_partitions sd_revalidate_disk Oopses are reported here: http://marc.info/?l=linux-scsi&m=132388619710052 This patch separates the partition invalidation from rescan_partitions() and use it for -ENOMEDIUM case. Reported-by: Huajun Li Signed-off-by: Jun'ichi Nomura Acked-by: Tejun Heo Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

Revert "block: Remove extra discard_alignment from hd_struct."

2011-05-30T05:42:51Z

It was not a good idea to start dereferencing disk->queue from the fs sysfs strategy for displaying discard alignment. We ran into first a NULL pointer deref, and after fixing that we sometimes see unvalid disk->queue pointer values. Since discard is the only one of the bunch actually looking into the queue, just revert the change. This reverts commit 23ceb5b7719e9276d4fa72a3ecf94dd396755276. Conflicts: fs/partitions/check.c

block: Remove extra discard_alignment from hd_struct.

2011-05-07T01:30:02Z

Currently, hd_struct.discard_alignment is only used when we show /sys/block/sdx/sdx/discard_alignment. So remove it and calculate when it is asked to show. Signed-off-by: Tao Ma Signed-off-by: Jens Axboe

block: don't block events on excl write for non-optical devices

2011-04-21T18:54:46Z

Disk event code automatically blocks events on excl write. This is primarily to avoid issuing polling commands while burning is in progress. This behavior doesn't fit other types of devices with removeable media where polling commands don't have adverse side effects and door locking usually doesn't exist. This patch introduces new genhd flag which controls the auto-blocking behavior and uses it to enable auto-blocking only on optical devices. Note for stable: 2.6.38 and later only Cc: stable@kernel.org Signed-off-by: Tejun Heo Reported-by: Kay Sievers Signed-off-by: Jens Axboe

block: fix non-atomic access to genhd inflight structures

2011-03-22T07:35:35Z

After the stack plugging introduction, these are called lockless. Ensure that the counters are updated atomically. Signed-off-by: Shaohua Li Signed-off-by: Jens Axboe

Merge branch 'for-2.6.38/event-handling' into for-2.6.38/core

2011-01-13T13:47:54Z

block: add internal hd part table references

2011-01-07T07:43:37Z

We can't use krefs since it's apparently restricted to very basic reference counting. This reverts commit e4a683c8. Signed-off-by: Jens Axboe

block: fix accounting bug on cross partition merges

2011-01-05T15:57:38Z

/proc/diskstats would display a strange output as follows. $ cat /proc/diskstats |grep sda 8 0 sda 90524 7579 102154 20464 0 0 0 0 0 14096 20089 8 1 sda1 19085 1352 21841 4209 0 0 0 0 4294967064 15689 4293424691 ~~~~~~~~~~ 8 2 sda2 71252 3624 74891 15950 0 0 0 0 232 23995 1562390 8 3 sda3 54 487 2188 92 0 0 0 0 0 88 92 8 4 sda4 4 0 8 0 0 0 0 0 0 0 0 8 5 sda5 81 2027 2130 138 0 0 0 0 0 87 137 Its reason is the wrong way of accounting hd_struct->in_flight. When a bio is merged into a request belongs to different partition by ELEVATOR_FRONT_MERGE. The detailed root cause is as follows. Assuming that there are two partition, sda1 and sda2. 1. A request for sda2 is in request_queue. Hence sda1's hd_struct->in_flight is 0 and sda2's one is 1. | hd_struct->in_flight --------------------------- sda1 | 0 sda2 | 1 --------------------------- 2. A bio belongs to sda1 is issued and is merged into the request mentioned on step1 by ELEVATOR_BACK_MERGE. The first sector of the request is changed from sda2 region to sda1 region. However the two partition's hd_struct->in_flight are not changed. | hd_struct->in_flight --------------------------- sda1 | 0 sda2 | 1 --------------------------- 3. The request is finished and blk_account_io_done() is called. In this case, sda2's hd_struct->in_flight, not a sda1's one, is decremented. | hd_struct->in_flight --------------------------- sda1 | -1 sda2 | 1 --------------------------- The patch fixes the problem by caching the partition lookup inside the request structure, hence making sure that the increment and decrement will always happen on the same partition struct. This also speeds up IO with accounting enabled, since it cuts down on the number of lookups we have to do. Also add a refcount to struct hd_struct to keep the partition in memory as long as users exist. We use kref_test_and_get() to ensure we don't add a reference to a partition which is going away. Signed-off-by: Jerome Marchand Signed-off-by: Yasuaki Ishimatsu Cc: stable@kernel.org Signed-off-by: Jens Axboe

implement in-kernel gendisk events handling

2010-12-16T16:53:38Z

Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo Cc: Kay Sievers Cc: Jan Kara Signed-off-by: Jens Axboe