BMC/Intel-BMC/linux.git/drivers/block/xen-blkback, branch dev-4.4

xen-blkback: read from indirect descriptors only once

2015-12-18T15:00:37+00:00

Since indirect descriptors are in memory shared with the frontend, the frontend could alter the first_sect and last_sect values after they have been validated but before they are recorded in the request. This may result in I/O requests that overflow the foreign page, possibly overwriting local pages when the I/O request is executed. When parsing indirect descriptors, only read first_sect and last_sect once. This is part of XSA155. CC: stable@vger.kernel.org Signed-off-by: Roger Pau Monné Signed-off-by: David Vrabel Signed-off-by: Konrad Rzeszutek Wilk

xen-blkback: only read request operation from shared ring once

2015-12-18T15:00:32+00:00

A compiler may load a switch statement value multiple times, which could be bad when the value is in memory shared with the frontend. When converting a non-native request to a native one, ensure that src->operation is only loaded once by using READ_ONCE(). This is part of XSA155. CC: stable@vger.kernel.org Signed-off-by: Roger Pau Monné Signed-off-by: David Vrabel Signed-off-by: Konrad Rzeszutek Wilk

xen/xenbus: Rename RING_PAGE to RING_GRANT

2015-10-23T13:20:46+00:00

Linux may use a different page size than the size of grant. So make clear that the order is actually in number of grant. Signed-off-by: Julien Grall Signed-off-by: David Vrabel

block/xen-blkback: Make it running on 64KB page granularity

2015-10-23T13:20:40+00:00

The PV block protocol is using 4KB page granularity. The goal of this patch is to allow a Linux using 64KB page granularity behaving as a block backend on a non-modified Xen. It's only necessary to adapt the ring size and the number of request per indirect frames. The rest of the code is relying on the grant table code. Note that the grant table code is allocating a Linux page per grant which will result to waste 6OKB for every grant when Linux is using 64KB page granularity. This could be improved by sharing the page between multiple grants. Signed-off-by: Julien Grall Acked-by: "Roger Pau Monné" Signed-off-by: David Vrabel

Merge branch 'stable/for-jens-4.3' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen into for-linus

2015-09-23T16:59:44+00:00

Konrad writes: It has one fix that should go in and also be put in stable tree (I've added the CC already). It is a fix for a memory leak that can exposed via using UEFI xen-blkfront driver.

xen/blkback: free requests on disconnection

2015-09-23T16:09:19+00:00

This is due to commit 86839c56dee28c315a4c19b7bfee450ccd84cd25 "xen/block: add multi-page ring support" When using an guest under UEFI - after the domain is destroyed the following warning comes from blkback. ------------[ cut here ]------------ WARNING: CPU: 2 PID: 95 at /home/julien/works/linux/drivers/block/xen-blkback/xenbus.c:274 xen_blkif_deferred_free+0x1f4/0x1f8() Modules linked in: CPU: 2 PID: 95 Comm: kworker/2:1 Tainted: G W 4.2.0 #85 Hardware name: APM X-Gene Mustang board (DT) Workqueue: events xen_blkif_deferred_free Call trace: [] dump_backtrace+0x0/0x124 [] show_stack+0x10/0x1c [] dump_stack+0x78/0x98 [] warn_slowpath_common+0x9c/0xd4 [] warn_slowpath_null+0x14/0x20 [] xen_blkif_deferred_free+0x1f0/0x1f8 [] process_one_work+0x160/0x3b4 [] worker_thread+0x140/0x494 [] kthread+0xd8/0xf0 ---[ end trace 6f859b7883c88cdd ]--- Request allocation has been moved to connect_ring, which is called every time blkback connects to the frontend (this can happen multiple times during a blkback instance life cycle). On the other hand, request freeing has not been moved, so it's only called when destroying the backend instance. Due to this mismatch, blkback can allocate the request pool multiple times, without freeing it. In order to fix it, move the freeing of requests to xen_blkif_disconnect to restore the symmetry between request allocation and freeing. Reported-by: Julien Grall Signed-off-by: Roger Pau Monné Tested-by: Julien Grall Cc: Konrad Rzeszutek Wilk Cc: Boris Ostrovsky Cc: David Vrabel Cc: xen-devel@lists.xenproject.org CC: stable@vger.kernel.org # 4.2 Signed-off-by: Konrad Rzeszutek Wilk

Merge branch 'for-4.3/core' of git://git.kernel.dk/linux-block

2015-09-02T20:10:25+00:00

Pull core block updates from Jens Axboe: "This first core part of the block IO changes contains: - Cleanup of the bio IO error signaling from Christoph. We used to rely on the uptodate bit and passing around of an error, now we store the error in the bio itself. - Improvement of the above from myself, by shrinking the bio size down again to fit in two cachelines on x86-64. - Revert of the max_hw_sectors cap removal from a revision again, from Jeff Moyer. This caused performance regressions in various tests. Reinstate the limit, bump it to a more reasonable size instead. - Make /sys/block//queue/discard_max_bytes writeable, by me. Most devices have huge trim limits, which can cause nasty latencies when deleting files. Enable the admin to configure the size down. We will look into having a more sane default instead of UINT_MAX sectors. - Improvement of the SGP gaps logic from Keith Busch. - Enable the block core to handle arbitrarily sized bios, which enables a nice simplification of bio_add_page() (which is an IO hot path). From Kent. - Improvements to the partition io stats accounting, making it faster. From Ming Lei. - Also from Ming Lei, a basic fixup for overflow of the sysfs pending file in blk-mq, as well as a fix for a blk-mq timeout race condition. - Ming Lin has been carrying Kents above mentioned patches forward for a while, and testing them. Ming also did a few fixes around that. - Sasha Levin found and fixed a use-after-free problem introduced by the bio->bi_error changes from Christoph. - Small blk cgroup cleanup from Viresh Kumar" * 'for-4.3/core' of git://git.kernel.dk/linux-block: (26 commits) blk: Fix bio_io_vec index when checking bvec gaps block: Replace SG_GAPS with new queue limits mask block: bump BLK_DEF_MAX_SECTORS to 2560 Revert "block: remove artifical max_hw_sectors cap" blk-mq: fix race between timeout and freeing request blk-mq: fix buffer overflow when reading sysfs file of 'pending' Documentation: update notes in biovecs about arbitrarily sized bios block: remove bio_get_nr_vecs() fs: use helper bio_add_page() instead of open coding on bi_io_vec block: kill merge_bvec_fn() completely md/raid5: get rid of bio_fits_rdev() md/raid5: split bio for chunk_aligned_read block: remove split code in blkdev_issue_{discard,write_same} btrfs: remove bio splitting and merge_bvec_fn() calls bcache: remove driver private bio splitting code block: simplify bio_add_page() block: make generic_make_request handle arbitrarily sized bios blk-cgroup: Drop unlikely before IS_ERR(_OR_NULL) block: don't access bio->bi_error after bio_put() block: shrink struct bio down to 2 cache lines again ...

block: add a bi_error field to struct bio

2015-07-29T14:55:15+00:00

Currently we have two different ways to signal an I/O error on a BIO: (1) by clearing the BIO_UPTODATE flag (2) by returning a Linux errno value to the bi_end_io callback The first one has the drawback of only communicating a single possible error (-EIO), and the second one has the drawback of not beeing persistent when bios are queued up, and are not passed along from child to parent bio in the ever more popular chaining scenario. Having both mechanisms available has the additional drawback of utterly confusing driver authors and introducing bugs where various I/O submitters only deal with one of them, and the others have to add boilerplate code to deal with both kinds of error returns. So add a new bi_error field to store an errno value directly in struct bio and remove the existing mechanisms to clean all this up. Signed-off-by: Christoph Hellwig Reviewed-by: Hannes Reinecke Reviewed-by: NeilBrown Signed-off-by: Jens Axboe

Merge branch 'stable/for-jens-4.2' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen into for-linus

2015-07-27T17:58:41+00:00

Konrad writes: "There are three bugs that have been found in the xen-blkfront (and backend). Two of them have the stable tree CC-ed. They have been found where an guest is migrating to a host that is missing 'feature-persistent' support (from one that has it enabled). We end up hitting an BUG() in the driver code."

xen-blkback: replace work_pending with work_busy in purge_persistent_gnt()

2015-07-24T13:09:49+00:00

The BUG_ON() in purge_persistent_gnt() will be triggered when previous purge work haven't finished. There is a work_pending() before this BUG_ON, but it doesn't account if the work is still currently running. CC: stable@vger.kernel.org Acked-by: Roger Pau Monné Signed-off-by: Bob Liu Signed-off-by: Konrad Rzeszutek Wilk