kernel/drivers/md/dm.c, branch linux-5.1.y

dax: Arrange for dax_supported check to span multiple devices

2019-05-31T13:43:09Z

commit 7bf7eac8d648057519adb6fce1e31458c902212c upstream. Pankaj reports that starting with commit ad428cdb525a "dax: Check the end of the block-device capacity with dax_direct_access()" device-mapper no longer allows dax operation. This results from the stricter checks in __bdev_dax_supported() that validate that the start and end of a block-device map to the same 'pagemap' instance. Teach the dax-core and device-mapper to validate the 'pagemap' on a per-target basis. This is accomplished by refactoring the bdev_dax_supported() internals into generic_fsdax_supported() which takes a sector range to validate. Consequently generic_fsdax_supported() is suitable to be used in a device-mapper ->iterate_devices() callback. A new ->dax_supported() operation is added to allow composite devices to split and route upper-level bdev_dax_supported() requests. Fixes: ad428cdb525a ("dax: Check the end of the block-device...") Cc: Cc: Ira Weiny Cc: Dave Jiang Cc: Keith Busch Cc: Matthew Wilcox Cc: Vishal Verma Cc: Heiko Carstens Cc: Martin Schwidefsky Reviewed-by: Jan Kara Reported-by: Pankaj Gupta Reviewed-by: Pankaj Gupta Tested-by: Pankaj Gupta Tested-by: Vaibhav Jain Reviewed-by: Mike Snitzer Signed-off-by: Dan Williams Signed-off-by: Greg Kroah-Hartman

dm: make sure to obey max_io_len_target_boundary

2019-05-25T16:16:47Z

commit 51b86f9a8d1c4bb4e3862ee4b4c5f46072f7520d upstream. Commit 61697a6abd24 ("dm: eliminate 'split_discard_bios' flag from DM target interface") incorrectly removed code from __send_changing_extent_only() that is required to impose a per-target IO boundary on IO that exceeds max_io_len_target_boundary(). Otherwise "special" IO (e.g. DISCARD, WRITE SAME, WRITE ZEROES) can write beyond where allowed. Fix this by restoring the max_io_len_target_boundary() limit in __send_changing_extent_only() Fixes: 61697a6abd24 ("dm: eliminate 'split_discard_bios' flag from DM target interface") Cc: stable@vger.kernel.org # 5.1+ Signed-off-by: Michael Lass Signed-off-by: Mike Snitzer Signed-off-by: Greg Kroah-Hartman

dm: disable DISCARD if the underlying storage no longer supports it

2019-04-04T19:33:59Z

Storage devices which report supporting discard commands like WRITE_SAME_16 with unmap, but reject discard commands sent to the storage device. This is a clear storage firmware bug but it doesn't change the fact that should a program cause discards to be sent to a multipath device layered on this buggy storage, all paths can end up failed at the same time from the discards, causing possible I/O loss. The first discard to a path will fail with Illegal Request, Invalid field in cdb, e.g.: kernel: sd 8:0:8:19: [sdfn] tag#0 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE kernel: sd 8:0:8:19: [sdfn] tag#0 Sense Key : Illegal Request [current] kernel: sd 8:0:8:19: [sdfn] tag#0 Add. Sense: Invalid field in cdb kernel: sd 8:0:8:19: [sdfn] tag#0 CDB: Write same(16) 93 08 00 00 00 00 00 a0 08 00 00 00 80 00 00 00 kernel: blk_update_request: critical target error, dev sdfn, sector 10487808 The SCSI layer converts this to the BLK_STS_TARGET error number, the sd device disables its support for discard on this path, and because of the BLK_STS_TARGET error multipath fails the discard without failing any path or retrying down a different path. But subsequent discards can cause path failures. Any discards sent to the path which already failed a discard ends up failing with EIO from blk_cloned_rq_check_limits with an "over max size limit" error since the discard limit was set to 0 by the sd driver for the path. As the error is EIO, this now fails the path and multipath tries to send the discard down the next path. This cycle continues as discards are sent until all paths fail. Fix this by training DM core to disable DISCARD if the underlying storage already did so. Also, fix branching in dm_done() and clone_endio() to reflect the mutually exclussive nature of the IO operations in question. Cc: stable@vger.kernel.org Reported-by: David Jeffery Signed-off-by: Mike Snitzer

dm: revert 8f50e358153d ("dm: limit the max bio size as BIO_MAX_PAGES * PAGE_SIZE")

2019-04-01T20:20:36Z

The limit was already incorporated to dm-crypt with commit 4e870e948fba ("dm crypt: fix error with too large bios"), so we don't need to apply it globally to all targets. The quantity BIO_MAX_PAGES * PAGE_SIZE is wrong anyway because the variable ti->max_io_len it is supposed to be in the units of 512-byte sectors not in bytes. Reduction of the limit to 1048576 sectors could even cause data corruption in rare cases - suppose that we have a dm-striped device with stripe size 768MiB. The target will call dm_set_target_max_io_len with the value 1572864. The buggy code would reduce it to 1048576. Now, the dm-core will errorneously split the bios on 1048576-sector boundary insetad of 1572864-sector boundary and pass these stripe-crossing bios to the striped target. Cc: stable@vger.kernel.org # v4.16+ Fixes: 8f50e358153d ("dm: limit the max bio size as BIO_MAX_PAGES * PAGE_SIZE") Signed-off-by: Mikulas Patocka Acked-by: Ming Lei Signed-off-by: Mike Snitzer

dm: always call blk_queue_split() in dm_process_bio()

2019-03-05T19:53:32Z

Do not just call blk_queue_split() if the bio is_abnormal_io(). Fixes: 568c73a355e ("dm: update dm_process_bio() to split bio if in ->make_request_fn()") Signed-off-by: Mike Snitzer

dm: remove unused _rq_tio_cache and _rq_cache

2019-03-05T19:48:50Z

Also move dm_rq_target_io structure definition from dm-rq.h to dm-rq.c Fixes: 6a23e05c2fe3c6 ("dm: remove legacy request-based IO path") Signed-off-by: Mike Snitzer

dm: eliminate 'split_discard_bios' flag from DM target interface

2019-02-21T04:24:55Z

There is no need to have DM core split discards on behalf of a DM target now that blk_queue_split() handles splitting discards based on the queue_limits. A DM target just needs to set max_discard_sectors, discard_granularity, etc, in queue_limits. Signed-off-by: Mike Snitzer

dm: update dm_process_bio() to split bio if in ->make_request_fn()

2019-02-19T17:25:00Z

Must call blk_queue_split() otherwise queue_limits for abnormal requests (e.g. discard, writesame, etc) won't be imposed. In addition, add dm_queue_split() to simplify DM specific splitting that is needed for targets that impose ti->max_io_len. Signed-off-by: Mike Snitzer

dm: don't use bio_trim() afterall

2019-02-06T22:24:37Z

bio_trim() has an early return, which makes it _not_ idempotent, if the offset is 0 and the bio's bi_size already matches the requested size. Prior to DM, all users of bio_trim() were fine with this. But DM has exposed the fact that bio_trim()'s early return is incompatible with a cloned bio whose integrity payload must be trimmed via bio_integrity_trim(). Fix this by reverting DM back to doing the equivalent of bio_trim() but in an idempotent manner (so bio_integrity_trim is always performed). Follow-on work is needed to assess what benefit bio_trim()'s early return is providing to its existing callers. Reported-by: Milan Broz Fixes: 57c36519e4b94 ("dm: fix clone_bio() to trigger blk_recount_segments()") Signed-off-by: Mike Snitzer

dm: add memory barrier before waitqueue_active

2019-02-06T22:24:37Z

Block core changes to switch bio-based IO accounting to be percpu had a side-effect of altering DM core to now rely on calling waitqueue_active (in both bio-based and request-based) to check if another task is in dm_wait_for_completion(). A memory barrier is needed before calling waitqueue_active(). DM core doesn't piggyback on a preceding memory barrier so it must explicitly use its own. For more details on why using waitqueue_active() without a preceding barrier is unsafe, please see the comment before the waitqueue_active() definition in include/linux/wait.h. Add the missing memory barrier by switching to using wq_has_sleeper(). Fixes: 6f75723190d8 ("dm: remove the pending IO accounting") Fixes: c4576aed8d85 ("dm: fix request-based dm's use of dm_wait_for_completion") Signed-off-by: Mikulas Patocka Signed-off-by: Mike Snitzer