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path: root/drivers/md/dm-zoned-metadata.c
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2018-10-18dm zoned: fix various dmz_get_mblock() issuesDamien Le Moal1-24/+42
dmz_fetch_mblock() called from dmz_get_mblock() has a race since the allocation of the new metadata block descriptor and its insertion in the cache rbtree with the READING state is not atomic. Two different contexts requesting the same block may end up each adding two different descriptors of the same block to the cache. Another problem for this function is that the BIO for processing the block read is allocated after the metadata block descriptor is inserted in the cache rbtree. If the BIO allocation fails, the metadata block descriptor is freed without first being removed from the rbtree. Fix the first problem by checking again if the requested block is not in the cache right before inserting the newly allocated descriptor, atomically under the mblk_lock spinlock. The second problem is fixed by simply allocating the BIO before inserting the new block in the cache. Finally, since dmz_fetch_mblock() also increments a block reference counter, rename the function to dmz_get_mblock_slow(). To be symmetric and clear, also rename dmz_lookup_mblock() to dmz_get_mblock_fast() and increment the block reference counter directly in that function rather than in dmz_get_mblock(). Fixes: 3b1a94c88b79 ("dm zoned: drive-managed zoned block device target") Cc: stable@vger.kernel.org Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-10-18dm zoned: fix metadata block ref countingDamien Le Moal1-9/+11
Since the ref field of struct dmz_mblock is always used with the spinlock of struct dmz_metadata locked, there is no need to use an atomic_t type. Change the type of the ref field to an unsigne integer. Fixes: 3b1a94c88b79 ("dm zoned: drive-managed zoned block device target") Cc: stable@vger.kernel.org Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-01-17dm: backfill missing calls to mutex_destroy()Mike Snitzer1-0/+3
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2017-08-23block: replace bi_bdev with a gendisk pointer and partitions indexChristoph Hellwig1-3/+3
This way we don't need a block_device structure to submit I/O. The block_device has different life time rules from the gendisk and request_queue and is usually only available when the block device node is open. Other callers need to explicitly create one (e.g. the lightnvm passthrough code, or the new nvme multipathing code). For the actual I/O path all that we need is the gendisk, which exists once per block device. But given that the block layer also does partition remapping we additionally need a partition index, which is used for said remapping in generic_make_request. Note that all the block drivers generally want request_queue or sometimes the gendisk, so this removes a layer of indirection all over the stack. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-07-26dm zoned: use GFP_NOIO in I/O pathDamien Le Moal1-6/+6
Use GFP_NOIO for memory allocations in the I/O path. Other memory allocations in the initialization path can use GFP_KERNEL. Reported-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Reviewed-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2017-07-05dm zoned: fix overflow when converting zone ID to sectorsDamien Le Moal1-2/+2
A zone ID is a 32 bits unsigned int which can overflow when doing the bit shifts in dmz_start_sect(). With a 256 MB zone size drive, the overflow happens for a zone ID >= 8192. Fix this by casting the zone ID to a sector_t before doing the bit shift. While at it, similarly fix dmz_start_block(). Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2017-06-19dm zoned: drive-managed zoned block device targetDamien Le Moal1-0/+2509
The dm-zoned device mapper target provides transparent write access to zoned block devices (ZBC and ZAC compliant block devices). dm-zoned hides to the device user (a file system or an application doing raw block device accesses) any constraint imposed on write requests by the device, equivalent to a drive-managed zoned block device model. Write requests are processed using a combination of on-disk buffering using the device conventional zones and direct in-place processing for requests aligned to a zone sequential write pointer position. A background reclaim process implemented using dm_kcopyd_copy ensures that conventional zones are always available for executing unaligned write requests. The reclaim process overhead is minimized by managing buffer zones in a least-recently-written order and first targeting the oldest buffer zones. Doing so, blocks under regular write access (such as metadata blocks of a file system) remain stored in conventional zones, resulting in no apparent overhead. dm-zoned implementation focus on simplicity and on minimizing overhead (CPU, memory and storage overhead). For a 14TB host-managed disk with 256 MB zones, dm-zoned memory usage per disk instance is at most about 3 MB and as little as 5 zones will be used internally for storing metadata and performing buffer zone reclaim operations. This is achieved using zone level indirection rather than a full block indirection system for managing block movement between zones. dm-zoned primary target is host-managed zoned block devices but it can also be used with host-aware device models to mitigate potential device-side performance degradation due to excessive random writing. Zoned block devices can be formatted and checked for use with the dm-zoned target using the dmzadm utility available at: https://github.com/hgst/dm-zoned-tools Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Reviewed-by: Hannes Reinecke <hare@suse.com> Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com> [Mike Snitzer partly refactored Damien's original work to cleanup the code] Signed-off-by: Mike Snitzer <snitzer@redhat.com>