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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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e1777d0997
Commitaa1c09cb65("null_blk: Fix locking in zoned mode") changed zone locking to using the potentially sleeping wait_on_bit_io() function. This is acceptable when memory backing is enabled as the device queue is in that case marked as blocking, but this triggers a scheduling while in atomic context with memory backing disabled. Fix this by relying solely on the device zone spinlock for zone information protection without temporarily releasing this lock around null_process_cmd() execution in null_zone_write(). This is OK to do since when memory backing is disabled, command processing does not block and the memory backing lock nullb->lock is unused. This solution avoids the overhead of having to mark a zoned null_blk device queue as blocking when memory backing is unused. This patch also adds comments to the zone locking code to explain the unusual locking scheme. Fixes:aa1c09cb65("null_blk: Fix locking in zoned mode") Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Cc: stable@vger.kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
137 lines
4.2 KiB
C
137 lines
4.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __BLK_NULL_BLK_H
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#define __BLK_NULL_BLK_H
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#undef pr_fmt
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/blkdev.h>
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#include <linux/slab.h>
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#include <linux/blk-mq.h>
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#include <linux/hrtimer.h>
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#include <linux/configfs.h>
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#include <linux/badblocks.h>
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#include <linux/fault-inject.h>
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struct nullb_cmd {
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struct request *rq;
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struct bio *bio;
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unsigned int tag;
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blk_status_t error;
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struct nullb_queue *nq;
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struct hrtimer timer;
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};
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struct nullb_queue {
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unsigned long *tag_map;
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wait_queue_head_t wait;
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unsigned int queue_depth;
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struct nullb_device *dev;
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unsigned int requeue_selection;
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struct nullb_cmd *cmds;
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};
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struct nullb_device {
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struct nullb *nullb;
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struct config_item item;
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struct radix_tree_root data; /* data stored in the disk */
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struct radix_tree_root cache; /* disk cache data */
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unsigned long flags; /* device flags */
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unsigned int curr_cache;
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struct badblocks badblocks;
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unsigned int nr_zones;
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unsigned int nr_zones_imp_open;
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unsigned int nr_zones_exp_open;
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unsigned int nr_zones_closed;
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struct blk_zone *zones;
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sector_t zone_size_sects;
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spinlock_t zone_lock;
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unsigned long *zone_locks;
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unsigned long size; /* device size in MB */
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unsigned long completion_nsec; /* time in ns to complete a request */
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unsigned long cache_size; /* disk cache size in MB */
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unsigned long zone_size; /* zone size in MB if device is zoned */
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unsigned long zone_capacity; /* zone capacity in MB if device is zoned */
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unsigned int zone_nr_conv; /* number of conventional zones */
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unsigned int zone_max_open; /* max number of open zones */
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unsigned int zone_max_active; /* max number of active zones */
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unsigned int submit_queues; /* number of submission queues */
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unsigned int home_node; /* home node for the device */
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unsigned int queue_mode; /* block interface */
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unsigned int blocksize; /* block size */
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unsigned int irqmode; /* IRQ completion handler */
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unsigned int hw_queue_depth; /* queue depth */
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unsigned int index; /* index of the disk, only valid with a disk */
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unsigned int mbps; /* Bandwidth throttle cap (in MB/s) */
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bool blocking; /* blocking blk-mq device */
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bool use_per_node_hctx; /* use per-node allocation for hardware context */
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bool power; /* power on/off the device */
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bool memory_backed; /* if data is stored in memory */
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bool discard; /* if support discard */
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bool zoned; /* if device is zoned */
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};
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struct nullb {
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struct nullb_device *dev;
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struct list_head list;
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unsigned int index;
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struct request_queue *q;
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struct gendisk *disk;
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struct blk_mq_tag_set *tag_set;
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struct blk_mq_tag_set __tag_set;
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unsigned int queue_depth;
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atomic_long_t cur_bytes;
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struct hrtimer bw_timer;
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unsigned long cache_flush_pos;
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spinlock_t lock;
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struct nullb_queue *queues;
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unsigned int nr_queues;
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char disk_name[DISK_NAME_LEN];
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};
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blk_status_t null_process_cmd(struct nullb_cmd *cmd,
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enum req_opf op, sector_t sector,
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unsigned int nr_sectors);
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#ifdef CONFIG_BLK_DEV_ZONED
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int null_init_zoned_dev(struct nullb_device *dev, struct request_queue *q);
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int null_register_zoned_dev(struct nullb *nullb);
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void null_free_zoned_dev(struct nullb_device *dev);
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int null_report_zones(struct gendisk *disk, sector_t sector,
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unsigned int nr_zones, report_zones_cb cb, void *data);
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blk_status_t null_process_zoned_cmd(struct nullb_cmd *cmd,
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enum req_opf op, sector_t sector,
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sector_t nr_sectors);
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size_t null_zone_valid_read_len(struct nullb *nullb,
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sector_t sector, unsigned int len);
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#else
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static inline int null_init_zoned_dev(struct nullb_device *dev,
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struct request_queue *q)
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{
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pr_err("CONFIG_BLK_DEV_ZONED not enabled\n");
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return -EINVAL;
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}
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static inline int null_register_zoned_dev(struct nullb *nullb)
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{
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return -ENODEV;
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}
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static inline void null_free_zoned_dev(struct nullb_device *dev) {}
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static inline blk_status_t null_process_zoned_cmd(struct nullb_cmd *cmd,
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enum req_opf op, sector_t sector, sector_t nr_sectors)
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{
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return BLK_STS_NOTSUPP;
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}
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static inline size_t null_zone_valid_read_len(struct nullb *nullb,
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sector_t sector,
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unsigned int len)
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{
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return len;
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}
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#define null_report_zones NULL
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#endif /* CONFIG_BLK_DEV_ZONED */
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#endif /* __NULL_BLK_H */
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