d285203cf6
This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
187 lines
6.2 KiB
C
187 lines
6.2 KiB
C
#ifndef _SCSI_PRIV_H
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#define _SCSI_PRIV_H
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#include <linux/device.h>
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#include <linux/async.h>
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#include <scsi/scsi_device.h>
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struct request_queue;
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struct request;
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struct scsi_cmnd;
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struct scsi_device;
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struct scsi_target;
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struct scsi_host_template;
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struct Scsi_Host;
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struct scsi_nl_hdr;
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/*
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* Scsi Error Handler Flags
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*/
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#define SCSI_EH_CANCEL_CMD 0x0001 /* Cancel this cmd */
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#define SCSI_EH_ABORT_SCHEDULED 0x0002 /* Abort has been scheduled */
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#define SCSI_SENSE_VALID(scmd) \
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(((scmd)->sense_buffer[0] & 0x70) == 0x70)
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/* hosts.c */
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extern int scsi_init_hosts(void);
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extern void scsi_exit_hosts(void);
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/* scsi.c */
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extern int scsi_dispatch_cmd(struct scsi_cmnd *cmd);
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extern int scsi_setup_command_freelist(struct Scsi_Host *shost);
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extern void scsi_destroy_command_freelist(struct Scsi_Host *shost);
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#ifdef CONFIG_SCSI_LOGGING
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void scsi_log_send(struct scsi_cmnd *cmd);
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void scsi_log_completion(struct scsi_cmnd *cmd, int disposition);
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#else
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static inline void scsi_log_send(struct scsi_cmnd *cmd)
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{ };
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static inline void scsi_log_completion(struct scsi_cmnd *cmd, int disposition)
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{ };
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#endif
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/* scsi_devinfo.c */
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/* list of keys for the lists */
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enum {
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SCSI_DEVINFO_GLOBAL = 0,
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SCSI_DEVINFO_SPI,
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};
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extern int scsi_get_device_flags(struct scsi_device *sdev,
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const unsigned char *vendor,
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const unsigned char *model);
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extern int scsi_get_device_flags_keyed(struct scsi_device *sdev,
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const unsigned char *vendor,
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const unsigned char *model, int key);
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extern int scsi_dev_info_list_add_keyed(int compatible, char *vendor,
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char *model, char *strflags,
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int flags, int key);
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extern int scsi_dev_info_list_del_keyed(char *vendor, char *model, int key);
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extern int scsi_dev_info_add_list(int key, const char *name);
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extern int scsi_dev_info_remove_list(int key);
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extern int __init scsi_init_devinfo(void);
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extern void scsi_exit_devinfo(void);
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/* scsi_error.c */
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extern void scmd_eh_abort_handler(struct work_struct *work);
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extern enum blk_eh_timer_return scsi_times_out(struct request *req);
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extern int scsi_error_handler(void *host);
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extern int scsi_decide_disposition(struct scsi_cmnd *cmd);
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extern void scsi_eh_wakeup(struct Scsi_Host *shost);
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extern int scsi_eh_scmd_add(struct scsi_cmnd *, int);
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void scsi_eh_ready_devs(struct Scsi_Host *shost,
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struct list_head *work_q,
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struct list_head *done_q);
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int scsi_eh_get_sense(struct list_head *work_q,
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struct list_head *done_q);
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int scsi_noretry_cmd(struct scsi_cmnd *scmd);
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/* scsi_lib.c */
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extern int scsi_maybe_unblock_host(struct scsi_device *sdev);
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extern void scsi_device_unbusy(struct scsi_device *sdev);
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extern void scsi_queue_insert(struct scsi_cmnd *cmd, int reason);
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extern void scsi_next_command(struct scsi_cmnd *cmd);
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extern void scsi_io_completion(struct scsi_cmnd *, unsigned int);
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extern void scsi_run_host_queues(struct Scsi_Host *shost);
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extern struct request_queue *scsi_alloc_queue(struct scsi_device *sdev);
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extern struct request_queue *scsi_mq_alloc_queue(struct scsi_device *sdev);
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extern int scsi_mq_setup_tags(struct Scsi_Host *shost);
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extern void scsi_mq_destroy_tags(struct Scsi_Host *shost);
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extern int scsi_init_queue(void);
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extern void scsi_exit_queue(void);
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struct request_queue;
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struct request;
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extern struct kmem_cache *scsi_sdb_cache;
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/* scsi_proc.c */
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#ifdef CONFIG_SCSI_PROC_FS
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extern void scsi_proc_hostdir_add(struct scsi_host_template *);
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extern void scsi_proc_hostdir_rm(struct scsi_host_template *);
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extern void scsi_proc_host_add(struct Scsi_Host *);
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extern void scsi_proc_host_rm(struct Scsi_Host *);
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extern int scsi_init_procfs(void);
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extern void scsi_exit_procfs(void);
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#else
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# define scsi_proc_hostdir_add(sht) do { } while (0)
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# define scsi_proc_hostdir_rm(sht) do { } while (0)
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# define scsi_proc_host_add(shost) do { } while (0)
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# define scsi_proc_host_rm(shost) do { } while (0)
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# define scsi_init_procfs() (0)
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# define scsi_exit_procfs() do { } while (0)
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#endif /* CONFIG_PROC_FS */
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/* scsi_scan.c */
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extern char scsi_scan_type[];
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extern int scsi_complete_async_scans(void);
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extern int scsi_scan_host_selected(struct Scsi_Host *, unsigned int,
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unsigned int, u64, int);
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extern void scsi_forget_host(struct Scsi_Host *);
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extern void scsi_rescan_device(struct device *);
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/* scsi_sysctl.c */
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#ifdef CONFIG_SYSCTL
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extern int scsi_init_sysctl(void);
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extern void scsi_exit_sysctl(void);
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#else
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# define scsi_init_sysctl() (0)
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# define scsi_exit_sysctl() do { } while (0)
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#endif /* CONFIG_SYSCTL */
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/* scsi_sysfs.c */
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extern int scsi_sysfs_add_sdev(struct scsi_device *);
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extern int scsi_sysfs_add_host(struct Scsi_Host *);
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extern int scsi_sysfs_register(void);
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extern void scsi_sysfs_unregister(void);
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extern void scsi_sysfs_device_initialize(struct scsi_device *);
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extern int scsi_sysfs_target_initialize(struct scsi_device *);
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extern struct scsi_transport_template blank_transport_template;
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extern void __scsi_remove_device(struct scsi_device *);
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extern struct bus_type scsi_bus_type;
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extern const struct attribute_group *scsi_sysfs_shost_attr_groups[];
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/* scsi_netlink.c */
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#ifdef CONFIG_SCSI_NETLINK
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extern void scsi_netlink_init(void);
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extern void scsi_netlink_exit(void);
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extern struct sock *scsi_nl_sock;
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#else
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static inline void scsi_netlink_init(void) {}
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static inline void scsi_netlink_exit(void) {}
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#endif
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/* scsi_pm.c */
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#ifdef CONFIG_PM
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extern const struct dev_pm_ops scsi_bus_pm_ops;
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#endif
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#ifdef CONFIG_PM_RUNTIME
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extern void scsi_autopm_get_target(struct scsi_target *);
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extern void scsi_autopm_put_target(struct scsi_target *);
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extern int scsi_autopm_get_host(struct Scsi_Host *);
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extern void scsi_autopm_put_host(struct Scsi_Host *);
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#else
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static inline void scsi_autopm_get_target(struct scsi_target *t) {}
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static inline void scsi_autopm_put_target(struct scsi_target *t) {}
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static inline int scsi_autopm_get_host(struct Scsi_Host *h) { return 0; }
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static inline void scsi_autopm_put_host(struct Scsi_Host *h) {}
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#endif /* CONFIG_PM_RUNTIME */
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extern struct async_domain scsi_sd_pm_domain;
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extern struct async_domain scsi_sd_probe_domain;
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/*
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* internal scsi timeout functions: for use by mid-layer and transport
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* classes.
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*/
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#define SCSI_DEVICE_BLOCK_MAX_TIMEOUT 600 /* units in seconds */
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extern int scsi_internal_device_block(struct scsi_device *sdev);
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extern int scsi_internal_device_unblock(struct scsi_device *sdev,
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enum scsi_device_state new_state);
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#endif /* _SCSI_PRIV_H */
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