42  * Per-zone write plug.
43  * @node: hlist_node structure for managing the plug using a hash table.
44  * @link: To list the plug in the zone write plug error list of the disk.
45  * @ref: Zone write plug reference counter. A zone write plug reference is
46  *       always at least 1 when the plug is hashed in the disk plug hash table.
48  *       submitted and when a function needs to manipulate a plug. The
50  *       when a function that referenced the plug returns. The initial
51  *       reference is dropped whenever the zone of the zone write plug is reset,
54  * @lock: Spinlock to atomically manipulate the plug.
55  * @flags: Flags indicating the plug state.
56  * @zone_no: The number of the zone the plug is managing.
62  * @disk: The gendisk the plug belongs to.
79  * Zone write plug flags bits:
80  *  - BLK_ZONE_WPLUG_PLUGGED: Indicates that the zone write plug is plugged,
82  *    being executed or the zone write plug bio list is not empty.
85  *  - BLK_ZONE_WPLUG_UNHASHED: Indicates that the zone write plug was removed
87  *    write plug set when the plug was first added to the hash table has been
89  *    to prevent new references to the zone write plug to be taken for
90  *    newly incoming BIOs. A zone write plug flagged with this flag will be
386 	 * Add the new zone write plug to the hash table, but carefully as we  in disk_insert_zone_wplug()
388 	 * zone write plug for the same zone.  in disk_insert_zone_wplug()
447 	/* If the zone write plug was already removed, we are done. */  in disk_should_remove_zone_wplug()
451 	/* If the zone write plug is still busy, it cannot be removed. */  in disk_should_remove_zone_wplug()
460 	 * should not attempt to remove the zone write plug until all BIO  in disk_should_remove_zone_wplug()
461 	 * completions are seen. Check by looking at the zone write plug  in disk_should_remove_zone_wplug()
462 	 * reference count, which is 2 when the plug is unused (one reference  in disk_should_remove_zone_wplug()
463 	 * taken when the plug was allocated and another reference taken by the  in disk_should_remove_zone_wplug()
478 	/* If the zone write plug was already removed, we have nothing to do. */  in disk_remove_zone_wplug()
483 	 * Mark the zone write plug as unhashed and drop the extra reference we  in disk_remove_zone_wplug()
484 	 * took when the plug was inserted in the hash table.  in disk_remove_zone_wplug()
496  * Get a reference on the write plug for the zone containing @sector.
497  * If the plug does not exist, it is allocated and hashed.
498  * Return a pointer to the zone write plug with the plug spinlock held.
512 		 * operation has not already removed the zone write plug from  in disk_get_and_lock_zone_wplug()
514 		 * we need to get a new plug so start over from the beginning.  in disk_get_and_lock_zone_wplug()
526 	 * Allocate and initialize a zone write plug with an extra reference  in disk_get_and_lock_zone_wplug()
527 	 * so that it is not freed when the zone write plug becomes idle without  in disk_get_and_lock_zone_wplug()
548 	 * Insert the new zone write plug in the hash table. This can fail only  in disk_get_and_lock_zone_wplug()
549 	 * if another context already inserted a plug. Retry from the beginning  in disk_get_and_lock_zone_wplug()
573  * Abort (fail) all plugged BIOs of a zone write plug.
584  * Abort (fail) all plugged BIOs of a zone write plug that are not aligned
619 	 * At this point, we already have a reference on the zone write plug.  in disk_zone_wplug_set_error()
620 	 * However, since we are going to add the plug to the disk zone write  in disk_zone_wplug_set_error()
644 	 * on the zone write plug after handling the error state. So remove the  in disk_zone_wplug_clear_error()
645 	 * plug from the error list and drop its reference count only if the  in disk_zone_wplug_clear_error()
646 	 * error handling has not yet started, that is, if the zone write plug  in disk_zone_wplug_clear_error()
659  * Set a zone write plug write pointer offset to either 0 (zone reset case)
675 	 * operation has not already removed the plug from the hash table.  in disk_zone_wplug_set_wp_offset()
694 	 * The zone write plug now has no BIO plugged: remove it from the  in disk_zone_wplug_set_wp_offset()
695 	 * hash table so that it cannot be seen. The plug will be freed  in disk_zone_wplug_set_wp_offset()
718 	 * If we have a zone write plug, set its write pointer offset to 0  in blk_zone_wplug_handle_reset_or_finish()
800 	 * For this case, we already hold a reference on the zone write plug for  in blk_zone_write_plug_bio_merged()
810 	 * Get a reference on the zone write plug of the target zone and advance  in blk_zone_write_plug_bio_merged()
813 	 * plug. So this should not fail.  in blk_zone_write_plug_bio_merged()
846 	 * on the zone write plug we took above on entry to this function.  in blk_zone_write_plug_init_request()
891  * offset of its zone write plug and changing zone append operations into
954 	 * zone write plug for the entire BIO. For blk-mq devices, the block  in blk_zone_wplug_handle_write()
989 	 * to the plug BIO list. Otherwise, plug and let the BIO execute.  in blk_zone_wplug_handle_write()
992 		goto plug;  in blk_zone_wplug_handle_write()
999 		goto plug;  in blk_zone_wplug_handle_write()
1007 plug:  in blk_zone_wplug_handle_write()
1025  * write plug. Otherwise, return false to let the submission path process
1038 	 * plug bio submit work.  in blk_zone_plug_bio()
1055 	 * zone write plug. This includes writes with REQ_FUA | REQ_PREFLUSH  in blk_zone_plug_bio()
1058 	 * machinery operates at the request level, below the plug, and  in blk_zone_plug_bio()
1097 	 * Take a reference on the zone write plug and schedule the submission  in disk_zone_wplug_schedule_bio_work()
1134 	 * (it was reset), remove its zone write plug from the hash table.  in disk_zone_wplug_unplug_bio()
1152 	/* Make sure we do not see this BIO again by clearing the plug flag. */  in blk_zone_write_plug_bio_endio()
1165 	 * If the BIO failed, mark the plug as having an error to trigger  in blk_zone_write_plug_bio_endio()
1386  * For the size of a disk zone write plug hash table, use the size of the
1387  * zone write plug mempool, which is the maximum of the disk open zones and
1579 	 * dynamic zone write plug allocation when simultaneously writing to  in disk_update_zone_resources()
1653 	 * empty nor full. So make sure we have a zone write plug for  in blk_revalidate_seq_zone()
1654 	 * such zone if the device has a zone write plug hash table.  in blk_revalidate_seq_zone()