Based on kernel version 4.16.1. Page generated on 2018-04-09 11:52 EST.
1 2 struct request documentation 3 4 Jens Axboe <jens.axboe@oracle.com> 27/05/02 5 6 1.0 7 Index 8 9 2.0 Struct request members classification 10 11 2.1 struct request members explanation 12 13 3.0 14 15 16 2.0 17 Short explanation of request members 18 19 Classification flags: 20 21 D driver member 22 B block layer member 23 I I/O scheduler member 24 25 Unless an entry contains a D classification, a device driver must not access 26 this member. Some members may contain D classifications, but should only be 27 access through certain macros or functions (eg ->flags). 28 29 <linux/blkdev.h> 30 31 2.1 32 Member Flag Comment 33 ------ ---- ------- 34 35 struct list_head queuelist BI Organization on various internal 36 queues 37 38 void *elevator_private I I/O scheduler private data 39 40 unsigned char cmd[16] D Driver can use this for setting up 41 a cdb before execution, see 42 blk_queue_prep_rq 43 44 unsigned long flags DBI Contains info about data direction, 45 request type, etc. 46 47 int rq_status D Request status bits 48 49 kdev_t rq_dev DBI Target device 50 51 int errors DB Error counts 52 53 sector_t sector DBI Target location 54 55 unsigned long hard_nr_sectors B Used to keep sector sane 56 57 unsigned long nr_sectors DBI Total number of sectors in request 58 59 unsigned long hard_nr_sectors B Used to keep nr_sectors sane 60 61 unsigned short nr_phys_segments DB Number of physical scatter gather 62 segments in a request 63 64 unsigned short nr_hw_segments DB Number of hardware scatter gather 65 segments in a request 66 67 unsigned int current_nr_sectors DB Number of sectors in first segment 68 of request 69 70 unsigned int hard_cur_sectors B Used to keep current_nr_sectors sane 71 72 int tag DB TCQ tag, if assigned 73 74 void *special D Free to be used by driver 75 76 char *buffer D Map of first segment, also see 77 section on bouncing SECTION 78 79 struct completion *waiting D Can be used by driver to get signalled 80 on request completion 81 82 struct bio *bio DBI First bio in request 83 84 struct bio *biotail DBI Last bio in request 85 86 struct request_queue *q DB Request queue this request belongs to 87 88 struct request_list *rl B Request list this request came from