[PATCH] Split struct request ->flags into two parts

Right now ->flags is a bit of a mess: some are request types, and
others are just modifiers. Clean this up by splitting it into
->cmd_type and ->cmd_flags. This allows introduction of generic
Linux block message types, useful for sending generic Linux commands
to block devices.

Signed-off-by: Jens Axboe <axboe@suse.de>

2 files changed, 100 insertions, 82 deletions

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index cfde8b3ee919..b2a412cf468f 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -120,6 +120,86 @@ struct request_list {
         wait_queue_head_t wait[2];
 };
 
+/*
+ * request command types
+ */
+enum rq_cmd_type_bits {
+        REQ_TYPE_FS             = 1,    /* fs request */
+        REQ_TYPE_BLOCK_PC,              /* scsi command */
+        REQ_TYPE_SENSE,                 /* sense request */
+        REQ_TYPE_PM_SUSPEND,            /* suspend request */
+        REQ_TYPE_PM_RESUME,             /* resume request */
+        REQ_TYPE_PM_SHUTDOWN,           /* shutdown request */
+        REQ_TYPE_FLUSH,                 /* flush request */
+        REQ_TYPE_SPECIAL,               /* driver defined type */
+        REQ_TYPE_LINUX_BLOCK,           /* generic block layer message */
+        /*
+         * for ATA/ATAPI devices. this really doesn't belong here, ide should
+         * use REQ_TYPE_SPECIAL and use rq->cmd[0] with the range of driver
+         * private REQ_LB opcodes to differentiate what type of request this is
+         */
+        REQ_TYPE_ATA_CMD,
+        REQ_TYPE_ATA_TASK,
+        REQ_TYPE_ATA_TASKFILE,
+};
+
+/*
+ * For request of type REQ_TYPE_LINUX_BLOCK, rq->cmd[0] is the opcode being
+ * sent down (similar to how REQ_TYPE_BLOCK_PC means that ->cmd[] holds a
+ * SCSI cdb.
+ *
+ * 0x00 -> 0x3f are driver private, to be used for whatever purpose they need,
+ * typically to differentiate REQ_TYPE_SPECIAL requests.
+ *
+ */
+enum {
+        /*
+         * just examples for now
+         */
+        REQ_LB_OP_EJECT = 0x40,         /* eject request */
+        REQ_LB_OP_FLUSH = 0x41,         /* flush device */
+};
+
+/*
+ * request type modified bits. first three bits match BIO_RW* bits, important
+ */
+enum rq_flag_bits {
+        __REQ_RW,               /* not set, read. set, write */
+        __REQ_FAILFAST,         /* no low level driver retries */
+        __REQ_SORTED,           /* elevator knows about this request */
+        __REQ_SOFTBARRIER,      /* may not be passed by ioscheduler */
+        __REQ_HARDBARRIER,      /* may not be passed by drive either */
+        __REQ_FUA,              /* forced unit access */
+        __REQ_NOMERGE,          /* don't touch this for merging */
+        __REQ_STARTED,          /* drive already may have started this one */
+        __REQ_DONTPREP,         /* don't call prep for this one */
+        __REQ_QUEUED,           /* uses queueing */
+        __REQ_ELVPRIV,          /* elevator private data attached */
+        __REQ_FAILED,           /* set if the request failed */
+        __REQ_QUIET,            /* don't worry about errors */
+        __REQ_PREEMPT,          /* set for "ide_preempt" requests */
+        __REQ_ORDERED_COLOR,    /* is before or after barrier */
+        __REQ_RW_SYNC,          /* request is sync (O_DIRECT) */
+        __REQ_NR_BITS,          /* stops here */
+};
+
+#define REQ_RW          (1 << __REQ_RW)
+#define REQ_FAILFAST    (1 << __REQ_FAILFAST)
+#define REQ_SORTED      (1 << __REQ_SORTED)
+#define REQ_SOFTBARRIER (1 << __REQ_SOFTBARRIER)
+#define REQ_HARDBARRIER (1 << __REQ_HARDBARRIER)
+#define REQ_FUA         (1 << __REQ_FUA)
+#define REQ_NOMERGE     (1 << __REQ_NOMERGE)
+#define REQ_STARTED     (1 << __REQ_STARTED)
+#define REQ_DONTPREP    (1 << __REQ_DONTPREP)
+#define REQ_QUEUED      (1 << __REQ_QUEUED)
+#define REQ_ELVPRIV     (1 << __REQ_ELVPRIV)
+#define REQ_FAILED      (1 << __REQ_FAILED)
+#define REQ_QUIET       (1 << __REQ_QUIET)
+#define REQ_PREEMPT     (1 << __REQ_PREEMPT)
+#define REQ_ORDERED_COLOR       (1 << __REQ_ORDERED_COLOR)
+#define REQ_RW_SYNC     (1 << __REQ_RW_SYNC)
+
 #define BLK_MAX_CDB     16
 
 /*
@@ -129,7 +209,8 @@ struct request {
         struct list_head queuelist;
         struct list_head donelist;
 
-        unsigned long flags;            /* see REQ_ bits below */
+        unsigned int cmd_flags;
+        enum rq_cmd_type_bits cmd_type;
 
         /* Maintain bio traversal state for part by part I/O submission.
          * hard_* are block layer internals, no driver should touch them!
@@ -202,73 +283,7 @@ struct request {
 };
 
 /*
- * first three bits match BIO_RW* bits, important
- */
-enum rq_flag_bits {
-        __REQ_RW,               /* not set, read. set, write */
-        __REQ_FAILFAST,         /* no low level driver retries */
-        __REQ_SORTED,           /* elevator knows about this request */
-        __REQ_SOFTBARRIER,      /* may not be passed by ioscheduler */
-        __REQ_HARDBARRIER,      /* may not be passed by drive either */
-        __REQ_FUA,              /* forced unit access */
-        __REQ_CMD,              /* is a regular fs rw request */
-        __REQ_NOMERGE,          /* don't touch this for merging */
-        __REQ_STARTED,          /* drive already may have started this one */
-        __REQ_DONTPREP,         /* don't call prep for this one */
-        __REQ_QUEUED,           /* uses queueing */
-        __REQ_ELVPRIV,          /* elevator private data attached */
-        /*
-         * for ATA/ATAPI devices
-         */
-        __REQ_PC,               /* packet command (special) */
-        __REQ_BLOCK_PC,         /* queued down pc from block layer */
-        __REQ_SENSE,            /* sense retrival */
-
-        __REQ_FAILED,           /* set if the request failed */
-        __REQ_QUIET,            /* don't worry about errors */
-        __REQ_SPECIAL,          /* driver suplied command */
-        __REQ_DRIVE_CMD,
-        __REQ_DRIVE_TASK,
-        __REQ_DRIVE_TASKFILE,
-        __REQ_PREEMPT,          /* set for "ide_preempt" requests */
-        __REQ_PM_SUSPEND,       /* suspend request */
-        __REQ_PM_RESUME,        /* resume request */
-        __REQ_PM_SHUTDOWN,      /* shutdown request */
-        __REQ_ORDERED_COLOR,    /* is before or after barrier */
-        __REQ_RW_SYNC,          /* request is sync (O_DIRECT) */
-        __REQ_NR_BITS,          /* stops here */
-};
-
-#define REQ_RW          (1 << __REQ_RW)
-#define REQ_FAILFAST    (1 << __REQ_FAILFAST)
-#define REQ_SORTED      (1 << __REQ_SORTED)
-#define REQ_SOFTBARRIER (1 << __REQ_SOFTBARRIER)
-#define REQ_HARDBARRIER (1 << __REQ_HARDBARRIER)
-#define REQ_FUA         (1 << __REQ_FUA)
-#define REQ_CMD         (1 << __REQ_CMD)
-#define REQ_NOMERGE     (1 << __REQ_NOMERGE)
-#define REQ_STARTED     (1 << __REQ_STARTED)
-#define REQ_DONTPREP    (1 << __REQ_DONTPREP)
-#define REQ_QUEUED      (1 << __REQ_QUEUED)
-#define REQ_ELVPRIV     (1 << __REQ_ELVPRIV)
-#define REQ_PC          (1 << __REQ_PC)
-#define REQ_BLOCK_PC    (1 << __REQ_BLOCK_PC)
-#define REQ_SENSE       (1 << __REQ_SENSE)
-#define REQ_FAILED      (1 << __REQ_FAILED)
-#define REQ_QUIET       (1 << __REQ_QUIET)
-#define REQ_SPECIAL     (1 << __REQ_SPECIAL)
-#define REQ_DRIVE_CMD   (1 << __REQ_DRIVE_CMD)
-#define REQ_DRIVE_TASK  (1 << __REQ_DRIVE_TASK)
-#define REQ_DRIVE_TASKFILE      (1 << __REQ_DRIVE_TASKFILE)
-#define REQ_PREEMPT     (1 << __REQ_PREEMPT)
-#define REQ_PM_SUSPEND  (1 << __REQ_PM_SUSPEND)
-#define REQ_PM_RESUME   (1 << __REQ_PM_RESUME)
-#define REQ_PM_SHUTDOWN (1 << __REQ_PM_SHUTDOWN)
-#define REQ_ORDERED_COLOR       (1 << __REQ_ORDERED_COLOR)
-#define REQ_RW_SYNC     (1 << __REQ_RW_SYNC)
-
-/*
- * State information carried for REQ_PM_SUSPEND and REQ_PM_RESUME
+ * State information carried for REQ_TYPE_PM_SUSPEND and REQ_TYPE_PM_RESUME
  * requests. Some step values could eventually be made generic.
  */
 struct request_pm_state
@@ -490,25 +505,28 @@ enum {
 #define blk_queue_stopped(q)    test_bit(QUEUE_FLAG_STOPPED, &(q)->queue_flags)
 #define blk_queue_flushing(q)   ((q)->ordseq)
 
-#define blk_fs_request(rq)      ((rq)->flags & REQ_CMD)
-#define blk_pc_request(rq)      ((rq)->flags & REQ_BLOCK_PC)
-#define blk_noretry_request(rq) ((rq)->flags & REQ_FAILFAST)
-#define blk_rq_started(rq)      ((rq)->flags & REQ_STARTED)
+#define blk_fs_request(rq)      ((rq)->cmd_type == REQ_TYPE_FS)
+#define blk_pc_request(rq)      ((rq)->cmd_type == REQ_TYPE_BLOCK_PC)
+#define blk_special_request(rq) ((rq)->cmd_type == REQ_TYPE_SPECIAL)
+#define blk_sense_request(rq)   ((rq)->cmd_type == REQ_TYPE_SENSE)
+
+#define blk_noretry_request(rq) ((rq)->cmd_flags & REQ_FAILFAST)
+#define blk_rq_started(rq)      ((rq)->cmd_flags & REQ_STARTED)
 
 #define blk_account_rq(rq)      (blk_rq_started(rq) && blk_fs_request(rq))
 
-#define blk_pm_suspend_request(rq)      ((rq)->flags & REQ_PM_SUSPEND)
-#define blk_pm_resume_request(rq)       ((rq)->flags & REQ_PM_RESUME)
+#define blk_pm_suspend_request(rq)      ((rq)->cmd_type == REQ_TYPE_PM_SUSPEND)
+#define blk_pm_resume_request(rq)       ((rq)->cmd_type == REQ_TYPE_PM_RESUME)
 #define blk_pm_request(rq)      \
-        ((rq)->flags & (REQ_PM_SUSPEND | REQ_PM_RESUME))
+        (blk_pm_suspend_request(rq) || blk_pm_resume_request(rq))
 
-#define blk_sorted_rq(rq)       ((rq)->flags & REQ_SORTED)
-#define blk_barrier_rq(rq)      ((rq)->flags & REQ_HARDBARRIER)
-#define blk_fua_rq(rq)          ((rq)->flags & REQ_FUA)
+#define blk_sorted_rq(rq)       ((rq)->cmd_flags & REQ_SORTED)
+#define blk_barrier_rq(rq)      ((rq)->cmd_flags & REQ_HARDBARRIER)
+#define blk_fua_rq(rq)          ((rq)->cmd_flags & REQ_FUA)
 
 #define list_entry_rq(ptr)      list_entry((ptr), struct request, queuelist)
 
-#define rq_data_dir(rq)         ((rq)->flags & 1)
+#define rq_data_dir(rq)         ((rq)->cmd_flags & 1)
 
 static inline int blk_queue_full(struct request_queue *q, int rw)
 {
@@ -541,7 +559,7 @@ static inline void blk_clear_queue_full(struct request_queue *q, int rw)
 #define RQ_NOMERGE_FLAGS        \
         (REQ_NOMERGE | REQ_STARTED | REQ_HARDBARRIER | REQ_SOFTBARRIER)
 #define rq_mergeable(rq)        \
-        (!((rq)->flags & RQ_NOMERGE_FLAGS) && blk_fs_request((rq)))
+        (!((rq)->cmd_flags & RQ_NOMERGE_FLAGS) && blk_fs_request((rq)))
 
 /*
  * noop, requests are automagically marked as active/inactive by I/O
@@ -737,7 +755,7 @@ extern void blk_put_queue(request_queue_t *);
  */
 #define blk_queue_tag_depth(q)          ((q)->queue_tags->busy)
 #define blk_queue_tag_queue(q)          ((q)->queue_tags->busy < (q)->queue_tags->max_depth)
-#define blk_rq_tagged(rq)               ((rq)->flags & REQ_QUEUED)
+#define blk_rq_tagged(rq)               ((rq)->cmd_flags & REQ_QUEUED)
 extern int blk_queue_start_tag(request_queue_t *, struct request *);
 extern struct request *blk_queue_find_tag(request_queue_t *, int);
 extern void blk_queue_end_tag(request_queue_t *, struct request *);
diff --git a/include/linux/blktrace_api.h b/include/linux/blktrace_api.h
index 7520cc1ff9e2..ea48eb1b3fd3 100644
--- a/include/linux/blktrace_api.h
+++ b/include/linux/blktrace_api.h
@@ -148,7 +148,7 @@ static inline void blk_add_trace_rq(struct request_queue *q, struct request *rq,
                                     u32 what)
 {
         struct blk_trace *bt = q->blk_trace;
-        int rw = rq->flags & 0x03;
+        int rw = rq->cmd_flags & 0x03;
 
         if (likely(!bt))
                 return;