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Commit 3c98bf34 authored by Borislav Petkov's avatar Borislav Petkov Committed by Bartlomiej Zolnierkiewicz
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ide-tape: cleanup and fix comments 

Also, remove redundant ones and cleanup whitespace.

Bart:
- minor fixups
Signed-off-by: default avatarBorislav Petkov <petkovbb@gmail.com>
Signed-off-by: default avatarBartlomiej Zolnierkiewicz <bzolnier@gmail.com>
parent 8d06bfad
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Showing with 271 additions and 410 deletions
drivers/ide/ide-tape.c
View file @ 3c98bf34
......@@ -77,35 +77,32 @@ enum {
/*
* Pipelined mode parameters.
*
* We try to use the minimum number of stages which is enough to
* keep the tape constantly streaming. To accomplish that, we implement
* a feedback loop around the maximum number of stages:
* We try to use the minimum number of stages which is enough to keep the tape
* constantly streaming. To accomplish that, we implement a feedback loop around
* the maximum number of stages:
*
* We start from MIN maximum stages (we will not even use MIN stages
* if we don't need them), increment it by RATE*(MAX-MIN)
* whenever we sense that the pipeline is empty, until we reach
* the optimum value or until we reach MAX.
* We start from MIN maximum stages (we will not even use MIN stages if we don't
* need them), increment it by RATE*(MAX-MIN) whenever we sense that the
* pipeline is empty, until we reach the optimum value or until we reach MAX.
*
* Setting the following parameter to 0 is illegal: the pipelined mode
* cannot be disabled (idetape_calculate_speeds() divides by
* tape->max_stages.)
* Setting the following parameter to 0 is illegal: the pipelined mode cannot be
* disabled (idetape_calculate_speeds() divides by tape->max_stages.)
*/
#define IDETAPE_MIN_PIPELINE_STAGES 1
#define IDETAPE_MAX_PIPELINE_STAGES 400
#define IDETAPE_INCREASE_STAGES_RATE 20
/*
* After each failed packet command we issue a request sense command
* and retry the packet command IDETAPE_MAX_PC_RETRIES times.
* After each failed packet command we issue a request sense command and retry
* the packet command IDETAPE_MAX_PC_RETRIES times.
*
* Setting IDETAPE_MAX_PC_RETRIES to 0 will disable retries.
*/
#define IDETAPE_MAX_PC_RETRIES 3
/*
* With each packet command, we allocate a buffer of
* IDETAPE_PC_BUFFER_SIZE bytes. This is used for several packet
* commands (Not for READ/WRITE commands).
* With each packet command, we allocate a buffer of IDETAPE_PC_BUFFER_SIZE
* bytes. This is used for several packet commands (Not for READ/WRITE commands)
*/
#define IDETAPE_PC_BUFFER_SIZE 256
......@@ -124,48 +121,39 @@ enum {
#define IDETAPE_WAIT_CMD (900*HZ)
/*
* The following parameter is used to select the point in the internal
* tape fifo in which we will start to refill the buffer. Decreasing
* the following parameter will improve the system's latency and
* interactive response, while using a high value might improve system
* throughput.
* The following parameter is used to select the point in the internal tape fifo
* in which we will start to refill the buffer. Decreasing the following
* parameter will improve the system's latency and interactive response, while
* using a high value might improve system throughput.
*/
#define IDETAPE_FIFO_THRESHOLD 2
/*
* DSC polling parameters.
*
* Polling for DSC (a single bit in the status register) is a very
* important function in ide-tape. There are two cases in which we
* poll for DSC:
* Polling for DSC (a single bit in the status register) is a very important
* function in ide-tape. There are two cases in which we poll for DSC:
*
* 1. Before a read/write packet command, to ensure that we
* can transfer data from/to the tape's data buffers, without
* causing an actual media access. In case the tape is not
* ready yet, we take out our request from the device
* request queue, so that ide.c will service requests from
* the other device on the same interface meanwhile.
* 1. Before a read/write packet command, to ensure that we can transfer data
* from/to the tape's data buffers, without causing an actual media access.
* In case the tape is not ready yet, we take out our request from the device
* request queue, so that ide.c could service requests from the other device
* on the same interface in the meantime.
*
* 2. After the successful initialization of a "media access
* packet command", which is a command which can take a long
* time to complete (it can be several seconds or even an hour).
* 2. After the successful initialization of a "media access packet command",
* which is a command that can take a long time to complete (the interval can
* range from several seconds to even an hour). Again, we postpone our request
* in the middle to free the bus for the other device. The polling frequency
* here should be lower than the read/write frequency since those media access
* commands are slow. We start from a "fast" frequency - IDETAPE_DSC_MA_FAST
* (1 second), and if we don't receive DSC after IDETAPE_DSC_MA_THRESHOLD
* (5 min), we switch it to a lower frequency - IDETAPE_DSC_MA_SLOW (1 min).
*
* Again, we postpone our request in the middle to free the bus
* for the other device. The polling frequency here should be
* lower than the read/write frequency since those media access
* commands are slow. We start from a "fast" frequency -
* IDETAPE_DSC_MA_FAST (one second), and if we don't receive DSC
* after IDETAPE_DSC_MA_THRESHOLD (5 minutes), we switch it to a
* lower frequency - IDETAPE_DSC_MA_SLOW (1 minute).
*
* We also set a timeout for the timer, in case something goes wrong.
* The timeout should be longer then the maximum execution time of a
* tape operation.
* We also set a timeout for the timer, in case something goes wrong. The
* timeout should be longer then the maximum execution time of a tape operation.
*/
/*
* DSC timings.
*/
/* DSC timings. */
#define IDETAPE_DSC_RW_MIN 5*HZ/100 /* 50 msec */
#define IDETAPE_DSC_RW_MAX 40*HZ/100 /* 400 msec */
#define IDETAPE_DSC_RW_TIMEOUT 2*60*HZ /* 2 minutes */
......@@ -176,15 +164,9 @@ enum {
/*************************** End of tunable parameters ***********************/
/*
* Read/Write error simulation
*/
/* Read/Write error simulation */
#define SIMULATE_ERRORS 0
/*
* For general magnetic tape device compatibility.
*/
/* tape directions */
enum {
IDETAPE_DIR_NONE = (1 << 0),
......@@ -199,24 +181,32 @@ struct idetape_bh {
char *b_data;
};
/*
* Our view of a packet command.
*/
typedef struct idetape_packet_command_s {
u8 c[12]; /* Actual packet bytes */
int retries; /* On each retry, we increment retries */
int error; /* Error code */
int request_transfer; /* Bytes to transfer */
int actually_transferred; /* Bytes actually transferred */
int buffer_size; /* Size of our data buffer */
/* Actual packet bytes */
u8 c[12];
/* On each retry, we increment retries */
int retries;
/* Error code */
int error;
/* Bytes to transfer */
int request_transfer;
/* Bytes actually transferred */
int actually_transferred;
/* Size of our data buffer */
int buffer_size;
struct idetape_bh *bh;
char *b_data;
int b_count;
u8 *buffer; /* Data buffer */
u8 *current_position; /* Pointer into the above buffer */
ide_startstop_t (*callback) (ide_drive_t *); /* Called when this packet command is completed */
u8 pc_buffer[IDETAPE_PC_BUFFER_SIZE]; /* Temporary buffer */
unsigned long flags; /* Status/Action bit flags: long for set_bit */
/* Data buffer */
u8 *buffer;
/* Pointer into the above buffer */
u8 *current_position;
/* Called when this packet command is completed */
ide_startstop_t (*callback) (ide_drive_t *);
/* Temporary buffer */
u8 pc_buffer[IDETAPE_PC_BUFFER_SIZE];
/* Status/Action bit flags: long for set_bit */
unsigned long flags;
} idetape_pc_t;
/*
......@@ -235,9 +225,7 @@ typedef struct idetape_packet_command_s {
/* Data direction */
#define PC_WRITING 5
/*
* A pipeline stage.
*/
/* A pipeline stage. */
typedef struct idetape_stage_s {
struct request rq; /* The corresponding request */
struct idetape_bh *bh; /* The data buffers */
......@@ -245,9 +233,8 @@ typedef struct idetape_stage_s {
} idetape_stage_t;
/*
* Most of our global data which we need to save even as we leave the
* driver due to an interrupt or a timer event is stored in a variable
* of type idetape_tape_t, defined below.
* Most of our global data which we need to save even as we leave the driver due
* to an interrupt or a timer event is stored in the struct defined below.
*/
typedef struct ide_tape_obj {
ide_drive_t *drive;
......@@ -285,13 +272,12 @@ typedef struct ide_tape_obj {
/*
* DSC polling variables.
*
* While polling for DSC we use postponed_rq to postpone the
* current request so that ide.c will be able to service
* pending requests on the other device. Note that at most
* we will have only one DSC (usually data transfer) request
* in the device request queue. Additional requests can be
* queued in our internal pipeline, but they will be visible
* to ide.c only one at a time.
* While polling for DSC we use postponed_rq to postpone the current
* request so that ide.c will be able to service pending requests on the
* other device. Note that at most we will have only one DSC (usually
* data transfer) request in the device request queue. Additional
* requests can be queued in our internal pipeline, but they will be
* visible to ide.c only one at a time.
*/
struct request *postponed_rq;
/* The time in which we started polling for DSC */
......@@ -303,21 +289,15 @@ typedef struct ide_tape_obj {
unsigned long dsc_poll_freq;
unsigned long dsc_timeout;
/*
* Read position information
*/
/* Read position information */
u8 partition;
/* Current block */
unsigned int first_frame;
/*
* Last error information
*/
/* Last error information */
u8 sense_key, asc, ascq;
/*
* Character device operation
*/
/* Character device operation */
unsigned int minor;
/* device name */
char name[4];
......@@ -334,19 +314,16 @@ typedef struct ide_tape_obj {
/*
* Active data transfer request parameters.
*
* At most, there is only one ide-tape originated data transfer
* request in the device request queue. This allows ide.c to
* easily service requests from the other device when we
* postpone our active request. In the pipelined operation
* mode, we use our internal pipeline structure to hold
* more data requests.
*
* The data buffer size is chosen based on the tape's
* recommendation.
*/
/* Ptr to the request which is waiting in the device request queue */
* At most, there is only one ide-tape originated data transfer request
* in the device request queue. This allows ide.c to easily service
* requests from the other device when we postpone our active request.
* In the pipelined operation mode, we use our internal pipeline
* structure to hold more data requests. The data buffer size is chosen
* based on the tape's recommendation.
*/
/* ptr to the request which is waiting in the device request queue */
struct request *active_data_rq;
/* Data buffer size (chosen based on the tape's recommendation */
/* Data buffer size chosen based on the tape's recommendation */
int stage_size;
idetape_stage_t *merge_stage;
int merge_stage_size;
......@@ -385,9 +362,7 @@ typedef struct ide_tape_obj {
/* protects the ide-tape queue */
spinlock_t lock;
/*
* Measures average tape speed
*/
/* Measures average tape speed */
unsigned long avg_time;
int avg_size;
int avg_speed;
......@@ -400,11 +375,9 @@ typedef struct ide_tape_obj {
char write_prot;
/*
* Limit the number of times a request can
* be postponed, to avoid an infinite postpone
* deadlock.
* Limit the number of times a request can be postponed, to avoid an
* infinite postpone deadlock.
*/
/* request postpone count limit */
int postpone_cnt;
/*
......@@ -419,18 +392,14 @@ typedef struct ide_tape_obj {
int tape_head;
int last_tape_head;
/*
* Speed control at the tape buffers input/output
*/
/* Speed control at the tape buffers input/output */
unsigned long insert_time;
int insert_size;
int insert_speed;
int max_insert_speed;
int measure_insert_time;
/*
* Speed regulation negative feedback loop
*/
/* Speed regulation negative feedback loop */
int speed_control;
int pipeline_head_speed;
int controlled_pipeline_head_speed;
......@@ -477,9 +446,7 @@ static void ide_tape_put(struct ide_tape_obj *tape)
mutex_unlock(&idetape_ref_mutex);
}
/*
* Tape door status
*/
/* Tape door status */
#define DOOR_UNLOCKED 0
#define DOOR_LOCKED 1
#define DOOR_EXPLICITLY_LOCKED 2
......@@ -499,20 +466,14 @@ static void ide_tape_put(struct ide_tape_obj *tape)
/* 0 = no tape is loaded, so we don't rewind after ejecting */
#define IDETAPE_MEDIUM_PRESENT 9
/*
* Some defines for the READ BUFFER command
*/
/* A define for the READ BUFFER command */
#define IDETAPE_RETRIEVE_FAULTY_BLOCK 6
/*
* Some defines for the SPACE command
*/
/* Some defines for the SPACE command */
#define IDETAPE_SPACE_OVER_FILEMARK 1
#define IDETAPE_SPACE_TO_EOD 3
/*
* Some defines for the LOAD UNLOAD command
*/
/* Some defines for the LOAD UNLOAD command */
#define IDETAPE_LU_LOAD_MASK 1
#define IDETAPE_LU_RETENSION_MASK 2
#define IDETAPE_LU_EOT_MASK 4
......@@ -520,9 +481,8 @@ static void ide_tape_put(struct ide_tape_obj *tape)
/*
* Special requests for our block device strategy routine.
*
* In order to service a character device command, we add special
* requests to the tail of our block device request queue and wait
* for their completion.
* In order to service a character device command, we add special requests to
* the tail of our block device request queue and wait for their completion.
*/
enum {
......@@ -533,10 +493,7 @@ enum {
REQ_IDETAPE_READ_BUFFER = (1 << 4),
};
/*
* Error codes which are returned in rq->errors to the higher part
* of the driver.
*/
/* Error codes returned in rq->errors to the higher part of the driver. */
#define IDETAPE_ERROR_GENERAL 101
#define IDETAPE_ERROR_FILEMARK 102
#define IDETAPE_ERROR_EOD 103
......@@ -560,8 +517,8 @@ struct idetape_id_gcw {
#define IDETAPE_CAPABILITIES_PAGE 0x2a
/*
* The variables below are used for the character device interface.
* Additional state variables are defined in our ide_drive_t structure.
* The variables below are used for the character device interface. Additional
* state variables are defined in our ide_drive_t structure.
*/
static struct ide_tape_obj * idetape_devs[MAX_HWIFS * MAX_DRIVES];
......@@ -579,10 +536,6 @@ static struct ide_tape_obj *ide_tape_chrdev_get(unsigned int i)
return tape;
}
/*
* Function declarations
*
*/
static int idetape_chrdev_release (struct inode *inode, struct file *filp);
static void idetape_write_release (ide_drive_t *drive, unsigned int minor);
......@@ -711,9 +664,6 @@ static struct request *idetape_next_rq_storage (ide_drive_t *drive)
return (&tape->rq_stack[tape->rq_stack_index++]);
}
/*
* idetape_init_pc initializes a packet command.
*/
static void idetape_init_pc (idetape_pc_t *pc)
{
memset(pc->c, 0, 12);
......@@ -809,10 +759,7 @@ static void idetape_activate_next_stage(ide_drive_t *drive)
tape->next_stage = stage->next;
}
/*
* idetape_kfree_stage calls kfree to completely free a stage, along with
* its related buffers.
*/
/* Free a stage along with its related buffers completely. */
static void __idetape_kfree_stage (idetape_stage_t *stage)
{
struct idetape_bh *prev_bh, *bh = stage->bh;
......@@ -840,8 +787,8 @@ static void idetape_kfree_stage (idetape_tape_t *tape, idetape_stage_t *stage)
}
/*
* idetape_remove_stage_head removes tape->first_stage from the pipeline.
* The caller should avoid race conditions.
* Remove tape->first_stage from the pipeline. The caller should avoid race
* conditions.
*/
static void idetape_remove_stage_head (ide_drive_t *drive)
{
......@@ -899,8 +846,8 @@ static void idetape_abort_pipeline(ide_drive_t *drive,
}
/*
* idetape_end_request is used to finish servicing a request, and to
* insert a pending pipeline request into the main device queue.
* Finish servicing a request and insert a pending pipeline request into the
* main device queue.
*/
static int idetape_end_request(ide_drive_t *drive, int uptodate, int nr_sects)
{
......@@ -951,9 +898,7 @@ static int idetape_end_request(ide_drive_t *drive, int uptodate, int nr_sects)
if (tape->next_stage != NULL) {
idetape_activate_next_stage(drive);
/*
* Insert the next request into the request queue.
*/
/* Insert the next request into the request queue. */
(void)ide_do_drive_cmd(drive, tape->active_data_rq,
ide_end);
} else if (!error) {
......@@ -1020,23 +965,19 @@ static void idetape_init_rq(struct request *rq, u8 cmd)
}
/*
* idetape_queue_pc_head generates a new packet command request in front
* of the request queue, before the current request, so that it will be
* processed immediately, on the next pass through the driver.
*
* idetape_queue_pc_head is called from the request handling part of
* the driver (the "bottom" part). Safe storage for the request should
* be allocated with idetape_next_pc_storage and idetape_next_rq_storage
* before calling idetape_queue_pc_head.
* Generate a new packet command request in front of the request queue, before
* the current request, so that it will be processed immediately, on the next
* pass through the driver. The function below is called from the request
* handling part of the driver (the "bottom" part). Safe storage for the request
* should be allocated with ide_tape_next_{pc,rq}_storage() prior to that.
*
* Memory for those requests is pre-allocated at initialization time, and
* is limited to IDETAPE_PC_STACK requests. We assume that we have enough
* space for the maximum possible number of inter-dependent packet commands.
* Memory for those requests is pre-allocated at initialization time, and is
* limited to IDETAPE_PC_STACK requests. We assume that we have enough space for
* the maximum possible number of inter-dependent packet commands.
*
* The higher level of the driver - The ioctl handler and the character
* device handling functions should queue request to the lower level part
* and wait for their completion using idetape_queue_pc_tail or
* idetape_queue_rw_tail.
* The higher level of the driver - The ioctl handler and the character device
* handling functions should queue request to the lower level part and wait for
* their completion using idetape_queue_pc_tail or idetape_queue_rw_tail.
*/
static void idetape_queue_pc_head (ide_drive_t *drive, idetape_pc_t *pc,struct request *rq)
{
......@@ -1069,9 +1010,8 @@ static ide_startstop_t idetape_retry_pc (ide_drive_t *drive)
}
/*
* idetape_postpone_request postpones the current request so that
* ide.c will be able to service requests from another device on
* the same hwgroup while we are polling for DSC.
* Postpone the current request so that ide.c will be able to service requests
* from another device on the same hwgroup while we are polling for DSC.
*/
static void idetape_postpone_request (ide_drive_t *drive)
{
......@@ -1260,44 +1200,38 @@ static ide_startstop_t idetape_pc_intr(ide_drive_t *drive)
/*
* Packet Command Interface
*
* The current Packet Command is available in tape->pc, and will not
* change until we finish handling it. Each packet command is associated
* with a callback function that will be called when the command is
* finished.
* The current Packet Command is available in tape->pc, and will not change
* until we finish handling it. Each packet command is associated with a
* callback function that will be called when the command is finished.
*
* The handling will be done in three stages:
*
* 1. idetape_issue_pc will send the packet command to the
* drive, and will set the interrupt handler to idetape_pc_intr.
* 1. idetape_issue_pc will send the packet command to the drive, and will set
* the interrupt handler to idetape_pc_intr.
*
* 2. On each interrupt, idetape_pc_intr will be called. This step
* will be repeated until the device signals us that no more
* interrupts will be issued.
* 2. On each interrupt, idetape_pc_intr will be called. This step will be
* repeated until the device signals us that no more interrupts will be issued.
*
* 3. ATAPI Tape media access commands have immediate status with a
* delayed process. In case of a successful initiation of a
* media access packet command, the DSC bit will be set when the
* actual execution of the command is finished.
* Since the tape drive will not issue an interrupt, we have to
* poll for this event. In this case, we define the request as
* "low priority request" by setting rq_status to
* IDETAPE_RQ_POSTPONED, set a timer to poll for DSC and exit
* the driver.
* 3. ATAPI Tape media access commands have immediate status with a delayed
* process. In case of a successful initiation of a media access packet command,
* the DSC bit will be set when the actual execution of the command is finished.
* Since the tape drive will not issue an interrupt, we have to poll for this
* event. In this case, we define the request as "low priority request" by
* setting rq_status to IDETAPE_RQ_POSTPONED, set a timer to poll for DSC and
* exit the driver.
*
* ide.c will then give higher priority to requests which
* originate from the other device, until will change rq_status
* to RQ_ACTIVE.
* ide.c will then give higher priority to requests which originate from the
* other device, until will change rq_status to RQ_ACTIVE.
*
* 4. When the packet command is finished, it will be checked for errors.
*
* 5. In case an error was found, we queue a request sense packet
* command in front of the request queue and retry the operation
* up to IDETAPE_MAX_PC_RETRIES times.
*
* 6. In case no error was found, or we decided to give up and not
* to retry again, the callback function will be called and then
* we will handle the next request.
* 5. In case an error was found, we queue a request sense packet command in
* front of the request queue and retry the operation up to
* IDETAPE_MAX_PC_RETRIES times.
*
* 6. In case no error was found, or we decided to give up and not to retry
* again, the callback function will be called and then we will handle the next
* request.
*/
static ide_startstop_t idetape_transfer_pc(ide_drive_t *drive)
{
......@@ -1363,9 +1297,9 @@ static ide_startstop_t idetape_issue_pc(ide_drive_t *drive, idetape_pc_t *pc)
if (pc->retries > IDETAPE_MAX_PC_RETRIES ||
test_bit(PC_ABORT, &pc->flags)) {
/*
* We will "abort" retrying a packet command in case
* a legitimate error code was received (crossing a
* filemark, or end of the media, for example).
* We will "abort" retrying a packet command in case legitimate
* error code was received (crossing a filemark, or end of the
* media, for example).
*/
if (!test_bit(PC_ABORT, &pc->flags)) {
if (!(pc->c[0] == TEST_UNIT_READY &&
......@@ -1416,9 +1350,6 @@ static ide_startstop_t idetape_issue_pc(ide_drive_t *drive, idetape_pc_t *pc)
}
}
/*
* General packet command callback function.
*/
static ide_startstop_t idetape_pc_callback (ide_drive_t *drive)
{
idetape_tape_t *tape = drive->driver_data;
......@@ -1429,15 +1360,14 @@ static ide_startstop_t idetape_pc_callback (ide_drive_t *drive)
return ide_stopped;
}
/*
* A mode sense command is used to "sense" tape parameters.
*/
/* A mode sense command is used to "sense" tape parameters. */
static void idetape_create_mode_sense_cmd (idetape_pc_t *pc, u8 page_code)
{
idetape_init_pc(pc);
pc->c[0] = MODE_SENSE;
if (page_code != IDETAPE_BLOCK_DESCRIPTOR)
pc->c[1] = 8; /* DBD = 1 - Don't return block descriptors */
/* DBD = 1 - Don't return block descriptors */
pc->c[1] = 8;
pc->c[2] = page_code;
/*
* Changed pc->c[3] to 0 (255 will at best return unused info).
......@@ -1447,7 +1377,8 @@ static void idetape_create_mode_sense_cmd (idetape_pc_t *pc, u8 page_code)
* and return an error when 255 is used.
*/
pc->c[3] = 0;
pc->c[4] = 255; /* (We will just discard data in that case) */
/* We will just discard data in that case */
pc->c[4] = 255;
if (page_code == IDETAPE_BLOCK_DESCRIPTOR)
pc->request_transfer = 12;
else if (page_code == IDETAPE_CAPABILITIES_PAGE)
......@@ -1619,9 +1550,6 @@ static void idetape_create_write_cmd(idetape_tape_t *tape, idetape_pc_t *pc, uns
set_bit(PC_DMA_RECOMMENDED, &pc->flags);
}
/*
* idetape_do_request is our request handling function.
*/
static ide_startstop_t idetape_do_request(ide_drive_t *drive,
struct request *rq, sector_t block)
{
......@@ -1635,18 +1563,14 @@ static ide_startstop_t idetape_do_request(ide_drive_t *drive,
rq->sector, rq->nr_sectors, rq->current_nr_sectors);
if (!blk_special_request(rq)) {
/*
* We do not support buffer cache originated requests.
*/
/* We do not support buffer cache originated requests. */
printk(KERN_NOTICE "ide-tape: %s: Unsupported request in "
"request queue (%d)\n", drive->name, rq->cmd_type);
ide_end_request(drive, 0, 0);
return ide_stopped;
}
/*
* Retry a failed packet command
*/
/* Retry a failed packet command */
if (tape->failed_pc != NULL &&
tape->pc->c[0] == REQUEST_SENSE) {
return idetape_issue_pc(drive, tape->failed_pc);
......@@ -1733,9 +1657,7 @@ static ide_startstop_t idetape_do_request(ide_drive_t *drive,
return idetape_issue_pc(drive, pc);
}
/*
* Pipeline related functions
*/
/* Pipeline related functions */
static inline int idetape_pipeline_active (idetape_tape_t *tape)
{
int rc1, rc2;
......@@ -1746,16 +1668,16 @@ static inline int idetape_pipeline_active (idetape_tape_t *tape)
}
/*
* idetape_kmalloc_stage uses __get_free_page to allocate a pipeline
* stage, along with all the necessary small buffers which together make
* a buffer of size tape->stage_size (or a bit more). We attempt to
* combine sequential pages as much as possible.
* The function below uses __get_free_page to allocate a pipeline stage, along
* with all the necessary small buffers which together make a buffer of size
* tape->stage_size (or a bit more). We attempt to combine sequential pages as
* much as possible.
*
* Returns a pointer to the new allocated stage, or NULL if we
* can't (or don't want to) allocate a stage.
* It returns a pointer to the new allocated stage, or NULL if we can't (or
* don't want to) allocate a stage.
*
* Pipeline stages are optional and are used to increase performance.
* If we can't allocate them, we'll manage without them.
* Pipeline stages are optional and are used to increase performance. If we
* can't allocate them, we'll manage without them.
*/
static idetape_stage_t *__idetape_kmalloc_stage (idetape_tape_t *tape, int full, int clear)
{
......@@ -1913,9 +1835,7 @@ static void idetape_switch_buffers (idetape_tape_t *tape, idetape_stage_t *stage
idetape_init_merge_stage(tape);
}
/*
* idetape_add_stage_tail adds a new stage at the end of the pipeline.
*/
/* Add a new stage at the end of the pipeline. */
static void idetape_add_stage_tail (ide_drive_t *drive,idetape_stage_t *stage)
{
idetape_tape_t *tape = drive->driver_data;
......@@ -1937,12 +1857,9 @@ static void idetape_add_stage_tail (ide_drive_t *drive,idetape_stage_t *stage)
spin_unlock_irqrestore(&tape->lock, flags);
}
/*
* idetape_wait_for_request installs a completion in a pending request
* and sleeps until it is serviced.
*
* The caller should ensure that the request will not be serviced
* before we install the completion (usually by disabling interrupts).
/* Install a completion in a pending request and sleep until it is serviced. The
* caller should ensure that the request will not be serviced before we install
* the completion (usually by disabling interrupts).
*/
static void idetape_wait_for_request (ide_drive_t *drive, struct request *rq)
{
......@@ -1996,12 +1913,8 @@ static ide_startstop_t idetape_read_position_callback(ide_drive_t *drive)
}
/*
* idetape_create_write_filemark_cmd will:
*
* 1. Write a filemark if write_filemark=1.
* 2. Flush the device buffers without writing a filemark
* if write_filemark=0.
*
* Write a filemark if write_filemark=1. Flush the device buffers without
* writing a filemark otherwise.
*/
static void idetape_create_write_filemark_cmd (ide_drive_t *drive, idetape_pc_t *pc,int write_filemark)
{
......@@ -2020,24 +1933,17 @@ static void idetape_create_test_unit_ready_cmd(idetape_pc_t *pc)
}
/*
* idetape_queue_pc_tail is based on the following functions:
*
* ide_do_drive_cmd from ide.c
* cdrom_queue_request and cdrom_queue_packet_command from ide-cd.c
*
* We add a special packet command request to the tail of the request
* queue, and wait for it to be serviced.
*
* This is not to be called from within the request handling part
* of the driver ! We allocate here data in the stack, and it is valid
* until the request is finished. This is not the case for the bottom
* part of the driver, where we are always leaving the functions to wait
* for an interrupt or a timer event.
* We add a special packet command request to the tail of the request queue, and
* wait for it to be serviced. This is not to be called from within the request
* handling part of the driver! We allocate here data on the stack and it is
* valid until the request is finished. This is not the case for the bottom part
* of the driver, where we are always leaving the functions to wait for an
* interrupt or a timer event.
*
* From the bottom part of the driver, we should allocate safe memory
* using idetape_next_pc_storage and idetape_next_rq_storage, and add
* the request to the request list without waiting for it to be serviced !
* In that case, we usually use idetape_queue_pc_head.
* From the bottom part of the driver, we should allocate safe memory using
* idetape_next_pc_storage() and ide_tape_next_rq_storage(), and add the request
* to the request list without waiting for it to be serviced! In that case, we
* usually use idetape_queue_pc_head().
*/
static int __idetape_queue_pc_tail (ide_drive_t *drive, idetape_pc_t *pc)
{
......@@ -2065,9 +1971,7 @@ static int idetape_wait_ready(ide_drive_t *drive, unsigned long timeout)
idetape_pc_t pc;
int load_attempted = 0;
/*
* Wait for the tape to become ready
*/
/* Wait for the tape to become ready */
set_bit(IDETAPE_MEDIUM_PRESENT, &tape->flags);
timeout += jiffies;
while (time_before(jiffies, timeout)) {
......@@ -2075,7 +1979,8 @@ static int idetape_wait_ready(ide_drive_t *drive, unsigned long timeout)
if (!__idetape_queue_pc_tail(drive, &pc))
return 0;
if ((tape->sense_key == 2 && tape->asc == 4 && tape->ascq == 2)
|| (tape->asc == 0x3A)) { /* no media */
|| (tape->asc == 0x3A)) {
/* no media */
if (load_attempted)
return -ENOMEDIUM;
idetape_create_load_unload_cmd(drive, &pc, IDETAPE_LU_LOAD_MASK);
......@@ -2203,13 +2108,10 @@ static int __idetape_discard_read_pipeline (ide_drive_t *drive)
}
/*
* idetape_position_tape positions the tape to the requested block
* using the LOCATE packet command. A READ POSITION command is then
* issued to check where we are positioned.
*
* Like all higher level operations, we queue the commands at the tail
* of the request queue and wait for their completion.
*
* Position the tape to the requested block using the LOCATE packet command.
* A READ POSITION command is then issued to check where we are positioned. Like
* all higher level operations, we queue the commands at the tail of the request
* queue and wait for their completion.
*/
static int idetape_position_tape (ide_drive_t *drive, unsigned int block, u8 partition, int skip)
{
......@@ -2247,8 +2149,8 @@ static void idetape_discard_read_pipeline (ide_drive_t *drive, int restore_posit
}
/*
* idetape_queue_rw_tail generates a read/write request for the block
* device interface and wait for it to be serviced.
* Generate a read/write request for the block device interface and wait for it
* to be serviced.
*/
static int idetape_queue_rw_tail(ide_drive_t *drive, int cmd, int blocks, struct idetape_bh *bh)
{
......@@ -2343,15 +2245,15 @@ static void idetape_wait_first_stage (ide_drive_t *drive)
}
/*
* idetape_add_chrdev_write_request tries to add a character device
* originated write request to our pipeline. In case we don't succeed,
* we revert to non-pipelined operation mode for this request.
* Try to add a character device originated write request to our pipeline. In
* case we don't succeed, we revert to non-pipelined operation mode for this
* request. In order to accomplish that, we
*
* 1. Try to allocate a new pipeline stage.
* 2. If we can't, wait for more and more requests to be serviced
* and try again each time.
* 3. If we still can't allocate a stage, fallback to
* non-pipelined operation mode for this request.
* 2. If we can't, wait for more and more requests to be serviced and try again
* each time.
* 3. If we still can't allocate a stage, fallback to non-pipelined operation
* mode for this request.
*/
static int idetape_add_chrdev_write_request (ide_drive_t *drive, int blocks)
{
......@@ -2362,10 +2264,7 @@ static int idetape_add_chrdev_write_request (ide_drive_t *drive, int blocks)
debug_log(DBG_CHRDEV, "Enter %s\n", __func__);
/*
* Attempt to allocate a new stage.
* Pay special attention to possible race conditions.
*/
/* Attempt to allocate a new stage. Beware possible race conditions. */
while ((new_stage = idetape_kmalloc_stage(tape)) == NULL) {
spin_lock_irqsave(&tape->lock, flags);
if (idetape_pipeline_active(tape)) {
......@@ -2377,8 +2276,8 @@ static int idetape_add_chrdev_write_request (ide_drive_t *drive, int blocks)
if (idetape_pipeline_active(tape))
continue;
/*
* Linux is short on memory. Fallback to
* non-pipelined operation mode for this request.
* The machine is short on memory. Fallback to non-
* pipelined operation mode for this request.
*/
return idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE, blocks, tape->merge_stage->bh);
}
......@@ -2395,11 +2294,11 @@ static int idetape_add_chrdev_write_request (ide_drive_t *drive, int blocks)
idetape_calculate_speeds(drive);
/*
* Estimate whether the tape has stopped writing by checking
* if our write pipeline is currently empty. If we are not
* writing anymore, wait for the pipeline to be full enough
* (90%) before starting to service requests, so that we will
* be able to keep up with the higher speeds of the tape.
* Estimate whether the tape has stopped writing by checking if our
* write pipeline is currently empty. If we are not writing anymore,
* wait for the pipeline to be almost completely full (90%) before
* starting to service requests, so that we will be able to keep up with
* the higher speeds of the tape.
*/
if (!idetape_pipeline_active(tape)) {
if (tape->nr_stages >= tape->max_stages * 9 / 10 ||
......@@ -2420,8 +2319,8 @@ static int idetape_add_chrdev_write_request (ide_drive_t *drive, int blocks)
}
/*
* idetape_wait_for_pipeline will wait until all pending pipeline
* requests are serviced. Typically called on device close.
* Wait until all pending pipeline requests are serviced. Typically called on
* device close.
*/
static void idetape_wait_for_pipeline (ide_drive_t *drive)
{
......@@ -2490,10 +2389,10 @@ static void idetape_empty_write_pipeline (ide_drive_t *drive)
tape->chrdev_dir = IDETAPE_DIR_NONE;
/*
* On the next backup, perform the feedback loop again.
* (I don't want to keep sense information between backups,
* as some systems are constantly on, and the system load
* can be totally different on the next backup).
* On the next backup, perform the feedback loop again. (I don't want to
* keep sense information between backups, as some systems are
* constantly on, and the system load can be totally different on the
* next backup).
*/
tape->max_stages = tape->min_pipeline;
if (tape->first_stage != NULL ||
......@@ -2545,11 +2444,10 @@ static int idetape_init_read(ide_drive_t *drive, int max_stages)
tape->chrdev_dir = IDETAPE_DIR_READ;
/*
* Issue a read 0 command to ensure that DSC handshake
* is switched from completion mode to buffer available
* mode.
* No point in issuing this if DSC overlap isn't supported,
* some drives (Seagate STT3401A) will return an error.
* Issue a read 0 command to ensure that DSC handshake is
* switched from completion mode to buffer available mode.
* No point in issuing this if DSC overlap isn't supported, some
* drives (Seagate STT3401A) will return an error.
*/
if (drive->dsc_overlap) {
bytes_read = idetape_queue_rw_tail(drive, REQ_IDETAPE_READ, 0, tape->merge_stage->bh);
......@@ -2590,9 +2488,8 @@ static int idetape_init_read(ide_drive_t *drive, int max_stages)
}
/*
* idetape_add_chrdev_read_request is called from idetape_chrdev_read
* to service a character device read request and add read-ahead
* requests to our pipeline.
* Called from idetape_chrdev_read() to service a character device read request
* and add read-ahead requests to our pipeline.
*/
static int idetape_add_chrdev_read_request (ide_drive_t *drive,int blocks)
{
......@@ -2603,16 +2500,11 @@ static int idetape_add_chrdev_read_request (ide_drive_t *drive,int blocks)
debug_log(DBG_PROCS, "Enter %s, %d blocks\n", __func__, blocks);
/*
* If we are at a filemark, return a read length of 0
*/
/* If we are at a filemark, return a read length of 0 */
if (test_bit(IDETAPE_FILEMARK, &tape->flags))
return 0;
/*
* Wait for the next block to be available at the head
* of the pipeline
*/
/* Wait for the next block to reach the head of the pipeline. */
idetape_init_read(drive, tape->max_stages);
if (tape->first_stage == NULL) {
if (test_bit(IDETAPE_PIPELINE_ERROR, &tape->flags))
......@@ -2691,9 +2583,8 @@ static int idetape_pipeline_size (ide_drive_t *drive)
}
/*
* Rewinds the tape to the Beginning Of the current Partition (BOP).
*
* We currently support only one partition.
* Rewinds the tape to the Beginning Of the current Partition (BOP). We
* currently support only one partition.
*/
static int idetape_rewind_tape (ide_drive_t *drive)
{
......@@ -2716,13 +2607,7 @@ static int idetape_rewind_tape (ide_drive_t *drive)
return 0;
}
/*
* Our special ide-tape ioctl's.
*
* Currently there aren't any ioctl's.
* mtio.h compatible commands should be issued to the character device
* interface.
*/
/* mtio.h compatible commands should be issued to the chrdev interface. */
static int idetape_blkdev_ioctl(ide_drive_t *drive, unsigned int cmd, unsigned long arg)
{
idetape_tape_t *tape = drive->driver_data;
......@@ -2756,13 +2641,11 @@ static int idetape_blkdev_ioctl(ide_drive_t *drive, unsigned int cmd, unsigned l
}
/*
* idetape_space_over_filemarks is now a bit more complicated than just
* passing the command to the tape since we may have crossed some
* filemarks during our pipelined read-ahead mode.
*
* As a minor side effect, the pipeline enables us to support MTFSFM when
* the filemark is in our internal pipeline even if the tape doesn't
* support spacing over filemarks in the reverse direction.
* The function below is now a bit more complicated than just passing the
* command to the tape since we may have crossed some filemarks during our
* pipelined read-ahead mode. As a minor side effect, the pipeline enables us to
* support MTFSFM when the filemark is in our internal pipeline even if the tape
* doesn't support spacing over filemarks in the reverse direction.
*/
static int idetape_space_over_filemarks (ide_drive_t *drive,short mt_op,int mt_count)
{
......@@ -2781,10 +2664,7 @@ static int idetape_space_over_filemarks (ide_drive_t *drive,short mt_op,int mt_c
}
if (tape->chrdev_dir == IDETAPE_DIR_READ) {
/*
* We have a read-ahead buffer. Scan it for crossed
* filemarks.
*/
/* its a read-ahead buffer, scan it for crossed filemarks. */
tape->merge_stage_size = 0;
if (test_and_clear_bit(IDETAPE_FILEMARK, &tape->flags))
++count;
......@@ -2797,13 +2677,15 @@ static int idetape_space_over_filemarks (ide_drive_t *drive,short mt_op,int mt_c
spin_lock_irqsave(&tape->lock, flags);
if (tape->first_stage == tape->active_stage) {
/*
* We have reached the active stage in the read pipeline.
* There is no point in allowing the drive to continue
* reading any farther, so we stop the pipeline.
* We have reached the active stage in the read
* pipeline. There is no point in allowing the
* drive to continue reading any farther, so we
* stop the pipeline.
*
* This section should be moved to a separate subroutine,
* because a similar function is performed in
* __idetape_discard_read_pipeline(), for example.
* This section should be moved to a separate
* subroutine because similar operations are
* done in __idetape_discard_read_pipeline(),
* for example.
*/
tape->next_stage = NULL;
spin_unlock_irqrestore(&tape->lock, flags);
......@@ -2819,8 +2701,8 @@ static int idetape_space_over_filemarks (ide_drive_t *drive,short mt_op,int mt_c
}
/*
* The filemark was not found in our internal pipeline.
* Now we can issue the space command.
* The filemark was not found in our internal pipeline; now we can issue
* the space command.
*/
switch (mt_op) {
case MTFSF:
......@@ -2845,18 +2727,16 @@ static int idetape_space_over_filemarks (ide_drive_t *drive,short mt_op,int mt_c
/*
* Our character device read / write functions.
*
* The tape is optimized to maximize throughput when it is transferring
* an integral number of the "continuous transfer limit", which is
* a parameter of the specific tape (26 KB on my particular tape).
* (32 kB for Onstream)
* The tape is optimized to maximize throughput when it is transferring an
* integral number of the "continuous transfer limit", which is a parameter of
* the specific tape (26kB on my particular tape, 32kB for Onstream).
*
* As of version 1.3 of the driver, the character device provides an
* abstract continuous view of the media - any mix of block sizes (even 1
* byte) on the same backup/restore procedure is supported. The driver
* will internally convert the requests to the recommended transfer unit,
* so that an unmatch between the user's block size to the recommended
* size will only result in a (slightly) increased driver overhead, but
* will no longer hit performance.
* As of version 1.3 of the driver, the character device provides an abstract
* continuous view of the media - any mix of block sizes (even 1 byte) on the
* same backup/restore procedure is supported. The driver will internally
* convert the requests to the recommended transfer unit, so that an unmatch
* between the user's block size to the recommended size will only result in a
* (slightly) increased driver overhead, but will no longer hit performance.
* This is not applicable to Onstream.
*/
static ssize_t idetape_chrdev_read (struct file *file, char __user *buf,
......@@ -2950,11 +2830,10 @@ static ssize_t idetape_chrdev_write (struct file *file, const char __user *buf,
idetape_init_merge_stage(tape);
/*
* Issue a write 0 command to ensure that DSC handshake
* is switched from completion mode to buffer available
* mode.
* No point in issuing this if DSC overlap isn't supported,
* some drives (Seagate STT3401A) will return an error.
* Issue a write 0 command to ensure that DSC handshake is
* switched from completion mode to buffer available mode. No
* point in issuing this if DSC overlap isn't supported, some
* drives (Seagate STT3401A) will return an error.
*/
if (drive->dsc_overlap) {
ssize_t retval = idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE, 0, tape->merge_stage->bh);
......@@ -3045,9 +2924,7 @@ static int idetape_mtioctop(ide_drive_t *drive, short mt_op, int mt_count)
debug_log(DBG_ERR, "Handling MTIOCTOP ioctl: mt_op=%d, mt_count=%d\n",
mt_op, mt_count);
/*
* Commands which need our pipelined read-ahead stages.
*/
/* Commands which need our pipelined read-ahead stages. */
switch (mt_op) {
case MTFSF:
case MTFSFM:
......@@ -3235,9 +3112,6 @@ static void ide_tape_get_bsize_from_bdesc(ide_drive_t *drive)
tape->drv_write_prot = (pc.buffer[2] & 0x80) >> 7;
}
/*
* Our character device open function.
*/
static int idetape_chrdev_open (struct inode *inode, struct file *filp)
{
unsigned int minor = iminor(inode), i = minor & ~0xc0;
......@@ -3304,9 +3178,7 @@ static int idetape_chrdev_open (struct inode *inode, struct file *filp)
}
}
/*
* Lock the tape drive door so user can't eject.
*/
/* Lock the tape drive door so user can't eject. */
if (tape->chrdev_dir == IDETAPE_DIR_NONE) {
if (idetape_create_prevent_cmd(drive, &pc, 1)) {
if (!idetape_queue_pc_tail(drive, &pc)) {
......@@ -3341,9 +3213,6 @@ static void idetape_write_release (ide_drive_t *drive, unsigned int minor)
idetape_flush_tape_buffers(drive);
}
/*
* Our character device release function.
*/
static int idetape_chrdev_release (struct inode *inode, struct file *filp)
{
struct ide_tape_obj *tape = ide_tape_f(filp);
......@@ -3500,9 +3369,6 @@ static void idetape_add_settings (ide_drive_t *drive)
{
idetape_tape_t *tape = drive->driver_data;
/*
* drive setting name read/write data type min max mul_factor div_factor data pointer set function
*/
ide_add_setting(drive, "buffer", SETTING_READ, TYPE_SHORT, 0, 0xffff,
1, 2, (u16 *)&tape->caps[16], NULL);
ide_add_setting(drive, "pipeline_min", SETTING_RW, TYPE_INT, 1, 0xffff, tape->stage_size / 1024, 1, &tape->min_pipeline, NULL);
......@@ -3529,16 +3395,15 @@ static inline void idetape_add_settings(ide_drive_t *drive) { ; }
#endif
/*
* ide_setup is called to:
* The function below is called to:
*
* 1. Initialize our various state variables.
* 2. Ask the tape for its capabilities.
* 3. Allocate a buffer which will be used for data
* transfer. The buffer size is chosen based on
* the recommendation which we received in step (2).
* 3. Allocate a buffer which will be used for data transfer. The buffer size
* is chosen based on the recommendation which we received in step 2.
*
* Note that at this point ide.c already assigned us an irq, so that
* we can queue requests here and wait for their completion.
* Note that at this point ide.c already assigned us an irq, so that we can
* queue requests here and wait for their completion.
*/
static void idetape_setup (ide_drive_t *drive, idetape_tape_t *tape, int minor)
{
......@@ -3595,9 +3460,7 @@ static void idetape_setup (ide_drive_t *drive, idetape_tape_t *tape, int minor)
tape->max_stages = speed * 1000 * 10 / tape->stage_size;
/*
* Limit memory use for pipeline to 10% of physical memory
*/
/* Limit memory use for pipeline to 10% of physical memory */
si_meminfo(&si);
if (tape->max_stages * tape->stage_size > si.totalram * si.mem_unit / 10)
tape->max_stages = si.totalram * si.mem_unit / (10 * tape->stage_size);
......@@ -3617,8 +3480,8 @@ static void idetape_setup (ide_drive_t *drive, idetape_tape_t *tape, int minor)
t = t1;
/*
* Ensure that the number we got makes sense; limit
* it within IDETAPE_DSC_RW_MIN and IDETAPE_DSC_RW_MAX.
* Ensure that the number we got makes sense; limit it within
* IDETAPE_DSC_RW_MIN and IDETAPE_DSC_RW_MAX.
*/
tape->best_dsc_rw_freq = max_t(unsigned long,
min_t(unsigned long, t, IDETAPE_DSC_RW_MAX),
......@@ -3706,9 +3569,7 @@ static ide_driver_t idetape_driver = {
#endif
};
/*
* Our character device supporting functions, passed to register_chrdev.
*/
/* Our character device supporting functions, passed to register_chrdev. */
static const struct file_operations idetape_fops = {
.owner = THIS_MODULE,
.read = idetape_chrdev_read,
......
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