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ide-cd: remove the internal 64k buffer
This removes the internal ide-cd buffer and falls back to read-ahead block layer capabilities. Thorough testing (cd burning, dvd read, raw read) gives with the bufferless mode marginally better performance in addition to simplified code. bufferless: dd: reading `/dev/hdc': Input/output error 6238+0 records in 6238+0 records out 204406784 bytes (204 MB) copied, 259.891 s, 787 kB/s real 4m21.598s user 0m0.014s sys 0m0.744s with the old buffer (2.6.25-rc1): dd: reading `/dev/hdc': Input/output error 6238+0 records in 6238+0 records out 204406784 bytes (204 MB) copied, 262.893 s, 778 kB/s real 4m22.938s user 0m0.009s sys 0m0.771s Signed-off-by: Borislav Petkov <petkovbb@gmail.com> Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
This commit is contained in:
Borislav Petkov
Bartlomiej Zolnierkiewicz
parent
9841654949
commit
968c496413
2 changed files with 4 additions and 123 deletions
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@ -89,7 +89,6 @@ static void cdrom_saw_media_change (ide_drive_t *drive)
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cd->cd_flags |= IDE_CD_FLAG_MEDIA_CHANGED;
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cd->cd_flags &= ~IDE_CD_FLAG_TOC_VALID;
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cd->nsectors_buffered = 0;
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}
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static int cdrom_log_sense(ide_drive_t *drive, struct request *rq,
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@ -625,47 +624,6 @@ static void ide_cd_drain_data(ide_drive_t *drive, int nsects)
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}
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}
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/*
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* Buffer up to SECTORS_TO_TRANSFER sectors from the drive in our sector
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* buffer. Once the first sector is added, any subsequent sectors are
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* assumed to be continuous (until the buffer is cleared). For the first
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* sector added, SECTOR is its sector number. (SECTOR is then ignored until
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* the buffer is cleared.)
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*/
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static void cdrom_buffer_sectors (ide_drive_t *drive, unsigned long sector,
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int sectors_to_transfer)
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{
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struct cdrom_info *info = drive->driver_data;
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/* Number of sectors to read into the buffer. */
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int sectors_to_buffer = min_t(int, sectors_to_transfer,
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(SECTOR_BUFFER_SIZE >> SECTOR_BITS) -
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info->nsectors_buffered);
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char *dest;
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/* If we couldn't get a buffer, don't try to buffer anything... */
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if (info->buffer == NULL)
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sectors_to_buffer = 0;
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/* If this is the first sector in the buffer, remember its number. */
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if (info->nsectors_buffered == 0)
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info->sector_buffered = sector;
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/* Read the data into the buffer. */
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dest = info->buffer + info->nsectors_buffered * SECTOR_SIZE;
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while (sectors_to_buffer > 0) {
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HWIF(drive)->atapi_input_bytes(drive, dest, SECTOR_SIZE);
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--sectors_to_buffer;
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--sectors_to_transfer;
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++info->nsectors_buffered;
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dest += SECTOR_SIZE;
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}
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/* Throw away any remaining data. */
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ide_cd_drain_data(drive, sectors_to_transfer);
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}
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/*
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* Check the contents of the interrupt reason register from the cdrom
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* and attempt to recover if there are problems. Returns 0 if everything's
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@ -734,65 +692,6 @@ static int ide_cd_check_transfer_size(ide_drive_t *drive, int len)
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return 1;
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}
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/*
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* Try to satisfy some of the current read request from our cached data.
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* Returns nonzero if the request has been completed, zero otherwise.
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*/
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static int cdrom_read_from_buffer (ide_drive_t *drive)
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{
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struct cdrom_info *info = drive->driver_data;
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struct request *rq = HWGROUP(drive)->rq;
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unsigned short sectors_per_frame;
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sectors_per_frame = queue_hardsect_size(drive->queue) >> SECTOR_BITS;
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/* Can't do anything if there's no buffer. */
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if (info->buffer == NULL) return 0;
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/* Loop while this request needs data and the next block is present
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in our cache. */
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while (rq->nr_sectors > 0 &&
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rq->sector >= info->sector_buffered &&
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rq->sector < info->sector_buffered + info->nsectors_buffered) {
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if (rq->current_nr_sectors == 0)
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cdrom_end_request(drive, 1);
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memcpy (rq->buffer,
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info->buffer +
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(rq->sector - info->sector_buffered) * SECTOR_SIZE,
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SECTOR_SIZE);
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rq->buffer += SECTOR_SIZE;
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--rq->current_nr_sectors;
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--rq->nr_sectors;
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++rq->sector;
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}
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/* If we've satisfied the current request,
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terminate it successfully. */
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if (rq->nr_sectors == 0) {
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cdrom_end_request(drive, 1);
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return -1;
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}
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/* Move on to the next buffer if needed. */
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if (rq->current_nr_sectors == 0)
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cdrom_end_request(drive, 1);
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/* If this condition does not hold, then the kluge i use to
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represent the number of sectors to skip at the start of a transfer
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will fail. I think that this will never happen, but let's be
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paranoid and check. */
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if (rq->current_nr_sectors < bio_cur_sectors(rq->bio) &&
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(rq->sector & (sectors_per_frame - 1))) {
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printk(KERN_ERR "%s: cdrom_read_from_buffer: buffer botch (%ld)\n",
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drive->name, (long)rq->sector);
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cdrom_end_request(drive, 0);
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return -1;
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}
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return 0;
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}
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static ide_startstop_t cdrom_newpc_intr(ide_drive_t *);
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/*
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@ -1134,11 +1033,9 @@ static ide_startstop_t cdrom_newpc_intr(ide_drive_t *drive)
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if (!ptr) {
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if (blk_fs_request(rq) && !write)
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/*
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* If the buffers are full, cache the rest
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* of the data in our internal buffer.
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*/
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cdrom_buffer_sectors(drive, rq->sector,
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thislen >> 9);
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* If the buffers are full, pipe the rest into
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* oblivion. */
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ide_cd_drain_data(drive, thislen >> 9);
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else {
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printk(KERN_ERR "%s: confused, missing data\n",
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drive->name);
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@ -1243,10 +1140,6 @@ static ide_startstop_t cdrom_start_rw(ide_drive_t *drive, struct request *rq)
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* weirdness which might be present in the request packet.
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*/
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restore_request(rq);
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/* Satisfy whatever we can of this request from our cache. */
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if (cdrom_read_from_buffer(drive))
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return ide_stopped;
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}
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/*
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@ -1262,9 +1155,6 @@ static ide_startstop_t cdrom_start_rw(ide_drive_t *drive, struct request *rq)
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} else
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cd->dma = drive->using_dma;
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/* Clear the local sector buffer. */
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cd->nsectors_buffered = 0;
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if (write)
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cd->devinfo.media_written = 1;
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@ -2030,7 +1920,6 @@ static void ide_cd_release(struct kref *kref)
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ide_drive_t *drive = info->drive;
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struct gendisk *g = info->disk;
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kfree(info->buffer);
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kfree(info->toc);
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if (devinfo->handle == drive)
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unregister_cdrom(devinfo);
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@ -2090,11 +1979,7 @@ static int idecd_open(struct inode * inode, struct file * file)
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if (!(info = ide_cd_get(disk)))
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return -ENXIO;
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if (!info->buffer)
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info->buffer = kmalloc(SECTOR_BUFFER_SIZE, GFP_KERNEL|__GFP_REPEAT);
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if (info->buffer)
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rc = cdrom_open(&info->devinfo, inode, file);
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rc = cdrom_open(&info->devinfo, inode, file);
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if (rc < 0)
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ide_cd_put(info);
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@ -119,10 +119,6 @@ struct cdrom_info {
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struct atapi_toc *toc;
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unsigned long sector_buffered;
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unsigned long nsectors_buffered;
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unsigned char *buffer;
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/* The result of the last successful request sense command
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on this device. */
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struct request_sense sense_data;
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