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>
diff --git a/drivers/ide/ide-cd.c b/drivers/ide/ide-cd.c
index fe5aefb..5163f60 100644
--- a/drivers/ide/ide-cd.c
+++ b/drivers/ide/ide-cd.c
@@ -89,7 +89,6 @@
cd->cd_flags |= IDE_CD_FLAG_MEDIA_CHANGED;
cd->cd_flags &= ~IDE_CD_FLAG_TOC_VALID;
- cd->nsectors_buffered = 0;
}
static int cdrom_log_sense(ide_drive_t *drive, struct request *rq,
@@ -626,47 +625,6 @@
}
/*
- * Buffer up to SECTORS_TO_TRANSFER sectors from the drive in our sector
- * buffer. Once the first sector is added, any subsequent sectors are
- * assumed to be continuous (until the buffer is cleared). For the first
- * sector added, SECTOR is its sector number. (SECTOR is then ignored until
- * the buffer is cleared.)
- */
-static void cdrom_buffer_sectors (ide_drive_t *drive, unsigned long sector,
- int sectors_to_transfer)
-{
- struct cdrom_info *info = drive->driver_data;
-
- /* Number of sectors to read into the buffer. */
- int sectors_to_buffer = min_t(int, sectors_to_transfer,
- (SECTOR_BUFFER_SIZE >> SECTOR_BITS) -
- info->nsectors_buffered);
-
- char *dest;
-
- /* If we couldn't get a buffer, don't try to buffer anything... */
- if (info->buffer == NULL)
- sectors_to_buffer = 0;
-
- /* If this is the first sector in the buffer, remember its number. */
- if (info->nsectors_buffered == 0)
- info->sector_buffered = sector;
-
- /* Read the data into the buffer. */
- dest = info->buffer + info->nsectors_buffered * SECTOR_SIZE;
- while (sectors_to_buffer > 0) {
- HWIF(drive)->atapi_input_bytes(drive, dest, SECTOR_SIZE);
- --sectors_to_buffer;
- --sectors_to_transfer;
- ++info->nsectors_buffered;
- dest += SECTOR_SIZE;
- }
-
- /* Throw away any remaining data. */
- ide_cd_drain_data(drive, sectors_to_transfer);
-}
-
-/*
* Check the contents of the interrupt reason register from the cdrom
* and attempt to recover if there are problems. Returns 0 if everything's
* ok; nonzero if the request has been terminated.
@@ -734,65 +692,6 @@
return 1;
}
-/*
- * Try to satisfy some of the current read request from our cached data.
- * Returns nonzero if the request has been completed, zero otherwise.
- */
-static int cdrom_read_from_buffer (ide_drive_t *drive)
-{
- struct cdrom_info *info = drive->driver_data;
- struct request *rq = HWGROUP(drive)->rq;
- unsigned short sectors_per_frame;
-
- sectors_per_frame = queue_hardsect_size(drive->queue) >> SECTOR_BITS;
-
- /* Can't do anything if there's no buffer. */
- if (info->buffer == NULL) return 0;
-
- /* Loop while this request needs data and the next block is present
- in our cache. */
- while (rq->nr_sectors > 0 &&
- rq->sector >= info->sector_buffered &&
- rq->sector < info->sector_buffered + info->nsectors_buffered) {
- if (rq->current_nr_sectors == 0)
- cdrom_end_request(drive, 1);
-
- memcpy (rq->buffer,
- info->buffer +
- (rq->sector - info->sector_buffered) * SECTOR_SIZE,
- SECTOR_SIZE);
- rq->buffer += SECTOR_SIZE;
- --rq->current_nr_sectors;
- --rq->nr_sectors;
- ++rq->sector;
- }
-
- /* If we've satisfied the current request,
- terminate it successfully. */
- if (rq->nr_sectors == 0) {
- cdrom_end_request(drive, 1);
- return -1;
- }
-
- /* Move on to the next buffer if needed. */
- if (rq->current_nr_sectors == 0)
- cdrom_end_request(drive, 1);
-
- /* If this condition does not hold, then the kluge i use to
- represent the number of sectors to skip at the start of a transfer
- will fail. I think that this will never happen, but let's be
- paranoid and check. */
- if (rq->current_nr_sectors < bio_cur_sectors(rq->bio) &&
- (rq->sector & (sectors_per_frame - 1))) {
- printk(KERN_ERR "%s: cdrom_read_from_buffer: buffer botch (%ld)\n",
- drive->name, (long)rq->sector);
- cdrom_end_request(drive, 0);
- return -1;
- }
-
- return 0;
-}
-
static ide_startstop_t cdrom_newpc_intr(ide_drive_t *);
/*
@@ -1134,11 +1033,9 @@
if (!ptr) {
if (blk_fs_request(rq) && !write)
/*
- * If the buffers are full, cache the rest
- * of the data in our internal buffer.
- */
- cdrom_buffer_sectors(drive, rq->sector,
- thislen >> 9);
+ * If the buffers are full, pipe the rest into
+ * oblivion. */
+ ide_cd_drain_data(drive, thislen >> 9);
else {
printk(KERN_ERR "%s: confused, missing data\n",
drive->name);
@@ -1243,10 +1140,6 @@
* weirdness which might be present in the request packet.
*/
restore_request(rq);
-
- /* Satisfy whatever we can of this request from our cache. */
- if (cdrom_read_from_buffer(drive))
- return ide_stopped;
}
/*
@@ -1262,9 +1155,6 @@
} else
cd->dma = drive->using_dma;
- /* Clear the local sector buffer. */
- cd->nsectors_buffered = 0;
-
if (write)
cd->devinfo.media_written = 1;
@@ -2030,7 +1920,6 @@
ide_drive_t *drive = info->drive;
struct gendisk *g = info->disk;
- kfree(info->buffer);
kfree(info->toc);
if (devinfo->handle == drive)
unregister_cdrom(devinfo);
@@ -2090,11 +1979,7 @@
if (!(info = ide_cd_get(disk)))
return -ENXIO;
- if (!info->buffer)
- info->buffer = kmalloc(SECTOR_BUFFER_SIZE, GFP_KERNEL|__GFP_REPEAT);
-
- if (info->buffer)
- rc = cdrom_open(&info->devinfo, inode, file);
+ rc = cdrom_open(&info->devinfo, inode, file);
if (rc < 0)
ide_cd_put(info);