Re: Force IDE cache flush on shutdown

[Arjan van de Ven <arjanv@redhat.com>]

On Thu, May 06, 2004 at 09:58:10AM +0200, Jens Axboe wrote:> On Thu, May 06 2004, Arjan van de Ven wrote:
> > Hi,
> > 
> > Alan discovered the hard way that the current 2.6 IDE code doesn't do a
> > cache-flush on shutdown. The patch below forward ports this from 2.4. In
> > addition it fixes a bug where the ->wcache value only got determined for
> > removable disks not all disks. (that fix is from Alan, all other bugs are
> > mine ;)
> 
> Yeah that's a dumb bug, I fixed that in the barrier patches as well (but
> forgot to send it in).
> 
> Maybe you could send that in seperately first, it needs to go in
> regardless.


ok below are the uncontended bits
1) calculate wcache for non-removable disks too
2) flush the cache BEFORE unlocking the door on removable media,
   otherwise you have a small race with the human..

it makes sense for these to go in separate; I'm working on the shutdown hook
now (and testing which is the fun part ;)

diff -urNp linux-1110/drivers/ide/ide-disk.c linux-1120/drivers/ide/ide-disk.c
--- linux-1110/drivers/ide/ide-disk.c
+++ linux-1120/drivers/ide/ide-disk.c
@@ -1729,11 +1733,11 @@ static ide_driver_t idedisk_driver = {
 
 static int idedisk_open(struct inode *inode, struct file *filp)
 {
+	u8 cf;
 	ide_drive_t *drive = inode->i_bdev->bd_disk->private_data;
 	drive->usage++;
 	if (drive->removable && drive->usage == 1) {
 		ide_task_t args;
-		u8 cf;
 		memset(&args, 0, sizeof(ide_task_t));
 		args.tfRegister[IDE_COMMAND_OFFSET] = WIN_DOORLOCK;
 		args.command_type = IDE_DRIVE_TASK_NO_DATA;
@@ -1746,18 +1750,18 @@ static int idedisk_open(struct inode *in
 		 */
 		if (drive->doorlocking && ide_raw_taskfile(drive, &args, NULL))
 			drive->doorlocking = 0;
-		drive->wcache = 0;
-		/* Cache enabled ? */
-		if (drive->id->csfo & 1)
-		drive->wcache = 1;
-		/* Cache command set available ? */
-		if (drive->id->cfs_enable_1 & (1<<5))
-			drive->wcache = 1;
-		/* ATA6 cache extended commands */
-		cf = drive->id->command_set_2 >> 24;
-		if((cf & 0xC0) == 0x40 && (cf & 0x30) != 0)
-			drive->wcache = 1;
 	}
+	drive->wcache = 0;
+	/* Cache enabled ? */
+	if (drive->id->csfo & 1)
+		drive->wcache = 1;
+	/* Cache command set available ? */
+	if (drive->id->cfs_enable_1 & (1<<5))
+		drive->wcache = 1;
+	/* ATA6 cache extended commands */
+	cf = drive->id->command_set_2 >> 24;
+	if((cf & 0xC0) == 0x40 && (cf & 0x30) != 0)
+		drive->wcache = 1;
 	return 0;
 }
 
@@ -1779,6 +1783,7 @@ static int ide_cacheflush_p(ide_drive_t 
 static int idedisk_release(struct inode *inode, struct file *filp)
 {
 	ide_drive_t *drive = inode->i_bdev->bd_disk->private_data;
+	ide_cacheflush_p(drive);
 	if (drive->removable && drive->usage == 1) {
 		ide_task_t args;
 		memset(&args, 0, sizeof(ide_task_t));
@@ -1788,7 +1793,6 @@ static int idedisk_release(struct inode 
 		if (drive->doorlocking && ide_raw_taskfile(drive, &args, NULL))
 			drive->doorlocking = 0;
 	}
-	ide_cacheflush_p(drive);
 	drive->usage--;
 	return 0;
 }