Since 2.6.37-rc barriers have been replaced with the REQ_FLUSH and
REQ_FUA flags. Both flags work on all devices without a need to check
for barrier functionality.
Use this fact to simplify the iblock code. Use the REQ_FUA flag when
we report a write cache or if the target set the FUA bit, and remove
all the barrier detection code.
Btw, I think iblock would benefit from sharing a common option with
the file backend for enabling or disabling the option to provide
a voltile write cache to the initiator or not.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Index: lio-core-2.6/drivers/target/target_core_iblock.c
===================================================================
--- lio-core-2.6.orig/drivers/target/target_core_iblock.c 2010-11-09 11:23:20.921529680 +0100
+++ lio-core-2.6/drivers/target/target_core_iblock.c 2010-11-09 12:16:20.918196346 +0100
@@ -130,8 +130,6 @@ static void *iblock_allocate_virtdevice(
return ib_dev;
}
-static int __iblock_do_sync_cache(struct se_device *);
-
static struct se_device *iblock_create_virtdevice(
struct se_hba *hba,
struct se_subsystem_dev *se_dev,
@@ -194,14 +192,7 @@ static struct se_device *iblock_create_v
goto failed;
ib_dev->ibd_depth = dev->queue_depth;
- /*
- * Check if the underlying struct block_device supports the
- * block/blk-barrier.c:blkdev_issue_flush() call, depending upon
- * which the SCSI mode page bits for WriteCache=1 and DPOFUA=1
- * will be enabled by TCM Core.
- */
- if (__iblock_do_sync_cache(dev) == 0)
- ib_dev->ibd_flags |= IBDF_BDEV_ISSUE_FLUSH;
+
/*
* Check if the underlying struct block_device request_queue supports
* the QUEUE_FLAG_DISCARD bit for UNMAP/WRITE_SAME in SCSI + TRIM
@@ -352,51 +343,37 @@ static unsigned long long iblock_emulate
return blocks_long;
}
-static int __iblock_do_sync_cache(struct se_device *dev)
-{
- struct iblock_dev *ib_dev = (struct iblock_dev *)dev->dev_ptr;
- sector_t error_sector;
- int ret;
-
- ret = blkdev_issue_flush(ib_dev->ibd_bd, GFP_KERNEL, &error_sector);
- if (ret != 0) {
- printk(KERN_ERR "IBLOCK: block_issue_flush() failed: %d "
- " error_sector: %llu\n", ret,
- (unsigned long long)error_sector);
- return -1;
- }
- DEBUG_IBLOCK("IBLOCK: Called block_issue_flush()\n");
- return 0;
-}
-
/*
- * Called by target_core_transport():transport_emulate_control_cdb()
- * to emulate SYCHRONIZE_CACHE_*
+ * Emulate SYCHRONIZE_CACHE_*
*/
-void iblock_emulate_sync_cache(struct se_task *task)
+static void iblock_emulate_sync_cache(struct se_task *task)
{
struct se_cmd *cmd = TASK_CMD(task);
- int ret, immed = (T_TASK(cmd)->t_task_cdb[1] & 0x2);
+ struct iblock_dev *ib_dev = cmd->se_dev->dev_ptr;
+ int immed = (T_TASK(cmd)->t_task_cdb[1] & 0x2);
+ sector_t error_sector;
+ int ret;
+
/*
* If the Immediate bit is set, queue up the GOOD response
* for this SYNCHRONIZE_CACHE op
*/
if (immed)
transport_complete_sync_cache(cmd, 1);
+
/*
- * block/blk-barrier.c:block_issue_flush() does not support a
- * LBA + Range synchronization method, so for this case we
- * have to flush the entire cache.
+ * blkdev_issue_flush() does not support a specifying a range, so
+ * we have to flush the entire cache.
*/
- ret = __iblock_do_sync_cache(cmd->se_dev);
- if (ret < 0) {
- if (!(immed))
- transport_complete_sync_cache(cmd, 0);
- return;
+ ret = blkdev_issue_flush(ib_dev->ibd_bd, GFP_KERNEL, &error_sector);
+ if (ret != 0) {
+ printk(KERN_ERR "IBLOCK: block_issue_flush() failed: %d "
+ " error_sector: %llu\n", ret,
+ (unsigned long long)error_sector);
}
- if (!(immed))
- transport_complete_sync_cache(cmd, 1);
+ if (!immed)
+ transport_complete_sync_cache(cmd, ret == 0);
}
/*
@@ -405,11 +382,7 @@ void iblock_emulate_sync_cache(struct se
*/
int iblock_emulated_write_cache(struct se_device *dev)
{
- struct iblock_dev *ib_dev = (struct iblock_dev *)dev->dev_ptr;
- /*
- * Only return WCE if ISSUE_FLUSH is supported
- */
- return (ib_dev->ibd_flags & IBDF_BDEV_ISSUE_FLUSH) ? 1 : 0;
+ return 1;
}
int iblock_emulated_dpo(struct se_device *dev)
@@ -423,11 +396,7 @@ int iblock_emulated_dpo(struct se_device
*/
int iblock_emulated_fua_write(struct se_device *dev)
{
- struct iblock_dev *ib_dev = (struct iblock_dev *)dev->dev_ptr;
- /*
- * Only return FUA WRITE if ISSUE_FLUSH is supported
- */
- return (ib_dev->ibd_flags & IBDF_BDEV_ISSUE_FLUSH) ? 1 : 0;
+ return 1;
}
int iblock_emulated_fua_read(struct se_device *dev)
@@ -442,8 +411,22 @@ static int iblock_do_task(struct se_task
struct iblock_dev *ibd = (struct iblock_dev *)req->ib_dev;
struct request_queue *q = bdev_get_queue(ibd->ibd_bd);
struct bio *bio = req->ib_bio, *nbio = NULL;
- int write = (TASK_CMD(task)->data_direction == DMA_TO_DEVICE);
- int ret;
+ int rw;
+
+ if (TASK_CMD(task)->data_direction == DMA_TO_DEVICE) {
+ /*
+ * Force data to disk if we pretend to not have a volatile
+ * write cache, or the initiator set the Force Unit Access bit.
+ */
+ if (DEV_ATTRIB(dev)->emulate_write_cache == 0 ||
+ (DEV_ATTRIB(dev)->emulate_fua_write > 0 &&
+ T_TASK(task->task_se_cmd)->t_tasks_fua))
+ rw = WRITE_FUA;
+ else
+ rw = WRITE;
+ } else {
+ rw = READ;
+ }
while (bio) {
nbio = bio->bi_next;
@@ -451,30 +434,12 @@ static int iblock_do_task(struct se_task
DEBUG_IBLOCK("Calling submit_bio() task: %p bio: %p"
" bio->bi_sector: %llu\n", task, bio, bio->bi_sector);
- submit_bio(write, bio);
+ submit_bio(rw, bio);
bio = nbio;
}
if (q->unplug_fn)
q->unplug_fn(q);
- /*
- * Check for Forced Unit Access WRITE emulation
- */
- if ((DEV_ATTRIB(dev)->emulate_write_cache > 0) &&
- (DEV_ATTRIB(dev)->emulate_fua_write > 0) &&
- write && T_TASK(task->task_se_cmd)->t_tasks_fua) {
- /*
- * We might need to be a bit smarter here
- * and return some sense data to let the initiator
- * know the FUA WRITE cache sync failed..?
- */
- ret = __iblock_do_sync_cache(dev);
- if (ret < 0) {
- printk(KERN_ERR "__iblock_do_sync_cache()"
- " failed for FUA Write\n");
- }
- }
-
return PYX_TRANSPORT_SENT_TO_TRANSPORT;
}
Index: lio-core-2.6/drivers/target/target_core_iblock.h
===================================================================
--- lio-core-2.6.orig/drivers/target/target_core_iblock.h 2010-11-09 11:23:25.454863013 +0100
+++ lio-core-2.6/drivers/target/target_core_iblock.h 2010-11-09 11:23:35.334863016 +0100
@@ -23,7 +23,6 @@ struct iblock_req {
#define IBDF_HAS_UDEV_PATH 0x01
#define IBDF_HAS_FORCE 0x02
-#define IBDF_BDEV_ISSUE_FLUSH 0x04
struct iblock_dev {
unsigned char ibd_udev_path[SE_UDEV_PATH_LEN];
--
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