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authorNicholas Bellinger <nab@linux-iscsi.org>2013-01-29 22:10:06 -0800
committerNicholas Bellinger <nab@linux-iscsi.org>2013-02-13 11:27:51 -0800
commitd0c8b259f8970d39354c1966853363345d401330 (patch)
treee6739094ba5db9ca88038f0e047e83e82bf21088 /drivers/target/target_core_iblock.c
parent1be2956d30b2b6200ebb26ffb758ed3c8071303c (diff)
target/iblock: Use backend REQ_FLUSH hint for WriteCacheEnabled status
This patch allows IBLOCK to check block hints in request_queue->flush_flags when reporting current backend device WriteCacheEnabled status to a remote SCSI initiator port. This is done via a se_subsystem_api->get_write_cache() call instead of a backend se_device creation time flag, as we expect REQ_FLUSH bits to possibly change from an underlying blk_queue_flush() by the SCSI disk driver, or internal raw struct block_device driver usage. Also go ahead and update iblock_execute_rw() bio I/O path code to use REQ_FLUSH + REQ_FUA hints when determining WRITE_FUA usage, and make SPC emulation code use a spc_check_dev_wce() helper to handle both types of cases for virtual backend subsystem drivers. (asias: Drop unnecessary comparsion operators) Reported-by: majianpeng <majianpeng@gmail.com> Cc: majianpeng <majianpeng@gmail.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: James Bottomley <JBottomley@Parallels.com> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Diffstat (limited to 'drivers/target/target_core_iblock.c')
-rw-r--r--drivers/target/target_core_iblock.c31
1 files changed, 23 insertions, 8 deletions
diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c
index b526d23dcd4f..2f74e17ad3e6 100644
--- a/drivers/target/target_core_iblock.c
+++ b/drivers/target/target_core_iblock.c
@@ -154,6 +154,7 @@ static int iblock_configure_device(struct se_device *dev)
if (blk_queue_nonrot(q))
dev->dev_attrib.is_nonrot = 1;
+
return 0;
out_free_bioset:
@@ -654,20 +655,24 @@ iblock_execute_rw(struct se_cmd *cmd)
u32 sg_num = sgl_nents;
sector_t block_lba;
unsigned bio_cnt;
- int rw;
+ int rw = 0;
int i;
if (data_direction == DMA_TO_DEVICE) {
+ struct iblock_dev *ib_dev = IBLOCK_DEV(dev);
+ struct request_queue *q = bdev_get_queue(ib_dev->ibd_bd);
/*
- * Force data to disk if we pretend to not have a volatile
- * write cache, or the initiator set the Force Unit Access bit.
+ * Force writethrough using WRITE_FUA if a volatile write cache
+ * is not enabled, or if initiator set the Force Unit Access bit.
*/
- if (dev->dev_attrib.emulate_write_cache == 0 ||
- (dev->dev_attrib.emulate_fua_write > 0 &&
- (cmd->se_cmd_flags & SCF_FUA)))
- rw = WRITE_FUA;
- else
+ if (q->flush_flags & REQ_FUA) {
+ if (cmd->se_cmd_flags & SCF_FUA)
+ rw = WRITE_FUA;
+ else if (!(q->flush_flags & REQ_FLUSH))
+ rw = WRITE_FUA;
+ } else {
rw = WRITE;
+ }
} else {
rw = READ;
}
@@ -774,6 +779,15 @@ iblock_parse_cdb(struct se_cmd *cmd)
return sbc_parse_cdb(cmd, &iblock_sbc_ops);
}
+bool iblock_get_write_cache(struct se_device *dev)
+{
+ struct iblock_dev *ib_dev = IBLOCK_DEV(dev);
+ struct block_device *bd = ib_dev->ibd_bd;
+ struct request_queue *q = bdev_get_queue(bd);
+
+ return q->flush_flags & REQ_FLUSH;
+}
+
static struct se_subsystem_api iblock_template = {
.name = "iblock",
.inquiry_prod = "IBLOCK",
@@ -790,6 +804,7 @@ static struct se_subsystem_api iblock_template = {
.show_configfs_dev_params = iblock_show_configfs_dev_params,
.get_device_type = sbc_get_device_type,
.get_blocks = iblock_get_blocks,
+ .get_write_cache = iblock_get_write_cache,
};
static int __init iblock_module_init(void)