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| author | Nicholas Bellinger <nab@linux-iscsi.org> | 2013-01-29 22:10:06 -0800 |
|---|---|---|
| committer | Nicholas Bellinger <nab@linux-iscsi.org> | 2013-02-13 11:27:51 -0800 |
| commit | d0c8b259f8970d39354c1966853363345d401330 (patch) | |
| tree | e6739094ba5db9ca88038f0e047e83e82bf21088 /drivers/target/target_core_iblock.c | |
| parent | 1be2956d30b2b6200ebb26ffb758ed3c8071303c (diff) | |
| download | lwn-d0c8b259f8970d39354c1966853363345d401330.tar.gz lwn-d0c8b259f8970d39354c1966853363345d401330.zip | |
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.c | 31 |
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) |