From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
This patch adds UNMAP emulation support using Block layer DISCARD in fd_emulate_scsi_cdb()
-> transport_generic_unmap(). This includes the use of blk_queue_discard() in
fd_create_virtdevice() to determine when to set DEV_ATTRIB(dev)->emulate_tpe=1 to
signal to TCM Core to perform the necessary control CDB emulation for TPE=1 / UNMAP.
Note this patch igrab() + iput() when accessing struct block_device via
I_BDEV(file->f_mapping->host) that is required for transport_generic_unmap()
within fd_emulate_scsi_cdb().
Also note that when (S_ISBLK(inode->i_mode) is NULL, the TPE=1 and UNMAP emulation
are disabled for non BD struct file I/O.
Signed-off-by: Nicholas A. Bellinger <nab@xxxxxxxxxxxxxxx>
---
drivers/target/target_core_file.c | 53 ++++++++++++++++++++++++++++++++++++-
1 files changed, 52 insertions(+), 1 deletions(-)
diff --git a/drivers/target/target_core_file.c b/drivers/target/target_core_file.c
index 93d3f63..3b91556 100644
--- a/drivers/target/target_core_file.c
+++ b/drivers/target/target_core_file.c
@@ -235,6 +235,17 @@ static struct se_device *fd_create_virtdevice(
fd_dev->fd_dev_id = fd_host->fd_host_dev_id_count++;
fd_dev->fd_queue_depth = dev->queue_depth;
+ /*
+ * Check for QUEUE_FLAG_DISCARD and enable TCM TPE emulation
+ * if present for struct block_device backend
+ */
+ if (S_ISBLK(inode->i_mode)) {
+ if (blk_queue_discard(bdev_get_queue(inode->i_bdev))) {
+ DEV_ATTRIB(dev)->emulate_tpe = 1;
+ printk(KERN_INFO "FILEIO: Enabling BLOCK Discard"
+ " and TPE=1 emulation\n");
+ }
+ }
printk(KERN_INFO "CORE_FILE[%u] - Added TCM FILEIO Device ID: %u at %s,"
" %llu total bytes\n", fd_host->fd_host_id, fd_dev->fd_dev_id,
@@ -388,9 +399,13 @@ static int fd_emulate_read_cap16(struct se_task *task)
*/
static int fd_emulate_scsi_cdb(struct se_task *task)
{
- int ret;
struct se_cmd *cmd = TASK_CMD(task);
+ struct fd_dev *fd_dev = (struct fd_dev *) task->se_dev->dev_ptr;
struct fd_request *fd_req = (struct fd_request *) task->transport_req;
+ struct file *f = fd_dev->fd_file;
+ struct inode *i;
+ struct block_device *bd;
+ int ret;
switch (fd_req->fd_scsi_cdb[0]) {
case INQUIRY:
@@ -433,6 +448,42 @@ static int fd_emulate_scsi_cdb(struct se_task *task)
if (ret < 0)
return ret;
break;
+ case UNMAP:
+ i = igrab(f->f_mapping->host);
+ if (!(i)) {
+ printk(KERN_ERR "FILEIO: Unable to locate inode for"
+ " backend for UNMAP\n");
+ return PYX_TRANSPORT_LU_COMM_FAILURE;
+ }
+ /*
+ * Currently for struct file w/o a struct block_device
+ * backend we return a success..
+ */
+ if (!(S_ISBLK(i->i_mode))) {
+ printk(KERN_WARNING "Ignoring UNMAP for non BD"
+ " backend for struct file\n");
+ iput(i);
+ return PYX_TRANSPORT_LU_COMM_FAILURE;
+ }
+ bd = I_BDEV(f->f_mapping->host);
+ if (!(bd)) {
+ printk(KERN_ERR "FILEIO: Unable to locate struct"
+ " block_device for UNMAP\n");
+ iput(i);
+ return PYX_TRANSPORT_LU_COMM_FAILURE;
+ }
+ /*
+ * Now call the transport_generic_unmap() -> blkdev_issue_discard()
+ * wrapper to translate SCSI UNMAP into Linux/BLOCK discards on
+ * LBA+Range descriptors in the UNMAP write paylaod.
+ */
+ ret = transport_generic_unmap(cmd, bd);
+ if (ret < 0) {
+ iput(i);
+ return ret;
+ }
+ iput(i);
+ break;
case ALLOW_MEDIUM_REMOVAL:
case ERASE:
case REZERO_UNIT:
--
1.5.6.5
--
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