target/file: Add WRITE_SAME w/ UNMAP=0 emulation support
This patch adds support for emulation of WRITE_SAME w/ UNMAP=0 within
fd_execute_write_same() backend code.
The emulation uses vfs_writev() to submit a locally populated buffer
from the received WRITE_SAME scatterlist block for duplication, and by
default enforces a limit of max_write_same_len=0x1000 (8192) sectors up
to the limit of 1024 iovec entries for the single call to vfs_writev().
It also sets max_write_same_len to the operational default at setup ->
fd_configure_device() time.
Tested with 512, 1k, 2k, and 4k block_sizes.
(asias: convert to vzalloc)
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Asias He <asias@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
diff --git a/drivers/target/target_core_file.c b/drivers/target/target_core_file.c
index b9c8849..94383a5 100644
--- a/drivers/target/target_core_file.c
+++ b/drivers/target/target_core_file.c
@@ -190,6 +190,11 @@
fd_dev->fd_dev_id = fd_host->fd_host_dev_id_count++;
fd_dev->fd_queue_depth = dev->queue_depth;
+ /*
+ * Limit WRITE_SAME w/ UNMAP=0 emulation to 8k Number of LBAs (NoLB)
+ * based upon struct iovec limit for vfs_writev()
+ */
+ dev->dev_attrib.max_write_same_len = 0x1000;
pr_debug("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,
@@ -328,6 +333,114 @@
return 0;
}
+static unsigned char *
+fd_setup_write_same_buf(struct se_cmd *cmd, struct scatterlist *sg,
+ unsigned int len)
+{
+ struct se_device *se_dev = cmd->se_dev;
+ unsigned int block_size = se_dev->dev_attrib.block_size;
+ unsigned int i = 0, end;
+ unsigned char *buf, *p, *kmap_buf;
+
+ buf = kzalloc(min_t(unsigned int, len, PAGE_SIZE), GFP_KERNEL);
+ if (!buf) {
+ pr_err("Unable to allocate fd_execute_write_same buf\n");
+ return NULL;
+ }
+
+ kmap_buf = kmap(sg_page(sg)) + sg->offset;
+ if (!kmap_buf) {
+ pr_err("kmap() failed in fd_setup_write_same\n");
+ kfree(buf);
+ return NULL;
+ }
+ /*
+ * Fill local *buf to contain multiple WRITE_SAME blocks up to
+ * min(len, PAGE_SIZE)
+ */
+ p = buf;
+ end = min_t(unsigned int, len, PAGE_SIZE);
+
+ while (i < end) {
+ memcpy(p, kmap_buf, block_size);
+
+ i += block_size;
+ p += block_size;
+ }
+ kunmap(sg_page(sg));
+
+ return buf;
+}
+
+static sense_reason_t
+fd_execute_write_same(struct se_cmd *cmd)
+{
+ struct se_device *se_dev = cmd->se_dev;
+ struct fd_dev *fd_dev = FD_DEV(se_dev);
+ struct file *f = fd_dev->fd_file;
+ struct scatterlist *sg;
+ struct iovec *iov;
+ mm_segment_t old_fs;
+ sector_t nolb = spc_get_write_same_sectors(cmd);
+ loff_t pos = cmd->t_task_lba * se_dev->dev_attrib.block_size;
+ unsigned int len, len_tmp, iov_num;
+ int i, rc;
+ unsigned char *buf;
+
+ if (!nolb) {
+ target_complete_cmd(cmd, SAM_STAT_GOOD);
+ return 0;
+ }
+ sg = &cmd->t_data_sg[0];
+
+ if (cmd->t_data_nents > 1 ||
+ sg->length != cmd->se_dev->dev_attrib.block_size) {
+ pr_err("WRITE_SAME: Illegal SGL t_data_nents: %u length: %u"
+ " block_size: %u\n", cmd->t_data_nents, sg->length,
+ cmd->se_dev->dev_attrib.block_size);
+ return TCM_INVALID_CDB_FIELD;
+ }
+
+ len = len_tmp = nolb * se_dev->dev_attrib.block_size;
+ iov_num = DIV_ROUND_UP(len, PAGE_SIZE);
+
+ buf = fd_setup_write_same_buf(cmd, sg, len);
+ if (!buf)
+ return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+
+ iov = vzalloc(sizeof(struct iovec) * iov_num);
+ if (!iov) {
+ pr_err("Unable to allocate fd_execute_write_same iovecs\n");
+ kfree(buf);
+ return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+ }
+ /*
+ * Map the single fabric received scatterlist block now populated
+ * in *buf into each iovec for I/O submission.
+ */
+ for (i = 0; i < iov_num; i++) {
+ iov[i].iov_base = buf;
+ iov[i].iov_len = min_t(unsigned int, len_tmp, PAGE_SIZE);
+ len_tmp -= iov[i].iov_len;
+ }
+
+ old_fs = get_fs();
+ set_fs(get_ds());
+ rc = vfs_writev(f, &iov[0], iov_num, &pos);
+ set_fs(old_fs);
+
+ vfree(iov);
+ kfree(buf);
+
+ if (rc < 0 || rc != len) {
+ pr_err("vfs_writev() returned %d for write same\n", rc);
+ return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+ }
+
+ target_complete_cmd(cmd, SAM_STAT_GOOD);
+ return 0;
+}
+
static sense_reason_t
fd_execute_rw(struct se_cmd *cmd)
{
@@ -486,6 +599,7 @@
static struct sbc_ops fd_sbc_ops = {
.execute_rw = fd_execute_rw,
.execute_sync_cache = fd_execute_sync_cache,
+ .execute_write_same = fd_execute_write_same,
};
static sense_reason_t