target: rewrite fd_execute_write_same

With the new bio_vec backed iov_iter helpers we can simply set up
on bio_vec per LBA, all pointing to the same initiator-supplied
buffer.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 22 insertions, 78 deletions

diff --git a/drivers/target/target_core_file.c b/drivers/target/target_core_file.c
index ea6e14e3ac5a..8800d54f743b 100644
--- a/drivers/target/target_core_file.c
+++ b/drivers/target/target_core_file.c
@@ -433,59 +433,17 @@ fd_execute_sync_cache(struct se_cmd *cmd)
         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 = sbc_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;
+        sector_t nolb = sbc_get_write_same_sectors(cmd);
+        struct iov_iter iter;
+        struct bio_vec *bvec;
+        unsigned int len = 0, i;
+        ssize_t ret;
 
         if (!nolb) {
                 target_complete_cmd(cmd, SAM_STAT_GOOD);
@@ -496,49 +454,35 @@ fd_execute_write_same(struct se_cmd *cmd)
                        " backends not supported\n");
                 return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
         }
-        sg = &cmd->t_data_sg[0];
 
         if (cmd->t_data_nents > 1 ||
-            sg->length != cmd->se_dev->dev_attrib.block_size) {
+            cmd->t_data_sg[0].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,
+                        " block_size: %u\n",
+                        cmd->t_data_nents,
+                        cmd->t_data_sg[0].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)
+        bvec = kcalloc(nolb, sizeof(struct bio_vec), GFP_KERNEL);
+        if (!bvec)
                 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;
-        }
+        for (i = 0; i < nolb; i++) {
+                bvec[i].bv_page = sg_page(&cmd->t_data_sg[0]);
+                bvec[i].bv_len = cmd->t_data_sg[0].length;
+                bvec[i].bv_offset = cmd->t_data_sg[0].offset;
 
-        old_fs = get_fs();
-        set_fs(get_ds());
-        rc = vfs_writev(f, &iov[0], iov_num, &pos);
-        set_fs(old_fs);
+                len += se_dev->dev_attrib.block_size;
+        }
 
-        vfree(iov);
-        kfree(buf);
+        iov_iter_bvec(&iter, ITER_BVEC, bvec, nolb, len);
+        ret = vfs_iter_write(fd_dev->fd_file, &iter, &pos);
 
-        if (rc < 0 || rc != len) {
-                pr_err("vfs_writev() returned %d for write same\n", rc);
+        kfree(bvec);
+        if (ret < 0 || ret != len) {
+                pr_err("vfs_iter_write() returned %zd for write same\n", ret);
                 return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
         }