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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>
This commit is contained in:
Nicholas Bellinger 2013-02-19 17:30:34 -08:00
parent 6e5459353d
commit 7b745c84a9
1 changed files with 114 additions and 0 deletions
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114
drivers/target/target_core_file.c
View File

@ -190,6 +190,11 @@ static int fd_configure_device(struct se_device *dev)
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 @@ 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 = 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 sector_t fd_get_blocks(struct se_device *dev)
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