target/user: Introduce data_bitmap, replace data_length/data_head/data_tail
The data_bitmap was introduced to support asynchornization accessing of
data area.
We divide mailbox data area into blocks, and use data_bitmap to track the
usage of data area. All the new command's data would start with a new block,
and may left unusable space after it end. But it's easy to track using
data_bitmap.
Now we can allocate data area for asynchronization accessing from userspace,
since we can track the allocation using data_bitmap. The userspace part would
be the same as Maxim's previous asynchronized implementation.
Signed-off-by: Sheng Yang <sheng@yasker.org>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
index baa8720..b1539f3 100644
--- a/drivers/target/target_core_user.c
+++ b/drivers/target/target_core_user.c
@@ -26,6 +26,7 @@
#include <linux/vmalloc.h>
#include <linux/uio_driver.h>
#include <linux/stringify.h>
+#include <linux/bitops.h>
#include <net/genetlink.h>
#include <scsi/scsi_common.h>
#include <scsi/scsi_proto.h>
@@ -63,8 +64,11 @@
#define TCMU_TIME_OUT (30 * MSEC_PER_SEC)
+#define DATA_BLOCK_BITS 256
+#define DATA_BLOCK_SIZE 4096
+
#define CMDR_SIZE (16 * 4096)
-#define DATA_SIZE (257 * 4096)
+#define DATA_SIZE (DATA_BLOCK_BITS * DATA_BLOCK_SIZE)
#define TCMU_RING_SIZE (CMDR_SIZE + DATA_SIZE)
@@ -93,12 +97,11 @@
u32 cmdr_size;
u32 cmdr_last_cleaned;
/* Offset of data ring from start of mb */
+ /* Must add data_off and mb_addr to get the address */
size_t data_off;
size_t data_size;
- /* Ring head + tail values. */
- /* Must add data_off and mb_addr to get the address */
- size_t data_head;
- size_t data_tail;
+
+ DECLARE_BITMAP(data_bitmap, DATA_BLOCK_BITS);
wait_queue_head_t wait_cmdr;
/* TODO should this be a mutex? */
@@ -122,9 +125,9 @@
uint16_t cmd_id;
- /* Can't use se_cmd->data_length when cleaning up expired cmds, because if
+ /* Can't use se_cmd when cleaning up expired cmds, because if
cmd has been completed then accessing se_cmd is off limits */
- size_t data_length;
+ DECLARE_BITMAP(data_bitmap, DATA_BLOCK_BITS);
unsigned long deadline;
@@ -168,13 +171,6 @@
tcmu_cmd->se_cmd = se_cmd;
tcmu_cmd->tcmu_dev = udev;
- tcmu_cmd->data_length = se_cmd->data_length;
-
- if (se_cmd->se_cmd_flags & SCF_BIDI) {
- BUG_ON(!(se_cmd->t_bidi_data_sg && se_cmd->t_bidi_data_nents));
- tcmu_cmd->data_length += se_cmd->t_bidi_data_sg->length;
- }
-
tcmu_cmd->deadline = jiffies + msecs_to_jiffies(TCMU_TIME_OUT);
idr_preload(GFP_KERNEL);
@@ -242,111 +238,115 @@
iovec = *iov;
memset(iovec, 0, sizeof(struct iovec));
-
- /* Even iov_base is relative to mb_addr */
- iovec->iov_base = (void __user *) udev->data_off +
- udev->data_head;
}
#define UPDATE_HEAD(head, used, size) smp_store_release(&head, ((head % size) + used) % size)
+/* offset is relative to mb_addr */
+static inline size_t get_block_offset(struct tcmu_dev *dev,
+ int block, int remaining)
+{
+ return dev->data_off + block * DATA_BLOCK_SIZE +
+ DATA_BLOCK_SIZE - remaining;
+}
+
+static inline size_t iov_tail(struct tcmu_dev *udev, struct iovec *iov)
+{
+ return (size_t)iov->iov_base + iov->iov_len;
+}
+
static void alloc_and_scatter_data_area(struct tcmu_dev *udev,
struct scatterlist *data_sg, unsigned int data_nents,
struct iovec **iov, int *iov_cnt, bool copy_data)
{
- int i;
+ int i, block;
+ int block_remaining = 0;
void *from, *to;
- size_t copy_bytes;
+ size_t copy_bytes, to_offset;
struct scatterlist *sg;
- if (data_nents == 0)
- return;
-
- new_iov(iov, iov_cnt, udev);
for_each_sg(data_sg, sg, data_nents, i) {
- copy_bytes = min_t(size_t, sg->length,
- head_to_end(udev->data_head, udev->data_size));
+ int sg_remaining = sg->length;
from = kmap_atomic(sg_page(sg)) + sg->offset;
- to = (void *) udev->mb_addr + udev->data_off + udev->data_head;
-
- if (copy_data) {
- memcpy(to, from, copy_bytes);
- tcmu_flush_dcache_range(to, copy_bytes);
- }
-
- (*iov)->iov_len += copy_bytes;
-
- UPDATE_HEAD(udev->data_head, copy_bytes, udev->data_size);
-
- /* Uh oh, we wrapped the buffer. Must split sg across 2 iovs. */
- if (sg->length != copy_bytes) {
- void *from_skip = from + copy_bytes;
-
- copy_bytes = sg->length - copy_bytes;
-
- new_iov(iov, iov_cnt, udev);
- (*iov)->iov_len = copy_bytes;
-
+ while (sg_remaining > 0) {
+ if (block_remaining == 0) {
+ block = find_first_zero_bit(udev->data_bitmap,
+ DATA_BLOCK_BITS);
+ block_remaining = DATA_BLOCK_SIZE;
+ set_bit(block, udev->data_bitmap);
+ }
+ copy_bytes = min_t(size_t, sg_remaining,
+ block_remaining);
+ to_offset = get_block_offset(udev, block,
+ block_remaining);
+ to = (void *)udev->mb_addr + to_offset;
+ if (*iov_cnt != 0 &&
+ to_offset == iov_tail(udev, *iov)) {
+ (*iov)->iov_len += copy_bytes;
+ } else {
+ new_iov(iov, iov_cnt, udev);
+ (*iov)->iov_base = (void __user *) to_offset;
+ (*iov)->iov_len = copy_bytes;
+ }
if (copy_data) {
- to = (void *) udev->mb_addr +
- udev->data_off + udev->data_head;
- memcpy(to, from_skip, copy_bytes);
+ memcpy(to, from + sg->length - sg_remaining,
+ copy_bytes);
tcmu_flush_dcache_range(to, copy_bytes);
}
-
-
- UPDATE_HEAD(udev->data_head,
- copy_bytes, udev->data_size);
+ sg_remaining -= copy_bytes;
+ block_remaining -= copy_bytes;
}
-
kunmap_atomic(from - sg->offset);
}
}
-static void free_data_area(struct tcmu_dev *udev, size_t length)
+static void free_data_area(struct tcmu_dev *udev, struct tcmu_cmd *cmd)
{
- UPDATE_HEAD(udev->data_tail, length, udev->data_size);
+ bitmap_xor(udev->data_bitmap, udev->data_bitmap, cmd->data_bitmap,
+ DATA_BLOCK_BITS);
}
-static void gather_and_free_data_area(struct tcmu_dev *udev,
- struct scatterlist *data_sg, unsigned int data_nents)
+static void gather_data_area(struct tcmu_dev *udev, unsigned long *cmd_bitmap,
+ struct scatterlist *data_sg, unsigned int data_nents)
{
- int i;
+ int i, block;
+ int block_remaining = 0;
void *from, *to;
- size_t copy_bytes;
+ size_t copy_bytes, from_offset;
struct scatterlist *sg;
- /* It'd be easier to look at entry's iovec again, but UAM */
for_each_sg(data_sg, sg, data_nents, i) {
- copy_bytes = min_t(size_t, sg->length,
- head_to_end(udev->data_tail, udev->data_size));
-
+ int sg_remaining = sg->length;
to = kmap_atomic(sg_page(sg)) + sg->offset;
- WARN_ON(sg->length + sg->offset > PAGE_SIZE);
- from = (void *) udev->mb_addr +
- udev->data_off + udev->data_tail;
- tcmu_flush_dcache_range(from, copy_bytes);
- memcpy(to, from, copy_bytes);
-
- free_data_area(udev, copy_bytes);
-
- /* Uh oh, wrapped the data buffer for this sg's data */
- if (sg->length != copy_bytes) {
- void *to_skip = to + copy_bytes;
-
- from = (void *) udev->mb_addr +
- udev->data_off + udev->data_tail;
- WARN_ON(udev->data_tail);
- copy_bytes = sg->length - copy_bytes;
+ while (sg_remaining > 0) {
+ if (block_remaining == 0) {
+ block = find_first_bit(cmd_bitmap,
+ DATA_BLOCK_BITS);
+ block_remaining = DATA_BLOCK_SIZE;
+ clear_bit(block, cmd_bitmap);
+ }
+ copy_bytes = min_t(size_t, sg_remaining,
+ block_remaining);
+ from_offset = get_block_offset(udev, block,
+ block_remaining);
+ from = (void *) udev->mb_addr + from_offset;
tcmu_flush_dcache_range(from, copy_bytes);
- memcpy(to_skip, from, copy_bytes);
+ memcpy(to + sg->length - sg_remaining, from,
+ copy_bytes);
- free_data_area(udev, copy_bytes);
+ sg_remaining -= copy_bytes;
+ block_remaining -= copy_bytes;
}
kunmap_atomic(to - sg->offset);
}
}
+static inline size_t spc_bitmap_free(unsigned long *bitmap)
+{
+ return DATA_BLOCK_SIZE * (DATA_BLOCK_BITS -
+ bitmap_weight(bitmap, DATA_BLOCK_BITS));
+}
+
/*
* We can't queue a command until we have space available on the cmd ring *and*
* space available on the data ring.
@@ -380,10 +380,10 @@
return false;
}
- space = spc_free(udev->data_head, udev->data_tail, udev->data_size);
+ space = spc_bitmap_free(udev->data_bitmap);
if (space < data_needed) {
- pr_debug("no data space: %zu %zu %zu\n", udev->data_head,
- udev->data_tail, udev->data_size);
+ pr_debug("no data space: only %lu available, but ask for %lu\n",
+ space, data_needed);
return false;
}
@@ -402,6 +402,8 @@
uint32_t cmd_head;
uint64_t cdb_off;
bool copy_to_data_area;
+ size_t data_length;
+ DECLARE_BITMAP(old_bitmap, DATA_BLOCK_BITS);
if (test_bit(TCMU_DEV_BIT_BROKEN, &udev->flags))
return -EINVAL;
@@ -410,10 +412,12 @@
* Must be a certain minimum size for response sense info, but
* also may be larger if the iov array is large.
*
- * 3 iovs since we can describe the whole continuous are using one
- * for data, one for bidi and one more in the case of wrap.
+ * We prepare way too many iovs for potential uses here, because it's
+ * expensive to tell how many regions are freed in the bitmap
*/
- base_command_size = max(offsetof(struct tcmu_cmd_entry, req.iov[3]),
+ base_command_size = max(offsetof(struct tcmu_cmd_entry,
+ req.iov[se_cmd->t_bidi_data_nents +
+ se_cmd->t_data_nents]),
sizeof(struct tcmu_cmd_entry));
command_size = base_command_size
+ round_up(scsi_command_size(se_cmd->t_task_cdb), TCMU_OP_ALIGN_SIZE);
@@ -424,13 +428,18 @@
mb = udev->mb_addr;
cmd_head = mb->cmd_head % udev->cmdr_size; /* UAM */
+ data_length = se_cmd->data_length;
+ if (se_cmd->se_cmd_flags & SCF_BIDI) {
+ BUG_ON(!(se_cmd->t_bidi_data_sg && se_cmd->t_bidi_data_nents));
+ data_length += se_cmd->t_bidi_data_sg->length;
+ }
if ((command_size > (udev->cmdr_size / 2))
- || tcmu_cmd->data_length > (udev->data_size - 1))
+ || data_length > udev->data_size)
pr_warn("TCMU: Request of size %zu/%zu may be too big for %u/%zu "
- "cmd/data ring buffers\n", command_size, tcmu_cmd->data_length,
+ "cmd/data ring buffers\n", command_size, data_length,
udev->cmdr_size, udev->data_size);
- while (!is_ring_space_avail(udev, command_size, tcmu_cmd->data_length)) {
+ while (!is_ring_space_avail(udev, command_size, data_length)) {
int ret;
DEFINE_WAIT(__wait);
@@ -477,6 +486,8 @@
entry->hdr.kflags = 0;
entry->hdr.uflags = 0;
+ bitmap_copy(old_bitmap, udev->data_bitmap, DATA_BLOCK_BITS);
+
/*
* Fix up iovecs, and handle if allocation in data ring wrapped.
*/
@@ -495,6 +506,10 @@
se_cmd->t_bidi_data_nents, &iov, &iov_cnt, false);
entry->req.iov_bidi_cnt = iov_cnt;
+ /* cmd's data_bitmap is what changed in process */
+ bitmap_xor(tcmu_cmd->data_bitmap, old_bitmap, udev->data_bitmap,
+ DATA_BLOCK_BITS);
+
/* All offsets relative to mb_addr, not start of entry! */
cdb_off = CMDR_OFF + cmd_head + base_command_size;
memcpy((void *) mb + cdb_off, se_cmd->t_task_cdb, scsi_command_size(se_cmd->t_task_cdb));
@@ -547,31 +562,36 @@
if (test_bit(TCMU_CMD_BIT_EXPIRED, &cmd->flags)) {
/* cmd has been completed already from timeout, just reclaim data
ring space */
- free_data_area(udev, cmd->data_length);
+ free_data_area(udev, cmd);
return;
}
if (entry->hdr.uflags & TCMU_UFLAG_UNKNOWN_OP) {
- free_data_area(udev, cmd->data_length);
+ free_data_area(udev, cmd);
pr_warn("TCMU: Userspace set UNKNOWN_OP flag on se_cmd %p\n",
cmd->se_cmd);
entry->rsp.scsi_status = SAM_STAT_CHECK_CONDITION;
} else if (entry->rsp.scsi_status == SAM_STAT_CHECK_CONDITION) {
memcpy(se_cmd->sense_buffer, entry->rsp.sense_buffer,
se_cmd->scsi_sense_length);
- free_data_area(udev, cmd->data_length);
+ free_data_area(udev, cmd);
} else if (se_cmd->se_cmd_flags & SCF_BIDI) {
- /* Discard data_out buffer */
- free_data_area(udev, (size_t)se_cmd->t_data_sg->length);
+ DECLARE_BITMAP(bitmap, DATA_BLOCK_BITS);
- /* Get Data-In buffer */
- gather_and_free_data_area(udev,
+ /* Get Data-In buffer before clean up */
+ bitmap_copy(bitmap, cmd->data_bitmap, DATA_BLOCK_BITS);
+ gather_data_area(udev, bitmap,
se_cmd->t_bidi_data_sg, se_cmd->t_bidi_data_nents);
+ free_data_area(udev, cmd);
} else if (se_cmd->data_direction == DMA_FROM_DEVICE) {
- gather_and_free_data_area(udev,
+ DECLARE_BITMAP(bitmap, DATA_BLOCK_BITS);
+
+ bitmap_copy(bitmap, cmd->data_bitmap, DATA_BLOCK_BITS);
+ gather_data_area(udev, bitmap,
se_cmd->t_data_sg, se_cmd->t_data_nents);
+ free_data_area(udev, cmd);
} else if (se_cmd->data_direction == DMA_TO_DEVICE) {
- free_data_area(udev, cmd->data_length);
+ free_data_area(udev, cmd);
} else if (se_cmd->data_direction != DMA_NONE) {
pr_warn("TCMU: data direction was %d!\n",
se_cmd->data_direction);
@@ -912,6 +932,7 @@
WARN_ON(!PAGE_ALIGNED(udev->data_off));
WARN_ON(udev->data_size % PAGE_SIZE);
+ WARN_ON(udev->data_size % DATA_BLOCK_SIZE);
info->version = __stringify(TCMU_MAILBOX_VERSION);