This patch converts blktrace to use the Generic Trace Setup and
Control (GTSC) interface. Also attached is a small patch to the
blktrace user code, needed for the ioctl change.
Signed-off-by: Tom Zanussi <[email protected]>
Signed-off-by: David Wilder <[email protected]>
---
block/Kconfig | 2
block/blktrace.c | 188 +++++--------------------------------------
include/linux/blktrace_api.h | 30 +++---
3 files changed, 40 insertions(+), 180 deletions(-)
diff --git a/block/Kconfig b/block/Kconfig
index a50f481..9ae9a8c 100644
--- a/block/Kconfig
+++ b/block/Kconfig
@@ -30,7 +30,7 @@ config LBD
config BLK_DEV_IO_TRACE
bool "Support for tracing block io actions"
depends on SYSFS
- select RELAY
+ select GTSC
select DEBUG_FS
help
Say Y here, if you want to be able to trace the block layer actions
diff --git a/block/blktrace.c b/block/blktrace.c
index 3f0e7c3..c5d5821 100644
--- a/block/blktrace.c
+++ b/block/blktrace.c
@@ -36,7 +36,7 @@ static void trace_note(struct blk_trace *bt, pid_t pid, int action,
{
struct blk_io_trace *t;
- t = relay_reserve(bt->rchan, sizeof(*t) + len);
+ t = relay_reserve(bt->trace->rchan, sizeof(*t) + len);
if (t) {
const int cpu = smp_processor_id();
@@ -126,7 +126,7 @@ void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
pid_t pid;
int cpu;
- if (unlikely(bt->trace_state != Blktrace_running))
+ if (unlikely(!trace_running(bt->trace)))
return;
what |= ddir_act[rw & WRITE];
@@ -152,7 +152,7 @@ void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
if (unlikely(tsk->btrace_seq != blktrace_seq))
trace_note_tsk(bt, tsk);
- t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len);
+ t = relay_reserve(bt->trace->rchan, sizeof(*t) + pdu_len);
if (t) {
cpu = smp_processor_id();
sequence = per_cpu_ptr(bt->sequence, cpu);
@@ -178,55 +178,8 @@ void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
EXPORT_SYMBOL_GPL(__blk_add_trace);
-static struct dentry *blk_tree_root;
-static struct mutex blk_tree_mutex;
-static unsigned int root_users;
-
-static inline void blk_remove_root(void)
-{
- if (blk_tree_root) {
- debugfs_remove(blk_tree_root);
- blk_tree_root = NULL;
- }
-}
-
-static void blk_remove_tree(struct dentry *dir)
-{
- mutex_lock(&blk_tree_mutex);
- debugfs_remove(dir);
- if (--root_users == 0)
- blk_remove_root();
- mutex_unlock(&blk_tree_mutex);
-}
-
-static struct dentry *blk_create_tree(const char *blk_name)
-{
- struct dentry *dir = NULL;
-
- mutex_lock(&blk_tree_mutex);
-
- if (!blk_tree_root) {
- blk_tree_root = debugfs_create_dir("block", NULL);
- if (!blk_tree_root)
- goto err;
- }
-
- dir = debugfs_create_dir(blk_name, blk_tree_root);
- if (dir)
- root_users++;
- else
- blk_remove_root();
-
-err:
- mutex_unlock(&blk_tree_mutex);
- return dir;
-}
-
static void blk_trace_cleanup(struct blk_trace *bt)
{
- relay_close(bt->rchan);
- debugfs_remove(bt->dropped_file);
- blk_remove_tree(bt->dir);
free_percpu(bt->sequence);
kfree(bt);
}
@@ -239,76 +192,14 @@ static int blk_trace_remove(request_queue_t *q)
if (!bt)
return -EINVAL;
- if (bt->trace_state == Blktrace_setup ||
- bt->trace_state == Blktrace_stopped)
+ if (!trace_running(bt->trace)) {
+ trace_cleanup(bt->trace);
blk_trace_cleanup(bt);
+ }
return 0;
}
-static int blk_dropped_open(struct inode *inode, struct file *filp)
-{
- filp->private_data = inode->i_private;
-
- return 0;
-}
-
-static ssize_t blk_dropped_read(struct file *filp, char __user *buffer,
- size_t count, loff_t *ppos)
-{
- struct blk_trace *bt = filp->private_data;
- char buf[16];
-
- snprintf(buf, sizeof(buf), "%u\n", atomic_read(&bt->dropped));
-
- return simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf));
-}
-
-static const struct file_operations blk_dropped_fops = {
- .owner = THIS_MODULE,
- .open = blk_dropped_open,
- .read = blk_dropped_read,
-};
-
-/*
- * Keep track of how many times we encountered a full subbuffer, to aid
- * the user space app in telling how many lost events there were.
- */
-static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf,
- void *prev_subbuf, size_t prev_padding)
-{
- struct blk_trace *bt;
-
- if (!relay_buf_full(buf))
- return 1;
-
- bt = buf->chan->private_data;
- atomic_inc(&bt->dropped);
- return 0;
-}
-
-static int blk_remove_buf_file_callback(struct dentry *dentry)
-{
- debugfs_remove(dentry);
- return 0;
-}
-
-static struct dentry *blk_create_buf_file_callback(const char *filename,
- struct dentry *parent,
- int mode,
- struct rchan_buf *buf,
- int *is_global)
-{
- return debugfs_create_file(filename, mode, parent, buf,
- &relay_file_operations);
-}
-
-static struct rchan_callbacks blk_relay_callbacks = {
- .subbuf_start = blk_subbuf_start_callback,
- .create_buf_file = blk_create_buf_file_callback,
- .remove_buf_file = blk_remove_buf_file_callback,
-};
-
/*
* Setup everything required to start tracing
*/
@@ -317,25 +208,23 @@ static int blk_trace_setup(request_queue_t *q, struct block_device *bdev,
{
struct blk_user_trace_setup buts;
struct blk_trace *old_bt, *bt = NULL;
- struct dentry *dir = NULL;
char b[BDEVNAME_SIZE];
int ret, i;
+ struct gtsc_trace_setup *gts = &buts.gts;
if (copy_from_user(&buts, arg, sizeof(buts)))
return -EFAULT;
- if (!buts.buf_size || !buts.buf_nr)
- return -EINVAL;
-
- strcpy(buts.name, bdevname(bdev, b));
+ strcpy(gts->root, "block");
+ strcpy(gts->name, bdevname(bdev, b));
/*
* some device names have larger paths - convert the slashes
* to underscores for this to work as expected
*/
- for (i = 0; i < strlen(buts.name); i++)
- if (buts.name[i] == '/')
- buts.name[i] = '_';
+ for (i = 0; i < strlen(gts->name); i++)
+ if (gts->name[i] == '/')
+ gts->name[i] = '_';
if (copy_to_user(arg, &buts, sizeof(buts)))
return -EFAULT;
@@ -349,23 +238,12 @@ static int blk_trace_setup(request_queue_t *q, struct block_device *bdev,
if (!bt->sequence)
goto err;
- ret = -ENOENT;
- dir = blk_create_tree(buts.name);
- if (!dir)
+ bt->trace = trace_setup(gts->root, gts->name, gts->buf_size,
+ gts->buf_nr, 0);
+ if (!bt->trace)
goto err;
- bt->dir = dir;
bt->dev = bdev->bd_dev;
- atomic_set(&bt->dropped, 0);
-
- ret = -EIO;
- bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt, &blk_dropped_fops);
- if (!bt->dropped_file)
- goto err;
-
- bt->rchan = relay_open("trace", dir, buts.buf_size, buts.buf_nr, &blk_relay_callbacks, bt);
- if (!bt->rchan)
- goto err;
bt->act_mask = buts.act_mask;
if (!bt->act_mask)
@@ -377,7 +255,6 @@ static int blk_trace_setup(request_queue_t *q, struct block_device *bdev,
bt->end_lba = -1ULL;
bt->pid = buts.pid;
- bt->trace_state = Blktrace_setup;
ret = -EBUSY;
old_bt = xchg(&q->blk_trace, bt);
@@ -388,14 +265,10 @@ static int blk_trace_setup(request_queue_t *q, struct block_device *bdev,
return 0;
err:
- if (dir)
- blk_remove_tree(dir);
if (bt) {
- if (bt->dropped_file)
- debugfs_remove(bt->dropped_file);
free_percpu(bt->sequence);
- if (bt->rchan)
- relay_close(bt->rchan);
+ if (bt->trace)
+ trace_cleanup(bt->trace);
kfree(bt);
}
return ret;
@@ -404,33 +277,21 @@ err:
static int blk_trace_startstop(request_queue_t *q, int start)
{
struct blk_trace *bt;
- int ret;
+ int ret = 0;
if ((bt = q->blk_trace) == NULL)
return -EINVAL;
- /*
- * For starting a trace, we can transition from a setup or stopped
- * trace. For stopping a trace, the state must be running
- */
- ret = -EINVAL;
if (start) {
- if (bt->trace_state == Blktrace_setup ||
- bt->trace_state == Blktrace_stopped) {
+ if (!trace_running(bt->trace)) {
blktrace_seq++;
smp_mb();
- bt->trace_state = Blktrace_running;
-
- trace_note_time(bt);
- ret = 0;
- }
- } else {
- if (bt->trace_state == Blktrace_running) {
- bt->trace_state = Blktrace_stopped;
- relay_flush(bt->rchan);
- ret = 0;
+ ret = trace_start(bt->trace);
+ if (!ret)
+ trace_note_time(bt);
}
- }
+ } else
+ ret = trace_stop(bt->trace);
return ret;
}
@@ -551,7 +412,6 @@ static void blk_trace_set_ht_offsets(void)
static __init int blk_trace_init(void)
{
- mutex_init(&blk_tree_mutex);
on_each_cpu(blk_trace_check_cpu_time, NULL, 1, 1);
blk_trace_set_ht_offsets();
diff --git a/include/linux/blktrace_api.h b/include/linux/blktrace_api.h
index 3680ff9..875323e 100644
--- a/include/linux/blktrace_api.h
+++ b/include/linux/blktrace_api.h
@@ -2,7 +2,7 @@
#define BLKTRACE_H
#include <linux/blkdev.h>
-#include <linux/relay.h>
+#include <linux/gtsc.h>
/*
* Trace categories
@@ -109,34 +109,34 @@ struct blk_io_trace_remap {
__be64 sector;
};
-enum {
- Blktrace_setup = 1,
- Blktrace_running,
- Blktrace_stopped,
-};
-
struct blk_trace {
- int trace_state;
- struct rchan *rchan;
+ struct trace_info *trace;
unsigned long *sequence;
u16 act_mask;
u64 start_lba;
u64 end_lba;
u32 pid;
u32 dev;
- struct dentry *dir;
- struct dentry *dropped_file;
- atomic_t dropped;
+};
+
+/*
+ * User setup structure
+ */
+struct gtsc_trace_setup
+{
+ char root[TRACE_ROOT_NAME_SIZE];
+ char name[TRACE_NAME_SIZE];
+ u32 buf_size;
+ u32 buf_nr;
+ u32 flags;
};
/*
* User setup structure passed with BLKTRACESTART
*/
struct blk_user_trace_setup {
- char name[BDEVNAME_SIZE]; /* output */
+ struct gtsc_trace_setup gts; /* input */
u16 act_mask; /* input */
- u32 buf_size; /* input */
- u32 buf_nr; /* input */
u64 start_lba;
u64 end_lba;
u32 pid;