[PATCH 06/10] nbd: Add debugfs entries

Markus Pargmann
2015-07-27T07:14:47Z

drivers/block/nbd.c | 178 +++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 177 insertions(+), 1 deletion(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 0075554a05b7..188fe0d2b1ac 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -33,6 +33,7 @@
#include <linux/net.h>
#include <linux/kthread.h>
#include <linux/types.h>
+#include <linux/debugfs.h>

#include <asm/uaccess.h>
#include <asm/types.h>
@@ -61,8 +62,18 @@ struct nbd_device {
struct timer_list timeout_timer;
struct task_struct *task_recv;
struct task_struct *task_send;
+
+#if IS_ENABLED(CONFIG_DEBUG_FS)
+ struct dentry *dbg_dir;
+#endif
};

+#if IS_ENABLED(CONFIG_DEBUG_FS)
+static struct dentry *nbd_dbg_dir;
+#endif
+
+#define nbd_name(nbd) ((nbd)->disk->disk_name)
+
#define NBD_MAGIC 0x68797548

static unsigned int nbds_max = 16;
@@ -609,6 +620,9 @@ static void do_nbd_request(struct request_queue *q)
}
}

+static int nbd_dev_dbg_init(struct nbd_device *nbd);
+static void nbd_dev_dbg_close(struct nbd_device *nbd);
+
/* Must be called with tx_lock held */

static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd,
@@ -725,13 +739,15 @@ static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd,
blk_queue_flush(nbd->disk->queue, 0);

thread = kthread_run(nbd_thread, nbd, "%s",
- nbd->disk->disk_name);
+ nbd_name(nbd));
if (IS_ERR(thread)) {
mutex_lock(&nbd->tx_lock);
return PTR_ERR(thread);
}

+ nbd_dev_dbg_init(nbd);
error = nbd_do_it(nbd);
+ nbd_dev_dbg_close(nbd);
kthread_stop(thread);

mutex_lock(&nbd->tx_lock);
@@ -797,6 +813,161 @@ static const struct block_device_operations nbd_fops =
.ioctl = nbd_ioctl,
};

+#if IS_ENABLED(CONFIG_DEBUG_FS)
+
+static int nbd_dbg_tasks_show(struct seq_file *s, void *unused)
+{
+ struct nbd_device *nbd = s->private;
+
+ if (nbd->task_recv)
+ seq_printf(s, "recv: %d\n", task_pid_nr(nbd->task_recv));
+ if (nbd->task_send)
+ seq_printf(s, "send: %d\n", task_pid_nr(nbd->task_send));
+
+ return 0;
+}
+
+static int nbd_dbg_tasks_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, nbd_dbg_tasks_show, inode->i_private);
+}
+
+static const struct file_operations nbd_dbg_tasks_ops = {
+ .open = nbd_dbg_tasks_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+static int nbd_dbg_flags_show(struct seq_file *s, void *unused)
+{
+ struct nbd_device *nbd = s->private;
+ u32 flags = nbd->flags;
+
+ seq_printf(s, "Hex: 0x%08x\n\n", flags);
+
+ seq_puts(s, "Known flags:\n");
+
+ if (flags & NBD_FLAG_HAS_FLAGS)
+ seq_puts(s, "NBD_FLAG_HAS_FLAGS\n");
+ if (flags & NBD_FLAG_READ_ONLY)
+ seq_puts(s, "NBD_FLAG_READ_ONLY\n");
+ if (flags & NBD_FLAG_SEND_FLUSH)
+ seq_puts(s, "NBD_FLAG_SEND_FLUSH\n");
+ if (flags & NBD_FLAG_SEND_TRIM)
+ seq_puts(s, "NBD_FLAG_SEND_TRIM\n");
+
+ return 0;
+}
+
+static int nbd_dbg_flags_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, nbd_dbg_flags_show, inode->i_private);
+}
+
+static const struct file_operations nbd_dbg_flags_ops = {
+ .open = nbd_dbg_flags_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+static int nbd_dev_dbg_init(struct nbd_device *nbd)
+{
+ struct dentry *dir;
+ struct dentry *f;
+
+ dir = debugfs_create_dir(nbd_name(nbd), nbd_dbg_dir);
+ if (IS_ERR_OR_NULL(dir)) {
+ dev_err(nbd_to_dev(nbd), "Failed to create debugfs dir for '%s' (%ld)\n",
+ nbd_name(nbd), PTR_ERR(dir));
+ return PTR_ERR(dir);
+ }
+ nbd->dbg_dir = dir;
+
+ f = debugfs_create_file("tasks", 0444, dir, nbd, &nbd_dbg_tasks_ops);
+ if (IS_ERR_OR_NULL(f)) {
+ dev_err(nbd_to_dev(nbd), "Failed to create debugfs file 'tasks', %ld\n",
+ PTR_ERR(f));
+ return PTR_ERR(f);
+ }
+
+ f = debugfs_create_u64("size_bytes", 0444, dir, &nbd->bytesize);
+ if (IS_ERR_OR_NULL(f)) {
+ dev_err(nbd_to_dev(nbd), "Failed to create debugfs file 'size_bytes', %ld\n",
+ PTR_ERR(f));
+ return PTR_ERR(f);
+ }
+
+ f = debugfs_create_u32("timeout", 0444, dir, &nbd->xmit_timeout);
+ if (IS_ERR_OR_NULL(f)) {
+ dev_err(nbd_to_dev(nbd), "Failed to create debugfs file 'timeout', %ld\n",
+ PTR_ERR(f));
+ return PTR_ERR(f);
+ }
+
+ f = debugfs_create_u32("blocksize", 0444, dir, &nbd->blksize);
+ if (IS_ERR_OR_NULL(f)) {
+ dev_err(nbd_to_dev(nbd), "Failed to create debugfs file 'blocksize', %ld\n",
+ PTR_ERR(f));
+ return PTR_ERR(f);
+ }
+
+ f = debugfs_create_file("flags", 0444, dir, &nbd, &nbd_dbg_flags_ops);
+ if (IS_ERR_OR_NULL(f)) {
+ dev_err(nbd_to_dev(nbd), "Failed to create debugfs file 'flags', %ld\n",
+ PTR_ERR(f));
+ return PTR_ERR(f);
+ }
+
+ return 0;
+}
+
+static void nbd_dev_dbg_close(struct nbd_device *nbd)
+{
+ debugfs_remove_recursive(nbd->dbg_dir);
+}
+
+static int nbd_dbg_init(void)
+{
+ struct dentry *dbg_dir;
+
+ dbg_dir = debugfs_create_dir("nbd", NULL);
+ if (IS_ERR(dbg_dir))
+ return PTR_ERR(dbg_dir);
+
+ nbd_dbg_dir = dbg_dir;
+
+ return 0;
+}
+
+static void nbd_dbg_close(void)
+{
+ debugfs_remove_recursive(nbd_dbg_dir);
+}
+
+#else /* IS_ENABLED(CONFIG_DEBUG_FS) */
+
+static int nbd_dev_dbg_init(struct nbd_device *nbd)
+{
+ return 0;
+}
+
+static void nbd_dev_dbg_close(struct nbd_device *nbd)
+{
+}
+
+static int nbd_dbg_init(void)
+{
+ return 0;
+}
+
+static void nbd_dbg_close(void)
+{
+}
+
+#endif
+
/*
* And here should be modules and kernel interface
* (Just smiley confuses emacs :-)
@@ -874,6 +1045,8 @@ static int __init nbd_init(void)

printk(KERN_INFO "nbd: registered device at major %d\n", NBD_MAJOR);

+ nbd_dbg_init();
+
for (i = 0; i < nbds_max; i++) {
struct gendisk *disk = nbd_dev[i].disk;
nbd_dev[i].magic = NBD_MAGIC;
@@ -910,6 +1083,9 @@ out:
static void __exit nbd_cleanup(void)
{
int i;
+
+ nbd_dbg_close();
+
for (i = 0; i < nbds_max; i++) {
struct gendisk *disk = nbd_dev[i].disk;
nbd_dev[i].magic = 0;
--
2.1.4