[PATCH 1/6] bcachefs: thread_with_file

Kent Overstreet
2023-12-06T20:33:23Z

Abstract out a new helper from the data job code, for connecting a
kthread to a file descriptor.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
---
fs/bcachefs/chardev.c | 113 ++++++++++++++++++++++++++----------------
1 file changed, 69 insertions(+), 44 deletions(-)

diff --git a/fs/bcachefs/chardev.c b/fs/bcachefs/chardev.c
index ba0436ae6b05..8e3ac2d32298 100644
--- a/fs/bcachefs/chardev.c
+++ b/fs/bcachefs/chardev.c
@@ -29,6 +29,61 @@ static int copy_to_user_errcode(void __user *to, const void *from, unsigned long
return copy_to_user(to, from, n) ? -EFAULT : 0;
}

+struct thread_with_file {
+ struct task_struct *task;
+ int ret;
+};
+
+static void thread_with_file_exit(struct thread_with_file *thr)
+{
+ kthread_stop(thr->task);
+ put_task_struct(thr->task);
+}
+
+static int run_thread_with_file(struct thread_with_file *thr,
+ const struct file_operations *fops,
+ int (*fn)(void *), const char *fmt, ...)
+{
+ va_list args;
+ struct file *file = NULL;
+ int ret, fd = -1;
+ struct printbuf name = PRINTBUF;
+ unsigned fd_flags = O_RDONLY|O_CLOEXEC|O_NONBLOCK;
+
+ va_start(args, fmt);
+ prt_vprintf(&name, fmt, args);
+ va_end(args);
+
+ thr->ret = 0;
+ thr->task = kthread_create(fn, thr, name.buf);
+ ret = PTR_ERR_OR_ZERO(thr->task);
+ if (ret)
+ goto err;
+
+ ret = get_unused_fd_flags(fd_flags);
+ if (ret < 0)
+ goto err_stop_task;
+ fd = ret;
+
+ file = anon_inode_getfile(name.buf, fops, thr, fd_flags);
+ ret = PTR_ERR_OR_ZERO(file);
+ if (ret)
+ goto err_put_fd;
+
+ fd_install(fd, file);
+ get_task_struct(thr->task);
+ wake_up_process(thr->task);
+ printbuf_exit(&name);
+ return fd;
+err_put_fd:
+ put_unused_fd(fd);
+err_stop_task:
+ kthread_stop(thr->task);
+err:
+ printbuf_exit(&name);
+ return ret;
+}
+
/* returns with ref on ca->ref */
static struct bch_dev *bch2_device_lookup(struct bch_fs *c, u64 dev,
unsigned flags)
@@ -299,31 +354,27 @@ static long bch2_ioctl_disk_set_state(struct bch_fs *c,
}

struct bch_data_ctx {
+ struct thread_with_file thr;
+
struct bch_fs *c;
struct bch_ioctl_data arg;
struct bch_move_stats stats;
-
- int ret;
-
- struct task_struct *thread;
};

static int bch2_data_thread(void *arg)
{
- struct bch_data_ctx *ctx = arg;
-
- ctx->ret = bch2_data_job(ctx->c, &ctx->stats, ctx->arg);
+ struct bch_data_ctx *ctx = container_of(arg, struct bch_data_ctx, thr);

+ ctx->thr.ret = bch2_data_job(ctx->c, &ctx->stats, ctx->arg);
ctx->stats.data_type = U8_MAX;
return 0;
}

static int bch2_data_job_release(struct inode *inode, struct file *file)
{
- struct bch_data_ctx *ctx = file->private_data;
+ struct bch_data_ctx *ctx = container_of(file->private_data, struct bch_data_ctx, thr);

- kthread_stop(ctx->thread);
- put_task_struct(ctx->thread);
+ thread_with_file_exit(&ctx->thr);
kfree(ctx);
return 0;
}
@@ -331,7 +382,7 @@ static int bch2_data_job_release(struct inode *inode, struct file *file)
static ssize_t bch2_data_job_read(struct file *file, char __user *buf,
size_t len, loff_t *ppos)
{
- struct bch_data_ctx *ctx = file->private_data;
+ struct bch_data_ctx *ctx = container_of(file->private_data, struct bch_data_ctx, thr);
struct bch_fs *c = ctx->c;
struct bch_ioctl_data_event e = {
.type = BCH_DATA_EVENT_PROGRESS,
@@ -357,10 +408,8 @@ static const struct file_operations bcachefs_data_ops = {
static long bch2_ioctl_data(struct bch_fs *c,
struct bch_ioctl_data arg)
{
- struct bch_data_ctx *ctx = NULL;
- struct file *file = NULL;
- unsigned flags = O_RDONLY|O_CLOEXEC|O_NONBLOCK;
- int ret, fd = -1;
+ struct bch_data_ctx *ctx;
+ int ret;

if (!capable(CAP_SYS_ADMIN))
return -EPERM;
@@ -375,36 +424,12 @@ static long bch2_ioctl_data(struct bch_fs *c,
ctx->c = c;
ctx->arg = arg;

- ctx->thread = kthread_create(bch2_data_thread, ctx,
- "bch-data/%s", c->name);
- if (IS_ERR(ctx->thread)) {
- ret = PTR_ERR(ctx->thread);
- goto err;
- }
-
- ret = get_unused_fd_flags(flags);
+ ret = run_thread_with_file(&ctx->thr,
+ &bcachefs_data_ops,
+ bch2_data_thread,
+ "bch-data/%s", c->name);
if (ret < 0)
- goto err;
- fd = ret;
-
- file = anon_inode_getfile("[bcachefs]", &bcachefs_data_ops, ctx, flags);
- if (IS_ERR(file)) {
- ret = PTR_ERR(file);
- goto err;
- }
-
- fd_install(fd, file);
-
- get_task_struct(ctx->thread);
- wake_up_process(ctx->thread);
-
- return fd;
-err:
- if (fd >= 0)
- put_unused_fd(fd);
- if (!IS_ERR_OR_NULL(ctx->thread))
- kthread_stop(ctx->thread);
- kfree(ctx);
+ kfree(ctx);
return ret;
}

--
2.42.0