Signed-off-by: Etienne Martineau <etmartin4313@xxxxxxxxx>
---
fs/fuse/dev.c | 68 ++++++++++++++++++++++++++++++++++++++++++++++++
fs/fuse/fuse_i.h | 13 +++++++++
fs/fuse/inode.c | 7 +++++
3 files changed, 88 insertions(+)
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 27ccae63495d..351787363444 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -21,6 +21,8 @@
#include <linux/swap.h>
#include <linux/splice.h>
#include <linux/sched.h>
+#include <linux/completion.h>
+#include <linux/sched/sysctl.h>
#define CREATE_TRACE_POINTS
#include "fuse_trace.h"
@@ -307,11 +309,75 @@ const struct fuse_iqueue_ops fuse_dev_fiq_ops = {
};
EXPORT_SYMBOL_GPL(fuse_dev_fiq_ops);
+static void fuse_timeout_checkpoint_in(struct fuse_req *req)
+{
+ int idx;
+ struct fuse_conn *fc = req->fm->fc;
+
+ if (!sysctl_hung_task_timeout_secs)
+ return;
+ req->checkpoint_time = jiffies;
+ idx = (req->checkpoint_time >> FUSE_TIMEOUT_JIFFIES) % FUSE_TIMEOUT_DISTRIBUTION;
+ atomic_inc(&fc->timeout_distribution[idx]);
+}
+
+static void fuse_timeout_checkpoint_out(struct fuse_req *req)
+{
+ int idx;
+ struct fuse_conn *fc = req->fm->fc;
+
+ if (!sysctl_hung_task_timeout_secs)
+ return;
+ idx = (req->checkpoint_time >> FUSE_TIMEOUT_JIFFIES) % FUSE_TIMEOUT_DISTRIBUTION;
+ atomic_dec(&fc->timeout_distribution[idx]);
+}
+
+/*
+ * The fuse timeout logic maintain a time distribution sliding window
+ * made of FUSE_TIMEOUT_DISTRIBUTION entries where each entries span over a
+ * number of jiffies defined by FUSE_TIMEOUT_JIFFIES in base 2.
+ * Just before sending the request to the server, we increment the coresponding
+ * distribution entry and once the request is ack back, we decrement that same
+ * entry because we remember req->checkpoint_time.
+ * Now, a timeout can be detected by simply looking at the old entries in the
+ * distribution and see if there is something hanging past a certain point.
+ */
+void fuse_check_timeout(struct work_struct *wk)
+{
+ int idx, x;
+ struct timespec64 t;
+ struct fuse_conn *fc = container_of(wk, struct fuse_conn, work.work);
+
+ if (!atomic_read(&fc->num_waiting))
+ goto out;
+
+ /* Current position in the distribution */
+ idx = (jiffies >> FUSE_TIMEOUT_JIFFIES) % FUSE_TIMEOUT_DISTRIBUTION;
+
+ /* Walk back and trigger abort when detecting old entries in the second half */
+ for (x = 0; x < FUSE_TIMEOUT_DISTRIBUTION; x++,
+ idx == 0 ? idx = FUSE_TIMEOUT_DISTRIBUTION-1 : idx--) {
+ /* First half, keep going */
+ if (x < FUSE_TIMEOUT_DISTRIBUTION>>1)
+ continue;
+ if (atomic_read(&fc->timeout_distribution[idx])) {
+ pr_info("fuse %u is stuck, aborting\n", fc->dev);
+ fuse_abort_conn(fc);
+ return;
+ }
+ }
+out:
+ if (sysctl_hung_task_timeout_secs)
+ queue_delayed_work(system_wq, &fc->work,
+ sysctl_hung_task_timeout_secs * (HZ / 2));
+}
+
static void fuse_send_one(struct fuse_iqueue *fiq, struct fuse_req *req)
{
req->in.h.len = sizeof(struct fuse_in_header) +
fuse_len_args(req->args->in_numargs,
(struct fuse_arg *) req->args->in_args);
+ fuse_timeout_checkpoint_in(req);
trace_fuse_request_send(req);
fiq->ops->send_req(fiq, req);
}
@@ -359,6 +425,7 @@ void fuse_request_end(struct fuse_req *req)
if (test_and_set_bit(FR_FINISHED, &req->flags))
goto put_request;
+ fuse_timeout_checkpoint_out(req);
trace_fuse_request_end(req);
/*
* test_and_set_bit() implies smp_mb() between bit
@@ -2260,6 +2327,7 @@ void fuse_abort_conn(struct fuse_conn *fc)
LIST_HEAD(to_end);
unsigned int i;
+ cancel_delayed_work(&fc->work);
/* Background queuing checks fc->connected under bg_lock */
spin_lock(&fc->bg_lock);
fc->connected = 0;
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 74744c6f2860..243d482a057d 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -44,6 +44,12 @@
/** Number of dentries for each connection in the control filesystem */
#define FUSE_CTL_NUM_DENTRIES 5
+/** Request timeout handling */
+#define FUSE_TIMEOUT_DISTRIBUTION_SHIFT 3
+#define FUSE_TIMEOUT_DISTRIBUTION (1L << FUSE_TIMEOUT_DISTRIBUTION_SHIFT)
+#define FUSE_TIMEOUT_JIFFIES (order_base_2( \
+ (sysctl_hung_task_timeout_secs * HZ) >> FUSE_TIMEOUT_DISTRIBUTION_SHIFT))
+
/** Maximum of max_pages received in init_out */
extern unsigned int fuse_max_pages_limit;
@@ -438,6 +444,8 @@ struct fuse_req {
/** fuse_mount this request belongs to */
struct fuse_mount *fm;
+
+ unsigned long checkpoint_time;
};
struct fuse_iqueue;
@@ -923,8 +931,12 @@ struct fuse_conn {
/** IDR for backing files ids */
struct idr backing_files_map;
#endif
+
+ atomic_t timeout_distribution[FUSE_TIMEOUT_DISTRIBUTION];
+ struct delayed_work work;
};
+
/*
* Represents a mounted filesystem, potentially a submount.
*
@@ -1190,6 +1202,7 @@ void fuse_request_end(struct fuse_req *req);
/* Abort all requests */
void fuse_abort_conn(struct fuse_conn *fc);
void fuse_wait_aborted(struct fuse_conn *fc);
+void fuse_check_timeout(struct work_struct *wk);
/**
* Invalidate inode attributes
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 3ce4f4e81d09..9f8fe17801c4 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -23,6 +23,8 @@
#include <linux/exportfs.h>
#include <linux/posix_acl.h>
#include <linux/pid_namespace.h>
+#include <linux/completion.h>
+#include <linux/sched/sysctl.h>
#include <uapi/linux/magic.h>
MODULE_AUTHOR("Miklos Szeredi <miklos@xxxxxxxxxx>");
@@ -1002,6 +1004,7 @@ void fuse_conn_put(struct fuse_conn *fc)
struct fuse_iqueue *fiq = &fc->iq;
struct fuse_sync_bucket *bucket;
+ cancel_delayed_work_sync(&fc->work);
if (IS_ENABLED(CONFIG_FUSE_DAX))
fuse_dax_conn_free(fc);
if (fiq->ops->release)
@@ -1785,6 +1788,10 @@ int fuse_fill_super_common(struct super_block *sb, struct fuse_fs_context *ctx)
fc->destroy = ctx->destroy;
fc->no_control = ctx->no_control;
fc->no_force_umount = ctx->no_force_umount;
+ INIT_DELAYED_WORK(&fc->work, fuse_check_timeout);
+ if (sysctl_hung_task_timeout_secs)
+ queue_delayed_work(system_wq, &fc->work,
+ sysctl_hung_task_timeout_secs * (HZ / 2));
err = -ENOMEM;
root = fuse_get_root_inode(sb, ctx->rootmode);
--
2.34.1
