fuse: add memory barrier to INIT

Theoretically we need to order setting of various fields in fc with
fc->initialized.

No known bug reports related to this yet.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index c847d6b..ed19a7d 100644 (file)
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -131,6 +131,13 @@ static void fuse_req_init_context(struct fuse_req *req)
        req->in.h.pid = current->pid;
 }
 
+void fuse_set_initialized(struct fuse_conn *fc)
+{
+       /* Make sure stores before this are seen on another CPU */
+       smp_wmb();
+       fc->initialized = 1;
+}
+
 static bool fuse_block_alloc(struct fuse_conn *fc, bool for_background)
 {
        return !fc->initialized || (for_background && fc->blocked);
@@ -155,6 +162,8 @@ static struct fuse_req *__fuse_get_req(struct fuse_conn *fc, unsigned npages,
                if (intr)
                        goto out;
        }
+       /* Matches smp_wmb() in fuse_set_initialized() */
+       smp_rmb();
 
        err = -ENOTCONN;
        if (!fc->connected)
@@ -253,6 +262,8 @@ struct fuse_req *fuse_get_req_nofail_nopages(struct fuse_conn *fc,
 
        atomic_inc(&fc->num_waiting);
        wait_event(fc->blocked_waitq, fc->initialized);
+       /* Matches smp_wmb() in fuse_set_initialized() */
+       smp_rmb();
        req = fuse_request_alloc(0);
        if (!req)
                req = get_reserved_req(fc, file);
@@ -2163,7 +2174,7 @@ void fuse_abort_conn(struct fuse_conn *fc)
        if (fc->connected) {
                fc->connected = 0;
                fc->blocked = 0;
-               fc->initialized = 1;
+               fuse_set_initialized(fc);
                end_io_requests(fc);
                end_queued_requests(fc);
                end_polls(fc);
@@ -2182,7 +2193,7 @@ int fuse_dev_release(struct inode *inode, struct file *file)
                spin_lock(&fc->lock);
                fc->connected = 0;
                fc->blocked = 0;
-               fc->initialized = 1;
+               fuse_set_initialized(fc);
                end_queued_requests(fc);
                end_polls(fc);
                wake_up_all(&fc->blocked_waitq);

diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index e0fc672..1cdfb07 100644 (file)
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -906,4 +906,6 @@ int fuse_write_inode(struct inode *inode, struct writeback_control *wbc);
 int fuse_do_setattr(struct inode *inode, struct iattr *attr,
                    struct file *file);
 
+void fuse_set_initialized(struct fuse_conn *fc);
+
 #endif /* _FS_FUSE_I_H */

diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 6a20f2f..f38256e 100644 (file)
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -897,7 +897,7 @@ static void process_init_reply(struct fuse_conn *fc, struct fuse_req *req)
                fc->max_write = max_t(unsigned, 4096, fc->max_write);
                fc->conn_init = 1;
        }
-       fc->initialized = 1;
+       fuse_set_initialized(fc);
        wake_up_all(&fc->blocked_waitq);
 }