Backport from ml:
commit 9759bd51899458af4f4bcc11046f01285642ca10
Author: Miklos Szeredi <[email protected]>
Date: Tue Jan 6 10:45:35 2015 +0100
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 <[email protected]>
Signed-off-by: Maxim Patlasov <[email protected]>
---
fs/fuse/dev.c | 15 +++++++++++++--
fs/fuse/fuse_i.h | 2 ++
fs/fuse/inode.c | 2 +-
3 files changed, 16 insertions(+), 3 deletions(-)
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index c2a3392..5e7f812 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -119,6 +119,13 @@ static void fuse_req_init_context(struct fuse_req *req)
req->in.h.pid = task_pid_vnr(current);
}
+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);
@@ -137,6 +144,8 @@ static struct fuse_req *__fuse_get_req(struct fuse_conn
*fc, unsigned npages,
!fuse_block_alloc(fc, for_background)))
goto out;
}
+ /* Matches smp_wmb() in fuse_set_initialized() */
+ smp_rmb();
err = -ENOTCONN;
if (!fc->connected)
@@ -239,6 +248,8 @@ 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);
@@ -2178,7 +2189,7 @@ 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);
@@ -2197,7 +2208,7 @@ 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 fefa8ff..09aab7e 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -964,4 +964,6 @@ int fuse_flush_mtime(struct file *file, bool nofail);
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 7dea77f..9bd2490 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -1029,7 +1029,7 @@ 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);
}
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