From: Amir Goldstein <amir73il@gmail.com> mainline inclusion from mainline-v6.9-rc5 commit 7cc911262835419fe469ebfae89891c0e97c62ef category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IBHLU4 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- Parallel dio write takes a negative refcount of fi->iocachectr and so does open of file in passthrough mode. The refcount of passthrough mode is associated with attach/detach of a fuse_backing object to fuse inode. For parallel dio write, the backing file is irrelevant, so the call to fuse_inode_uncached_io_start() passes a NULL fuse_backing object. Passing a NULL fuse_backing will result in false -EBUSY error if the file is already open in passthrough mode. Allow taking negative fi->iocachectr refcount with NULL fuse_backing, because it does not conflict with an already attached fuse_backing object. Fixes: 4a90451bbc7f ("fuse: implement open in passthrough mode") Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Yifan Qiao <qiaoyifan4@huawei.com> --- fs/fuse/iomode.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/fuse/iomode.c b/fs/fuse/iomode.c index 98f1fd523dae..c99e285f3183 100644 --- a/fs/fuse/iomode.c +++ b/fs/fuse/iomode.c @@ -90,7 +90,7 @@ int fuse_inode_uncached_io_start(struct fuse_inode *fi, struct fuse_backing *fb) spin_lock(&fi->lock); /* deny conflicting backing files on same fuse inode */ oldfb = fuse_inode_backing(fi); - if (oldfb && oldfb != fb) { + if (fb && oldfb && oldfb != fb) { err = -EBUSY; goto unlock; } @@ -101,7 +101,7 @@ int fuse_inode_uncached_io_start(struct fuse_inode *fi, struct fuse_backing *fb) fi->iocachectr--; /* fuse inode holds a single refcount of backing file */ - if (!oldfb) { + if (fb && !oldfb) { oldfb = fuse_inode_backing_set(fi, fb); WARN_ON_ONCE(oldfb != NULL); } else { -- 2.39.2