Miklos Szeredi d58366aab8 fuse: fix deadlock between atomic O_TRUNC and page invalidation ... commit 2fdbb8dd01 upstream. fuse_finish_open() will be called with FUSE_NOWRITE set in case of atomic O_TRUNC open(), so commit 76224355db ("fuse: truncate pagecache on atomic_o_trunc") replaced invalidate_inode_pages2() by truncate_pagecache() in such a case to avoid the A-A deadlock. However, we found another A-B-B-A deadlock related to the case above, which will cause the xfstests generic/464 testcase hung in our virtio-fs test environment. For example, consider two processes concurrently open one same file, one with O_TRUNC and another without O_TRUNC. The deadlock case is described below, if open(O_TRUNC) is already set_nowrite(acquired A), and is trying to lock a page (acquiring B), open() could have held the page lock (acquired B), and waiting on the page writeback (acquiring A). This would lead to deadlocks. open(O_TRUNC) ---------------------------------------------------------------- fuse_open_common inode_lock [C acquire] fuse_set_nowrite [A acquire] fuse_finish_open truncate_pagecache lock_page [B acquire] truncate_inode_page unlock_page [B release] fuse_release_nowrite [A release] inode_unlock [C release] ---------------------------------------------------------------- open() ---------------------------------------------------------------- fuse_open_common fuse_finish_open invalidate_inode_pages2 lock_page [B acquire] fuse_launder_page fuse_wait_on_page_writeback [A acquire & release] unlock_page [B release] ---------------------------------------------------------------- Besides this case, all calls of invalidate_inode_pages2() and invalidate_inode_pages2_range() in fuse code also can deadlock with open(O_TRUNC). Fix by moving the truncate_pagecache() call outside the nowrite protected region. The nowrite protection is only for delayed writeback (writeback_cache) case, where inode lock does not protect against truncation racing with writes on the server. Write syscalls racing with page cache truncation still get the inode lock protection. This patch also changes the order of filemap_invalidate_lock() vs. fuse_set_nowrite() in fuse_open_common(). This new order matches the order found in fuse_file_fallocate() and fuse_do_setattr(). Reported-by: Jiachen Zhang <zhangjiachen.jaycee@bytedance.com> Tested-by: Jiachen Zhang <zhangjiachen.jaycee@bytedance.com> Fixes: e4648309b8 ("fuse: truncate pending writes on O_TRUNC") Cc: <stable@vger.kernel.org> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Yang Bo <yb203166@antfin.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2023-04-26 13:51:54 +02:00
..
acl.c	vfs: add rcu argument to ->get_acl() callback	2021-08-18 22:08:24 +02:00
control.c	fuse: Remove the control interface for virtio-fs	2022-08-17 14:24:11 +02:00
cuse.c	cuse: simplify refcount	2021-04-14 10:40:58 +02:00
dax.c	\n	2021-08-30 10:24:50 -07:00
dev.c	fuse: fix pipe buffer lifetime for direct_io	2022-03-16 14:23:42 +01:00
dir.c	fuse: fix deadlock between atomic O_TRUNC and page invalidation	2023-04-26 13:51:54 +02:00
file.c	fuse: fix deadlock between atomic O_TRUNC and page invalidation	2023-04-26 13:51:54 +02:00
fuse_i.h	fuse: fix pipe buffer lifetime for direct_io	2022-03-16 14:23:42 +01:00
inode.c	fuse: limit nsec	2022-08-17 14:22:56 +02:00
ioctl.c	fuse: add inode/permission checks to fileattr_get/fileattr_set	2023-03-10 09:40:08 +01:00
Kconfig
Makefile
readdir.c	fuse: fix readdir cache race	2022-11-16 09:58:13 +01:00
virtio_fs.c	fuse: clean up fuse_mount destruction	2021-10-21 10:01:39 +02:00
xattr.c