On Mon, Sep 13, 2021 at 1:32 PM <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>
>
> The patch below does not apply to the 4.19-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@xxxxxxxxxxxxxxx>.
Hi Greg,
Attaching the backport of commit 76224355db75 ("fuse: truncate
pagecache on atomic_o_trunc") to v4.19.217.
Thanks,
Miklos
From 56d08204f7da642c3c914fb5b5208bffe9debe3a Mon Sep 17 00:00:00 2001
From: Miklos Szeredi <mszeredi@xxxxxxxxxx>
Date: Tue, 17 Aug 2021 21:05:16 +0200
Subject: [PATCH] fuse: truncate pagecache on atomic_o_trunc
fuse_finish_open() will be called with FUSE_NOWRITE in case of atomic
O_TRUNC. This can deadlock with fuse_wait_on_page_writeback() in
fuse_launder_page() triggered by invalidate_inode_pages2().
Fix by replacing invalidate_inode_pages2() in fuse_finish_open() with a
truncate_pagecache() call. This makes sense regardless of FOPEN_KEEP_CACHE
or fc->writeback cache, so do it unconditionally.
Reported-by: Xie Yongji <xieyongji@xxxxxxxxxxxxx>
Reported-and-tested-by: syzbot+bea44a5189836d956894@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: e4648309b85a ("fuse: truncate pending writes on O_TRUNC")
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
(cherry picked from commit 76224355db7570cbe6b6f75c8929a1558828dd55)
---
fs/fuse/file.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 6a3d89672ff7..13371a40f7a1 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -178,12 +178,11 @@ void fuse_finish_open(struct inode *inode, struct file *file)
if (ff->open_flags & FOPEN_DIRECT_IO)
file->f_op = &fuse_direct_io_file_operations;
- if (!(ff->open_flags & FOPEN_KEEP_CACHE))
- invalidate_inode_pages2(inode->i_mapping);
if (ff->open_flags & FOPEN_STREAM)
stream_open(inode, file);
else if (ff->open_flags & FOPEN_NONSEEKABLE)
nonseekable_open(inode, file);
+
if (fc->atomic_o_trunc && (file->f_flags & O_TRUNC)) {
struct fuse_inode *fi = get_fuse_inode(inode);
@@ -191,10 +190,14 @@ void fuse_finish_open(struct inode *inode, struct file *file)
fi->attr_version = ++fc->attr_version;
i_size_write(inode, 0);
spin_unlock(&fc->lock);
+ truncate_pagecache(inode, 0);
fuse_invalidate_attr(inode);
if (fc->writeback_cache)
file_update_time(file);
+ } else if (!(ff->open_flags & FOPEN_KEEP_CACHE)) {
+ invalidate_inode_pages2(inode->i_mapping);
}
+
if ((file->f_mode & FMODE_WRITE) && fc->writeback_cache)
fuse_link_write_file(file);
}
--
2.31.1
