Patch "NFS: nfs_find_open_context() may only select open files" has been added to the 5.4-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    NFS: nfs_find_open_context() may only select open files

to the 5.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     nfs-nfs_find_open_context-may-only-select-open-files.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 156d0c741f72ca35732050723a8bb76f65854afa
Author: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
Date:   Tue May 11 23:41:10 2021 -0400

    NFS: nfs_find_open_context() may only select open files
    
    [ Upstream commit e97bc66377bca097e1f3349ca18ca17f202ff659 ]
    
    If a file has already been closed, then it should not be selected to
    support further I/O.
    
    Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
    [Trond: Fix an invalid pointer deref reported by Colin Ian King]
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 8c0f916380c4..209263c0c537 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -1048,6 +1048,7 @@ EXPORT_SYMBOL_GPL(nfs_inode_attach_open_context);
 void nfs_file_set_open_context(struct file *filp, struct nfs_open_context *ctx)
 {
 	filp->private_data = get_nfs_open_context(ctx);
+	set_bit(NFS_CONTEXT_FILE_OPEN, &ctx->flags);
 	if (list_empty(&ctx->list))
 		nfs_inode_attach_open_context(ctx);
 }
@@ -1067,6 +1068,8 @@ struct nfs_open_context *nfs_find_open_context(struct inode *inode, const struct
 			continue;
 		if ((pos->mode & (FMODE_READ|FMODE_WRITE)) != mode)
 			continue;
+		if (!test_bit(NFS_CONTEXT_FILE_OPEN, &pos->flags))
+			continue;
 		ctx = get_nfs_open_context(pos);
 		if (ctx)
 			break;
@@ -1082,6 +1085,7 @@ void nfs_file_clear_open_context(struct file *filp)
 	if (ctx) {
 		struct inode *inode = d_inode(ctx->dentry);
 
+		clear_bit(NFS_CONTEXT_FILE_OPEN, &ctx->flags);
 		/*
 		 * We fatal error on write before. Try to writeback
 		 * every page again.
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index ad09c0cc5464..978ef674f038 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -79,6 +79,7 @@ struct nfs_open_context {
 #define NFS_CONTEXT_RESEND_WRITES	(1)
 #define NFS_CONTEXT_BAD			(2)
 #define NFS_CONTEXT_UNLOCK	(3)
+#define NFS_CONTEXT_FILE_OPEN		(4)
 	int error;
 
 	struct list_head list;