5.10-stable review patch. If anyone has any objections, please let me know.
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From: Eric W. Biederman ebiederm@xmission.com
[ Upstream commit 3a879fb38082125cc0d8aa89b70c7f3a7cdf584b ]
As a companion to lookup_fd_rcu implement task_lookup_fd_rcu for querying an arbitrary process about a specific file.
Acked-by: Christian Brauner christian.brauner@ubuntu.com v1: https://lkml.kernel.org/r/20200818103713.aw46m7vprsy4vlve@wittgenstein Link: https://lkml.kernel.org/r/20201120231441.29911-11-ebiederm@xmission.com Signed-off-by: Eric W. Biederman ebiederm@xmission.com Signed-off-by: Chuck Lever chuck.lever@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/file.c | 15 +++++++++++++++ include/linux/fdtable.h | 2 ++ 2 files changed, 17 insertions(+)
diff --git a/fs/file.c b/fs/file.c index 6149f75a18a66..60a3ccba728cd 100644 --- a/fs/file.c +++ b/fs/file.c @@ -911,6 +911,21 @@ struct file *fget_task(struct task_struct *task, unsigned int fd) return file; }
+struct file *task_lookup_fd_rcu(struct task_struct *task, unsigned int fd) +{ + /* Must be called with rcu_read_lock held */ + struct files_struct *files; + struct file *file = NULL; + + task_lock(task); + files = task->files; + if (files) + file = files_lookup_fd_rcu(files, fd); + task_unlock(task); + + return file; +} + /* * Lightweight file lookup - no refcnt increment if fd table isn't shared. * diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h index 695306cc5337a..a88f68f740677 100644 --- a/include/linux/fdtable.h +++ b/include/linux/fdtable.h @@ -110,6 +110,8 @@ static inline struct file *lookup_fd_rcu(unsigned int fd) return files_lookup_fd_rcu(current->files, fd); }
+struct file *task_lookup_fd_rcu(struct task_struct *task, unsigned int fd); + struct task_struct;
struct files_struct *get_files_struct(struct task_struct *);