fs: provide locked helper variant of close_fd_get_file()
Assumes current->files->file_lock is already held on invocation. Helps
the caller check the file before removing the fd, if it needs to.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/fs/file.c b/fs/file.c
index dab120b..f3a4bac 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -22,6 +22,8 @@
#include <linux/close_range.h>
#include <net/sock.h>
+#include "internal.h"
+
unsigned int sysctl_nr_open __read_mostly = 1024*1024;
unsigned int sysctl_nr_open_min = BITS_PER_LONG;
/* our min() is unusable in constant expressions ;-/ */
@@ -732,6 +734,32 @@ int __close_range(unsigned fd, unsigned max_fd, unsigned int flags)
}
/*
+ * See close_fd_get_file() below, this variant assumes current->files->file_lock
+ * is held.
+ */
+int __close_fd_get_file(unsigned int fd, struct file **res)
+{
+ struct files_struct *files = current->files;
+ struct file *file;
+ struct fdtable *fdt;
+
+ fdt = files_fdtable(files);
+ if (fd >= fdt->max_fds)
+ goto out_err;
+ file = fdt->fd[fd];
+ if (!file)
+ goto out_err;
+ rcu_assign_pointer(fdt->fd[fd], NULL);
+ __put_unused_fd(files, fd);
+ get_file(file);
+ *res = file;
+ return 0;
+out_err:
+ *res = NULL;
+ return -ENOENT;
+}
+
+/*
* variant of close_fd that gets a ref on the file for later fput.
* The caller must ensure that filp_close() called on the file, and then
* an fput().
@@ -739,27 +767,13 @@ int __close_range(unsigned fd, unsigned max_fd, unsigned int flags)
int close_fd_get_file(unsigned int fd, struct file **res)
{
struct files_struct *files = current->files;
- struct file *file;
- struct fdtable *fdt;
+ int ret;
spin_lock(&files->file_lock);
- fdt = files_fdtable(files);
- if (fd >= fdt->max_fds)
- goto out_unlock;
- file = fdt->fd[fd];
- if (!file)
- goto out_unlock;
- rcu_assign_pointer(fdt->fd[fd], NULL);
- __put_unused_fd(files, fd);
+ ret = __close_fd_get_file(fd, res);
spin_unlock(&files->file_lock);
- get_file(file);
- *res = file;
- return 0;
-out_unlock:
- spin_unlock(&files->file_lock);
- *res = NULL;
- return -ENOENT;
+ return ret;
}
void do_close_on_exec(struct files_struct *files)
