[PATCH 14/17] file: Merge __fd_install into fd_install

Eric W. Biederman
2020-08-17T22:12:31Z

The function __fd_install was added to support binder[1]. With binder
fixed[2] there are no more users. Further with get_files_struct
removed there can be no more users of __fd_install that pass anything
except current->files.

As fd_install just calls __fd_install with "files=current->files",
merge them together by transforming the files parameter into a
local variable initialized to current->files.

[1] f869e8a7f753 ("expose a low-level variant of fd_install() for binder")
[2] 44d8047f1d87 ("binder: use standard functions to allocate fds")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
fs/file.c | 25 ++++++-------------------
include/linux/fdtable.h | 2 --
2 files changed, 6 insertions(+), 21 deletions(-)

diff --git a/fs/file.c b/fs/file.c
index 605e756f3c63..1a755811669d 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -157,7 +157,7 @@ static int expand_fdtable(struct files_struct *files, unsigned int nr)
spin_unlock(&files->file_lock);
new_fdt = alloc_fdtable(nr);

- /* make sure all __fd_install() have seen resize_in_progress
+ /* make sure all fd_install() have seen resize_in_progress
* or have finished their rcu_read_lock_sched() section.
*/
if (atomic_read(&files->count) > 1)
@@ -180,7 +180,7 @@ static int expand_fdtable(struct files_struct *files, unsigned int nr)
rcu_assign_pointer(files->fdt, new_fdt);
if (cur_fdt != &files->fdtab)
call_rcu(&cur_fdt->rcu, free_fdtable_rcu);
- /* coupled with smp_rmb() in __fd_install() */
+ /* coupled with smp_rmb() in fd_install() */
smp_wmb();
return 1;
}
@@ -569,17 +569,13 @@ EXPORT_SYMBOL(put_unused_fd);
* It should never happen - if we allow dup2() do it, _really_ bad things
* will follow.
*
- * NOTE: __fd_install() variant is really, really low-level; don't
- * use it unless you are forced to by truly lousy API shoved down
- * your throat. 'files' *MUST* be either current->files or obtained
- * by get_files_struct(current) done by whoever had given it to you,
- * or really bad things will happen. Normally you want to use
- * fd_install() instead.
+ * This consumes the "file" refcount, so callers should treat it
+ * as if they had called fput(file).
*/

-void __fd_install(struct files_struct *files, unsigned int fd,
- struct file *file)
+void fd_install(unsigned int fd, struct file *file)
{
+ struct files_struct *files = current->files;
struct fdtable *fdt;

rcu_read_lock_sched();
@@ -601,15 +597,6 @@ void __fd_install(struct files_struct *files, unsigned int fd,
rcu_read_unlock_sched();
}

-/*
- * This consumes the "file" refcount, so callers should treat it
- * as if they had called fput(file).
- */
-void fd_install(unsigned int fd, struct file *file)
-{
- __fd_install(current->files, fd, file);
-}
-
EXPORT_SYMBOL(fd_install);

static struct file *pick_file(struct files_struct *files, unsigned fd)
diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h
index 8c4bc6aa19c9..4da8aacc461a 100644
--- a/include/linux/fdtable.h
+++ b/include/linux/fdtable.h
@@ -118,8 +118,6 @@ int iterate_fd(struct files_struct *, unsigned,

extern int __alloc_fd(struct files_struct *files,
unsigned start, unsigned end, unsigned flags);
-extern void __fd_install(struct files_struct *files,
- unsigned int fd, struct file *file);
extern int __close_fd(struct files_struct *files,
unsigned int fd);
extern int __close_range(unsigned int fd, unsigned int max_fd, unsigned int flags);
--
2.25.0