introduce fd_file(), convert all accessors to it.

	For any changes of struct fd representation we need to
turn existing accesses to fields into calls of wrappers.
Accesses to struct fd::flags are very few (3 in linux/file.h,
1 in net/socket.c, 3 in fs/overlayfs/file.c and 3 more in
explicit initializers).
	Those can be dealt with in the commit converting to
new layout; accesses to struct fd::file are too many for that.
	This commit converts (almost) all of f.file to
fd_file(f).  It's not entirely mechanical ('file' is used as
a member name more than just in struct fd) and it does not
even attempt to distinguish the uses in pointer context from
those in boolean context; the latter will be eventually turned
into a separate helper (fd_empty()).

	NOTE: mass conversion to fd_empty(), tempting as it
might be, is a bad idea; better do that piecewise in commit
that convert from fdget...() to CLASS(...).

[conflicts in fs/fhandle.c, kernel/bpf/syscall.c, mm/memcontrol.c
caught by git; fs/stat.c one got caught by git grep]
[fs/xattr.c conflict]

Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

4 files changed, 16 insertions, 16 deletions

diff --git a/mm/fadvise.c b/mm/fadvise.c
index 6c39d42f16dc..532dee205c6e 100644
--- a/mm/fadvise.c
+++ b/mm/fadvise.c
@@ -193,10 +193,10 @@ int ksys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice)
 	struct fd f = fdget(fd);
 	int ret;
 
-	if (!f.file)
+	if (!fd_file(f))
 		return -EBADF;
 
-	ret = vfs_fadvise(f.file, offset, len, advice);
+	ret = vfs_fadvise(fd_file(f), offset, len, advice);
 
 	fdput(f);
 	return ret;
diff --git a/mm/filemap.c b/mm/filemap.c
index d62150418b91..0b5cbd644fdd 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -4393,7 +4393,7 @@ SYSCALL_DEFINE4(cachestat, unsigned int, fd,
 	struct cachestat cs;
 	pgoff_t first_index, last_index;
 
-	if (!f.file)
+	if (!fd_file(f))
 		return -EBADF;
 
 	if (copy_from_user(&csr, cstat_range,
@@ -4403,7 +4403,7 @@ SYSCALL_DEFINE4(cachestat, unsigned int, fd,
 	}
 
 	/* hugetlbfs is not supported */
-	if (is_file_hugepages(f.file)) {
+	if (is_file_hugepages(fd_file(f))) {
 		fdput(f);
 		return -EOPNOTSUPP;
 	}
@@ -4417,7 +4417,7 @@ SYSCALL_DEFINE4(cachestat, unsigned int, fd,
 	last_index =
 		csr.len == 0 ? ULONG_MAX : (csr.off + csr.len - 1) >> PAGE_SHIFT;
 	memset(&cs, 0, sizeof(struct cachestat));
-	mapping = f.file->f_mapping;
+	mapping = fd_file(f)->f_mapping;
 	filemap_cachestat(mapping, first_index, last_index, &cs);
 	fdput(f);
 
diff --git a/mm/memcontrol-v1.c b/mm/memcontrol-v1.c
index 2aeea4d8bf8e..da626ddccffd 100644
--- a/mm/memcontrol-v1.c
+++ b/mm/memcontrol-v1.c
@@ -1857,26 +1857,26 @@ static ssize_t memcg_write_event_control(struct kernfs_open_file *of,
 	INIT_WORK(&event->remove, memcg_event_remove);
 
 	efile = fdget(efd);
-	if (!efile.file) {
+	if (!fd_file(efile)) {
 		ret = -EBADF;
 		goto out_kfree;
 	}
 
-	event->eventfd = eventfd_ctx_fileget(efile.file);
+	event->eventfd = eventfd_ctx_fileget(fd_file(efile));
 	if (IS_ERR(event->eventfd)) {
 		ret = PTR_ERR(event->eventfd);
 		goto out_put_efile;
 	}
 
 	cfile = fdget(cfd);
-	if (!cfile.file) {
+	if (!fd_file(cfile)) {
 		ret = -EBADF;
 		goto out_put_eventfd;
 	}
 
 	/* the process need read permission on control file */
 	/* AV: shouldn't we check that it's been opened for read instead? */
-	ret = file_permission(cfile.file, MAY_READ);
+	ret = file_permission(fd_file(cfile), MAY_READ);
 	if (ret < 0)
 		goto out_put_cfile;
 
@@ -1884,7 +1884,7 @@ static ssize_t memcg_write_event_control(struct kernfs_open_file *of,
 	 * The control file must be a regular cgroup1 file. As a regular cgroup
 	 * file can't be renamed, it's safe to access its name afterwards.
 	 */
-	cdentry = cfile.file->f_path.dentry;
+	cdentry = fd_file(cfile)->f_path.dentry;
 	if (cdentry->d_sb->s_type != &cgroup_fs_type || !d_is_reg(cdentry)) {
 		ret = -EINVAL;
 		goto out_put_cfile;
@@ -1936,7 +1936,7 @@ static ssize_t memcg_write_event_control(struct kernfs_open_file *of,
 	if (ret)
 		goto out_put_css;
 
-	vfs_poll(efile.file, &event->pt);
+	vfs_poll(fd_file(efile), &event->pt);
 
 	spin_lock_irq(&memcg->event_list_lock);
 	list_add(&event->list, &memcg->event_list);
diff --git a/mm/readahead.c b/mm/readahead.c
index 517c0be7ce66..e83fe1c6e5ac 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -646,7 +646,7 @@ ssize_t ksys_readahead(int fd, loff_t offset, size_t count)
 
 	ret = -EBADF;
 	f = fdget(fd);
-	if (!f.file || !(f.file->f_mode & FMODE_READ))
+	if (!fd_file(f) || !(fd_file(f)->f_mode & FMODE_READ))
 		goto out;
 
 	/*
@@ -655,12 +655,12 @@ ssize_t ksys_readahead(int fd, loff_t offset, size_t count)
 	 * on this file, then we must return -EINVAL.
 	 */
 	ret = -EINVAL;
-	if (!f.file->f_mapping || !f.file->f_mapping->a_ops ||
-	    (!S_ISREG(file_inode(f.file)->i_mode) &&
-	    !S_ISBLK(file_inode(f.file)->i_mode)))
+	if (!fd_file(f)->f_mapping || !fd_file(f)->f_mapping->a_ops ||
+	    (!S_ISREG(file_inode(fd_file(f))->i_mode) &&
+	    !S_ISBLK(file_inode(fd_file(f))->i_mode)))
 		goto out;
 
-	ret = vfs_fadvise(f.file, offset, count, POSIX_FADV_WILLNEED);
+	ret = vfs_fadvise(fd_file(f), offset, count, POSIX_FADV_WILLNEED);
 out:
 	fdput(f);
 	return ret;