Change calling conventions for filldir_t

filldir_t instances (directory iterators callbacks) used to return 0 for
"OK, keep going" or -E... for "stop".  Note that it's *NOT* how the
error values are reported - the rules for those are callback-dependent
and ->iterate{,_shared}() instances only care about zero vs. non-zero
(look at emit_dir() and friends).

So let's just return bool ("should we keep going?") - it's less confusing
that way.  The choice between "true means keep going" and "true means
stop" is bikesheddable; we have two groups of callbacks -
	do something for everything in directory, until we run into problem
and
	find an entry in directory and do something to it.

The former tended to use 0/-E... conventions - -E<something> on failure.
The latter tended to use 0/1, 1 being "stop, we are done".
The callers treated anything non-zero as "stop", ignoring which
non-zero value did they get.

"true means stop" would be more natural for the second group; "true
means keep going" - for the first one.  I tried both variants and
the things like
	if allocation failed
		something = -ENOMEM;
		return true;
just looked unnatural and asking for trouble.

[folded suggestion from Matthew Wilcox <willy@infradead.org>]
Acked-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 5 insertions, 4 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 9eced4cc286e..c40f68f62941 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2038,9 +2038,10 @@ umode_t mode_strip_sgid(struct user_namespace *mnt_userns,
  * the kernel specify what kind of dirent layout it wants to have.
  * This allows the kernel to read directories into kernel space or
  * to have different dirent layouts depending on the binary type.
+ * Return 'true' to keep going and 'false' if there are no more entries.
  */
 struct dir_context;
-typedef int (*filldir_t)(struct dir_context *, const char *, int, loff_t, u64,
+typedef bool (*filldir_t)(struct dir_context *, const char *, int, loff_t, u64,
 			 unsigned);
 
 struct dir_context {
@@ -3540,17 +3541,17 @@ static inline bool dir_emit(struct dir_context *ctx,
 			    const char *name, int namelen,
 			    u64 ino, unsigned type)
 {
-	return ctx->actor(ctx, name, namelen, ctx->pos, ino, type) == 0;
+	return ctx->actor(ctx, name, namelen, ctx->pos, ino, type);
 }
 static inline bool dir_emit_dot(struct file *file, struct dir_context *ctx)
 {
 	return ctx->actor(ctx, ".", 1, ctx->pos,
-			  file->f_path.dentry->d_inode->i_ino, DT_DIR) == 0;
+			  file->f_path.dentry->d_inode->i_ino, DT_DIR);
 }
 static inline bool dir_emit_dotdot(struct file *file, struct dir_context *ctx)
 {
 	return ctx->actor(ctx, "..", 2, ctx->pos,
-			  parent_ino(file->f_path.dentry), DT_DIR) == 0;
+			  parent_ino(file->f_path.dentry), DT_DIR);
 }
 static inline bool dir_emit_dots(struct file *file, struct dir_context *ctx)
 {