[RFC PATCH 1/6 6.6] libfs: Define a minimum directory offset

[cel]

From: Chuck Lever <chuck.lever@xxxxxxxxxx>

[ Upstream commit 7beea725a8ca412c6190090ce7c3a13b169592a1 ]

This value is used in several places, so make it a symbolic
constant.

Reviewed-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
Link: https://lore.kernel.org/r/170820142741.6328.12428356024575347885.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
Stable-dep-of: ecba88a3b32d ("libfs: Add simple_offset_empty()")
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
 fs/libfs.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/fs/libfs.c b/fs/libfs.c
index dc0f7519045f..4a2205afcc88 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -239,6 +239,11 @@ const struct inode_operations simple_dir_inode_operations = {
 };
 EXPORT_SYMBOL(simple_dir_inode_operations);
 
+/* 0 is '.', 1 is '..', so always start with offset 2 or more */
+enum {
+	DIR_OFFSET_MIN	= 2,
+};
+
 static void offset_set(struct dentry *dentry, u32 offset)
 {
 	dentry->d_fsdata = (void *)((uintptr_t)(offset));
@@ -260,9 +265,7 @@ void simple_offset_init(struct offset_ctx *octx)
 {
 	xa_init_flags(&octx->xa, XA_FLAGS_ALLOC1);
 	lockdep_set_class(&octx->xa.xa_lock, &simple_offset_xa_lock);
-
-	/* 0 is '.', 1 is '..', so always start with offset 2 */
-	octx->next_offset = 2;
+	octx->next_offset = DIR_OFFSET_MIN;
 }
 
 /**
@@ -275,7 +278,7 @@ void simple_offset_init(struct offset_ctx *octx)
  */
 int simple_offset_add(struct offset_ctx *octx, struct dentry *dentry)
 {
-	static const struct xa_limit limit = XA_LIMIT(2, U32_MAX);
+	static const struct xa_limit limit = XA_LIMIT(DIR_OFFSET_MIN, U32_MAX);
 	u32 offset;
 	int ret;
 
@@ -480,7 +483,7 @@ static int offset_readdir(struct file *file, struct dir_context *ctx)
 		return 0;
 
 	/* In this case, ->private_data is protected by f_pos_lock */
-	if (ctx->pos == 2)
+	if (ctx->pos == DIR_OFFSET_MIN)
 		file->private_data = NULL;
 	else if (file->private_data == ERR_PTR(-ENOENT))
 		return 0;
-- 
2.47.0