libfs: Define a minimum directory offset

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

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Link: https://lore.kernel.org/r/170820142741.6328.12428356024575347885.stgit@91.116.238.104.host.secureserver.net
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/fs/libfs.c b/fs/libfs.c
index 752e24c669d974c5df4657262887708b61a061e6..f0045db739df892efae90730517279620a6cfc01 100644 (file)
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -240,6 +240,11 @@ 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));
@@ -261,9 +266,7 @@ 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;
 }
 
 /**
@@ -276,7 +279,7 @@ 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;
 
@@ -481,7 +484,7 @@ 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;