um: hostfs: Reduce number of syscalls in readdir

Currently hostfs issues every time a seekdir(), in fact
it has to do this only upon the first call.
Also telldir() can be omitted as we can obtain the directory
offset from readdir().

Signed-off-by: Richard Weinberger <richard@nod.at>

3 files changed, 12 insertions, 4 deletions

diff --git a/fs/hostfs/hostfs.h b/fs/hostfs/hostfs.h
index 493262e43443..91e19f9dffe5 100644
--- a/fs/hostfs/hostfs.h
+++ b/fs/hostfs/hostfs.h
@@ -66,7 +66,8 @@ extern int stat_file(const char *path, struct hostfs_stat *p, int fd);
 extern int access_file(char *path, int r, int w, int x);
 extern int open_file(char *path, int r, int w, int append);
 extern void *open_dir(char *path, int *err_out);
-extern char *read_dir(void *stream, unsigned long long *pos,
+extern void seek_dir(void *stream, unsigned long long pos);
+extern char *read_dir(void *stream, unsigned long long *pos_out,
                       unsigned long long *ino_out, int *len_out,
                       unsigned int *type_out);
 extern void close_file(void *stream);
diff --git a/fs/hostfs/hostfs_kern.c b/fs/hostfs/hostfs_kern.c
index e77da44a235c..d0a2f68a0eea 100644
--- a/fs/hostfs/hostfs_kern.c
+++ b/fs/hostfs/hostfs_kern.c
@@ -292,6 +292,7 @@ static int hostfs_readdir(struct file *file, struct dir_context *ctx)
         if (dir == NULL)
                 return -error;
         next = ctx->pos;
+        seek_dir(dir, next);
         while ((name = read_dir(dir, &next, &ino, &len, &type)) != NULL) {
                 if (!dir_emit(ctx, name, len, ino, type))
                         break;
diff --git a/fs/hostfs/hostfs_user.c b/fs/hostfs/hostfs_user.c
index 34ab81b21c93..9c1e0f019880 100644
--- a/fs/hostfs/hostfs_user.c
+++ b/fs/hostfs/hostfs_user.c
@@ -97,21 +97,27 @@ void *open_dir(char *path, int *err_out)
         return dir;
 }
 
-char *read_dir(void *stream, unsigned long long *pos,
+void seek_dir(void *stream, unsigned long long pos)
+{
+        DIR *dir = stream;
+
+        seekdir(dir, pos);
+}
+
+char *read_dir(void *stream, unsigned long long *pos_out,
                unsigned long long *ino_out, int *len_out,
                unsigned int *type_out)
 {
         DIR *dir = stream;
         struct dirent *ent;
 
-        seekdir(dir, *pos);
         ent = readdir(dir);
         if (ent == NULL)
                 return NULL;
         *len_out = strlen(ent->d_name);
         *ino_out = ent->d_ino;
         *type_out = ent->d_type;
-        *pos = telldir(dir);
+        *pos_out = ent->d_off;
         return ent->d_name;
 }