On 2014/12/11 10:30, hujianyang wrote:
> Since the ovl_dir_cache is stable during a directory reading, the cursor
> of struct ovl_dir_file don't need to be an independent entry in the list
> of a merged directory.
>
> This patch changes *cursor* to a pointer which points to the entry in the
> ovl_dir_cache. After this, we don't need to check *is_cursor* either.
>
> Signed-off-by: hujianyang <hujianyang@xxxxxxxxxx>
> ---
> fs/overlayfs/readdir.c | 33 ++++++++++++---------------------
> 1 files changed, 12 insertions(+), 21 deletions(-)
>
> diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
> index 8087b63..b65e1ed 100644
> --- a/fs/overlayfs/readdir.c
> +++ b/fs/overlayfs/readdir.c
> @@ -24,7 +24,6 @@ struct ovl_cache_entry {
> struct list_head l_node;
> struct rb_node node;
> bool is_whiteout;
> - bool is_cursor;
> char name[];
> };
>
> @@ -49,7 +48,7 @@ struct ovl_dir_file {
> bool is_real;
> bool is_upper;
> struct ovl_dir_cache *cache;
> - struct ovl_cache_entry cursor;
> + struct ovl_cache_entry *cursor;
> struct file *realfile;
> struct file *upperfile;
> };
> @@ -94,7 +93,6 @@ static struct ovl_cache_entry *ovl_cache_entry_new(const char *name, int len,
> p->type = d_type;
> p->ino = ino;
> p->is_whiteout = false;
> - p->is_cursor = false;
> }
>
> return p;
> @@ -195,7 +193,7 @@ static void ovl_cache_put(struct ovl_dir_file *od, struct dentry *dentry)
> {
> struct ovl_dir_cache *cache = od->cache;
>
> - list_del_init(&od->cursor.l_node);
> + od->cursor = NULL;
> WARN_ON(cache->refcount <= 0);
> cache->refcount--;
> if (!cache->refcount) {
> @@ -298,13 +296,12 @@ static void ovl_seek_cursor(struct ovl_dir_file *od, loff_t pos)
> loff_t off = 0;
>
> list_for_each_entry(p, &od->cache->entries, l_node) {
> - if (p->is_cursor)
> - continue;
> if (off >= pos)
> break;
> off++;
> }
> - list_move_tail(&od->cursor.l_node, &p->l_node);
> + /* Curosr is safe since the cache is stable */
> + od->cursor = p;
> }
>
> static struct ovl_dir_cache *ovl_cache_get(struct dentry *dentry)
> @@ -361,19 +358,14 @@ static int ovl_iterate(struct file *file, struct dir_context *ctx)
> ovl_seek_cursor(od, ctx->pos);
> }
>
> - while (od->cursor.l_node.next != &od->cache->entries) {
> - struct ovl_cache_entry *p;
> + while (&od->cursor->l_node != &od->cache->entries) {
> + struct ovl_cache_entry *p = od->cursor;
>
> - p = list_entry(od->cursor.l_node.next, struct ovl_cache_entry, l_node);
> - /* Skip cursors */
> - if (!p->is_cursor) {
> - if (!p->is_whiteout) {
> - if (!dir_emit(ctx, p->name, p->len, p->ino, p->type))
> - break;
> - }
> - ctx->pos++;
> - }
> - list_move(&od->cursor.l_node, &p->l_node);
> + if (!p->is_whiteout)
> + if (!dir_emit(ctx, p->name, p->len, p->ino, p->type))
> + break;
> + od->cursor = list_next_entry(p, l_node);
> + ctx->pos++;
> }
> return 0;
> }
> @@ -492,11 +484,10 @@ static int ovl_dir_open(struct inode *inode, struct file *file)
> kfree(od);
> return PTR_ERR(realfile);
> }
> - INIT_LIST_HEAD(&od->cursor.l_node);
> od->realfile = realfile;
> od->is_real = !OVL_TYPE_MERGE(type);
> od->is_upper = OVL_TYPE_UPPER(type);
> - od->cursor.is_cursor = true;
> + od->cursor = NULL;
> file->private_data = od;
>
> return 0;
>
Hi Miklos,
How do you feel about this cleanup?
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