diff options
| -rw-r--r-- | fs/libfs.c | 77 |
1 files changed, 47 insertions, 30 deletions
diff --git a/fs/libfs.c b/fs/libfs.c index f56acb1e5fbc..b05b74ae3f16 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -84,6 +84,39 @@ int dcache_dir_close(struct inode *inode, struct file *file) } EXPORT_SYMBOL(dcache_dir_close); +/* parent is locked at least shared */ +static struct dentry *next_positive(struct dentry *parent, + struct list_head *from, + int count) +{ + struct dentry *res = NULL; + struct list_head *p; + + spin_lock(&parent->d_lock); + for (p = from->next; p != &parent->d_subdirs; p = p->next) { + struct dentry *d = list_entry(p, struct dentry, d_child); + if (simple_positive(d) && !--count) { + res = d; + break; + } + } + spin_unlock(&parent->d_lock); + return res; +} + +static void move_cursor(struct dentry *cursor, struct list_head *after) +{ + struct dentry *parent = cursor->d_parent; + + spin_lock(&parent->d_lock); + __list_del(cursor->d_child.prev, cursor->d_child.next); + if (after) + list_add(&cursor->d_child, after); + else + list_add_tail(&cursor->d_child, &parent->d_subdirs); + spin_unlock(&parent->d_lock); +} + loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence) { struct dentry *dentry = file->f_path.dentry; @@ -99,24 +132,13 @@ loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence) if (offset != file->f_pos) { file->f_pos = offset; if (file->f_pos >= 2) { - struct list_head *p; struct dentry *cursor = file->private_data; + struct dentry *to; loff_t n = file->f_pos - 2; inode_lock_shared(dentry->d_inode); - spin_lock(&dentry->d_lock); - /* d_lock not required for cursor */ - list_del(&cursor->d_child); - p = dentry->d_subdirs.next; - while (n && p != &dentry->d_subdirs) { - struct dentry *next; - next = list_entry(p, struct dentry, d_child); - if (simple_positive(next)) - n--; - p = p->next; - } - list_add_tail(&cursor->d_child, p); - spin_unlock(&dentry->d_lock); + to = next_positive(dentry, &dentry->d_subdirs, n); + move_cursor(cursor, to ? &to->d_child : NULL); inode_unlock_shared(dentry->d_inode); } } @@ -140,30 +162,25 @@ int dcache_readdir(struct file *file, struct dir_context *ctx) { struct dentry *dentry = file->f_path.dentry; struct dentry *cursor = file->private_data; - struct list_head *p, *q = &cursor->d_child; + struct list_head *p = &cursor->d_child; + struct dentry *next; + bool moved = false; if (!dir_emit_dots(file, ctx)) return 0; - spin_lock(&dentry->d_lock); - if (ctx->pos == 2) - list_move(q, &dentry->d_subdirs); - for (p = q->next; p != &dentry->d_subdirs; p = p->next) { - struct dentry *next = list_entry(p, struct dentry, d_child); - if (!simple_positive(next)) - continue; - - spin_unlock(&dentry->d_lock); + if (ctx->pos == 2) + p = &dentry->d_subdirs; + while ((next = next_positive(dentry, p, 1)) != NULL) { if (!dir_emit(ctx, next->d_name.name, next->d_name.len, d_inode(next)->i_ino, dt_type(d_inode(next)))) - return 0; - spin_lock(&dentry->d_lock); - /* next is still alive */ - list_move(q, p); - p = q; + break; + moved = true; + p = &next->d_child; ctx->pos++; } - spin_unlock(&dentry->d_lock); + if (moved) + move_cursor(cursor, p); return 0; } EXPORT_SYMBOL(dcache_readdir); |