configfs_readdir(): make safe under shared lock

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 7 insertions, 13 deletions

diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c
index 48929c408e04..56fb26127fef 100644
--- a/fs/configfs/dir.c
+++ b/fs/configfs/dir.c
@@ -1633,11 +1633,9 @@ static int configfs_readdir(struct file *file, struct dir_context *ctx)
 
         if (!dir_emit_dots(file, ctx))
                 return 0;
-        if (ctx->pos == 2) {
-                spin_lock(&configfs_dirent_lock);
+        spin_lock(&configfs_dirent_lock);
+        if (ctx->pos == 2)
                 list_move(q, &parent_sd->s_children);
-                spin_unlock(&configfs_dirent_lock);
-        }
         for (p = q->next; p != &parent_sd->s_children; p = p->next) {
                 struct configfs_dirent *next;
                 const char *name;
@@ -1648,9 +1646,6 @@ static int configfs_readdir(struct file *file, struct dir_context *ctx)
                 if (!next->s_element)
                         continue;
 
-                name = configfs_get_name(next);
-                len = strlen(name);
-
                 /*
                  * We'll have a dentry and an inode for
                  * PINNED items and for open attribute
@@ -1664,7 +1659,6 @@ static int configfs_readdir(struct file *file, struct dir_context *ctx)
                  * they close it.  Beyond that, we don't
                  * care.
                  */
-                spin_lock(&configfs_dirent_lock);
                 dentry = next->s_dentry;
                 if (dentry)
                         inode = d_inode(dentry);
@@ -1674,15 +1668,18 @@ static int configfs_readdir(struct file *file, struct dir_context *ctx)
                 if (!inode)
                         ino = iunique(sb, 2);
 
+                name = configfs_get_name(next);
+                len = strlen(name);
+
                 if (!dir_emit(ctx, name, len, ino, dt_type(next)))
                         return 0;
 
                 spin_lock(&configfs_dirent_lock);
                 list_move(q, p);
-                spin_unlock(&configfs_dirent_lock);
                 p = q;
                 ctx->pos++;
         }
+        spin_unlock(&configfs_dirent_lock);
         return 0;
 }
 
@@ -1690,7 +1687,6 @@ static loff_t configfs_dir_lseek(struct file *file, loff_t offset, int whence)
 {
         struct dentry * dentry = file->f_path.dentry;
 
-        inode_lock(d_inode(dentry));
         switch (whence) {
                 case 1:
                         offset += file->f_pos;
@@ -1698,7 +1694,6 @@ static loff_t configfs_dir_lseek(struct file *file, loff_t offset, int whence)
                         if (offset >= 0)
                                 break;
                 default:
-                        inode_unlock(d_inode(dentry));
                         return -EINVAL;
         }
         if (offset != file->f_pos) {
@@ -1724,7 +1719,6 @@ static loff_t configfs_dir_lseek(struct file *file, loff_t offset, int whence)
                         spin_unlock(&configfs_dirent_lock);
                 }
         }
-        inode_unlock(d_inode(dentry));
         return offset;
 }
 
@@ -1733,7 +1727,7 @@ const struct file_operations configfs_dir_operations = {
         .release        = configfs_dir_close,
         .llseek         = configfs_dir_lseek,
         .read           = generic_read_dir,
-        .iterate        = configfs_readdir,
+        .iterate_shared = configfs_readdir,
 };
 
 /**