Merge tag 'pull-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull hostfs fix from Al Viro:
 "Fix hostfs __dentry_name() string handling.

  The use of strcpy() with overlapping source and destination is a UB;
  original loop hadn't been. More to the point, the whole thing is much
  easier done with memcpy() + memmove()"

* tag 'pull-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  hostfs: fix string handling in __dentry_name()

diff --combined fs/hostfs/hostfs_kern.c
index 844c452534525c106503a063f4a1924d34a67e6c,bd6503b731426443379cbe696f294200746b003e..e0741e468956dda545224ebe9cc0de8a73ecadbb
--- 1/fs/hostfs/hostfs_kern.c
--- 2/fs/hostfs/hostfs_kern.c
+++ b/fs/hostfs/hostfs_kern.c
@@@ -95,32 -95,17 +95,17 @@@ __uml_setup("hostfs=", hostfs_args
  static char *__dentry_name(struct dentry *dentry, char *name)
  {
        char *p = dentry_path_raw(dentry, name, PATH_MAX);
-       char *root;
-       size_t len;
-       struct hostfs_fs_info *fsi;
- 
-       fsi = dentry->d_sb->s_fs_info;
-       root = fsi->host_root_path;
-       len = strlen(root);
-       if (IS_ERR(p)) {
-               __putname(name);
-               return NULL;
-       }
- 
-       /*
-        * This function relies on the fact that dentry_path_raw() will place
-        * the path name at the end of the provided buffer.
-        */
-       BUG_ON(p + strlen(p) + 1 != name + PATH_MAX);
+       struct hostfs_fs_info *fsi = dentry->d_sb->s_fs_info;
+       char *root = fsi->host_root_path;
+       size_t len = strlen(root);
  
-       strscpy(name, root, PATH_MAX);
-       if (len > p - name) {
+       if (IS_ERR(p) || len > p - name) {
                __putname(name);
                return NULL;
        }
  
-       if (p > name + len)
-               strcpy(name + len, p);
+       memcpy(name, root, len);
+       memmove(name + len, p, name + PATH_MAX - p);
  
        return name;
  }
@@@ -410,33 -395,38 +395,33 @@@ static const struct file_operations hos
        .fsync          = hostfs_fsync,
  };
  
 -static int hostfs_writepage(struct page *page, struct writeback_control *wbc)
 +static int hostfs_writepages(struct address_space *mapping,
 +              struct writeback_control *wbc)
  {
 -      struct address_space *mapping = page->mapping;
        struct inode *inode = mapping->host;
 -      char *buffer;
 -      loff_t base = page_offset(page);
 -      int count = PAGE_SIZE;
 -      int end_index = inode->i_size >> PAGE_SHIFT;
 -      int err;
 -
 -      if (page->index >= end_index)
 -              count = inode->i_size & (PAGE_SIZE-1);
 -
 -      buffer = kmap_local_page(page);
 -
 -      err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count);
 -      if (err != count) {
 -              if (err >= 0)
 -                      err = -EIO;
 -              mapping_set_error(mapping, err);
 -              goto out;
 +      struct folio *folio = NULL;
 +      loff_t i_size = i_size_read(inode);
 +      int err = 0;
 +
 +      while ((folio = writeback_iter(mapping, wbc, folio, &err))) {
 +              loff_t pos = folio_pos(folio);
 +              size_t count = folio_size(folio);
 +              char *buffer;
 +              int ret;
 +
 +              if (count > i_size - pos)
 +                      count = i_size - pos;
 +
 +              buffer = kmap_local_folio(folio, 0);
 +              ret = write_file(HOSTFS_I(inode)->fd, &pos, buffer, count);
 +              kunmap_local(buffer);
 +              folio_unlock(folio);
 +              if (ret != count) {
 +                      err = ret < 0 ? ret : -EIO;
 +                      mapping_set_error(mapping, err);
 +              }
        }
  
 -      if (base > inode->i_size)
 -              inode->i_size = base;
 -
 -      err = 0;
 -
 - out:
 -      kunmap_local(buffer);
 -      unlock_page(page);
 -
        return err;
  }
  
@@@ -501,12 -491,11 +486,12 @@@ static int hostfs_write_end(struct fil
  }
  
  static const struct address_space_operations hostfs_aops = {
 -      .writepage      = hostfs_writepage,
 +      .writepages     = hostfs_writepages,
        .read_folio     = hostfs_read_folio,
        .dirty_folio    = filemap_dirty_folio,
        .write_begin    = hostfs_write_begin,
        .write_end      = hostfs_write_end,
 +      .migrate_folio  = filemap_migrate_folio,
  };
  
  static int hostfs_inode_update(struct inode *ino, const struct hostfs_stat *st)