Hi Chao,

2014-05-16 (금), 17:14 +0800, Chao Yu:
> Previously we allocate pages with no mapping in ra_sum_pages(), so we may
> encounter a crash in event trace of f2fs_submit_page_mbio where we access
> mapping data of the page.
> 
> We'd better allocate pages in bd_inode mapping and invalidate these pages 
> after
> we restore data from pages. It could avoid crash in above scenario.
> 
> Call Trace:
>  [<f1031630>] ? ftrace_raw_event_f2fs_write_checkpoint+0x80/0x80 [f2fs]
>  [<f10377bb>] f2fs_submit_page_mbio+0x1cb/0x200 [f2fs]
>  [<f103c5da>] restore_node_summary+0x13a/0x280 [f2fs]
>  [<f103e22d>] build_curseg+0x2bd/0x620 [f2fs]
>  [<f104043b>] build_segment_manager+0x1cb/0x920 [f2fs]
>  [<f1032c85>] f2fs_fill_super+0x535/0x8e0 [f2fs]
>  [<c115b66a>] mount_bdev+0x16a/0x1a0
>  [<f102f63f>] f2fs_mount+0x1f/0x30 [f2fs]
>  [<c115c096>] mount_fs+0x36/0x170
>  [<c1173635>] vfs_kern_mount+0x55/0xe0
>  [<c1175388>] do_mount+0x1e8/0x900
>  [<c1175d72>] SyS_mount+0x82/0xc0
>  [<c16059cc>] sysenter_do_call+0x12/0x22
> 
> Signed-off-by: Chao Yu <chao2...@samsung.com>
> ---
>  fs/f2fs/node.c |   49 ++++++++++++++++++++++++++++---------------------
>  1 file changed, 28 insertions(+), 21 deletions(-)
> 
> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> index 3d60d3d..b5cd814 100644
> --- a/fs/f2fs/node.c
> +++ b/fs/f2fs/node.c
> @@ -1658,13 +1658,16 @@ int recover_inode_page(struct f2fs_sb_info *sbi, 
> struct page *page)
>  
>  /*
>   * ra_sum_pages() merge contiguous pages into one bio and submit.
> - * these pre-readed pages are linked in pages list.
> + * these pre-readed pages are alloced in bd_inode's mapping tree.
>   */
> -static int ra_sum_pages(struct f2fs_sb_info *sbi, struct list_head *pages,
> +static int ra_sum_pages(struct f2fs_sb_info *sbi, struct page **pages,
>                               int start, int nrpages)
>  {
>       struct page *page;
> +     struct inode *inode = sbi->sb->s_bdev->bd_inode;
> +     struct address_space *mapping = inode->i_mapping;
>       int page_idx = start;
> +     int alloced, readed;
>       struct f2fs_io_info fio = {
>               .type = META,
>               .rw = READ_SYNC | REQ_META | REQ_PRIO
> @@ -1672,21 +1675,23 @@ static int ra_sum_pages(struct f2fs_sb_info *sbi, 
> struct list_head *pages,
>  
>       for (; page_idx < start + nrpages; page_idx++) {
>               /* alloc temporal page for read node summary info*/
> -             page = alloc_page(GFP_F2FS_ZERO);
> +             page = grab_cache_page(mapping, page_idx);
>               if (!page)
>                       break;
> -
> -             lock_page(page);
> -             page->index = page_idx;
> -             list_add_tail(&page->lru, pages);
> +             page_cache_release(page);

IMO, we don't need to do like this.
Instead,
        for() {
                page = grab_cache_page();
                if (!page)
                        break;
                page[page_idx] = page;
                f2fs_submit_page_mbio(sbi, page, &fio);
        }
        f2fs_submit_merged_bio(sbi, META, READ);
        return page_idx - start;

Afterwards, in restore_node_summry(),
        lock_page() will wait the end_io for read.
        ...
        f2fs_put_page(pages[index], 1);

Thanks,

>       }
>  
> -     list_for_each_entry(page, pages, lru)
> -             f2fs_submit_page_mbio(sbi, page, page->index, &fio);
> +     alloced = page_idx - start;
> +     readed = find_get_pages_contig(mapping, start, alloced, pages);
> +     BUG_ON(alloced != readed);
> +
> +     for (page_idx = 0; page_idx < readed; page_idx++)
> +             f2fs_submit_page_mbio(sbi, pages[page_idx],
> +                                     pages[page_idx]->index, &fio);
>  
>       f2fs_submit_merged_bio(sbi, META, READ);
>  
> -     return page_idx - start;
> +     return readed;
>  }
>  
>  int restore_node_summary(struct f2fs_sb_info *sbi,
> @@ -1694,11 +1699,11 @@ int restore_node_summary(struct f2fs_sb_info *sbi,
>  {
>       struct f2fs_node *rn;
>       struct f2fs_summary *sum_entry;
> -     struct page *page, *tmp;
> +     struct inode *inode = sbi->sb->s_bdev->bd_inode;
>       block_t addr;
>       int bio_blocks = MAX_BIO_BLOCKS(max_hw_blocks(sbi));
> -     int i, last_offset, nrpages, err = 0;
> -     LIST_HEAD(page_list);
> +     struct page *pages[bio_blocks];
> +     int i, index, last_offset, nrpages, err = 0;
>  
>       /* scan the node segment */
>       last_offset = sbi->blocks_per_seg;
> @@ -1709,29 +1714,31 @@ int restore_node_summary(struct f2fs_sb_info *sbi,
>               nrpages = min(last_offset - i, bio_blocks);
>  
>               /* read ahead node pages */
> -             nrpages = ra_sum_pages(sbi, &page_list, addr, nrpages);
> +             nrpages = ra_sum_pages(sbi, pages, addr, nrpages);
>               if (!nrpages)
>                       return -ENOMEM;
>  
> -             list_for_each_entry_safe(page, tmp, &page_list, lru) {
> +             for (index = 0; index < nrpages; index++) {
>                       if (err)
>                               goto skip;
>  
> -                     lock_page(page);
> -                     if (unlikely(!PageUptodate(page))) {
> +                     lock_page(pages[index]);
> +                     if (unlikely(!PageUptodate(pages[index]))) {
>                               err = -EIO;
>                       } else {
> -                             rn = F2FS_NODE(page);
> +                             rn = F2FS_NODE(pages[index]);
>                               sum_entry->nid = rn->footer.nid;
>                               sum_entry->version = 0;
>                               sum_entry->ofs_in_node = 0;
>                               sum_entry++;
>                       }
> -                     unlock_page(page);
> +                     unlock_page(pages[index]);
>  skip:
> -                     list_del(&page->lru);
> -                     __free_pages(page, 0);
> +                     page_cache_release(pages[index]);
>               }
> +
> +             invalidate_mapping_pages(inode->i_mapping, addr,
> +                                                     addr + nrpages);
>       }
>       return err;
>  }

-- 
Jaegeuk Kim

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