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Message-ID: <1400643406.12240.6.camel@kjgkr>
Date: Wed, 21 May 2014 12:36:46 +0900
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: Chao Yu <chao2.yu@...sung.com>
Cc: Jaegeuk Kim <jaegeuk.kim@...sung.com>,
linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH] f2fs: avoid crash when trace
f2fs_submit_page_mbio event in ra_sum_pages
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.yu@...sung.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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