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Commit f1406b66 authored by Sayali Lokhande's avatar Sayali Lokhande Committed by Gerrit - the friendly Code Review server
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f2fs: Avoid double lock for cp_rwsem during checkpoint 



There could be a scenario where f2fs_sync_node_pages gets
called during checkpoint, which in turn tries to flush
inline data and calls iput(). This results in deadlock as
iput() tries to hold cp_rwsem, which is already held at the
beginning by checkpoint->block_operations().

Call stack :

Thread A		Thread B
f2fs_write_checkpoint()
- block_operations(sbi)
 - f2fs_lock_all(sbi);
  - down_write(&sbi->cp_rwsem);

                        - open()
                         - igrab()
                        - write() write inline data
                        - unlink()
- f2fs_sync_node_pages()
 - if (is_inline_node(page))
  - flush_inline_data()
   - ilookup()
     page = f2fs_pagecache_get_page()
     if (!page)
      goto iput_out;
     iput_out:
			-close()
			-iput()
       iput(inode);
       - f2fs_evict_inode()
        - f2fs_truncate_blocks()
         - f2fs_lock_op()
           - down_read(&sbi->cp_rwsem);

Change-Id: I048bbf42c0b11108e2444f4d9df5d58e7a779c3c
Fixes: 2049d4fc ("f2fs: avoid multiple node page writes due to inline_data")
Signed-off-by: default avatarSayali Lokhande <sayalil@codeaurora.org>
Signed-off-by: default avatarJaegeuk Kim <jaegeuk@kernel.org>
Git-commit: 34c061ad85a2f5d5e9e3b045d72f3b211db6e282
Git-repo: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/


Signed-off-by: default avatarSayali Lokhande <sayalil@codeaurora.org>
parent 603e25f0

fs/f2fs/checkpoint.c

+5 −0
Original line number Diff line number Diff line
@@ -1168,6 +1168,11 @@ static int block_operations(struct f2fs_sb_info *sbi) 


	blk_start_plug(&plug);



	/*

	 * Let's flush inline_data in dirty node pages.

	 */

	f2fs_flush_inline_data(sbi);



retry_flush_quotas:

	f2fs_lock_all(sbi);

	if (__need_flush_quota(sbi)) {

fs/f2fs/f2fs.h

+1 −0
Original line number Diff line number Diff line
@@ -3175,6 +3175,7 @@ void f2fs_ra_node_page(struct f2fs_sb_info *sbi, nid_t nid); 
struct page *f2fs_get_node_page(struct f2fs_sb_info *sbi, pgoff_t nid);

struct page *f2fs_get_node_page_ra(struct page *parent, int start);

int f2fs_move_node_page(struct page *node_page, int gc_type);

int f2fs_flush_inline_data(struct f2fs_sb_info *sbi);

int f2fs_fsync_node_pages(struct f2fs_sb_info *sbi, struct inode *inode,

			struct writeback_control *wbc, bool atomic,

			unsigned int *seq_id);

fs/f2fs/node.c

+49 −2
Original line number Diff line number Diff line
@@ -1804,6 +1804,53 @@ static bool flush_dirty_inode(struct page *page) 
	return true;

}



int f2fs_flush_inline_data(struct f2fs_sb_info *sbi)

{

	pgoff_t index = 0;

	struct pagevec pvec;

	int nr_pages;

	int ret = 0;



	pagevec_init(&pvec);



	while ((nr_pages = pagevec_lookup_tag(&pvec,

			NODE_MAPPING(sbi), &index, PAGECACHE_TAG_DIRTY))) {

		int i;



		for (i = 0; i < nr_pages; i++) {

			struct page *page = pvec.pages[i];



			if (!IS_DNODE(page))

				continue;



			lock_page(page);



			if (unlikely(page->mapping != NODE_MAPPING(sbi))) {

continue_unlock:

				unlock_page(page);

				continue;

			}



			if (!PageDirty(page)) {

				/* someone wrote it for us */

				goto continue_unlock;

			}



			/* flush inline_data, if it's async context. */

			if (is_inline_node(page)) {

				clear_inline_node(page);

				unlock_page(page);

				flush_inline_data(sbi, ino_of_node(page));

				continue;

			}

			unlock_page(page);

		}

		pagevec_release(&pvec);

		cond_resched();

	}

	return ret;

}



int f2fs_sync_node_pages(struct f2fs_sb_info *sbi,

				struct writeback_control *wbc,

				bool do_balance, enum iostat_type io_type)
@@ -1867,8 +1914,8 @@ int f2fs_sync_node_pages(struct f2fs_sb_info *sbi, 
				goto continue_unlock;

			}



			/* flush inline_data */

			if (is_inline_node(page)) {

			/* flush inline_data, if it's async context. */

			if (do_balance && is_inline_node(page)) {

				clear_inline_node(page);

				unlock_page(page);

				flush_inline_data(sbi, ino_of_node(page));