f2fs: fix deadlock during inline_data conversion (5f727395) · Commits · 戴 / test

A deadlock can be occurred: Thread 1] Thread 2] - f2fs_write_data_pages - f2fs_write_begin - lock_page(page #0) - grab_cache_page(page #X) - get_node_page(inode_page) - grab_cache_page(page #0) : to convert inline_data - f2fs_write_data_page - f2fs_write_inline_data - get_node_page(inode_page) In this case, trying to lock inode_page and page #0 causes deadlock. In order to avoid this, this patch adds a rule for this locking policy, which is that page #0 should be locked followed by inode_page lock. Signed-off-by:

Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/data.c

+14 −14

Original line number	Diff line number	Diff line
		@@ -936,6 +936,17 @@ static int f2fs_write_begin(struct file file, struct address_space mapping,
		trace_f2fs_write_begin(inode, pos, len, flags);

		f2fs_balance_fs(sbi);

		/*
		* We should check this at this moment to avoid deadlock on inode page
		* and #0 page. The locking rule for inline_data conversion should be:
		* lock_page(page #0) -> lock_page(inode_page)
		*/
		if (index != 0) {
		err = f2fs_convert_inline_inode(inode);
		if (err)
		goto fail;
		}
		repeat:
		page = grab_cache_page_write_begin(mapping, index, flags);
		if (!page) {
		@@ -960,22 +971,11 @@ repeat:
		set_inode_flag(F2FS_I(inode), FI_DATA_EXIST);
		sync_inode_page(&dn);
		goto put_next;
		} else if (page->index == 0) {
		err = f2fs_convert_inline_page(&dn, page);
		if (err)
		goto put_fail;
		} else {
		struct page *p = grab_cache_page(inode->i_mapping, 0);
		if (!p) {
		err = -ENOMEM;
		goto put_fail;
		}
		err = f2fs_convert_inline_page(&dn, p);
		f2fs_put_page(p, 1);
		err = f2fs_convert_inline_page(&dn, page);
		if (err)
		goto put_fail;
		}
		}
		err = f2fs_reserve_block(&dn, index);
		if (err)
		goto put_fail;

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