Commit 3e5e479a authored by Chao Yu's avatar Chao Yu Committed by Jaegeuk Kim
Browse files

f2fs: fix to add swap extent correctly 

As Youling reported in mailing list:

https://www.linuxquestions.org/questions/linux-newbie-8/the-file-system-f2fs-is-broken-4175666043/

https://www.linux.org/threads/the-file-system-f2fs-is-broken.26490/



There is a test case can corrupt f2fs image:
- dd if=/dev/zero of=/swapfile bs=1M count=4096
- chmod 600 /swapfile
- mkswap /swapfile
- swapon --discard /swapfile

The root cause is f2fs_swap_activate() intends to return zero value
to setup_swap_extents() to enable SWP_FS mode (swap file goes through
fs), in this flow, setup_swap_extents() setups swap extent with wrong
block address range, result in discard_swap() erasing incorrect address.

Because f2fs_swap_activate() has pinned swapfile, its data block
address will not change, it's safe to let swap to handle IO through
raw device, so we can get rid of SWAP_FS mode and initial swap extents
inside f2fs_swap_activate(), by this way, later discard_swap() can trim
in right address range.

Fixes: 4969c06a ("f2fs: support swap file w/ DIO")
Signed-off-by: default avatarChao Yu <yuchao0@huawei.com>
Signed-off-by: default avatarJaegeuk Kim <jaegeuk@kernel.org>
parent 4eea93e3

fs/f2fs/data.c

+25 −7
Original line number Diff line number Diff line
@@ -3627,7 +3627,8 @@ int f2fs_migrate_page(struct address_space *mapping, 


#ifdef CONFIG_SWAP

/* Copied from generic_swapfile_activate() to check any holes */

static int check_swap_activate(struct file *swap_file, unsigned int max)

static int check_swap_activate(struct swap_info_struct *sis,

				struct file *swap_file, sector_t *span)

{

	struct address_space *mapping = swap_file->f_mapping;

	struct inode *inode = mapping->host;
@@ -3638,6 +3639,8 @@ static int check_swap_activate(struct file *swap_file, unsigned int max) 
	sector_t last_block;

	sector_t lowest_block = -1;

	sector_t highest_block = 0;

	int nr_extents = 0;

	int ret;



	blkbits = inode->i_blkbits;

	blocks_per_page = PAGE_SIZE >> blkbits;
@@ -3649,7 +3652,8 @@ static int check_swap_activate(struct file *swap_file, unsigned int max) 
	probe_block = 0;

	page_no = 0;

	last_block = i_size_read(inode) >> blkbits;

	while ((probe_block + blocks_per_page) <= last_block && page_no < max) {

	while ((probe_block + blocks_per_page) <= last_block &&

			page_no < sis->max) {

		unsigned block_in_page;

		sector_t first_block;
@@ -3689,13 +3693,27 @@ static int check_swap_activate(struct file *swap_file, unsigned int max) 
				highest_block = first_block;

		}



		/*

		 * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks

		 */

		ret = add_swap_extent(sis, page_no, 1, first_block);

		if (ret < 0)

			goto out;

		nr_extents += ret;

		page_no++;

		probe_block += blocks_per_page;

reprobe:

		continue;

	}

	return 0;



	ret = nr_extents;

	*span = 1 + highest_block - lowest_block;

	if (page_no == 0)

		page_no = 1;	/* force Empty message */

	sis->max = page_no;

	sis->pages = page_no - 1;

	sis->highest_bit = page_no - 1;

out:

	return ret;

bad_bmap:

	pr_err("swapon: swapfile has holes\n");

	return -EINVAL;
@@ -3720,14 +3738,14 @@ static int f2fs_swap_activate(struct swap_info_struct *sis, struct file *file, 
	if (f2fs_disable_compressed_file(inode))

		return -EINVAL;



	ret = check_swap_activate(file, sis->max);

	if (ret)

	ret = check_swap_activate(sis, file, span);

	if (ret < 0)

		return ret;



	set_inode_flag(inode, FI_PIN_FILE);

	f2fs_precache_extents(inode);

	f2fs_update_time(F2FS_I_SB(inode), REQ_TIME);

	return 0;

	return ret;

}



static void f2fs_swap_deactivate(struct file *file)

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