Commit e2b4e2bc authored by Chao Yu's avatar Chao Yu Committed by Jaegeuk Kim
Browse files

f2fs: fix incorrect mapping for bmap 



The test step is like below:
1. touch file
2. truncate -s $((1024*1024)) file
3. fallocate -o 0 -l $((1024*1024)) file
4. fibmap.f2fs file

Our result of fibmap.f2fs showed below is not correct:

file_pos   start_blk     end_blk        blks
       0    -937166132    -937166132           1
    4096    -937166132    -937166132           1
    8192    -937166132    -937166132           1
   12288    -937166132    -937166132           1
   16384    -937166132    -937166132           1
   20480    -937166132    -937166132           1
...
 1040384    -937166132    -937166132           1
 1044480    -937166132    -937166132           1

This is because f2fs_map_blocks will return with no error when meeting
a hole or preallocated block, the caller __get_data_block will map the
uninitialized variable value to bh->b_blocknr.

Unfortunately generic_block_bmap will neither check the return value of
get_data() nor check mapping info of buffer_head, result in returning
the random block address.

After fixing the issue, our result shows correctly:

file_pos   start_blk     end_blk        blks
       0           0           0         256

Signed-off-by: default avatarChao Yu <chao2.yu@samsung.com>
Signed-off-by: default avatarJaegeuk Kim <jaegeuk@kernel.org>
parent c031f6a9

fs/f2fs/data.c

+36 −12
Original line number Diff line number Diff line
@@ -561,7 +561,7 @@ out: 
 *     c. give the block addresses to blockdev

 */

static int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,

			int create, bool fiemap)

						int create, int flag)

{

	unsigned int maxblocks = map->m_len;

	struct dnode_of_data dn;
@@ -595,8 +595,19 @@ static int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map, 
			err = 0;

		goto unlock_out;

	}

	if (dn.data_blkaddr == NEW_ADDR && !fiemap)

	if (dn.data_blkaddr == NEW_ADDR) {

		if (flag == F2FS_GET_BLOCK_BMAP) {

			err = -ENOENT;

			goto put_out;

		} else if (flag == F2FS_GET_BLOCK_READ ||

				flag == F2FS_GET_BLOCK_DIO) {

			goto put_out;

		}

		/*

		 * if it is in fiemap call path (flag = F2FS_GET_BLOCK_FIEMAP),

		 * mark it as mapped and unwritten block.

		 */

	}



	if (dn.data_blkaddr != NULL_ADDR) {

		map->m_flags = F2FS_MAP_MAPPED;
@@ -611,6 +622,8 @@ static int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map, 
		map->m_flags = F2FS_MAP_NEW | F2FS_MAP_MAPPED;

		map->m_pblk = dn.data_blkaddr;

	} else {

		if (flag == F2FS_GET_BLOCK_BMAP)

			err = -ENOENT;

		goto put_out;

	}
@@ -633,7 +646,9 @@ get_next: 
				err = 0;

			goto unlock_out;

		}

		if (dn.data_blkaddr == NEW_ADDR && !fiemap)



		if (dn.data_blkaddr == NEW_ADDR &&

				flag != F2FS_GET_BLOCK_FIEMAP)

			goto put_out;



		end_offset = ADDRS_PER_PAGE(dn.node_page, F2FS_I(inode));
@@ -675,7 +690,7 @@ out: 
}



static int __get_data_block(struct inode *inode, sector_t iblock,

			struct buffer_head *bh, int create, bool fiemap)

			struct buffer_head *bh, int create, int flag)

{

	struct f2fs_map_blocks map;

	int ret;
@@ -683,7 +698,7 @@ static int __get_data_block(struct inode *inode, sector_t iblock, 
	map.m_lblk = iblock;

	map.m_len = bh->b_size >> inode->i_blkbits;



	ret = f2fs_map_blocks(inode, &map, create, fiemap);

	ret = f2fs_map_blocks(inode, &map, create, flag);

	if (!ret) {

		map_bh(bh, inode->i_sb, map.m_pblk);

		bh->b_state = (bh->b_state & ~F2FS_MAP_FLAGS) | map.m_flags;
@@ -693,15 +708,23 @@ static int __get_data_block(struct inode *inode, sector_t iblock, 
}



static int get_data_block(struct inode *inode, sector_t iblock,

			struct buffer_head *bh_result, int create, int flag)

{

	return __get_data_block(inode, iblock, bh_result, create, flag);

}



static int get_data_block_dio(struct inode *inode, sector_t iblock,

			struct buffer_head *bh_result, int create)

{

	return __get_data_block(inode, iblock, bh_result, create, false);

	return __get_data_block(inode, iblock, bh_result, create,

						F2FS_GET_BLOCK_DIO);

}



static int get_data_block_fiemap(struct inode *inode, sector_t iblock,

static int get_data_block_bmap(struct inode *inode, sector_t iblock,

			struct buffer_head *bh_result, int create)

{

	return __get_data_block(inode, iblock, bh_result, create, true);

	return __get_data_block(inode, iblock, bh_result, create,

						F2FS_GET_BLOCK_BMAP);

}



static inline sector_t logical_to_blk(struct inode *inode, loff_t offset)
@@ -745,7 +768,8 @@ next: 
	memset(&map_bh, 0, sizeof(struct buffer_head));

	map_bh.b_size = len;



	ret = get_data_block_fiemap(inode, start_blk, &map_bh, 0);

	ret = get_data_block(inode, start_blk, &map_bh, 0,

					F2FS_GET_BLOCK_FIEMAP);

	if (ret)

		goto out;
@@ -1530,7 +1554,7 @@ static ssize_t f2fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter, 
	if (iov_iter_rw(iter) == WRITE)

		__allocate_data_blocks(inode, offset, count);



	err = blockdev_direct_IO(iocb, inode, iter, offset, get_data_block);

	err = blockdev_direct_IO(iocb, inode, iter, offset, get_data_block_dio);

	if (err < 0 && iov_iter_rw(iter) == WRITE)

		f2fs_write_failed(mapping, offset + count);
@@ -1618,7 +1642,7 @@ static sector_t f2fs_bmap(struct address_space *mapping, sector_t block) 
		if (err)

			return err;

	}

	return generic_block_bmap(mapping, block, get_data_block);

	return generic_block_bmap(mapping, block, get_data_block_bmap);

}



const struct address_space_operations f2fs_dblock_aops = {

fs/f2fs/f2fs.h

+6 −0
Original line number Diff line number Diff line
@@ -375,6 +375,12 @@ struct f2fs_map_blocks { 
	unsigned int m_flags;

};



/* for flag in get_data_block */

#define F2FS_GET_BLOCK_READ		0

#define F2FS_GET_BLOCK_DIO		1

#define F2FS_GET_BLOCK_FIEMAP		2

#define F2FS_GET_BLOCK_BMAP		3



/*

 * i_advise uses FADVISE_XXX_BIT. We can add additional hints later.

 */

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