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Commit 973163fc authored by Chao Yu's avatar Chao Yu Committed by Jaegeuk Kim
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f2fs: reorganize f2fs_map_blocks 



In this patch, we try to reorganize f2fs_map_blocks to make block mapping
flow more clear by using following structure:

/* check status of mapping */

if (unmapped) {
	/* blkaddr == NULL_ADDR || blkaddr == NEW_ADDR */

	if (create) {
		/* write path, handle dio write case here */
		alloc_and_map;
	} else {
		/*
		 * handle read cases from all call paths:
		 *     1. generic read;
		 *     2. dio read;
		 *     3. fiemap;
		 *     4. bmap
		 */
	}
}

/* map buffer_header */

Besides, this patch handles the missing case correctly for dio write:
When we fail in __allocate_data_blocks, then in f2fs_map_blocks, we will
not allocate blocks correctly for preallocated blocks, but returning with
an unmapped buffer head, which will result in failure of dio write.

Signed-off-by: default avatarChao Yu <chao2.yu@samsung.com>
Signed-off-by: default avatarJaegeuk Kim <jaegeuk@kernel.org>
parent 514053e4

fs/f2fs/data.c

+44 −40
Original line number Diff line number Diff line
@@ -596,40 +596,36 @@ static int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map, 
			err = 0;

		goto unlock_out;

	}

	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;

		map->m_pblk = dn.data_blkaddr;

		if (dn.data_blkaddr == NEW_ADDR)

			map->m_flags |= F2FS_MAP_UNWRITTEN;

	} else if (create) {

	if (dn.data_blkaddr == NEW_ADDR || dn.data_blkaddr == NULL_ADDR) {

		if (create) {

			err = __allocate_data_block(&dn);

			if (err)

				goto put_out;

			allocated = true;

		map->m_flags = F2FS_MAP_NEW | F2FS_MAP_MAPPED;

		map->m_pblk = dn.data_blkaddr;

			map->m_flags = F2FS_MAP_NEW;

		} else {

			if (flag != F2FS_GET_BLOCK_FIEMAP ||

						dn.data_blkaddr != NEW_ADDR) {

				if (flag == F2FS_GET_BLOCK_BMAP)

					err = -ENOENT;

				goto put_out;

			}



	end_offset = ADDRS_PER_PAGE(dn.node_page, F2FS_I(inode));

			/*

			 * preallocated unwritten block should be mapped

			 * for fiemap.

			 */

			if (dn.data_blkaddr == NEW_ADDR)

				map->m_flags = F2FS_MAP_UNWRITTEN;

		}

	}



	map->m_flags |= F2FS_MAP_MAPPED;

	map->m_pblk = dn.data_blkaddr;

	map->m_len = 1;



	end_offset = ADDRS_PER_PAGE(dn.node_page, F2FS_I(inode));

	dn.ofs_in_node++;

	pgofs++;
@@ -648,23 +644,31 @@ static int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map, 
			goto unlock_out;

		}



		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));

	}



	if (maxblocks > map->m_len) {

		block_t blkaddr = datablock_addr(dn.node_page, dn.ofs_in_node);

		if (blkaddr == NULL_ADDR && create) {



		if (blkaddr == NEW_ADDR || blkaddr == NULL_ADDR) {

			if (create) {

				err = __allocate_data_block(&dn);

				if (err)

					goto sync_out;

				allocated = true;

				map->m_flags |= F2FS_MAP_NEW;

				blkaddr = dn.data_blkaddr;

			} else {

				/*

				 * we only merge preallocated unwritten blocks

				 * for fiemap.

				 */

				if (flag != F2FS_GET_BLOCK_FIEMAP ||

						blkaddr != NEW_ADDR)

					goto sync_out;

			}

		}



		/* Give more consecutive addresses for the readahead */

		if ((map->m_pblk != NEW_ADDR &&

				blkaddr == (map->m_pblk + ofs)) ||