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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: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This commit is contained in:
Chao Yu 2015-09-18 16:51:51 +08:00 committed by Jaegeuk Kim
parent 514053e454
commit 973163fc0c
1 changed files with 44 additions and 40 deletions
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84
fs/f2fs/data.c
View File

@ -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 (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;
} else {
if (flag != F2FS_GET_BLOCK_FIEMAP ||
dn.data_blkaddr != NEW_ADDR) {
if (flag == F2FS_GET_BLOCK_BMAP)
err = -ENOENT;
goto put_out;
}
/*
* preallocated unwritten block should be mapped
* for fiemap.
*/
if (dn.data_blkaddr == NEW_ADDR)
map->m_flags = F2FS_MAP_UNWRITTEN;
}
/*
* 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) {
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;
} else {
if (flag == F2FS_GET_BLOCK_BMAP)
err = -ENOENT;
goto put_out;
}
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));
map->m_len = 1;
dn.ofs_in_node++;
pgofs++;
@ -648,23 +644,31 @@ get_next:
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) {
err = __allocate_data_block(&dn);
if (err)
goto sync_out;
allocated = true;
map->m_flags |= F2FS_MAP_NEW;
blkaddr = dn.data_blkaddr;
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)) ||