luck/tmp_suning_uos_patched
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f2fs: refactor bio->rw handling

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This patch introduces f2fs_io_info to mitigate the complex parameter list.

struct f2fs_io_info {
	enum page_type type;		/* contains DATA/NODE/META/META_FLUSH */
	int rw;				/* contains R/RS/W/WS */
	int rw_flag;			/* contains REQ_META/REQ_PRIO */
}

1. f2fs_write_data_pages
 - DATA
 - WRITE_SYNC is set when wbc->WB_SYNC_ALL.

2. sync_node_pages
 - NODE
 - WRITE_SYNC all the time

3. sync_meta_pages
 - META
 - WRITE_SYNC all the time
 - REQ_META | REQ_PRIO all the time

 ** f2fs_submit_merged_bio() handles META_FLUSH.

4. ra_nat_pages, ra_sit_pages, ra_sum_pages
 - META
 - READ_SYNC

Cc: Fan Li <fanofcode.li@samsung.com>
Cc: Changman Lee <cm224.lee@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
This commit is contained in:
Jaegeuk Kim 2013-12-11 13:54:01 +09:00
parent 63a0b7cb33
commit 458e6197c3
7 changed files with 132 additions and 95 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
fs/f2fs/checkpoint.c
View File

@ -164,8 +164,7 @@ long sync_meta_pages(struct f2fs_sb_info *sbi, enum page_type type,
}
if (nwritten)
f2fs_submit_merged_bio(sbi, type, nr_to_write == LONG_MAX,
WRITE);
f2fs_submit_merged_bio(sbi, type, WRITE);
return nwritten;
}
@ -598,7 +597,7 @@ void sync_dirty_dir_inodes(struct f2fs_sb_info *sbi)
* We should submit bio, since it exists several
* wribacking dentry pages in the freeing inode.
*/
f2fs_submit_merged_bio(sbi, DATA, true, WRITE);
f2fs_submit_merged_bio(sbi, DATA, WRITE);
}
goto retry;
}
@ -804,9 +803,9 @@ void write_checkpoint(struct f2fs_sb_info *sbi, bool is_umount)
trace_f2fs_write_checkpoint(sbi->sb, is_umount, "finish block_ops");
f2fs_submit_merged_bio(sbi, DATA, true, WRITE);
f2fs_submit_merged_bio(sbi, NODE, true, WRITE);
f2fs_submit_merged_bio(sbi, META, true, WRITE);
f2fs_submit_merged_bio(sbi, DATA, WRITE);
f2fs_submit_merged_bio(sbi, NODE, WRITE);
f2fs_submit_merged_bio(sbi, META, WRITE);
/*
* update checkpoint pack index

85
fs/f2fs/data.c
View File

@ -93,37 +93,28 @@ static void f2fs_write_end_io(struct bio *bio, int err)
bio_put(bio);
}
static void __submit_merged_bio(struct f2fs_sb_info *sbi,
struct f2fs_bio_info *io,
enum page_type type, bool sync, int rw)
static void __submit_merged_bio(struct f2fs_bio_info *io)
{
enum page_type btype = PAGE_TYPE_OF_BIO(type);
struct f2fs_io_info *fio = &io->fio;
int rw;
if (!io->bio)
return;
if (btype == META)
rw |= REQ_META;
rw = fio->rw | fio->rw_flag;
if (is_read_io(rw)) {
if (sync)
rw |= READ_SYNC;
submit_bio(rw, io->bio);
trace_f2fs_submit_read_bio(sbi->sb, rw, type, io->bio);
trace_f2fs_submit_read_bio(io->sbi->sb, rw, fio->type, io->bio);
io->bio = NULL;
return;
}
if (sync)
rw |= WRITE_SYNC;
if (type >= META_FLUSH)
rw |= WRITE_FLUSH_FUA;
/*
* META_FLUSH is only from the checkpoint procedure, and we should wait
* this metadata bio for FS consistency.
*/
if (type == META_FLUSH) {
if (fio->type == META_FLUSH) {
DECLARE_COMPLETION_ONSTACK(wait);
io->bio->bi_private = &wait;
submit_bio(rw, io->bio);
@ -131,12 +122,12 @@ static void __submit_merged_bio(struct f2fs_sb_info *sbi,
} else {
submit_bio(rw, io->bio);
}
trace_f2fs_submit_write_bio(sbi->sb, rw, btype, io->bio);
trace_f2fs_submit_write_bio(io->sbi->sb, rw, fio->type, io->bio);
io->bio = NULL;
}
void f2fs_submit_merged_bio(struct f2fs_sb_info *sbi,
enum page_type type, bool sync, int rw)
enum page_type type, int rw)
{
enum page_type btype = PAGE_TYPE_OF_BIO(type);
struct f2fs_bio_info *io;
@ -144,7 +135,13 @@ void f2fs_submit_merged_bio(struct f2fs_sb_info *sbi,
io = is_read_io(rw) ? &sbi->read_io : &sbi->write_io[btype];
mutex_lock(&io->io_mutex);
__submit_merged_bio(sbi, io, type, sync, rw);
/* change META to META_FLUSH in the checkpoint procedure */
if (type >= META_FLUSH) {
io->fio.type = META_FLUSH;
io->fio.rw = WRITE_FLUSH_FUA;
}
__submit_merged_bio(io);
mutex_unlock(&io->io_mutex);
}
@ -178,33 +175,33 @@ int f2fs_submit_page_bio(struct f2fs_sb_info *sbi, struct page *page,
}
void f2fs_submit_page_mbio(struct f2fs_sb_info *sbi, struct page *page,
block_t blk_addr, enum page_type type, int rw)
block_t blk_addr, struct f2fs_io_info *fio)
{
enum page_type btype = PAGE_TYPE_OF_BIO(type);
enum page_type btype = PAGE_TYPE_OF_BIO(fio->type);
struct block_device *bdev = sbi->sb->s_bdev;
struct f2fs_bio_info *io;
int bio_blocks;
io = is_read_io(rw) ? &sbi->read_io : &sbi->write_io[btype];
io = is_read_io(fio->rw) ? &sbi->read_io : &sbi->write_io[btype];
verify_block_addr(sbi, blk_addr);
mutex_lock(&io->io_mutex);
if (!is_read_io(rw))
if (!is_read_io(fio->rw))
inc_page_count(sbi, F2FS_WRITEBACK);
if (io->bio && (io->last_block_in_bio != blk_addr - 1 ||
io->rw_flag != rw))
__submit_merged_bio(sbi, io, type, false, io->rw_flag);
io->fio.rw != fio->rw))
__submit_merged_bio(io);
alloc_new:
if (io->bio == NULL) {
bio_blocks = MAX_BIO_BLOCKS(max_hw_blocks(sbi));
io->bio = __bio_alloc(bdev, bio_blocks);
io->bio->bi_sector = SECTOR_FROM_BLOCK(sbi, blk_addr);
io->bio->bi_end_io = is_read_io(rw) ? f2fs_read_end_io :
io->bio->bi_end_io = is_read_io(fio->rw) ? f2fs_read_end_io :
f2fs_write_end_io;
io->rw_flag = rw;
io->fio = *fio;
/*
* The end_io will be assigned at the sumbission phase.
* Until then, let bio_add_page() merge consecutive IOs as much
@ -214,14 +211,14 @@ void f2fs_submit_page_mbio(struct f2fs_sb_info *sbi, struct page *page,
if (bio_add_page(io->bio, page, PAGE_CACHE_SIZE, 0) <
PAGE_CACHE_SIZE) {
__submit_merged_bio(sbi, io, type, false, rw);
__submit_merged_bio(io);
goto alloc_new;
}
io->last_block_in_bio = blk_addr;
mutex_unlock(&io->io_mutex);
trace_f2fs_submit_page_mbio(page, rw, type, blk_addr);
trace_f2fs_submit_page_mbio(page, fio->rw, fio->type, blk_addr);
}
/*
@ -643,10 +640,10 @@ static int f2fs_read_data_pages(struct file *file,
return mpage_readpages(mapping, pages, nr_pages, get_data_block_ro);
}
int do_write_data_page(struct page *page, struct writeback_control *wbc)
int do_write_data_page(struct page *page, struct f2fs_io_info *fio)
{
struct inode *inode = page->mapping->host;
block_t old_blk_addr, new_blk_addr;
block_t old_blkaddr, new_blkaddr;
struct dnode_of_data dn;
int err = 0;
@ -655,10 +652,10 @@ int do_write_data_page(struct page *page, struct writeback_control *wbc)
if (err)
return err;
old_blk_addr = dn.data_blkaddr;
old_blkaddr = dn.data_blkaddr;
/* This page is already truncated */
if (old_blk_addr == NULL_ADDR)
if (old_blkaddr == NULL_ADDR)
goto out_writepage;
set_page_writeback(page);
@ -667,15 +664,13 @@ int do_write_data_page(struct page *page, struct writeback_control *wbc)
* If current allocation needs SSR,
* it had better in-place writes for updated data.
*/
if (unlikely(old_blk_addr != NEW_ADDR &&
if (unlikely(old_blkaddr != NEW_ADDR &&
!is_cold_data(page) &&
need_inplace_update(inode))) {
rewrite_data_page(F2FS_SB(inode->i_sb), page,
old_blk_addr, wbc);
rewrite_data_page(page, old_blkaddr, fio);
} else {
write_data_page(inode, page, &dn,
old_blk_addr, &new_blk_addr, wbc);
update_extent_cache(new_blk_addr, &dn);
write_data_page(page, &dn, &new_blkaddr, fio);
update_extent_cache(new_blkaddr, &dn);
}
out_writepage:
f2fs_put_dnode(&dn);
@ -693,6 +688,11 @@ static int f2fs_write_data_page(struct page *page,
unsigned offset;
bool need_balance_fs = false;
int err = 0;
struct f2fs_io_info fio = {
.type = DATA,
.rw = (wbc->sync_mode == WB_SYNC_ALL) ? WRITE_SYNC: WRITE,
.rw_flag = 0,
};
if (page->index < end_index)
goto write;
@ -721,10 +721,10 @@ static int f2fs_write_data_page(struct page *page,
if (S_ISDIR(inode->i_mode)) {
dec_page_count(sbi, F2FS_DIRTY_DENTS);
inode_dec_dirty_dents(inode);
err = do_write_data_page(page, wbc);
err = do_write_data_page(page, &fio);
} else {
f2fs_lock_op(sbi);
err = do_write_data_page(page, wbc);
err = do_write_data_page(page, &fio);
f2fs_unlock_op(sbi);
need_balance_fs = true;
}
@ -734,7 +734,7 @@ static int f2fs_write_data_page(struct page *page,
goto redirty_out;
if (wbc->for_reclaim)
f2fs_submit_merged_bio(sbi, DATA, true, WRITE);
f2fs_submit_merged_bio(sbi, DATA, WRITE);
clear_cold_data(page);
out:
@ -786,7 +786,8 @@ static int f2fs_write_data_pages(struct address_space *mapping,
ret = write_cache_pages(mapping, wbc, __f2fs_writepage, mapping);
if (locked)
mutex_unlock(&sbi->writepages);
f2fs_submit_merged_bio(sbi, DATA, wbc->sync_mode == WB_SYNC_ALL, WRITE);
f2fs_submit_merged_bio(sbi, DATA, WRITE);
remove_dirty_dir_inode(inode);

22
fs/f2fs/f2fs.h
View File

@ -364,11 +364,18 @@ enum page_type {
META_FLUSH,
};
struct f2fs_io_info {
enum page_type type; /* contains DATA/NODE/META/META_FLUSH */
int rw; /* contains R/RS/W/WS */
int rw_flag; /* contains REQ_META/REQ_PRIO */
};
#define is_read_io(rw) (((rw) & 1) == READ)
struct f2fs_bio_info {
struct f2fs_sb_info *sbi; /* f2fs superblock */
struct bio *bio; /* bios to merge */
sector_t last_block_in_bio; /* last block number */
int rw_flag; /* rw flag for all pages */
struct f2fs_io_info fio; /* store buffered io info. */
struct mutex io_mutex; /* mutex for bio */
};
@ -1098,10 +1105,9 @@ struct page *get_sum_page(struct f2fs_sb_info *, unsigned int);
void write_meta_page(struct f2fs_sb_info *, struct page *);
void write_node_page(struct f2fs_sb_info *, struct page *, unsigned int,
block_t, block_t *);
void write_data_page(struct inode *, struct page *, struct dnode_of_data*,
block_t, block_t *, struct writeback_control *);
void rewrite_data_page(struct f2fs_sb_info *, struct page *, block_t,
struct writeback_control *);
void write_data_page(struct page *, struct dnode_of_data *, block_t *,
struct f2fs_io_info *);
void rewrite_data_page(struct page *, block_t, struct f2fs_io_info *);
void recover_data_page(struct f2fs_sb_info *, struct page *,
struct f2fs_summary *, block_t, block_t);
void rewrite_node_page(struct f2fs_sb_info *, struct page *,
@ -1142,17 +1148,17 @@ void destroy_checkpoint_caches(void);
/*
* data.c
*/
void f2fs_submit_merged_bio(struct f2fs_sb_info *, enum page_type, bool, int);
void f2fs_submit_merged_bio(struct f2fs_sb_info *, enum page_type, int);
int f2fs_submit_page_bio(struct f2fs_sb_info *, struct page *, block_t, int);
void f2fs_submit_page_mbio(struct f2fs_sb_info *, struct page *, block_t,
enum page_type, int);
struct f2fs_io_info *);
int reserve_new_block(struct dnode_of_data *);
int f2fs_reserve_block(struct dnode_of_data *, pgoff_t);
void update_extent_cache(block_t, struct dnode_of_data *);
struct page *find_data_page(struct inode *, pgoff_t, bool);
struct page *get_lock_data_page(struct inode *, pgoff_t);
struct page *get_new_data_page(struct inode *, struct page *, pgoff_t, bool);
int do_write_data_page(struct page *, struct writeback_control *);
int do_write_data_page(struct page *, struct f2fs_io_info *);
/*
* gc.c

10
fs/f2fs/gc.c
View File

@ -520,8 +520,10 @@ static int check_dnode(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
static void move_data_page(struct inode *inode, struct page *page, int gc_type)
{
struct writeback_control wbc = {
.sync_mode = 1,
struct f2fs_io_info fio = {
.type = DATA,
.rw = WRITE_SYNC,
.rw_flag = 0,
};
if (gc_type == BG_GC) {
@ -540,7 +542,7 @@ static void move_data_page(struct inode *inode, struct page *page, int gc_type)
inode_dec_dirty_dents(inode);
}
set_cold_data(page);
do_write_data_page(page, &wbc);
do_write_data_page(page, &fio);
clear_cold_data(page);
}
out:
@ -634,7 +636,7 @@ static void gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
goto next_step;
if (gc_type == FG_GC) {
f2fs_submit_merged_bio(sbi, DATA, true, WRITE);
f2fs_submit_merged_bio(sbi, DATA, WRITE);
/*
* In the case of FG_GC, it'd be better to reclaim this victim

22
fs/f2fs/node.c
View File

@ -92,6 +92,12 @@ static void ra_nat_pages(struct f2fs_sb_info *sbi, int nid)
struct page *page;
pgoff_t index;
int i;
struct f2fs_io_info fio = {
.type = META,
.rw = READ_SYNC,
.rw_flag = REQ_META | REQ_PRIO
};
for (i = 0; i < FREE_NID_PAGES; i++, nid += NAT_ENTRY_PER_BLOCK) {
if (unlikely(nid >= nm_i->max_nid))
@ -106,11 +112,11 @@ static void ra_nat_pages(struct f2fs_sb_info *sbi, int nid)
f2fs_put_page(page, 1);
continue;
}
f2fs_submit_page_mbio(sbi, page, index, META, READ);
f2fs_submit_page_mbio(sbi, page, index, &fio);
mark_page_accessed(page);
f2fs_put_page(page, 0);
}
f2fs_submit_merged_bio(sbi, META, true, READ);
f2fs_submit_merged_bio(sbi, META, READ);
}
static struct nat_entry *__lookup_nat_cache(struct f2fs_nm_info *nm_i, nid_t n)
@ -1136,8 +1142,7 @@ int sync_node_pages(struct f2fs_sb_info *sbi, nid_t ino,
}
if (wrote)
f2fs_submit_merged_bio(sbi, NODE, wbc->sync_mode == WB_SYNC_ALL,
WRITE);
f2fs_submit_merged_bio(sbi, NODE, WRITE);
return nwritten;
}
@ -1574,6 +1579,11 @@ static int ra_sum_pages(struct f2fs_sb_info *sbi, struct list_head *pages,
{
struct page *page;
int page_idx = start;
struct f2fs_io_info fio = {
.type = META,
.rw = READ_SYNC,
.rw_flag = REQ_META | REQ_PRIO
};
for (; page_idx < start + nrpages; page_idx++) {
/* alloc temporal page for read node summary info*/
@ -1594,9 +1604,9 @@ static int ra_sum_pages(struct f2fs_sb_info *sbi, struct list_head *pages,
}
list_for_each_entry(page, pages, lru)
f2fs_submit_page_mbio(sbi, page, page->index, META, READ);
f2fs_submit_page_mbio(sbi, page, page->index, &fio);
f2fs_submit_merged_bio(sbi, META, true, READ);
f2fs_submit_merged_bio(sbi, META, READ);
return 0;
}

70
fs/f2fs/segment.c
View File

@ -856,15 +856,14 @@ static int __get_segment_type(struct page *page, enum page_type p_type)
static void do_write_page(struct f2fs_sb_info *sbi, struct page *page,
block_t old_blkaddr, block_t *new_blkaddr,
struct f2fs_summary *sum, enum page_type p_type,
struct writeback_control *wbc)
struct f2fs_summary *sum, struct f2fs_io_info *fio)
{
struct sit_info *sit_i = SIT_I(sbi);
struct curseg_info *curseg;
unsigned int old_cursegno;
int type, rw = WRITE;
int type;
type = __get_segment_type(page, p_type);
type = __get_segment_type(page, fio->type);
curseg = CURSEG_I(sbi, type);
mutex_lock(&curseg->curseg_mutex);
@ -897,55 +896,60 @@ static void do_write_page(struct f2fs_sb_info *sbi, struct page *page,
locate_dirty_segment(sbi, GET_SEGNO(sbi, old_blkaddr));
mutex_unlock(&sit_i->sentry_lock);
if (p_type == NODE)
if (fio->type == NODE)
fill_node_footer_blkaddr(page, NEXT_FREE_BLKADDR(sbi, curseg));
/* writeout dirty page into bdev */
if (wbc->sync_mode == WB_SYNC_ALL)
rw |= WRITE_SYNC;
f2fs_submit_page_mbio(sbi, page, *new_blkaddr, p_type, rw);
f2fs_submit_page_mbio(sbi, page, *new_blkaddr, fio);
mutex_unlock(&curseg->curseg_mutex);
}
void write_meta_page(struct f2fs_sb_info *sbi, struct page *page)
{
struct f2fs_io_info fio = {
.type = META,
.rw = WRITE_SYNC,
.rw_flag = REQ_META | REQ_PRIO
};
set_page_writeback(page);
f2fs_submit_page_mbio(sbi, page, page->index, META, WRITE);
f2fs_submit_page_mbio(sbi, page, page->index, &fio);
}
void write_node_page(struct f2fs_sb_info *sbi, struct page *page,
unsigned int nid, block_t old_blkaddr, block_t *new_blkaddr)
{
struct f2fs_summary sum;
struct writeback_control wbc = {
.sync_mode = 1,
struct f2fs_io_info fio = {
.type = NODE,
.rw = WRITE_SYNC,
.rw_flag = 0
};
set_summary(&sum, nid, 0, 0);
do_write_page(sbi, page, old_blkaddr, new_blkaddr, &sum, NODE, &wbc);
do_write_page(sbi, page, old_blkaddr, new_blkaddr, &sum, &fio);
}
void write_data_page(struct inode *inode, struct page *page,
struct dnode_of_data *dn, block_t old_blkaddr,
block_t *new_blkaddr, struct writeback_control *wbc)
void write_data_page(struct page *page, struct dnode_of_data *dn,
block_t *new_blkaddr, struct f2fs_io_info *fio)
{
struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
struct f2fs_sb_info *sbi = F2FS_SB(dn->inode->i_sb);
struct f2fs_summary sum;
struct node_info ni;
f2fs_bug_on(old_blkaddr == NULL_ADDR);
f2fs_bug_on(dn->data_blkaddr == NULL_ADDR);
get_node_info(sbi, dn->nid, &ni);
set_summary(&sum, dn->nid, dn->ofs_in_node, ni.version);
do_write_page(sbi, page, old_blkaddr,
new_blkaddr, &sum, DATA, wbc);
do_write_page(sbi, page, dn->data_blkaddr, new_blkaddr, &sum, fio);
}
void rewrite_data_page(struct f2fs_sb_info *sbi, struct page *page,
block_t old_blk_addr, struct writeback_control *wbc)
void rewrite_data_page(struct page *page, block_t old_blkaddr, struct f2fs_io_info *fio)
{
int rw = wbc->sync_mode == WB_SYNC_ALL ? WRITE_SYNC : WRITE;
f2fs_submit_page_mbio(sbi, page, old_blk_addr, DATA, rw);
struct inode *inode = page->mapping->host;
struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
f2fs_submit_page_mbio(sbi, page, old_blkaddr, fio);
}
void recover_data_page(struct f2fs_sb_info *sbi,
@ -1004,6 +1008,11 @@ void rewrite_node_page(struct f2fs_sb_info *sbi,
unsigned int segno, old_cursegno;
block_t next_blkaddr = next_blkaddr_of_node(page);
unsigned int next_segno = GET_SEGNO(sbi, next_blkaddr);
struct f2fs_io_info fio = {
.type = NODE,
.rw = WRITE_SYNC,
.rw_flag = 0
};
curseg = CURSEG_I(sbi, type);
@ -1032,8 +1041,8 @@ void rewrite_node_page(struct f2fs_sb_info *sbi,
/* rewrite node page */
set_page_writeback(page);
f2fs_submit_page_mbio(sbi, page, new_blkaddr, NODE, WRITE_SYNC);
f2fs_submit_merged_bio(sbi, NODE, true, WRITE);
f2fs_submit_page_mbio(sbi, page, new_blkaddr, &fio);
f2fs_submit_merged_bio(sbi, NODE, WRITE);
refresh_sit_entry(sbi, old_blkaddr, new_blkaddr);
locate_dirty_segment(sbi, old_cursegno);
@ -1048,7 +1057,7 @@ void f2fs_wait_on_page_writeback(struct page *page,
{
struct f2fs_sb_info *sbi = F2FS_SB(page->mapping->host->i_sb);
if (PageWriteback(page)) {
f2fs_submit_merged_bio(sbi, type, sync, WRITE);
f2fs_submit_merged_bio(sbi, type, WRITE);
wait_on_page_writeback(page);
}
}
@ -1580,6 +1589,11 @@ static int ra_sit_pages(struct f2fs_sb_info *sbi, int start, int nrpages)
block_t blk_addr, prev_blk_addr = 0;
int sit_blk_cnt = SIT_BLK_CNT(sbi);
int blkno = start;
struct f2fs_io_info fio = {
.type = META,
.rw = READ_SYNC,
.rw_flag = REQ_META | REQ_PRIO
};
for (; blkno < start + nrpages && blkno < sit_blk_cnt; blkno++) {
@ -1600,13 +1614,13 @@ static int ra_sit_pages(struct f2fs_sb_info *sbi, int start, int nrpages)
continue;
}
f2fs_submit_page_mbio(sbi, page, blk_addr, META, READ_SYNC);
f2fs_submit_page_mbio(sbi, page, blk_addr, &fio);
mark_page_accessed(page);
f2fs_put_page(page, 0);
}
f2fs_submit_merged_bio(sbi, META, true, READ);
f2fs_submit_merged_bio(sbi, META, READ);
return blkno - start;
}

7
fs/f2fs/super.c
View File

@ -885,8 +885,13 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
spin_lock_init(&sbi->stat_lock);
mutex_init(&sbi->read_io.io_mutex);
for (i = 0; i < NR_PAGE_TYPE; i++)
sbi->read_io.sbi = sbi;
sbi->read_io.bio = NULL;
for (i = 0; i < NR_PAGE_TYPE; i++) {
mutex_init(&sbi->write_io[i].io_mutex);
sbi->write_io[i].sbi = sbi;
sbi->write_io[i].bio = NULL;
}
init_rwsem(&sbi->cp_rwsem);
init_waitqueue_head(&sbi->cp_wait);