[PATCH] f2fs: cache global IPU bio

From: Chao Yu
Date: Mon Sep 30 2019 - 06:53:39 EST

In commit 8648de2c581e ("f2fs: add bio cache for IPU"), we added
f2fs_submit_ipu_bio() in __write_data_page() as below:

__write_data_page()

if (!S_ISDIR(inode->i_mode) && !IS_NOQUOTA(inode)) {
f2fs_submit_ipu_bio(sbi, bio, page);
....
}

in order to avoid below deadlock:

Thread A Thread B
- __write_data_page (inode x, page y)
- f2fs_do_write_data_page
- set_page_writeback ---- set writeback flag in page y
- f2fs_inplace_write_data
- f2fs_balance_fs
- lock gc_mutex
- lock gc_mutex
- f2fs_gc
- do_garbage_collect
- gc_data_segment
- move_data_page
- f2fs_wait_on_page_writeback
- wait_on_page_writeback --- wait writeback of page y

However, the bio submission breaks the merge of IPU IOs.

So in this patch let's add a global bio cache for merged IPU pages,
then f2fs_wait_on_page_writeback() is able to submit bio if a
writebacked page is cached in global bio cache.

Signed-off-by: Chao Yu <yuchao0@xxxxxxxxxx>
---
fs/f2fs/data.c | 179 +++++++++++++++++++++++++++++++++++++---------
fs/f2fs/f2fs.h | 11 +++
fs/f2fs/segment.c | 3 +
fs/f2fs/super.c | 8 +++
4 files changed, 169 insertions(+), 32 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 28665acb35a5..3eef7caee064 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -29,6 +29,7 @@
#define NUM_PREALLOC_POST_READ_CTXS 128

static struct kmem_cache *bio_post_read_ctx_cache;
+static struct kmem_cache *bio_entry_slab;
static mempool_t *bio_post_read_ctx_pool;

static bool __is_cp_guaranteed(struct page *page)
@@ -540,6 +541,126 @@ static bool io_is_mergeable(struct f2fs_sb_info *sbi, struct bio *bio,
return io_type_is_mergeable(io, fio);
}

+static void add_bio_entry(struct f2fs_sb_info *sbi, struct bio *bio,
+ struct page *page, enum temp_type temp)
+{
+ struct f2fs_bio_info *io = sbi->write_io[DATA] + temp;
+ struct bio_entry *be;
+
+ be = f2fs_kmem_cache_alloc(bio_entry_slab, GFP_NOFS);
+ be->bio = bio;
+ bio_get(bio);
+
+ if (bio_add_page(bio, page, PAGE_SIZE, 0) != PAGE_SIZE)
+ f2fs_bug_on(sbi, 1);
+
+ down_write(&io->bio_list_lock);
+ list_add_tail(&be->list, &io->bio_list);
+ up_write(&io->bio_list_lock);
+}
+
+static void del_bio_entry(struct bio_entry *be)
+{
+ list_del(&be->list);
+ kmem_cache_free(bio_entry_slab, be);
+}
+
+static int add_ipu_page(struct f2fs_sb_info *sbi, struct bio **bio,
+ struct page *page)
+{
+ enum temp_type temp;
+ bool found = false;
+ int ret = -EAGAIN;
+
+ for (temp = HOT; temp < NR_TEMP_TYPE && !found; temp++) {
+ struct f2fs_bio_info *io = sbi->write_io[DATA] + temp;
+ struct list_head *head = &io->bio_list;
+ struct bio_entry *be;
+
+ down_write(&io->bio_list_lock);
+ list_for_each_entry(be, head, list) {
+ if (be->bio != *bio)
+ continue;
+
+ found = true;
+
+ if (bio_add_page(*bio, page, PAGE_SIZE, 0) == PAGE_SIZE) {
+ ret = 0;
+ break;
+ }
+
+ /* bio is full */
+ del_bio_entry(be);
+ __submit_bio(sbi, *bio, DATA);
+ break;
+ }
+ up_write(&io->bio_list_lock);
+ }
+
+ if (ret) {
+ bio_put(*bio);
+ *bio = NULL;
+ }
+
+ return ret;
+}
+
+void f2fs_submit_merged_ipu_write(struct f2fs_sb_info *sbi,
+ struct bio **bio, struct page *page)
+{
+ enum temp_type temp;
+ bool found = false;
+ struct bio *target = bio ? *bio : NULL;
+
+ for (temp = HOT; temp < NR_TEMP_TYPE && !found; temp++) {
+ struct f2fs_bio_info *io = sbi->write_io[DATA] + temp;
+ struct list_head *head = &io->bio_list;
+ struct bio_entry *be;
+
+ if (list_empty(head))
+ continue;
+
+ down_read(&io->bio_list_lock);
+ list_for_each_entry(be, head, list) {
+ if (target)
+ found = (target == be->bio);
+ else
+ found = __has_merged_page(be->bio, NULL,
+ page, 0);
+ if (found)
+ break;
+ }
+ up_read(&io->bio_list_lock);
+
+ if (!found)
+ continue;
+
+ found = false;
+
+ down_write(&io->bio_list_lock);
+ list_for_each_entry(be, head, list) {
+ if (target)
+ found = (target == be->bio);
+ else
+ found = __has_merged_page(be->bio, NULL,
+ page, 0);
+ if (found) {
+ target = be->bio;
+ del_bio_entry(be);
+ break;
+ }
+ }
+ up_write(&io->bio_list_lock);
+ }
+
+ if (found)
+ __submit_bio(sbi, target, DATA);
+ if (bio && *bio) {
+ bio_put(*bio);
+ *bio = NULL;
+ }
+}
+
int f2fs_merge_page_bio(struct f2fs_io_info *fio)
{
struct bio *bio = *fio->bio;
@@ -554,20 +675,17 @@ int f2fs_merge_page_bio(struct f2fs_io_info *fio)
f2fs_trace_ios(fio, 0);

if (bio && !page_is_mergeable(fio->sbi, bio, *fio->last_block,
- fio->new_blkaddr)) {
- __submit_bio(fio->sbi, bio, fio->type);
- bio = NULL;
- }
+ fio->new_blkaddr))
+ f2fs_submit_merged_ipu_write(fio->sbi, &bio, NULL);
alloc_new:
if (!bio) {
bio = __bio_alloc(fio, BIO_MAX_PAGES);
bio_set_op_attrs(bio, fio->op, fio->op_flags);
- }

- if (bio_add_page(bio, page, PAGE_SIZE, 0) < PAGE_SIZE) {
- __submit_bio(fio->sbi, bio, fio->type);
- bio = NULL;
- goto alloc_new;
+ add_bio_entry(fio->sbi, bio, page, fio->temp);
+ } else {
+ if (add_ipu_page(fio->sbi, &bio, page))
+ goto alloc_new;
}

if (fio->io_wbc)
@@ -581,19 +699,6 @@ int f2fs_merge_page_bio(struct f2fs_io_info *fio)
return 0;
}

-static void f2fs_submit_ipu_bio(struct f2fs_sb_info *sbi, struct bio **bio,
- struct page *page)
-{
- if (!bio)
- return;
-
- if (!__has_merged_page(*bio, NULL, page, 0))
- return;
-
- __submit_bio(sbi, *bio, DATA);
- *bio = NULL;
-}
-
void f2fs_submit_page_write(struct f2fs_io_info *fio)
{
struct f2fs_sb_info *sbi = fio->sbi;
@@ -2206,14 +2311,12 @@ static int __write_data_page(struct page *page, bool *submitted,

unlock_page(page);
if (!S_ISDIR(inode->i_mode) && !IS_NOQUOTA(inode) &&
- !F2FS_I(inode)->cp_task) {
- f2fs_submit_ipu_bio(sbi, bio, page);
+ !F2FS_I(inode)->cp_task)
f2fs_balance_fs(sbi, need_balance_fs);
- }

if (unlikely(f2fs_cp_error(sbi))) {
- f2fs_submit_ipu_bio(sbi, bio, page);
f2fs_submit_merged_write(sbi, DATA);
+ f2fs_submit_merged_ipu_write(sbi, bio, NULL);
submitted = NULL;
}

@@ -2333,13 +2436,11 @@ static int f2fs_write_cache_pages(struct address_space *mapping,
}

if (PageWriteback(page)) {
- if (wbc->sync_mode != WB_SYNC_NONE) {
+ if (wbc->sync_mode != WB_SYNC_NONE)
f2fs_wait_on_page_writeback(page,
DATA, true, true);
- f2fs_submit_ipu_bio(sbi, &bio, page);
- } else {
+ else
goto continue_unlock;
- }
}

if (!clear_page_dirty_for_io(page))
@@ -2397,7 +2498,7 @@ static int f2fs_write_cache_pages(struct address_space *mapping,
NULL, 0, DATA);
/* submit cached bio of IPU write */
if (bio)
- __submit_bio(sbi, bio, DATA);
+ f2fs_submit_merged_ipu_write(sbi, &bio, NULL);

return ret;
}
@@ -3202,8 +3303,22 @@ int __init f2fs_init_post_read_processing(void)
return -ENOMEM;
}

-void __exit f2fs_destroy_post_read_processing(void)
+void f2fs_destroy_post_read_processing(void)
{
mempool_destroy(bio_post_read_ctx_pool);
kmem_cache_destroy(bio_post_read_ctx_cache);
}
+
+int __init f2fs_init_bio_entry_cache(void)
+{
+ bio_entry_slab = f2fs_kmem_cache_create("bio_entry_slab",
+ sizeof(struct bio_entry));
+ if (!bio_entry_slab)
+ return -ENOMEM;
+ return 0;
+}
+
+void __exit f2fs_destroy_bio_entry_cache(void)
+{
+ kmem_cache_destroy(bio_entry_slab);
+}
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 797e95933ce9..eed7918389ae 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1068,6 +1068,11 @@ struct f2fs_io_info {
unsigned char version; /* version of the node */
};

+struct bio_entry {
+ struct bio *bio;
+ struct list_head list;
+};
+
#define is_read_io(rw) ((rw) == READ)
struct f2fs_bio_info {
struct f2fs_sb_info *sbi; /* f2fs superblock */
@@ -1077,6 +1082,8 @@ struct f2fs_bio_info {
struct rw_semaphore io_rwsem; /* blocking op for bio */
spinlock_t io_lock; /* serialize DATA/NODE IOs */
struct list_head io_list; /* track fios */
+ struct list_head bio_list; /* bio entry list head */
+ struct rw_semaphore bio_list_lock; /* lock to protect bio entry list */
};

#define FDEV(i) (sbi->devs[i])
@@ -3210,10 +3217,14 @@ void f2fs_destroy_checkpoint_caches(void);
*/
int f2fs_init_post_read_processing(void);
void f2fs_destroy_post_read_processing(void);
+int f2fs_init_bio_entry_cache(void);
+void f2fs_destroy_bio_entry_cache(void);
void f2fs_submit_merged_write(struct f2fs_sb_info *sbi, enum page_type type);
void f2fs_submit_merged_write_cond(struct f2fs_sb_info *sbi,
struct inode *inode, struct page *page,
nid_t ino, enum page_type type);
+void f2fs_submit_merged_ipu_write(struct f2fs_sb_info *sbi,
+ struct bio **bio, struct page *page);
void f2fs_flush_merged_writes(struct f2fs_sb_info *sbi);
int f2fs_submit_page_bio(struct f2fs_io_info *fio);
int f2fs_merge_page_bio(struct f2fs_io_info *fio);
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 808709581481..25c750cd0272 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -3379,7 +3379,10 @@ void f2fs_wait_on_page_writeback(struct page *page,
if (PageWriteback(page)) {
struct f2fs_sb_info *sbi = F2FS_P_SB(page);

+ /* submit cached LFS IO */
f2fs_submit_merged_write_cond(sbi, NULL, page, 0, type);
+ /* sbumit cached IPU IO */
+ f2fs_submit_merged_ipu_write(sbi, NULL, page);
if (ordered) {
wait_on_page_writeback(page);
f2fs_bug_on(sbi, locked && PageWriteback(page));
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 0e6eb482e853..f770d0b347eb 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -3342,6 +3342,8 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
sbi->write_io[i][j].bio = NULL;
spin_lock_init(&sbi->write_io[i][j].io_lock);
INIT_LIST_HEAD(&sbi->write_io[i][j].io_list);
+ INIT_LIST_HEAD(&sbi->write_io[i][j].bio_list);
+ init_rwsem(&sbi->write_io[i][j].bio_list_lock);
}
}

@@ -3753,8 +3755,13 @@ static int __init init_f2fs_fs(void)
err = f2fs_init_post_read_processing();
if (err)
goto free_root_stats;
+ err = f2fs_init_bio_entry_cache();
+ if (err)
+ goto free_post_read;
return 0;

+free_post_read:
+ f2fs_destroy_post_read_processing();
free_root_stats:
f2fs_destroy_root_stats();
unregister_filesystem(&f2fs_fs_type);
@@ -3778,6 +3785,7 @@ static int __init init_f2fs_fs(void)

static void __exit exit_f2fs_fs(void)
{
+ f2fs_destroy_bio_entry_cache();
f2fs_destroy_post_read_processing();
f2fs_destroy_root_stats();
unregister_filesystem(&f2fs_fs_type);
--
2.18.0.rc1