[PATCH 1/2] f2fs: handle failed bio allocation

Jaegeuk Kim
2015-08-14T23:09:28Z

As the below comment of bio_alloc_bioset, f2fs can allocate multiple bios at the
same time. So, we can't guarantee that bio is allocated all the time.

"
* When @bs is not NULL, if %__GFP_WAIT is set then bio_alloc will always be
* able to allocate a bio. This is due to the mempool guarantees. To make this
* work, callers must never allocate more than 1 bio at a time from this pool.
* Callers that need to allocate more than 1 bio must always submit the
* previously allocated bio for IO before attempting to allocate a new one.
* Failure to do so can cause deadlocks under memory pressure.
"

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---
fs/f2fs/data.c | 3 +--
fs/f2fs/f2fs.h | 15 +++++++++++++++
fs/f2fs/segment.c | 14 +++++++++++---
3 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index cad9ebe..726e58b 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -90,8 +90,7 @@ static struct bio *__bio_alloc(struct f2fs_sb_info *sbi, block_t blk_addr,
{
struct bio *bio;

- /* No failure on bio allocation */
- bio = bio_alloc(GFP_NOIO, npages);
+ bio = f2fs_bio_alloc(npages);

bio->bi_bdev = sbi->sb->s_bdev;
bio->bi_iter.bi_sector = SECTOR_FROM_BLOCK(blk_addr);
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 23bfc0c..a55169a 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -19,6 +19,7 @@
#include <linux/magic.h>
#include <linux/kobject.h>
#include <linux/sched.h>
+#include <linux/bio.h>

#ifdef CONFIG_F2FS_CHECK_FS
#define f2fs_bug_on(sbi, condition) BUG_ON(condition)
@@ -1253,6 +1254,20 @@ retry:
return entry;
}

+static inline struct bio *f2fs_bio_alloc(int npages)
+{
+ struct bio *bio;
+
+ /* No failure on bio allocation */
+retry:
+ bio = bio_alloc(GFP_NOIO, npages);
+ if (!bio) {
+ cond_resched();
+ goto retry;
+ }
+ return bio;
+}
+
static inline void f2fs_radix_tree_insert(struct radix_tree_root *root,
unsigned long index, void *item)
{
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 1b42656..6d919fe 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -330,10 +330,12 @@ repeat:
return 0;

if (!llist_empty(&fcc->issue_list)) {
- struct bio *bio = bio_alloc(GFP_NOIO, 0);
+ struct bio *bio;
struct flush_cmd *cmd, *next;
int ret;

+ bio = f2fs_bio_alloc(0);
+
fcc->dispatch_list = llist_del_all(&fcc->issue_list);
fcc->dispatch_list = llist_reverse_order(fcc->dispatch_list);

@@ -365,8 +367,14 @@ int f2fs_issue_flush(struct f2fs_sb_info *sbi)
if (test_opt(sbi, NOBARRIER))
return 0;

- if (!test_opt(sbi, FLUSH_MERGE))
- return blkdev_issue_flush(sbi->sb->s_bdev, GFP_KERNEL, NULL);
+ if (!test_opt(sbi, FLUSH_MERGE)) {
+ struct bio *bio = f2fs_bio_alloc(0);
+ int ret;
+
+ ret = submit_bio_wait(WRITE_FLUSH, bio);
+ bio_put(bio);
+ return ret;
+ }

init_completion(&cmd.wait);

--
2.1.1