[f2fs-dev] [PATCH 1/2] f2fs: introduce get_available_block_count() for cleanup

[f2fs-dev] [PATCH 1/2] f2fs: introduce get_available_block_count() for cleanup

[Chao Yu]

There are very similar codes in inc_valid_block_count() and
inc_valid_node_count() which is used for available user block
count calculation.

This patch introduces a new helper get_available_block_count()
to include those common codes, and used it instead for cleanup.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
---
 fs/f2fs/f2fs.h | 48 ++++++++++++++++++++++++++++--------------------
 1 file changed, 28 insertions(+), 20 deletions(-)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index aafd9ff30f9e..c7b2b68c8c85 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1765,6 +1765,28 @@ static inline bool __allow_reserved_blocks(struct f2fs_sb_info *sbi,
 	return false;
 }
 
+static inline unsigned int get_available_block_count(struct inode *inode,
+								bool cap)
+{
+	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
+	block_t avail_user_block_count;
+
+	avail_user_block_count = sbi->user_block_count -
+					sbi->current_reserved_blocks;
+
+	if (!__allow_reserved_blocks(sbi, inode, cap))
+		avail_user_block_count -= F2FS_OPTION(sbi).root_reserved_blocks;
+
+	if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED))) {
+		if (avail_user_block_count > sbi->unusable_block_count)
+			avail_user_block_count -= sbi->unusable_block_count;
+		else
+			avail_user_block_count = 0;
+	}
+
+	return avail_user_block_count;
+}
+
 static inline void f2fs_i_blocks_write(struct inode *, block_t, bool, bool);
 static inline int inc_valid_block_count(struct f2fs_sb_info *sbi,
 				 struct inode *inode, blkcnt_t *count)
@@ -1791,17 +1813,8 @@ static inline int inc_valid_block_count(struct f2fs_sb_info *sbi,
 
 	spin_lock(&sbi->stat_lock);
 	sbi->total_valid_block_count += (block_t)(*count);
-	avail_user_block_count = sbi->user_block_count -
-					sbi->current_reserved_blocks;
+	avail_user_block_count = get_available_block_count(inode, true);
 
-	if (!__allow_reserved_blocks(sbi, inode, true))
-		avail_user_block_count -= F2FS_OPTION(sbi).root_reserved_blocks;
-	if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED))) {
-		if (avail_user_block_count > sbi->unusable_block_count)
-			avail_user_block_count -= sbi->unusable_block_count;
-		else
-			avail_user_block_count = 0;
-	}
 	if (unlikely(sbi->total_valid_block_count > avail_user_block_count)) {
 		diff = sbi->total_valid_block_count - avail_user_block_count;
 		if (diff > *count)
@@ -2014,7 +2027,8 @@ static inline int inc_valid_node_count(struct f2fs_sb_info *sbi,
 					struct inode *inode, bool is_inode)
 {
 	block_t	valid_block_count;
-	unsigned int valid_node_count, user_block_count;
+	unsigned int valid_node_count;
+	unsigned int avail_user_block_count;
 	int err;
 
 	if (is_inode) {
@@ -2036,16 +2050,10 @@ static inline int inc_valid_node_count(struct f2fs_sb_info *sbi,
 
 	spin_lock(&sbi->stat_lock);
 
-	valid_block_count = sbi->total_valid_block_count +
-					sbi->current_reserved_blocks + 1;
-
-	if (!__allow_reserved_blocks(sbi, inode, false))
-		valid_block_count += F2FS_OPTION(sbi).root_reserved_blocks;
-	user_block_count = sbi->user_block_count;
-	if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED)))
-		user_block_count -= sbi->unusable_block_count;
+	valid_block_count = sbi->total_valid_block_count + 1;
+	avail_user_block_count = get_available_block_count(inode, false);
 
-	if (unlikely(valid_block_count > user_block_count)) {
+	if (unlikely(valid_block_count > avail_user_block_count)) {
 		spin_unlock(&sbi->stat_lock);
 		goto enospc;
 	}
-- 
2.18.0.rc1



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[f2fs-dev] [PATCH 2/2] f2fs: fix to reserve space for IO align feature

[Chao Yu]

https://bugzilla.kernel.org/show_bug.cgi?id=204137

With below script, we will hit panic during new segment allocation:

DISK=bingo.img
MOUNT_DIR=/mnt/f2fs

dd if=/dev/zero of=$DISK bs=1M count=105
mkfs.f2fe -a 1 -o 19 -t 1 -z 1 -f -q $DISK

mount -t f2fs $DISK $MOUNT_DIR -o "noinline_dentry,flush_merge,noextent_cache,mode=lfs,io_bits=7,fsync_mode=strict"

for (( i = 0; i < 4096; i++ )); do
	name=`head /dev/urandom | tr -dc A-Za-z0-9 | head -c 10`
	mkdir $MOUNT_DIR/$name
done

umount $MOUNT_DIR
rm $DISK

--- Core dump ---
Call Trace:
 allocate_segment_by_default+0x9d/0x100 [f2fs]
 f2fs_allocate_data_block+0x3c0/0x5c0 [f2fs]
 do_write_page+0x62/0x110 [f2fs]
 f2fs_outplace_write_data+0x43/0xc0 [f2fs]
 f2fs_do_write_data_page+0x386/0x560 [f2fs]
 __write_data_page+0x706/0x850 [f2fs]
 f2fs_write_cache_pages+0x267/0x6a0 [f2fs]
 f2fs_write_data_pages+0x19c/0x2e0 [f2fs]
 do_writepages+0x1c/0x70
 __filemap_fdatawrite_range+0xaa/0xe0
 filemap_fdatawrite+0x1f/0x30
 f2fs_sync_dirty_inodes+0x74/0x1f0 [f2fs]
 block_operations+0xdc/0x350 [f2fs]
 f2fs_write_checkpoint+0x104/0x1150 [f2fs]
 f2fs_sync_fs+0xa2/0x120 [f2fs]
 f2fs_balance_fs_bg+0x33c/0x390 [f2fs]
 f2fs_write_node_pages+0x4c/0x1f0 [f2fs]
 do_writepages+0x1c/0x70
 __writeback_single_inode+0x45/0x320
 writeback_sb_inodes+0x273/0x5c0
 wb_writeback+0xff/0x2e0
 wb_workfn+0xa1/0x370
 process_one_work+0x138/0x350
 worker_thread+0x4d/0x3d0
 kthread+0x109/0x140
 ret_from_fork+0x25/0x30

The root cause here is, with IO alignment feature enables, in worst
case, we need F2FS_IO_SIZE() free blocks space for single one 4k write
due to filling dummy pages to make IO being aligned.

So we will easily run out of free segments during non-inline directory's
data writeback, even in process of foreground GC.

In order to fix this issue, I just propose to reserve additional free
space for IO alignment feature to handle worst case of free space usage
ratio during FGGC.

Fixes: 0a595ebaaa6b ("f2fs: support IO alignment for DATA and NODE writes")
Signed-off-by: Chao Yu <yuchao0@huawei.com>
---
 fs/f2fs/f2fs.h    |  5 +++++
 fs/f2fs/segment.h |  3 ++-
 fs/f2fs/super.c   | 43 +++++++++++++++++++++++++++++++++++++++++++
 fs/f2fs/sysfs.c   |  4 +++-
 4 files changed, 53 insertions(+), 2 deletions(-)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index c7b2b68c8c85..4b21ac42d44e 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -929,6 +929,7 @@ struct f2fs_sm_info {
 	unsigned int segment_count;	/* total # of segments */
 	unsigned int main_segments;	/* # of segments in main area */
 	unsigned int reserved_segments;	/* # of reserved segments */
+	unsigned int additional_reserved_segments;/* reserved segs for IO align feature */
 	unsigned int ovp_segments;	/* # of overprovision segments */
 
 	/* a threshold to reclaim prefree segments */
@@ -1777,6 +1778,10 @@ static inline unsigned int get_available_block_count(struct inode *inode,
 	if (!__allow_reserved_blocks(sbi, inode, cap))
 		avail_user_block_count -= F2FS_OPTION(sbi).root_reserved_blocks;
 
+	if (F2FS_IO_ALIGNED(sbi))
+		avail_user_block_count -= sbi->blocks_per_seg *
+				SM_I(sbi)->additional_reserved_segments;
+
 	if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED))) {
 		if (avail_user_block_count > sbi->unusable_block_count)
 			avail_user_block_count -= sbi->unusable_block_count;
diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
index 325781a1ae4d..78d0f7b4c47a 100644
--- a/fs/f2fs/segment.h
+++ b/fs/f2fs/segment.h
@@ -508,7 +508,8 @@ static inline unsigned int free_segments(struct f2fs_sb_info *sbi)
 
 static inline int reserved_segments(struct f2fs_sb_info *sbi)
 {
-	return SM_I(sbi)->reserved_segments;
+	return SM_I(sbi)->reserved_segments +
+			SM_I(sbi)->additional_reserved_segments;
 }
 
 static inline unsigned int free_sections(struct f2fs_sb_info *sbi)
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index bf642d1f25fc..c98f2db76cf8 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -277,6 +277,45 @@ static inline void limit_reserve_root(struct f2fs_sb_info *sbi)
 					   F2FS_OPTION(sbi).s_resgid));
 }
 
+static inline int adjust_reserved_segment(struct f2fs_sb_info *sbi)
+{
+	unsigned int sec_blks = sbi->blocks_per_seg * sbi->segs_per_sec;
+	unsigned int avg_vblocks;
+	unsigned int wanted_reserved_segments;
+	block_t avail_user_block_count;
+
+	if (!F2FS_IO_ALIGNED(sbi))
+		return 0;
+
+	/* average valid block count in section in worst case */
+	avg_vblocks = sec_blks / F2FS_IO_SIZE(sbi);
+
+	/*
+	 * we need enough free space when migrating one section in worst case
+	 */
+	wanted_reserved_segments = (F2FS_IO_SIZE(sbi) / avg_vblocks) *
+						reserved_segments(sbi);
+	wanted_reserved_segments -= reserved_segments(sbi);
+
+	avail_user_block_count = sbi->user_block_count -
+				sbi->current_reserved_blocks -
+				F2FS_OPTION(sbi).root_reserved_blocks;
+
+	if (wanted_reserved_segments * sbi->blocks_per_seg >
+					avail_user_block_count) {
+		f2fs_err(sbi, "IO align feature can't grab additional reserved segment: %u",
+				 wanted_reserved_segments);
+		return -ENOSPC;
+	}
+
+	SM_I(sbi)->additional_reserved_segments = wanted_reserved_segments;
+
+	f2fs_info(sbi, "IO align feature needs additional reserved segment: %u",
+			 wanted_reserved_segments);
+
+	return 0;
+}
+
 static void init_once(void *foo)
 {
 	struct f2fs_inode_info *fi = (struct f2fs_inode_info *) foo;
@@ -3424,6 +3463,10 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
 		goto free_nm;
 	}
 
+	err = adjust_reserved_segment(sbi);
+	if (err)
+		goto free_nm;
+
 	/* For write statistics */
 	if (sb->s_bdev->bd_part)
 		sbi->sectors_written_start =
diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
index f9fcca695db9..1824114d739c 100644
--- a/fs/f2fs/sysfs.c
+++ b/fs/f2fs/sysfs.c
@@ -259,7 +259,9 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
 	if (a->struct_type == RESERVED_BLOCKS) {
 		spin_lock(&sbi->stat_lock);
 		if (t > (unsigned long)(sbi->user_block_count -
-				F2FS_OPTION(sbi).root_reserved_blocks)) {
+				F2FS_OPTION(sbi).root_reserved_blocks -
+				sbi->blocks_per_seg *
+				SM_I(sbi)->additional_reserved_segments)) {
 			spin_unlock(&sbi->stat_lock);
 			return -EINVAL;
 		}
-- 
2.18.0.rc1



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