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 <yuch...@huawei.com> --- v2: - just rebase, no logic change 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 9c010e6cba5c..84fa41845e18 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -920,6 +920,7 @@ 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 */ @@ -1767,6 +1768,10 @@ static inline unsigned int get_available_block_count(struct f2fs_sb_info *sbi, 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 46d10a94721d..fd5efcd89f6e 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; @@ -3414,6 +3453,10 @@ 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