The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 300a842937fbcfb5a189cea9ba15374fdb0b5c6b Mon Sep 17 00:00:00 2001 From: Chao Yu chao@kernel.org Date: Sat, 11 Dec 2021 21:27:36 +0800 Subject: [PATCH] f2fs: fix to reserve space for IO align feature
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 IO alignment feature will fill 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 chao@kernel.org Signed-off-by: Jaegeuk Kim jaegeuk@kernel.org
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index 8601d5e979d4..842020311f83 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -1024,6 +1024,7 @@ 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 */ @@ -2205,6 +2206,11 @@ static inline int inc_valid_block_count(struct f2fs_sb_info *sbi,
if (!__allow_reserved_blocks(sbi, inode, true)) 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; @@ -2451,6 +2457,11 @@ static inline int inc_valid_node_count(struct f2fs_sb_info *sbi,
if (!__allow_reserved_blocks(sbi, inode, false)) valid_block_count += F2FS_OPTION(sbi).root_reserved_blocks; + + if (F2FS_IO_ALIGNED(sbi)) + valid_block_count += sbi->blocks_per_seg * + SM_I(sbi)->additional_reserved_segments; + user_block_count = sbi->user_block_count; if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED))) user_block_count -= sbi->unusable_block_count; diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h index 46fde9f3f28e..0291cd55cf09 100644 --- a/fs/f2fs/segment.h +++ b/fs/f2fs/segment.h @@ -538,7 +538,8 @@ static inline unsigned int free_segments(struct f2fs_sb_info *sbi)
static inline unsigned 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 ca5783fa56d5..053b508d1e4f 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -329,6 +329,46 @@ 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, available segments: %u", + wanted_reserved_segments, + avail_user_block_count >> sbi->log_blocks_per_seg); + 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 inline void adjust_unusable_cap_perc(struct f2fs_sb_info *sbi) { if (!F2FS_OPTION(sbi).unusable_cap_perc) @@ -4182,6 +4222,10 @@ 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 */ sbi->sectors_written_start = f2fs_get_sectors_written(sbi);
diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c index 55a7df17d5f3..c22bee84c8ec 100644 --- a/fs/f2fs/sysfs.c +++ b/fs/f2fs/sysfs.c @@ -424,7 +424,9 @@ 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; }