From 2ef79ecb5e906d87475d3e0c49b22425499a89f3 Mon Sep 17 00:00:00 2001 From: Chao Yu Date: Mon, 7 May 2018 20:28:54 +0800 Subject: f2fs: avoid stucking GC due to atomic write f2fs doesn't allow abuse on atomic write class interface, so except limiting in-mem pages' total memory usage capacity, we need to limit atomic-write usage as well when filesystem is seriously fragmented, otherwise we may run into infinite loop during foreground GC because target blocks in victim segment are belong to atomic opened file for long time. Now, we will detect failure due to atomic write in foreground GC, if the count exceeds threshold, we will drop all atomic written data in cache, by this, I expect it can keep our system running safely to prevent Dos attack. In addition, his patch adds to show GC skip information in debugfs, now it just shows count of skipped caused by atomic write. Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim --- fs/f2fs/debug.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'fs/f2fs/debug.c') diff --git a/fs/f2fs/debug.c b/fs/f2fs/debug.c index a66107b5cfff..2d65e77ae5cf 100644 --- a/fs/f2fs/debug.c +++ b/fs/f2fs/debug.c @@ -104,6 +104,8 @@ static void update_general_status(struct f2fs_sb_info *sbi) si->avail_nids = NM_I(sbi)->available_nids; si->alloc_nids = NM_I(sbi)->nid_cnt[PREALLOC_NID]; si->bg_gc = sbi->bg_gc; + si->skipped_atomic_files[BG_GC] = sbi->skipped_atomic_files[BG_GC]; + si->skipped_atomic_files[FG_GC] = sbi->skipped_atomic_files[FG_GC]; si->util_free = (int)(free_user_blocks(sbi) >> sbi->log_blocks_per_seg) * 100 / (int)(sbi->user_block_count >> sbi->log_blocks_per_seg) / 2; @@ -342,6 +344,10 @@ static int stat_show(struct seq_file *s, void *v) si->bg_data_blks); seq_printf(s, " - node blocks : %d (%d)\n", si->node_blks, si->bg_node_blks); + seq_printf(s, "Skipped : atomic write %llu (%llu)\n", + si->skipped_atomic_files[BG_GC] + + si->skipped_atomic_files[FG_GC], + si->skipped_atomic_files[BG_GC]); seq_puts(s, "\nExtent Cache:\n"); seq_printf(s, " - Hit Count: L1-1:%llu L1-2:%llu L2:%llu\n", si->hit_largest, si->hit_cached, -- cgit v1.2.3