On 04/18, Chao Yu wrote: > 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. > > Signed-off-by: Chao Yu <yuch...@huawei.com> > --- > fs/f2fs/f2fs.h | 1 + > fs/f2fs/file.c | 5 +++++ > fs/f2fs/gc.c | 27 +++++++++++++++++++++++---- > fs/f2fs/gc.h | 3 +++ > fs/f2fs/segment.c | 1 + > fs/f2fs/segment.h | 2 ++ > 6 files changed, 35 insertions(+), 4 deletions(-) > > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h > index c1c3a1d11186..3453288d6a71 100644 > --- a/fs/f2fs/f2fs.h > +++ b/fs/f2fs/f2fs.h > @@ -2249,6 +2249,7 @@ enum { > FI_EXTRA_ATTR, /* indicate file has extra attribute */ > FI_PROJ_INHERIT, /* indicate file inherits projectid */ > FI_PIN_FILE, /* indicate file should not be gced */ > + FI_ATOMIC_REVOKE_REQUEST,/* indicate atomic committed data has been > dropped */ > }; > > static inline void __mark_inode_dirty_flag(struct inode *inode, > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c > index 7c90ded5a431..cddd9aee1bb2 100644 > --- a/fs/f2fs/file.c > +++ b/fs/f2fs/file.c > @@ -1698,6 +1698,7 @@ static int f2fs_ioc_start_atomic_write(struct file > *filp) > skip_flush: > set_inode_flag(inode, FI_HOT_DATA); > set_inode_flag(inode, FI_ATOMIC_FILE); > + clear_inode_flag(inode, FI_ATOMIC_REVOKE_REQUEST); > f2fs_update_time(F2FS_I_SB(inode), REQ_TIME); > > F2FS_I(inode)->inmem_task = current; > @@ -1746,6 +1747,10 @@ static int f2fs_ioc_commit_atomic_write(struct file > *filp) > ret = f2fs_do_sync_file(filp, 0, LLONG_MAX, 1, false); > } > err_out: > + if (is_inode_flag_set(inode, FI_ATOMIC_REVOKE_REQUEST)) { > + clear_inode_flag(inode, FI_ATOMIC_REVOKE_REQUEST); > + ret = -EINVAL; > + } > up_write(&F2FS_I(inode)->dio_rwsem[WRITE]); > inode_unlock(inode); > mnt_drop_write_file(filp); > diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c > index bfb7a4a3a929..495876ca62b6 100644 > --- a/fs/f2fs/gc.c > +++ b/fs/f2fs/gc.c > @@ -135,6 +135,8 @@ int start_gc_thread(struct f2fs_sb_info *sbi) > gc_th->gc_urgent = 0; > gc_th->gc_wake= 0; > > + gc_th->atomic_file = 0; > + > sbi->gc_thread = gc_th; > init_waitqueue_head(&sbi->gc_thread->gc_wait_queue_head); > sbi->gc_thread->f2fs_gc_task = kthread_run(gc_thread_func, sbi, > @@ -603,7 +605,7 @@ static bool is_alive(struct f2fs_sb_info *sbi, struct > f2fs_summary *sum, > * This can be used to move blocks, aka LBAs, directly on disk. > */ > static void move_data_block(struct inode *inode, block_t bidx, > - unsigned int segno, int off) > + int gc_type, unsigned int segno, int off) > { > struct f2fs_io_info fio = { > .sbi = F2FS_I_SB(inode), > @@ -630,8 +632,10 @@ static void move_data_block(struct inode *inode, block_t > bidx, > if (!check_valid_map(F2FS_I_SB(inode), segno, off)) > goto out; > > - if (f2fs_is_atomic_file(inode)) > + if (f2fs_is_atomic_file(inode)) { > + F2FS_I_SB(inode)->gc_thread->atomic_file++; > goto out; > + } > > if (f2fs_is_pinned_file(inode)) { > f2fs_pin_file_control(inode, true); > @@ -737,8 +741,10 @@ static void move_data_page(struct inode *inode, block_t > bidx, int gc_type, > if (!check_valid_map(F2FS_I_SB(inode), segno, off)) > goto out; > > - if (f2fs_is_atomic_file(inode)) > + if (f2fs_is_atomic_file(inode)) { > + F2FS_I_SB(inode)->gc_thread->atomic_file++; > goto out; > + } > if (f2fs_is_pinned_file(inode)) { > if (gc_type == FG_GC) > f2fs_pin_file_control(inode, true); > @@ -900,7 +906,8 @@ static void gc_data_segment(struct f2fs_sb_info *sbi, > struct f2fs_summary *sum, > start_bidx = start_bidx_of_node(nofs, inode) > + ofs_in_node; > if (f2fs_encrypted_file(inode)) > - move_data_block(inode, start_bidx, segno, off); > + move_data_block(inode, start_bidx, gc_type, > + segno, off); > else > move_data_page(inode, start_bidx, gc_type, > segno, off); > @@ -1017,6 +1024,8 @@ int f2fs_gc(struct f2fs_sb_info *sbi, bool sync, > .ilist = LIST_HEAD_INIT(gc_list.ilist), > .iroot = RADIX_TREE_INIT(GFP_NOFS), > }; > + unsigned int last_atomic_file = sbi->gc_thread->atomic_file; > + unsigned int skipped_round = 0, round = 0; > > trace_f2fs_gc_begin(sbi->sb, sync, background, > get_pages(sbi, F2FS_DIRTY_NODES), > @@ -1068,11 +1077,21 @@ int f2fs_gc(struct f2fs_sb_info *sbi, bool sync, > sec_freed++; > total_freed += seg_freed; > > + if (gc_type == FG_GC) { > + if (sbi->gc_thread->atomic_file > last_atomic_file) > + skipped_round++; > + last_atomic_file = sbi->gc_thread->atomic_file;
How about resetting ->atomic_file to zero? > + round++; > + } > + > if (gc_type == FG_GC) > sbi->cur_victim_sec = NULL_SEGNO; > > if (!sync) { > if (has_not_enough_free_secs(sbi, sec_freed, 0)) { > + if (skipped_round > MAX_SKIP_ATOMIC_COUNT && > + skipped_round * 2 >= round) > + drop_inmem_pages_all(sbi); > segno = NULL_SEGNO; > goto gc_more; > } > diff --git a/fs/f2fs/gc.h b/fs/f2fs/gc.h > index b0045d4c8d1e..bc1d21d46ae7 100644 > --- a/fs/f2fs/gc.h > +++ b/fs/f2fs/gc.h > @@ -39,6 +39,9 @@ struct f2fs_gc_kthread { > unsigned int gc_idle; > unsigned int gc_urgent; > unsigned int gc_wake; > + > + /* for stuck statistic */ > + unsigned int atomic_file; > }; > > struct gc_inode_list { > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c > index d809f731bfd1..831cefa088bc 100644 > --- a/fs/f2fs/segment.c > +++ b/fs/f2fs/segment.c > @@ -287,6 +287,7 @@ void drop_inmem_pages_all(struct f2fs_sb_info *sbi) > spin_unlock(&sbi->inode_lock[ATOMIC_FILE]); > > if (inode) { > + set_inode_flag(inode, FI_ATOMIC_REVOKE_REQUEST); > drop_inmem_pages(inode); > iput(inode); > } > diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h > index 492ad0c86fa9..7702b054689c 100644 > --- a/fs/f2fs/segment.h > +++ b/fs/f2fs/segment.h > @@ -215,6 +215,8 @@ struct segment_allocation { > #define IS_DUMMY_WRITTEN_PAGE(page) \ > (page_private(page) == (unsigned long)DUMMY_WRITTEN_PAGE) > > +#define MAX_SKIP_ATOMIC_COUNT 16 > + > struct inmem_pages { > struct list_head list; > struct page *page; > -- > 2.15.0.55.gc2ece9dc4de6