From 2bebc6dcd3456c6ebae623c7564a41ffd18ee6a1 Mon Sep 17 00:00:00 2001 From: Chao Yu Date: Mon, 11 Jan 2021 17:42:53 +0800 Subject: [PATCH] f2fs: compress: fix potential deadlock [ Upstream commit 3afae09ffea5e08f523823be99a784675995d6bb ] generic/269 reports a hangtask issue, the root cause is ABBA deadlock described as below: Thread A Thread B - down_write(&sbi->gc_lock) -- A - f2fs_write_data_pages - lock all pages in cluster -- B - f2fs_write_multi_pages - f2fs_write_raw_pages - f2fs_write_single_data_page - f2fs_balance_fs - down_write(&sbi->gc_lock) -- A - f2fs_gc - do_garbage_collect - ra_data_block - pagecache_get_page -- B To fix this, it needs to avoid calling f2fs_balance_fs() if there is still cluster pages been locked in context of cluster writeback, so instead, let's call f2fs_balance_fs() in the end of f2fs_write_raw_pages() when all cluster pages were unlocked. Fixes: 4c8ff7095bef ("f2fs: support data compression") Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Sasha Levin --- fs/f2fs/compress.c | 5 ++++- fs/f2fs/data.c | 10 ++++++---- fs/f2fs/f2fs.h | 2 +- 3 files changed, 11 insertions(+), 6 deletions(-) diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c index c5fee4d..d3f407b 100644 --- a/fs/f2fs/compress.c +++ b/fs/f2fs/compress.c @@ -1393,7 +1393,7 @@ retry_write: ret = f2fs_write_single_data_page(cc->rpages[i], &_submitted, NULL, NULL, wbc, io_type, - compr_blocks); + compr_blocks, false); if (ret) { if (ret == AOP_WRITEPAGE_ACTIVATE) { unlock_page(cc->rpages[i]); @@ -1428,6 +1428,9 @@ retry_write: *submitted += _submitted; } + + f2fs_balance_fs(F2FS_M_SB(mapping), true); + return 0; out_err: for (++i; i < cc->cluster_size; i++) { diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c index b29243e..4f326bc 100644 --- a/fs/f2fs/data.c +++ b/fs/f2fs/data.c @@ -2757,7 +2757,8 @@ int f2fs_write_single_data_page(struct page *page, int *submitted, sector_t *last_block, struct writeback_control *wbc, enum iostat_type io_type, - int compr_blocks) + int compr_blocks, + bool allow_balance) { struct inode *inode = page->mapping->host; struct f2fs_sb_info *sbi = F2FS_I_SB(inode); @@ -2895,7 +2896,7 @@ out: } unlock_page(page); if (!S_ISDIR(inode->i_mode) && !IS_NOQUOTA(inode) && - !F2FS_I(inode)->cp_task) + !F2FS_I(inode)->cp_task && allow_balance) f2fs_balance_fs(sbi, need_balance_fs); if (unlikely(f2fs_cp_error(sbi))) { @@ -2942,7 +2943,7 @@ out: #endif return f2fs_write_single_data_page(page, NULL, NULL, NULL, - wbc, FS_DATA_IO, 0); + wbc, FS_DATA_IO, 0, true); } /* @@ -3110,7 +3111,8 @@ continue_unlock: } #endif ret = f2fs_write_single_data_page(page, &submitted, - &bio, &last_block, wbc, io_type, 0); + &bio, &last_block, wbc, io_type, + 0, true); if (ret == AOP_WRITEPAGE_ACTIVATE) unlock_page(page); #ifdef CONFIG_F2FS_FS_COMPRESSION diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index 06e5a60..699815e 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -3507,7 +3507,7 @@ int f2fs_write_single_data_page(struct page *page, int *submitted, struct bio **bio, sector_t *last_block, struct writeback_control *wbc, enum iostat_type io_type, - int compr_blocks); + int compr_blocks, bool allow_balance); void f2fs_invalidate_page(struct page *page, unsigned int offset, unsigned int length); int f2fs_release_page(struct page *page, gfp_t wait); -- 2.7.4