From c7079853c859c910b9d047a37891b4aafb8f8dd7 Mon Sep 17 00:00:00 2001 From: Chao Yu Date: Sun, 5 Aug 2018 23:02:22 +0800 Subject: [PATCH] f2fs: avoid race between zero_range and background GC Thread A Background GC - f2fs_zero_range - truncate_pagecache_range - gc_data_segment - get_read_data_page - move_data_page - set_page_dirty - set_cold_data - f2fs_do_zero_range - dn->data_blkaddr = NEW_ADDR; - f2fs_set_data_blkaddr Actually, we don't need to set dirty & checked flag on the page, since all valid data in the page should be zeroed by zero_range(). Use i_gc_rwsem[WRITE] to avoid such race condition. Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim --- fs/f2fs/file.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c index 67c9c2d4e2d9..4cb02027827e 100644 --- a/fs/f2fs/file.c +++ b/fs/f2fs/file.c @@ -1314,8 +1314,6 @@ static int f2fs_zero_range(struct inode *inode, loff_t offset, loff_t len, if (ret) goto out_sem; - truncate_pagecache_range(inode, offset, offset + len - 1); - pg_start = ((unsigned long long) offset) >> PAGE_SHIFT; pg_end = ((unsigned long long) offset + len) >> PAGE_SHIFT; @@ -1345,12 +1343,19 @@ static int f2fs_zero_range(struct inode *inode, loff_t offset, loff_t len, unsigned int end_offset; pgoff_t end; + down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); + + truncate_pagecache_range(inode, + (loff_t)index << PAGE_SHIFT, + ((loff_t)pg_end << PAGE_SHIFT) - 1); + f2fs_lock_op(sbi); set_new_dnode(&dn, inode, NULL, NULL, 0); ret = f2fs_get_dnode_of_data(&dn, index, ALLOC_NODE); if (ret) { f2fs_unlock_op(sbi); + up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); goto out; } @@ -1359,7 +1364,9 @@ static int f2fs_zero_range(struct inode *inode, loff_t offset, loff_t len, ret = f2fs_do_zero_range(&dn, index, end); f2fs_put_dnode(&dn); + f2fs_unlock_op(sbi); + up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); f2fs_balance_fs(sbi, dn.node_changed);