f2fs: avoid race between zero_range and background GC (c7079853) · Commits · 戴 / test

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 <yuchao0@huawei.com> Signed-off-by:

Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/file.c

+9 −2

Original line number	Diff line number	Diff line
		@@ -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);

Admin message