From edd1400be9f983f521c7397740d810fa210ee52f Mon Sep 17 00:00:00 2001 From: Miao Xie Date: Thu, 27 Jun 2013 18:51:00 +0800 Subject: [PATCH] Btrfs: fix several potential problems in copy_nocow_pages_for_inode - It makes no sense that we deal with a inode in the dead tree. - fix the race between dio and page copy by waiting the dio completion - avoid the page copy vs truncate/punch hole - check if the page is in the page cache or not Signed-off-by: Miao Xie Signed-off-by: Josef Bacik --- fs/btrfs/scrub.c | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c index 186ea82b75f7..4ba2a69a60ad 100644 --- a/fs/btrfs/scrub.c +++ b/fs/btrfs/scrub.c @@ -3224,6 +3224,11 @@ static int copy_nocow_pages_for_inode(u64 inum, u64 offset, u64 root, void *ctx) return PTR_ERR(local_root); } + if (btrfs_root_refs(&local_root->root_item) == 0) { + srcu_read_unlock(&fs_info->subvol_srcu, srcu_index); + return -ENOENT; + } + key.type = BTRFS_INODE_ITEM_KEY; key.objectid = inum; key.offset = 0; @@ -3232,12 +3237,16 @@ static int copy_nocow_pages_for_inode(u64 inum, u64 offset, u64 root, void *ctx) if (IS_ERR(inode)) return PTR_ERR(inode); + /* Avoid truncate/dio/punch hole.. */ + mutex_lock(&inode->i_mutex); + inode_dio_wait(inode); + ret = 0; physical_for_dev_replace = nocow_ctx->physical_for_dev_replace; len = nocow_ctx->len; while (len >= PAGE_CACHE_SIZE) { index = offset >> PAGE_CACHE_SHIFT; - +again: page = find_or_create_page(inode->i_mapping, index, GFP_NOFS); if (!page) { pr_err("find_or_create_page() failed\n"); @@ -3258,7 +3267,18 @@ static int copy_nocow_pages_for_inode(u64 inum, u64 offset, u64 root, void *ctx) ret = err; goto next_page; } + lock_page(page); + /* + * If the page has been remove from the page cache, + * the data on it is meaningless, because it may be + * old one, the new data may be written into the new + * page in the page cache. + */ + if (page->mapping != inode->i_mapping) { + page_cache_release(page); + goto again; + } if (!PageUptodate(page)) { ret = -EIO; goto next_page; @@ -3280,6 +3300,7 @@ next_page: len -= PAGE_CACHE_SIZE; } out: + mutex_unlock(&inode->i_mutex); iput(inode); return ret; } -- 2.39.5