From 24331050a3e6afcd4451409831dd9ae8085a42f6 Mon Sep 17 00:00:00 2001 From: Gao Xiang Date: Fri, 4 Feb 2022 03:02:03 +0800 Subject: erofs: fix small compressed files inlining Prior to ztailpacking feature, it's enough that each lcluster has two pclusters at most, and the last pcluster should be turned into an uncompressed pcluster when necessary. For example, _________________________________________________ |_ pcluster n-2 _|_ pcluster n-1 _|____ EOFed ____| which should be converted into: _________________________________________________ |_ pcluster n-2 _|_ pcluster n-1 (uncompressed)' _| That is fine since either pcluster n-1 or (uncompressed)' takes one physical block. However, after ztailpacking was supported, the game is changed since the last pcluster can be inlined now. And such case above is quite common for inlining small files. Therefore, in order to inline more effectively, special EOF lclusters are now supported which can have three parts at most, as illustrated below: _________________________________________________ |_ pcluster n-2 _|_ pcluster n-1 _|____ EOFed ____| ^ i_size Actually similar code exists in Yue Hu's original patchset [1], but I removed this part on purpose. After evaluating more real cases with small files, I've changed my mind. [1] https://lore.kernel.org/r/20211215094449.15162-1-huyue2@yulong.com Link: https://lore.kernel.org/r/20220203190203.30794-1-xiang@kernel.org Fixes: ab92184ff8f1 ("erofs: add on-disk compressed tail-packing inline support") Reviewed-by: Chao Yu Signed-off-by: Gao Xiang --- fs/erofs/zmap.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'fs') diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c index 18d7fd1a5064..361b1d6e4bf9 100644 --- a/fs/erofs/zmap.c +++ b/fs/erofs/zmap.c @@ -630,6 +630,13 @@ static int z_erofs_do_map_blocks(struct inode *inode, if (endoff >= m.clusterofs) { m.headtype = m.type; map->m_la = (m.lcn << lclusterbits) | m.clusterofs; + /* + * For ztailpacking files, in order to inline data more + * effectively, special EOF lclusters are now supported + * which can have three parts at most. + */ + if (ztailpacking && end > inode->i_size) + end = inode->i_size; break; } /* m.lcn should be >= 1 if endoff < m.clusterofs */ -- cgit 1.4.1