From 18b07c44f245beb03588b00b212b38fce9af7cc9 Mon Sep 17 00:00:00 2001 From: Viacheslav Dubeyko Date: Fri, 15 Aug 2025 12:49:19 -0700 Subject: [PATCH] hfs: clear offset and space out of valid records in b-tree node Currently, hfs_brec_remove() executes moving records towards the location of deleted record and it updates offsets of moved records. However, the hfs_brec_remove() logic ignores the "mess" of b-tree node's free space and it doesn't touch the offsets out of records number. Potentially, it could confuse fsck or driver logic or to be a reason of potential corruption cases. This patch reworks the logic of hfs_brec_remove() by means of clearing freed space of b-tree node after the records moving. And it clear the last offset that keeping old location of free space because now the offset before this one is keeping the actual offset to the free space after the record deletion. Signed-off-by: Viacheslav Dubeyko cc: John Paul Adrian Glaubitz cc: Yangtao Li cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/20250815194918.38165-1-slava@dubeyko.com Signed-off-by: Viacheslav Dubeyko --- fs/hfs/brec.c | 27 +++++++++++++++++++++++---- 1 file changed, 23 insertions(+), 4 deletions(-) diff --git a/fs/hfs/brec.c b/fs/hfs/brec.c index 896396554bcc1..b01db1fae147c 100644 --- a/fs/hfs/brec.c +++ b/fs/hfs/brec.c @@ -179,6 +179,7 @@ int hfs_brec_remove(struct hfs_find_data *fd) struct hfs_btree *tree; struct hfs_bnode *node, *parent; int end_off, rec_off, data_off, size; + int src, dst, len; tree = fd->tree; node = fd->bnode; @@ -208,10 +209,14 @@ again: } hfs_bnode_write_u16(node, offsetof(struct hfs_bnode_desc, num_recs), node->num_recs); - if (rec_off == end_off) - goto skip; size = fd->keylength + fd->entrylength; + if (rec_off == end_off) { + src = fd->keyoffset; + hfs_bnode_clear(node, src, size); + goto skip; + } + do { data_off = hfs_bnode_read_u16(node, rec_off); hfs_bnode_write_u16(node, rec_off + 2, data_off - size); @@ -219,9 +224,23 @@ again: } while (rec_off >= end_off); /* fill hole */ - hfs_bnode_move(node, fd->keyoffset, fd->keyoffset + size, - data_off - fd->keyoffset - size); + dst = fd->keyoffset; + src = fd->keyoffset + size; + len = data_off - src; + + hfs_bnode_move(node, dst, src, len); + + src = dst + len; + len = data_off - src; + + hfs_bnode_clear(node, src, len); + skip: + /* + * Remove the obsolete offset to free space. + */ + hfs_bnode_write_u16(node, end_off, 0); + hfs_bnode_dump(node); if (!fd->record) hfs_brec_update_parent(fd); -- 2.47.3