linux-ext4 - [PATCH v3] ext4: clear extent index structure after file delete

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Message-ID: <20250721021044.2402436-1-bretznic@gmail.com>
Date: Sun, 20 Jul 2025 19:10:44 -0700
From: Nicolas Bretz <bretznic@...il.com>
To: tytso@....edu,
	adilger.kernel@...ger.ca
Cc: linux-ext4@...r.kernel.org,
	Nicolas Bretz <bretznic@...il.com>,
	kernel test robot <lkp@...el.com>
Subject: [PATCH v3] ext4: clear extent index structure after file delete

The extent index structure in the top inode is not being cleared after a file
is deleted, which leaves the path to the data blocks intact. This patch clears
this extent index structure.

Extent structures are already being cleared, so this also makes the
behavior consistent between extent and extent _index_ structures.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=220342

Reported-by: kernel test robot <lkp@...el.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202507210558.sazSHcm1-lkp@intel.com/
Signed-off-by: Nicolas Bretz <bretznic@...il.com>
---
Changes in v2:
- corrected function name. Due to my incorrect use of git, attempting to ammend only the message led to code changes being reverted, after building successfully.
Changes in v3:
- corrected sparse: restricted __le16 degrades to integer
---
 fs/ext4/extents.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index b543a46fc809..17591a99dafd 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -2822,6 +2822,7 @@ int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start,
 	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 	int depth = ext_depth(inode);
 	struct ext4_ext_path *path = NULL;
+	struct ext4_extent_idx *ix = NULL;
 	struct partial_cluster partial;
 	handle_t *handle;
 	int i = 0, err = 0;
@@ -3060,6 +3061,9 @@ int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start,
 		 */
 		err = ext4_ext_get_access(handle, inode, path);
 		if (err == 0) {
+			ix = EXT_FIRST_INDEX(path->p_hdr);
+			if (ix && le16_to_cpu(ext_inode_hdr(inode)->eh_depth) > 0)
+				ext4_idx_store_pblock(ix, 0);
 			ext_inode_hdr(inode)->eh_depth = 0;
 			ext_inode_hdr(inode)->eh_max =
 				cpu_to_le16(ext4_ext_space_root(inode, 0));
-- 
2.47.2