[PATCH 6.18 0249/1250] hfs: rework hfsplus_readdir() logic

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

6.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Viacheslav Dubeyko <slava@dubeyko.com>

[ Upstream commit 7fde7e806657fbe0d33f489521b488eed94f9b39 ]

The xfstests' test-case generic/637 fails with error:

FSTYP -- hfs
PLATFORM -- Linux/x86_64 kvm-xfstests 6.15.0-rc4-xfstests-g00b827f0cffa #1 SMP PREEMPT_DYNAMIC Fri May 25
MKFS_OPTIONS -- /dev/vdc
MOUNT_OPTIONS -- /dev/vdc /vdc

QA output created by 637
entries 7 and 8 have duplicate d_off 8
Found unlinked files in open dir (see xfstests-dev/results//generic/637.full for details)

Likewise HFS+, currently, HFS has very complicated and
fragile logic of rd->file->f_pos correction in hfs_delete_cat().
This patch removes this logic and it stores the current
pos into hfs_readdir_data. Finally, if rd->pos == ctx->pos
then hfs_readdir() tries to find the position in
b-tree's node by means of hfs_cat_key. This position is
used to re-start the folder's content traversal.

sudo ./check generic/637
FSTYP         -- hfs
PLATFORM      -- Linux/x86_64 hfsplus-testing-0001 7.1.0-rc1+ #55 SMP PREEMPT_DYNAMIC Tue May 19 15:18:02 PDT 2026
MKFS_OPTIONS  -- /dev/loop51
MOUNT_OPTIONS -- /dev/loop51 /mnt/scratch

generic/637  32s ...  31s
Ran: generic/637
Passed all 1 tests

Closes: https://github.com/hfs-linux-kernel/hfs-linux-kernel/issues/65
cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
cc: Yangtao Li <frank.li@vivo.com>
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Viacheslav Dubeyko <slava@dubeyko.com>
Link: https://lore.kernel.org/r/20260519222811.1311071-2-slava@dubeyko.com
Signed-off-by: Viacheslav Dubeyko <slava@dubeyko.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/hfs/catalog.c |  9 ---------
 fs/hfs/dir.c     | 28 +++++++++++-----------------
 fs/hfs/hfs.h     |  3 +--
 fs/hfs/hfs_fs.h  |  2 --
 fs/hfs/inode.c   |  4 ----
 5 files changed, 12 insertions(+), 34 deletions(-)

diff --git a/fs/hfs/catalog.c b/fs/hfs/catalog.c
index b80ba40e38776..ccdbbffaaf7c1 100644
--- a/fs/hfs/catalog.c
+++ b/fs/hfs/catalog.c
@@ -340,7 +340,6 @@ int hfs_cat_delete(u32 cnid, struct inode *dir, const struct qstr *str)
 {
 	struct super_block *sb;
 	struct hfs_find_data fd;
-	struct hfs_readdir_data *rd;
 	int res, type;
 
 	hfs_dbg("name %s, cnid %u\n", str ? str->name : NULL, cnid);
@@ -366,14 +365,6 @@ int hfs_cat_delete(u32 cnid, struct inode *dir, const struct qstr *str)
 		}
 	}
 
-	/* we only need to take spinlock for exclusion with ->release() */
-	spin_lock(&HFS_I(dir)->open_dir_lock);
-	list_for_each_entry(rd, &HFS_I(dir)->open_dir_list, list) {
-		if (fd.tree->keycmp(fd.search_key, (void *)&rd->key) < 0)
-			rd->file->f_pos--;
-	}
-	spin_unlock(&HFS_I(dir)->open_dir_lock);
-
 	res = hfs_brec_remove(&fd);
 	if (res)
 		goto out;
diff --git a/fs/hfs/dir.c b/fs/hfs/dir.c
index 86a6b317b474a..130c2f3a417f0 100644
--- a/fs/hfs/dir.c
+++ b/fs/hfs/dir.c
@@ -97,7 +97,15 @@ static int hfs_readdir(struct file *file, struct dir_context *ctx)
 	}
 	if (ctx->pos >= inode->i_size)
 		goto out;
-	err = hfs_brec_goto(&fd, ctx->pos - 1);
+	rd = file->private_data;
+	if (rd && rd->pos == ctx->pos) {
+		memcpy(fd.search_key, &rd->key, sizeof(struct hfs_cat_key));
+		err = hfs_brec_find(&fd);
+		if (err == -ENOENT)
+			err = hfs_brec_goto(&fd, 1);
+	} else {
+		err = hfs_brec_goto(&fd, ctx->pos - 1);
+	}
 	if (err)
 		goto out;
 
@@ -146,7 +154,6 @@ static int hfs_readdir(struct file *file, struct dir_context *ctx)
 		if (err)
 			goto out;
 	}
-	rd = file->private_data;
 	if (!rd) {
 		rd = kmalloc(sizeof(struct hfs_readdir_data), GFP_KERNEL);
 		if (!rd) {
@@ -154,15 +161,8 @@ static int hfs_readdir(struct file *file, struct dir_context *ctx)
 			goto out;
 		}
 		file->private_data = rd;
-		rd->file = file;
-		spin_lock(&HFS_I(inode)->open_dir_lock);
-		list_add(&rd->list, &HFS_I(inode)->open_dir_list);
-		spin_unlock(&HFS_I(inode)->open_dir_lock);
 	}
-	/*
-	 * Can be done after the list insertion; exclusion with
-	 * hfs_delete_cat() is provided by directory lock.
-	 */
+	rd->pos = ctx->pos;
 	memcpy(&rd->key, &fd.key->cat, sizeof(struct hfs_cat_key));
 out:
 	hfs_find_exit(&fd);
@@ -171,13 +171,7 @@ static int hfs_readdir(struct file *file, struct dir_context *ctx)
 
 static int hfs_dir_release(struct inode *inode, struct file *file)
 {
-	struct hfs_readdir_data *rd = file->private_data;
-	if (rd) {
-		spin_lock(&HFS_I(inode)->open_dir_lock);
-		list_del(&rd->list);
-		spin_unlock(&HFS_I(inode)->open_dir_lock);
-		kfree(rd);
-	}
+	kfree(file->private_data);
 	return 0;
 }
 
diff --git a/fs/hfs/hfs.h b/fs/hfs/hfs.h
index 6f194d0768b6f..f46d12ce04a3f 100644
--- a/fs/hfs/hfs.h
+++ b/fs/hfs/hfs.h
@@ -281,8 +281,7 @@ struct hfs_mdb {
 /*======== Data structures kept in memory ========*/
 
 struct hfs_readdir_data {
-	struct list_head list;
-	struct file *file;
+	loff_t pos;
 	struct hfs_cat_key key;
 };
 
diff --git a/fs/hfs/hfs_fs.h b/fs/hfs/hfs_fs.h
index 38854df4c1b42..d9665226f5474 100644
--- a/fs/hfs/hfs_fs.h
+++ b/fs/hfs/hfs_fs.h
@@ -37,8 +37,6 @@ struct hfs_inode_info {
 
 	struct hfs_cat_key cat_key;
 
-	struct list_head open_dir_list;
-	spinlock_t open_dir_lock;
 	struct inode *rsrc_inode;
 
 	struct mutex extents_lock;
diff --git a/fs/hfs/inode.c b/fs/hfs/inode.c
index cd43eff72d13d..cd3dd5bd456e0 100644
--- a/fs/hfs/inode.c
+++ b/fs/hfs/inode.c
@@ -192,8 +192,6 @@ struct inode *hfs_new_inode(struct inode *dir, const struct qstr *name, umode_t
 		return NULL;
 
 	mutex_init(&HFS_I(inode)->extents_lock);
-	INIT_LIST_HEAD(&HFS_I(inode)->open_dir_list);
-	spin_lock_init(&HFS_I(inode)->open_dir_lock);
 	hfs_cat_build_key(sb, (btree_key *)&HFS_I(inode)->cat_key, dir->i_ino, name);
 	next_id = atomic64_inc_return(&HFS_SB(sb)->next_id);
 	BUG_ON(next_id > U32_MAX);
@@ -334,8 +332,6 @@ static int hfs_read_inode(struct inode *inode, void *data)
 	HFS_I(inode)->flags = 0;
 	HFS_I(inode)->rsrc_inode = NULL;
 	mutex_init(&HFS_I(inode)->extents_lock);
-	INIT_LIST_HEAD(&HFS_I(inode)->open_dir_list);
-	spin_lock_init(&HFS_I(inode)->open_dir_lock);
 
 	/* Initialize the inode */
 	inode->i_uid = hsb->s_uid;
-- 
2.53.0