Patch "libfs: Fix simple_offset_rename_exchange()" has been added to the 6.6-stable tree

gregkh
2025-01-30T08:59:43Z

This is a note to let you know that I've just added the patch titled

libfs: Fix simple_offset_rename_exchange()

to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
libfs-fix-simple_offset_rename_exchange.patch
and it can be found in the queue-6.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.

From stable+bounces-110404-greg=kroah.com@vger.kernel.org Fri Jan 24 20:21:48 2025
From: cel@kernel.org
Date: Fri, 24 Jan 2025 14:19:39 -0500
Subject: libfs: Fix simple_offset_rename_exchange()
To: Hugh Dickins <hughd@google.com>, Andrew Morten <akpm@linux-foundation.org>, Christian Brauner <brauner@kernel.org>, Al Viro <viro@zeniv.linux.org.uk>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Sasha Levin <sashal@kernel.org>
Cc: <linux-fsdevel@vger.kernel.org>, <stable@vger.kernel.org>, <linux-mm@kvack.org>, yukuai3@huawei.com, yangerkun@huawei.com, Chuck Lever <chuck.lever@oracle.com>
Message-ID: <20250124191946.22308-5-cel@kernel.org>

From: Chuck Lever <chuck.lever@oracle.com>

[ Upstream commit 23cdd0eed3f1fff3af323092b0b88945a7950d8e ]

User space expects the replacement (old) directory entry to have
the same directory offset after the rename.

Suggested-by: Christian Brauner <brauner@kernel.org>
Fixes: a2e459555c5f ("shmem: stable directory offsets")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Link: https://lore.kernel.org/r/20240415152057.4605-2-cel@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
[ cel: adjusted to apply to origin/linux-6.6.y ]
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/libfs.c | 25 +++++++++++++++++++------
1 file changed, 19 insertions(+), 6 deletions(-)

--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -294,6 +294,18 @@ int simple_offset_add(struct offset_ctx
return 0;
}

+static int simple_offset_replace(struct offset_ctx *octx, struct dentry *dentry,
+ long offset)
+{
+ void *ret;
+
+ ret = xa_store(&octx->xa, offset, dentry, GFP_KERNEL);
+ if (xa_is_err(ret))
+ return xa_err(ret);
+ offset_set(dentry, offset);
+ return 0;
+}
+
/**
* simple_offset_remove - Remove an entry to a directory's offset map
* @octx: directory offset ctx to be updated
@@ -351,6 +363,9 @@ int simple_offset_empty(struct dentry *d
* @new_dir: destination parent
* @new_dentry: destination dentry
*
+ * This API preserves the directory offset values. Caller provides
+ * appropriate serialization.
+ *
* Returns zero on success. Otherwise a negative errno is returned and the
* rename is rolled back.
*/
@@ -368,11 +383,11 @@ int simple_offset_rename_exchange(struct
simple_offset_remove(old_ctx, old_dentry);
simple_offset_remove(new_ctx, new_dentry);

- ret = simple_offset_add(new_ctx, old_dentry);
+ ret = simple_offset_replace(new_ctx, old_dentry, new_index);
if (ret)
goto out_restore;

- ret = simple_offset_add(old_ctx, new_dentry);
+ ret = simple_offset_replace(old_ctx, new_dentry, old_index);
if (ret) {
simple_offset_remove(new_ctx, old_dentry);
goto out_restore;
@@ -387,10 +402,8 @@ int simple_offset_rename_exchange(struct
return 0;

out_restore:
- offset_set(old_dentry, old_index);
- xa_store(&old_ctx->xa, old_index, old_dentry, GFP_KERNEL);
- offset_set(new_dentry, new_index);
- xa_store(&new_ctx->xa, new_index, new_dentry, GFP_KERNEL);
+ (void)simple_offset_replace(old_ctx, old_dentry, old_index);
+ (void)simple_offset_replace(new_ctx, new_dentry, new_index);
return ret;
}

Patches currently in stable-queue which might be from cel@kernel.org are

queue-6.6/libfs-replace-simple_offset-end-of-directory-detection.patch
queue-6.6/libfs-re-arrange-locking-in-offset_iterate_dir.patch
queue-6.6/libfs-add-simple_offset_empty.patch
queue-6.6/shmem-fix-shmem_rename2.patch
queue-6.6/revert-libfs-add-simple_offset_empty.patch
queue-6.6/libfs-use-d_children-list-to-iterate-simple_offset-directories.patch
queue-6.6/libfs-define-a-minimum-directory-offset.patch
queue-6.6/libfs-return-enospc-when-the-directory-offset-range-is-exhausted.patch
queue-6.6/libfs-fix-simple_offset_rename_exchange.patch
queue-6.6/libfs-add-simple_offset_rename-api.patch