6.8-stable review patch. If anyone has any objections, please let me know.
------------------
From: Chuck Lever <chuck.lever@xxxxxxxxxx>
[ 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@xxxxxxxxxx>
Fixes: a2e459555c5f ("shmem: stable directory offsets")
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240415152057.4605-2-cel@xxxxxxxxxx
Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
fs/libfs.c | 25 +++++++++++++++++++------
1 file changed, 19 insertions(+), 6 deletions(-)
diff --git a/fs/libfs.c b/fs/libfs.c
index d3d31197c8e43..c9516f3e14bb7 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -294,6 +294,18 @@ int simple_offset_add(struct offset_ctx *octx, struct dentry *dentry)
return 0;
}
+static int simple_offset_replace(struct offset_ctx *octx, struct dentry *dentry,
+ long offset)
+{
+ int ret;
+
+ ret = mtree_store(&octx->mt, offset, dentry, GFP_KERNEL);
+ if (ret)
+ return 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 *dentry)
* @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 inode *old_dir,
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 inode *old_dir,
return 0;
out_restore:
- offset_set(old_dentry, old_index);
- mtree_store(&old_ctx->mt, old_index, old_dentry, GFP_KERNEL);
- offset_set(new_dentry, new_index);
- mtree_store(&new_ctx->mt, 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;
}
--
2.43.0
