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 --- fs/libfs.c | 25 +++++++++++++++++++------ 1 file changed, 19 insertions(+), 6 deletions(-)
diff --git a/fs/libfs.c b/fs/libfs.c index 66b428f3fc41..9fec0113a83f 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, + u32 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 *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); - 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; }