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libfs: Fix simple_offset_rename_exchange()

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[ Upstream commit 23cdd0eed3 ]

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: a2e459555c ("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>
This commit is contained in:
Chuck Lever
2025-01-24 14:19:39 -05:00
committed by Greg Kroah-Hartman
parent 307f68e49d
commit 3e716f31ff
1 changed files with 19 additions and 6 deletions
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fs/libfs.c
+19 -6
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@@ -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)
{
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;
}