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sys: FspFileNodeRename: acquire resource of descendant file nodes when renaming them

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This commit is contained in:
Bill Zissimopoulos
2016-10-14 22:47:10 -07:00
parent 5a5a1008de
commit 5773c6eab7
3 changed files with 51 additions and 4 deletions
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25
src/sys/file.c
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@ -803,6 +803,25 @@ NTSTATUS FspFileNodeFlushAndPurgeCache(FSP_FILE_NODE *FileNode,
VOID FspFileNodeRename(FSP_FILE_NODE *FileNode, PUNICODE_STRING NewFileName)
{
/*
* FspFileNodeRename may block, because it attempts to acquire the Main
* resource of descendant file nodes. FspFileNodeRename is called at the
* completion path of IRP_MJ_SET_INFORMATION[Rename] and an IRP completion
* path should not block, with the notable exception of Rename.
*
* The original reason that Rename completion is allowed to block was that
* it was observed that IoCompleteRequest of a Rename could sometimes
* trigger a recursive call into the FSD (likely due to a filter). WinFsp
* was modified to accommodate this by allowing this recursive call to
* proceed on a different thread.
*
* Since WinFsp can already accommodate blocking on Rename completions,
* it is safe to acquire the Main resource of descendant file nodes.
*
* Note also that there can only be one rename at a time because of the
* device's FileRenameResource.
*/
PAGED_CODE();
PDEVICE_OBJECT FsvolDeviceObject = FileNode->FsvolDeviceObject;
@ -862,6 +881,9 @@ VOID FspFileNodeRename(FSP_FILE_NODE *FileNode, PUNICODE_STRING NewFileName)
DescendantFileNode = DescendantFileNodes[DescendantFileNodeIndex];
ASSERT(DescendantFileNode->FileName.Length >= FileNameLength);
if (0 != DescendantFileNodeIndex)
FspFileNodeAcquireExclusiveForeign(DescendantFileNode);
FspFsvolDeviceDeleteContextByName(FsvolDeviceObject, &DescendantFileNode->FileName, &Deleted);
ASSERT(Deleted);
@ -888,6 +910,9 @@ VOID FspFileNodeRename(FSP_FILE_NODE *FileNode, PUNICODE_STRING NewFileName)
FspFsvolDeviceInsertContextByName(FsvolDeviceObject, &DescendantFileNode->FileName, DescendantFileNode,
&DescendantFileNode->ContextByNameElementStorage, &Inserted);
ASSERT(Inserted);
if (0 != DescendantFileNodeIndex)
FspFileNodeReleaseForeign(DescendantFileNode);
}
FspFsvolDeviceUnlockContextTable(FsvolDeviceObject);