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* Resolved TODO in free_vnode(): There was a race condition between vnode

Browse Source 
destruction and VMVnodeCache::AcquireUnreferencedStoreRef(). Solved by
  adding a flag to VMVnodeCache and letting AcquireUnreferencedStoreRef()
  fail, if set.
* Added TODO regarding replacing the snooze() waiting for busy vnodes.
* get_vnode(): Unlock sVnodeMutex while calling the put_vnode() hook on
  error.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@34841 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Ingo Weinhold
2010-01-01 20:20:11 +00:00
parent a7cc5352d8
commit 3caec2871a
3 changed files with 33 additions and 12 deletions
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src/system/kernel/fs/vfs.cpp
+15 -8
View File
@@ -56,6 +56,7 @@
#include "fifo.h"
#include "IORequest.h"
#include "../cache/vnode_store.h"
//#define TRACE_VFS
@@ -1092,12 +1093,6 @@ free_vnode(struct vnode* vnode, bool reenter)
// count, so that it will neither become negative nor 0.
vnode->ref_count = 2;
// TODO: Usually, when the vnode is unreferenced, no one can get hold of the
// cache either (i.e. no one can get a cache reference while we're deleting
// the vnode).. This is, however, not the case for the page daemon. It gets
// its cache references via the pages it scans, so it can in fact get a
// vnode reference while we're deleting the vnode.
if (!vnode->unpublished) {
if (vnode->remove)
FS_CALL(vnode, remove_vnode, reenter);
@@ -1105,8 +1100,16 @@ free_vnode(struct vnode* vnode, bool reenter)
FS_CALL(vnode, put_vnode, reenter);
}
// If the vnode has a VMCache attached, make sure that it won't try to get
// another reference via VMVnodeCache::AcquireUnreferencedStoreRef(). As
// long as the vnode is busy and in the hash, that won't happen, but as
// soon as we've removed it from the hash, it could reload the vnode -- with
// a new cache attached!
if (vnode->cache != NULL)
((VMVnodeCache*)vnode->cache)->VnodeDeleted();
// The file system has removed the resources of the vnode now, so we can
// make it available again (and remove the busy vnode from the hash)
// make it available again (by removing the busy vnode from the hash).
mutex_lock(&sVnodeMutex);
hash_remove(sVnodeTable, vnode);
mutex_unlock(&sVnodeMutex);
@@ -1277,6 +1280,7 @@ restart:
vnodeID);
return B_BUSY;
}
// TODO: Replace this mechanism!
snooze(10000); // 10 ms
mutex_lock(&sVnodeMutex);
goto restart;
@@ -1323,8 +1327,11 @@ restart:
mutex_lock(&sVnodeMutex);
if (status != B_OK) {
if (gotNode)
if (gotNode) {
mutex_unlock(&sVnodeMutex);
FS_CALL(vnode, put_vnode, reenter);
mutex_lock(&sVnodeMutex);
}
goto err1;
}