Changeset 770 for Whitix/branches

Timestamp:

07/09/08 18:46:57 (5 months ago)

Author:

mwhitworth

Message:

Fix buffer locking behaviour to avoid races.

Location:

Whitix/branches/fs/fs/vfs

Files:

• bcache.c (modified) (6 diffs)
• dir.c (modified) (1 diff)
• file.c (modified) (4 diffs)
• load.c (modified) (4 diffs)

Whitix/branches/fs/fs/vfs/bcache.c

@@ -95 +95 @@
         INIT_WAITQUEUE_ENTRY(bufferWait);
 
-        WaitAddToQueue(&buffer->waitQueue, &bufferWait);
-
         do
         {
+                WaitAddToQueue(&buffer->waitQueue, &bufferWait);
                 ThrSuspendThread(currThread);
-
-                if (!BufferLocked(buffer))
-                        break;
-
                 ThrSchedule();
         }while (BufferLocked(buffer));
@@ -157 +152 @@
 
         INIT_WAITQUEUE_HEAD(&buff->waitQueue);
+        BufferLock(buff);
         BlockAddToHashTable(buff);
 
@@ -259 +255 @@
                 return -EFAULT;
 
-        /* The buffer will be unlocked in StorageEndRequest */
-        BufferLock(buff);
+        /* Buffer should already be locked if we're coming from BlockRead */
 
         err=BlockSendRequestRaw(device,request);
@@ -308 +303 @@
 
         request=StorageBuildRequest(buff, REQUEST_READ);
-
-        BufferLock(buff);
 
         StorageDoRequest(device,request);
@@ -479 +472 @@
 {
         struct ListHead* head=BUFFER_HASH(device, blockNum);
-        struct Buffer* curr;
+        struct Buffer* curr, *ret=NULL;
+
+        PreemptDisable();
 
         ListForEachEntry(curr, head, list)
@@ -485 +480 @@
                 {
                         BufferGet(curr);
-                        return curr;
+                        ret=curr;
+                        goto out;
                 }
 
-        return NULL;
+out:
+        PreemptEnable();
+        return ret;
 }
 

Whitix/branches/fs/fs/vfs/dir.c

@@ -372 +372 @@
                 return -ENOTIMPL;
         }
+
+        VfsFileAccessed(file->vNode);
 
         /* Check if an error occured during ReadDir. If not, return the total byte-count of

Whitix/branches/fs/fs/vfs/file.c

@@ -48 +48 @@
                 return;
 
-        vNode->aTime=currTime;
-        SetVNodeDirty(vNode);
+        /* TODO: Check granularity of vNode times on disk. No point dirtying a vNode if
+         * the time isn't updated. */
+
+        if (vNode->aTime.seconds < currTime.seconds)
+        {
+                vNode->aTime=currTime;
+                SetVNodeDirty(vNode);
+        }
 }
 
@@ -74 +80 @@
                 return;
 
-        vNode->mTime=currTime;
-
         /* Has the vNode just been created? If so, record its
         creation time */
@@ -81 +85 @@
                 vNode->cTime=currTime;
 
-        SetVNodeDirty(vNode);
+        /* See VfsFileAccessed comment. */
+        if (vNode->mTime.seconds < currTime.seconds || create)
+        {
+                vNode->mTime=currTime;
+                SetVNodeDirty(vNode);
+        }
 }
 
@@ -146 +155 @@
                 copyOffset+=readSize;
                 file->position+=readSize;
+
                 BlockFree(buff);
         }

Whitix/branches/fs/fs/vfs/load.c

@@ -72 +72 @@
         int err;
 
-        err=DoOpenFile(file,pathName,FILE_READ,0);
+        err=DoOpenFile(file, pathName, FILE_READ, 0);
 
         if (err)
                 return err;
-
+        
         if (file->vNode->mode & VFS_ATTR_DIR)
                 return -EISDIR;
@@ -377 +377 @@
         ExecSetupContext(&execArgs,pathName,fds,argv);
 
-        /* Open exectuable */
+        /* Open executable */
         err=ExecOpen(pathName,&execArgs.exec);
         if (err)
@@ -708 +708 @@
         /* Should calculate total program header size. TODO: Memory map in. See linker code. */
         buffer=(BYTE*)malloc(512);
-        if (!DoReadFile(&args->exec,buffer,512))
+        if (!DoReadFile(&args->exec, buffer, 512))
         {
                 KePrint("Failed to read file %s\n",args->pathName);
@@ -717 +717 @@
         header=(struct ElfHeader*)buffer;
 
-        if (ElfCheckHeader(header,ELF_EXEC | ELF_DYN))
-        {
-                KePrint("%s: not a valid ELF executable\n",args->pathName);
+        if (ElfCheckHeader(header, ELF_EXEC | ELF_DYN))
+        {
+                KePrint("%s: not a valid ELF executable\n", args->pathName);
                 err=-EINVAL;
                 goto freeBuffer;