file.c

Linux内核自带的cifs模块

	inode = file->f_path.dentry->d_inode;
	if (inode == NULL) {
		cERROR(1, ("inode not valid"));
		dump_stack();
		rc = -EBADF;
		goto reopen_error_exit;
	}

	cifs_sb = CIFS_SB(inode->i_sb);
	pTcon = cifs_sb->tcon;

/* can not grab rename sem here because various ops, including
   those that already have the rename sem can end up causing writepage
   to get called and if the server was down that means we end up here,
   and we can never tell if the caller already has the rename_sem */
	full_path = build_path_from_dentry(file->f_path.dentry);
#endif
	if (full_path == NULL) {
		rc = -ENOMEM;
reopen_error_exit:
		up(&pCifsFile->fh_sem);
		FreeXid(xid);
		return rc;
	}

	cFYI(1, ("inode = 0x%p file flags 0x%x for %s",
		 inode, file->f_flags, full_path));
	desiredAccess = cifs_convert_flags(file->f_flags);

	if (oplockEnabled)
		oplock = REQ_OPLOCK;
	else
		oplock = FALSE;

	/* Can not refresh inode by passing in file_info buf to be returned
	   by SMBOpen and then calling get_inode_info with returned buf
	   since file might have write behind data that needs to be flushed
	   and server version of file size can be stale. If we knew for sure
	   that inode was not dirty locally we could do this */

	rc = CIFSSMBOpen(xid, pTcon, full_path, disposition, desiredAccess,
			 CREATE_NOT_DIR, &netfid, &oplock, NULL,
			 cifs_sb->local_nls, cifs_sb->mnt_cifs_flags &
				CIFS_MOUNT_MAP_SPECIAL_CHR);
	if (rc) {
		up(&pCifsFile->fh_sem);
		cFYI(1, ("cifs_open returned 0x%x", rc));
		cFYI(1, ("oplock: %d", oplock));
	} else {
		pCifsFile->netfid = netfid;
		pCifsFile->invalidHandle = FALSE;
		up(&pCifsFile->fh_sem);
		pCifsInode = CIFS_I(inode);
		if (pCifsInode) {
			if (can_flush) {
#if LINUX_VERSION_CODE > KERNEL_VERSION(2, 6, 15)
				filemap_write_and_wait(inode->i_mapping);
#else
				filemap_fdatawrite(inode->i_mapping);
				filemap_fdatawait(inode->i_mapping);
#endif
			/* temporarily disable caching while we
			   go to server to get inode info */
				pCifsInode->clientCanCacheAll = FALSE;
				pCifsInode->clientCanCacheRead = FALSE;
				if (pTcon->unix_ext)
					rc = cifs_get_inode_info_unix(&inode,
						full_path, inode->i_sb, xid);
				else
					rc = cifs_get_inode_info(&inode,
						full_path, NULL, inode->i_sb,
						xid);
			} /* else we are writing out data to server already
			     and could deadlock if we tried to flush data, and
			     since we do not know if we have data that would
			     invalidate the current end of file on the server
			     we can not go to the server to get the new inod
			     info */
			if ((oplock & 0xF) == OPLOCK_EXCLUSIVE) {
				pCifsInode->clientCanCacheAll = TRUE;
				pCifsInode->clientCanCacheRead = TRUE;
#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 20)
				cFYI(1, ("Exclusive Oplock granted on inode %p",
					file->f_dentry->d_inode));
#else
				cFYI(1, ("Exclusive Oplock granted on inode %p",
					 file->f_path.dentry->d_inode));
#endif
			} else if ((oplock & 0xF) == OPLOCK_READ) {
				pCifsInode->clientCanCacheRead = TRUE;
				pCifsInode->clientCanCacheAll = FALSE;
			} else {
				pCifsInode->clientCanCacheRead = FALSE;
				pCifsInode->clientCanCacheAll = FALSE;
			}
			cifs_relock_file(pCifsFile);
		}
	}

	kfree(full_path);
	FreeXid(xid);
	return rc;
}

int cifs_close(struct inode *inode, struct file *file)
{
	int rc = 0;
	int xid, timeout;
	struct cifs_sb_info *cifs_sb;
	struct cifsTconInfo *pTcon;
	struct cifsFileInfo *pSMBFile =
		(struct cifsFileInfo *)file->private_data;

	xid = GetXid();

	cifs_sb = CIFS_SB(inode->i_sb);
	pTcon = cifs_sb->tcon;
	if (pSMBFile) {
		struct cifsLockInfo *li, *tmp;

		pSMBFile->closePend = TRUE;
		if (pTcon) {
			/* no sense reconnecting to close a file that is
			   already closed */
			if (pTcon->tidStatus != CifsNeedReconnect) {
				timeout = 2;
				while ((atomic_read(&pSMBFile->wrtPending) != 0)
					&& (timeout <= 2048)) {
					/* Give write a better chance to get to
					server ahead of the close.  We do not
					want to add a wait_q here as it would
					increase the memory utilization as
					the struct would be in each open file,
					but this should give enough time to
					clear the socket */
#ifdef CONFIG_CIFS_DEBUG2
					cFYI(1, ("close delay, write pending"));
#endif /* DEBUG2 */
					msleep(timeout);
					timeout *= 4;
				}
				if (atomic_read(&pSMBFile->wrtPending))
					cERROR(1,
						("close with pending writes"));
				rc = CIFSSMBClose(xid, pTcon,
						  pSMBFile->netfid);
			}
		}

		/* Delete any outstanding lock records.
		   We'll lose them when the file is closed anyway. */
		mutex_lock(&pSMBFile->lock_mutex);
		list_for_each_entry_safe(li, tmp, &pSMBFile->llist, llist) {
			list_del(&li->llist);
			kfree(li);
		}
		mutex_unlock(&pSMBFile->lock_mutex);

		write_lock(&GlobalSMBSeslock);
		list_del(&pSMBFile->flist);
		list_del(&pSMBFile->tlist);
		write_unlock(&GlobalSMBSeslock);
		timeout = 10;
		/* We waited above to give the SMBWrite a chance to issue
		   on the wire (so we do not get SMBWrite returning EBADF
		   if writepages is racing with close.  Note that writepages
		   does not specify a file handle, so it is possible for a file
		   to be opened twice, and the application close the "wrong"
		   file handle - in these cases we delay long enough to allow
		   the SMBWrite to get on the wire before the SMB Close.
		   We allow total wait here over 45 seconds, more than
		   oplock break time, and more than enough to allow any write
		   to complete on the server, or to time out on the client */
		while ((atomic_read(&pSMBFile->wrtPending) != 0)
				&& (timeout <= 50000)) {
			cERROR(1, ("writes pending, delay free of handle"));
			msleep(timeout);
			timeout *= 8;
		}
		kfree(pSMBFile->search_resume_name);
		kfree(file->private_data);
		file->private_data = NULL;
	} else
		rc = -EBADF;

	read_lock(&GlobalSMBSeslock);
	if (list_empty(&(CIFS_I(inode)->openFileList))) {
		cFYI(1, ("closing last open instance for inode %p", inode));
		/* if the file is not open we do not know if we can cache info
		   on this inode, much less write behind and read ahead */
		CIFS_I(inode)->clientCanCacheRead = FALSE;
		CIFS_I(inode)->clientCanCacheAll  = FALSE;
	}
	read_unlock(&GlobalSMBSeslock);
	if ((rc == 0) && CIFS_I(inode)->write_behind_rc)
		rc = CIFS_I(inode)->write_behind_rc;
	FreeXid(xid);
	return rc;
}

int cifs_closedir(struct inode *inode, struct file *file)
{
	int rc = 0;
	int xid;
	struct cifsFileInfo *pCFileStruct =
	    (struct cifsFileInfo *)file->private_data;
	char *ptmp;

	cFYI(1, ("Closedir inode = 0x%p", inode));

	xid = GetXid();

	if (pCFileStruct) {
		struct cifsTconInfo *pTcon;
		struct cifs_sb_info *cifs_sb =
#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 20)
			CIFS_SB(file->f_dentry->d_sb);
#else
			CIFS_SB(file->f_path.dentry->d_sb);
#endif

		pTcon = cifs_sb->tcon;

		cFYI(1, ("Freeing private data in close dir"));
		if ((pCFileStruct->srch_inf.endOfSearch == FALSE) &&
		   (pCFileStruct->invalidHandle == FALSE)) {
			pCFileStruct->invalidHandle = TRUE;
			rc = CIFSFindClose(xid, pTcon, pCFileStruct->netfid);
			cFYI(1, ("Closing uncompleted readdir with rc %d",
				 rc));
			/* not much we can do if it fails anyway, ignore rc */
			rc = 0;
		}
		ptmp = pCFileStruct->srch_inf.ntwrk_buf_start;
		if (ptmp) {
			cFYI(1, ("closedir free smb buf in srch struct"));
			pCFileStruct->srch_inf.ntwrk_buf_start = NULL;
			if (pCFileStruct->srch_inf.smallBuf)
				cifs_small_buf_release(ptmp);
			else
				cifs_buf_release(ptmp);
		}
		ptmp = pCFileStruct->search_resume_name;
		if (ptmp) {
			cFYI(1, ("closedir free resume name"));
			pCFileStruct->search_resume_name = NULL;
			kfree(ptmp);
		}
		kfree(file->private_data);
		file->private_data = NULL;
	}
	/* BB can we lock the filestruct while this is going on? */
	FreeXid(xid);
	return rc;
}

static int store_file_lock(struct cifsFileInfo *fid, __u64 len,
				__u64 offset, __u8 lockType)
{
	struct cifsLockInfo *li =
		kmalloc(sizeof(struct cifsLockInfo), GFP_KERNEL);
	if (li == NULL)
		return -ENOMEM;
	li->offset = offset;
	li->length = len;
	li->type = lockType;
	mutex_lock(&fid->lock_mutex);
	list_add(&li->llist, &fid->llist);
	mutex_unlock(&fid->lock_mutex);
	return 0;
}

int cifs_lock(struct file *file, int cmd, struct file_lock *pfLock)
{
	int rc, xid;
	__u32 numLock = 0;
	__u32 numUnlock = 0;
	__u64 length;
	int wait_flag = FALSE;
	struct cifs_sb_info *cifs_sb;
	struct cifsTconInfo *pTcon;
	__u16 netfid;
	__u8 lockType = LOCKING_ANDX_LARGE_FILES;
	int posix_locking;

	length = 1 + pfLock->fl_end - pfLock->fl_start;
	rc = -EACCES;
	xid = GetXid();

	cFYI(1, ("Lock parm: 0x%x flockflags: "
		 "0x%x flocktype: 0x%x start: %lld end: %lld",
		cmd, pfLock->fl_flags, pfLock->fl_type, pfLock->fl_start,
		pfLock->fl_end));

	if (pfLock->fl_flags & FL_POSIX)
		cFYI(1, ("Posix"));
	if (pfLock->fl_flags & FL_FLOCK)
		cFYI(1, ("Flock"));
	if (pfLock->fl_flags & FL_SLEEP) {
		cFYI(1, ("Blocking lock"));
		wait_flag = TRUE;
	}
	if (pfLock->fl_flags & FL_ACCESS)
		cFYI(1, ("Process suspended by mandatory locking - "
			 "not implemented yet"));
	if (pfLock->fl_flags & FL_LEASE)
		cFYI(1, ("Lease on file - not implemented yet"));
	if (pfLock->fl_flags &
	    (~(FL_POSIX | FL_FLOCK | FL_SLEEP | FL_ACCESS | FL_LEASE)))
		cFYI(1, ("Unknown lock flags 0x%x", pfLock->fl_flags));

	if (pfLock->fl_type == F_WRLCK) {
		cFYI(1, ("F_WRLCK "));
		numLock = 1;
	} else if (pfLock->fl_type == F_UNLCK) {
		cFYI(1, ("F_UNLCK"));
		numUnlock = 1;
		/* Check if unlock includes more than
		one lock range */
	} else if (pfLock->fl_type == F_RDLCK) {
		cFYI(1, ("F_RDLCK"));
		lockType |= LOCKING_ANDX_SHARED_LOCK;
		numLock = 1;
	} else if (pfLock->fl_type == F_EXLCK) {
		cFYI(1, ("F_EXLCK"));
		numLock = 1;
	} else if (pfLock->fl_type == F_SHLCK) {
		cFYI(1, ("F_SHLCK"));
		lockType |= LOCKING_ANDX_SHARED_LOCK;
		numLock = 1;
	} else
		cFYI(1, ("Unknown type of lock"));

#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 20)
	cifs_sb = CIFS_SB(file->f_dentry->d_sb);
#else
	cifs_sb = CIFS_SB(file->f_path.dentry->d_sb);
#endif
	pTcon = cifs_sb->tcon;

	if (file->private_data == NULL) {
		FreeXid(xid);
		return -EBADF;
	}
	netfid = ((struct cifsFileInfo *)file->private_data)->netfid;

	posix_locking = (cifs_sb->tcon->ses->capabilities & CAP_UNIX) &&
			(CIFS_UNIX_FCNTL_CAP & le64_to_cpu(cifs_sb->tcon->fsUnixInfo.Capability));

	/* BB add code here to normalize offset and length to
	account for negative length which we can not accept over the
	wire */
	if (IS_GETLK(cmd)) {
		if (posix_locking) {
			int posix_lock_type;
			if (lockType & LOCKING_ANDX_SHARED_LOCK)
				posix_lock_type = CIFS_RDLCK;
			else
				posix_lock_type = CIFS_WRLCK;
			rc = CIFSSMBPosixLock(xid, pTcon, netfid, 1 /* get */,
					length,	pfLock,
					posix_lock_type, wait_flag);
			FreeXid(xid);
			return rc;
		}

		/* BB we could chain these into one lock request BB */
		rc = CIFSSMBLock(xid, pTcon, netfid, length, pfLock->fl_start,
				 0, 1, lockType, 0 /* wait flag */ );
		if (rc == 0) {
			rc = CIFSSMBLock(xid, pTcon, netfid, length,
					 pfLock->fl_start, 1 /* numUnlock */ ,
					 0 /* numLock */ , lockType,
					 0 /* wait flag */ );
			pfLock->fl_type = F_UNLCK;
			if (rc != 0)
				cERROR(1, ("Error unlocking previously locked "
					   "range %d during test of lock", rc));
			rc = 0;

		} else {
			/* if rc == ERR_SHARING_VIOLATION ? */
			rc = 0;	/* do not change lock type to unlock
				   since range in use */
		}

		FreeXid(xid);
		return rc;
	}

	if (!numLock && !numUnlock) {
		/* if no lock or unlock then nothing
		to do since we do not know what it is */
		FreeXid(xid);
		return -EOPNOTSUPP;
	}

	if (posix_locking) {
		int posix_lock_type;
		if (lockType & LOCKING_ANDX_SHARED_LOCK)
			posix_lock_type = CIFS_RDLCK;
		else
			posix_lock_type = CIFS_WRLCK;

		if (numUnlock == 1)
			posix_lock_type = CIFS_UNLCK;

		rc = CIFSSMBPosixLock(xid, pTcon, netfid, 0 /* set */,
				      length, pfLock,
				      posix_lock_type, wait_flag);
	} else {
		struct cifsFileInfo *fid =
			(struct cifsFileInfo *)file->private_data;

		if (numLock) {
			rc = CIFSSMBLock(xid, pTcon, netfid, length,
					pfLock->fl_start,
					0, numLock, lockType, wait_flag);

			if (rc == 0) {
				/* For Windows locks we must store them. */
				rc = store_file_lock(fid, length,
						pfLock->fl_start, lockType);
			}
		} else if (numUnlock) {
			/* For each stored lock that this unlock overlaps
			   completely, unlock it. */
			int stored_rc = 0;
			struct cifsLockInfo *li, *tmp;

			rc = 0;
			mutex_lock(&fid->lock_mutex);
			list_for_each_entry_safe(li, tmp, &fid->llist, llist) {
				if (pfLock->fl_start <= li->offset &&
						(pfLock->fl_start + length) >=
						(li->offset + li->length)) {
					stored_rc = CIFSSMBLock(xid, pTcon,
							netfid,
							li->length, li->offset,
							1, 0, li->type, FALSE);
					if (stored_rc)
						rc = stored_rc;

					list_del(&li->llist);
					kfree(li);
				}
			}
			mutex_unlock(&fid->lock_mutex);
		}
	}

#if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,8)
	if (pfLock->fl_flags & FL_POSIX)
		posix_lock_file_wait(file, pfLock);
#endif
	FreeXid(xid);
	return rc;
}

ssize_t cifs_user_write(struct file *file, const char __user *write_data,
	size_t write_size, loff_t *poffset)
{