file_storage.c

h内核

			continue;
		}

		/* Write the received data to the backing file */
		bh = fsg->next_buffhd_to_drain;
		if (bh->state == BUF_STATE_EMPTY && !get_some_more)
			break;			// We stopped early
		if (bh->state == BUF_STATE_FULL) {
			fsg->next_buffhd_to_drain = bh->next;
			bh->state = BUF_STATE_EMPTY;

			/* Did something go wrong with the transfer? */
			if (bh->outreq->status != 0) {
				curlun->sense_data = SS_COMMUNICATION_FAILURE;
				curlun->sense_data_info = file_offset >> 9;
				break;
			}

			amount = bh->outreq->actual;
			if (curlun->file_length - file_offset < amount) {
				LERROR(curlun,
	"write %u @ %llu beyond end %llu\n",
	amount, (unsigned long long) file_offset,
	(unsigned long long) curlun->file_length);
				amount = curlun->file_length - file_offset;
			}

			/* Perform the write */
			file_offset_tmp = file_offset;
			nwritten = vfs_write(curlun->filp,
					(char __user *) bh->buf,
					amount, &file_offset_tmp);
			VLDBG(curlun, "file write %u @ %llu -> %d\n", amount,
					(unsigned long long) file_offset,
					(int) nwritten);
			if (signal_pending(current))
				return -EINTR;		// Interrupted!

			if (nwritten < 0) {
				LDBG(curlun, "error in file write: %d\n",
						(int) nwritten);
				nwritten = 0;
			} else if (nwritten < amount) {
				LDBG(curlun, "partial file write: %d/%u\n",
						(int) nwritten, amount);
				nwritten -= (nwritten & 511);
						// Round down to a block
			}
			file_offset += nwritten;
			amount_left_to_write -= nwritten;
			fsg->residue -= nwritten;

			/* If an error occurred, report it and its position */
			if (nwritten < amount) {
				curlun->sense_data = SS_WRITE_ERROR;
				curlun->sense_data_info = file_offset >> 9;
				break;
			}

			/* Did the host decide to stop early? */
			if (bh->outreq->actual != bh->outreq->length) {
				fsg->short_packet_received = 1;
				break;
			}
			continue;
		}

		/* Wait for something to happen */
		if ((rc = sleep_thread(fsg)) != 0)
			return rc;
	}

	return -EIO;		// No default reply
}


/*-------------------------------------------------------------------------*/

/* Sync the file data, don't bother with the metadata.
 * This code was copied from fs/buffer.c:sys_fdatasync(). */
static int fsync_sub(struct lun *curlun)
{
	struct file	*filp = curlun->filp;
	struct inode	*inode;
	int		rc, err;

	if (curlun->ro || !filp)
		return 0;
	if (!filp->f_op->fsync)
		return -EINVAL;

	inode = filp->f_dentry->d_inode;
	down(&inode->i_sem);
	current->flags |= PF_SYNCWRITE;
	rc = filemap_fdatawrite(inode->i_mapping);
	err = filp->f_op->fsync(filp, filp->f_dentry, 1);
	if (!rc)
		rc = err;
	err = filemap_fdatawait(inode->i_mapping);
	if (!rc)
		rc = err;
	current->flags &= ~PF_SYNCWRITE;
	up(&inode->i_sem);
	VLDBG(curlun, "fdatasync -> %d\n", rc);
	return rc;
}

static void fsync_all(struct fsg_dev *fsg)
{
	int	i;

	for (i = 0; i < fsg->nluns; ++i)
		fsync_sub(&fsg->luns[i]);
}

static int do_synchronize_cache(struct fsg_dev *fsg)
{
	struct lun	*curlun = fsg->curlun;
	int		rc;

	/* We ignore the requested LBA and write out all file's
	 * dirty data buffers. */
	rc = fsync_sub(curlun);
	if (rc)
		curlun->sense_data = SS_WRITE_ERROR;
	return 0;
}


/*-------------------------------------------------------------------------*/

static void invalidate_sub(struct lun *curlun)
{
	struct file	*filp = curlun->filp;
	struct inode	*inode = filp->f_dentry->d_inode;
	unsigned long	rc;

	rc = invalidate_inode_pages(inode->i_mapping);
	VLDBG(curlun, "invalidate_inode_pages -> %ld\n", rc);
}

static int do_verify(struct fsg_dev *fsg)
{
	struct lun		*curlun = fsg->curlun;
	u32			lba;
	u32			verification_length;
	struct fsg_buffhd	*bh = fsg->next_buffhd_to_fill;
	loff_t			file_offset, file_offset_tmp;
	u32			amount_left;
	unsigned int		amount;
	ssize_t			nread;

	/* Get the starting Logical Block Address and check that it's
	 * not too big */
	lba = get_be32(&fsg->cmnd[2]);
	if (lba >= curlun->num_sectors) {
		curlun->sense_data = SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE;
		return -EINVAL;
	}

	/* We allow DPO (Disable Page Out = don't save data in the
	 * cache) but we don't implement it. */
	if ((fsg->cmnd[1] & ~0x10) != 0) {
		curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
		return -EINVAL;
	}

	verification_length = get_be16(&fsg->cmnd[7]);
	if (unlikely(verification_length == 0))
		return -EIO;		// No default reply

	/* Prepare to carry out the file verify */
	amount_left = verification_length << 9;
	file_offset = ((loff_t) lba) << 9;

	/* Write out all the dirty buffers before invalidating them */
	fsync_sub(curlun);
	if (signal_pending(current))
		return -EINTR;

	invalidate_sub(curlun);
	if (signal_pending(current))
		return -EINTR;

	/* Just try to read the requested blocks */
	while (amount_left > 0) {

		/* Figure out how much we need to read:
		 * Try to read the remaining amount, but not more than
		 * the buffer size.
		 * And don't try to read past the end of the file.
		 * If this means reading 0 then we were asked to read
		 * past the end of file. */
		amount = min((unsigned int) amount_left, mod_data.buflen);
		amount = min((loff_t) amount,
				curlun->file_length - file_offset);
		if (amount == 0) {
			curlun->sense_data =
					SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE;
			curlun->sense_data_info = file_offset >> 9;
			break;
		}

		/* Perform the read */
		file_offset_tmp = file_offset;
		nread = vfs_read(curlun->filp,
				(char __user *) bh->buf,
				amount, &file_offset_tmp);
		VLDBG(curlun, "file read %u @ %llu -> %d\n", amount,
				(unsigned long long) file_offset,
				(int) nread);
		if (signal_pending(current))
			return -EINTR;

		if (nread < 0) {
			LDBG(curlun, "error in file verify: %d\n",
					(int) nread);
			nread = 0;
		} else if (nread < amount) {
			LDBG(curlun, "partial file verify: %d/%u\n",
					(int) nread, amount);
			nread -= (nread & 511);	// Round down to a sector
		}
		if (nread == 0) {
			curlun->sense_data = SS_UNRECOVERED_READ_ERROR;
			curlun->sense_data_info = file_offset >> 9;
			break;
		}
		file_offset += nread;
		amount_left -= nread;
	}
	return 0;
}


/*-------------------------------------------------------------------------*/

static int do_inquiry(struct fsg_dev *fsg, struct fsg_buffhd *bh)
{
	u8	*buf = (u8 *) bh->buf;

	static char vendor_id[] = "Linux   ";
	static char product_id[] = "File-Stor Gadget";

	if (!fsg->curlun) {		// Unsupported LUNs are okay
		fsg->bad_lun_okay = 1;
		memset(buf, 0, 36);
		buf[0] = 0x7f;		// Unsupported, no device-type
		return 36;
	}

	memset(buf, 0, 8);	// Non-removable, direct-access device
	if (mod_data.removable)
		buf[1] = 0x80;
	buf[2] = 2;		// ANSI SCSI level 2
	buf[3] = 2;		// SCSI-2 INQUIRY data format
	buf[4] = 31;		// Additional length
				// No special options
	sprintf(buf + 8, "%-8s%-16s%04x", vendor_id, product_id,
			mod_data.release);
	return 36;
}


static int do_request_sense(struct fsg_dev *fsg, struct fsg_buffhd *bh)
{
	struct lun	*curlun = fsg->curlun;
	u8		*buf = (u8 *) bh->buf;
	u32		sd, sdinfo;

	/*
	 * From the SCSI-2 spec., section 7.9 (Unit attention condition):
	 *
	 * If a REQUEST SENSE command is received from an initiator
	 * with a pending unit attention condition (before the target
	 * generates the contingent allegiance condition), then the
	 * target shall either:
	 *   a) report any pending sense data and preserve the unit
	 *	attention condition on the logical unit, or,
	 *   b) report the unit attention condition, may discard any
	 *	pending sense data, and clear the unit attention
	 *	condition on the logical unit for that initiator.
	 *
	 * FSG normally uses option a); enable this code to use option b).
	 */
#if 0
	if (curlun && curlun->unit_attention_data != SS_NO_SENSE) {
		curlun->sense_data = curlun->unit_attention_data;
		curlun->unit_attention_data = SS_NO_SENSE;
	}
#endif

	if (!curlun) {		// Unsupported LUNs are okay
		fsg->bad_lun_okay = 1;
		sd = SS_LOGICAL_UNIT_NOT_SUPPORTED;
		sdinfo = 0;
	} else {
		sd = curlun->sense_data;
		sdinfo = curlun->sense_data_info;
		curlun->sense_data = SS_NO_SENSE;
		curlun->sense_data_info = 0;
	}

	memset(buf, 0, 18);
	buf[0] = 0x80 | 0x70;			// Valid, current error
	buf[2] = SK(sd);
	put_be32(&buf[3], sdinfo);		// Sense information
	buf[7] = 18 - 8;			// Additional sense length
	buf[12] = ASC(sd);
	buf[13] = ASCQ(sd);
	return 18;
}


static int do_read_capacity(struct fsg_dev *fsg, struct fsg_buffhd *bh)
{
	struct lun	*curlun = fsg->curlun;
	u32		lba = get_be32(&fsg->cmnd[2]);
	int		pmi = fsg->cmnd[8];
	u8		*buf = (u8 *) bh->buf;

	/* Check the PMI and LBA fields */
	if (pmi > 1 || (pmi == 0 && lba != 0)) {
		curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
		return -EINVAL;
	}

	put_be32(&buf[0], curlun->num_sectors - 1);	// Max logical block
	put_be32(&buf[4], 512);				// Block length
	return 8;
}


static int do_mode_sense(struct fsg_dev *fsg, struct fsg_buffhd *bh)
{
	struct lun	*curlun = fsg->curlun;
	int		mscmnd = fsg->cmnd[0];
	u8		*buf = (u8 *) bh->buf;
	u8		*buf0 = buf;
	int		pc, page_code;
	int		changeable_values, all_pages;
	int		valid_page = 0;
	int		len, limit;

	if ((fsg->cmnd[1] & ~0x08) != 0) {		// Mask away DBD
		curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
		return -EINVAL;
	}
	pc = fsg->cmnd[2] >> 6;
	page_code = fsg->cmnd[2] & 0x3f;
	if (pc == 3) {
		curlun->sense_data = SS_SAVING_PARAMETERS_NOT_SUPPORTED;
		return -EINVAL;
	}
	changeable_values = (pc == 1);
	all_pages = (page_code == 0x3f);

	/* Write the mode parameter header.  Fixed values are: default
	 * medium type, no cache control (DPOFUA), and no block descriptors.
	 * The only variable value is the WriteProtect bit.  We will fill in
	 * the mode data length later. */
	memset(buf, 0, 8);
	if (mscmnd == SC_MODE_SENSE_6) {
		buf[2] = (curlun->ro ? 0x80 : 0x00);		// WP, DPOFUA
		buf += 4;
		limit = 255;
	} else {			// SC_MODE_SENSE_10
		buf[3] = (curlun->ro ? 0x80 : 0x00);		// WP, DPOFUA
		buf += 8;
		limit = 65535;		// Should really be mod_data.buflen
	}

	/* No block descriptors */

	/* The mode pages, in numerical order.  The only page we support
	 * is the Caching page. */
	if (page_code == 0x08 || all_pages) {
		valid_page = 1;
		buf[0] = 0x08;		// Page code
		buf[1] = 10;		// Page length
		memset(buf+2, 0, 10);	// None of the fields are changeable

		if (!changeable_values) {
			buf[2] = 0x04;	// Write cache enable,
					// Read cache not disabled
					// No cache retention priorities
			put_be16(&buf[4], 0xffff);  // Don't disable prefetch
					// Minimum prefetch = 0
			put_be16(&buf[8], 0xffff);  // Maximum prefetch
			put_be16(&buf[10], 0xffff); // Maximum prefetch ceiling
		}
		buf += 12;
	}

	/* Check that a valid page was requested and the mode data length
	 * isn't too long. */
	len = buf - buf0;
	if (!valid_page || len > limit) {
		curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
		return -EINVAL;
	}

	/*  Store the mode data length */
	if (mscmnd == SC_MODE_SENSE_6)
		buf0[0] = len - 1;
	else
		put_be16(buf0, len - 2);
	return len;
}


static int do_start_stop(struct fsg_dev *fsg)
{
	struct lun	*curlun = fsg->curlun;
	int		loej, start;

	if (!mod_data.removable) {
		curlun->sense_data = SS_INVALID_COMMAND;
		return -EINVAL;
	}

	// int immed = fsg->cmnd[1] & 0x01;
	loej = fsg->cmnd[4] & 0x02;
	start = fsg->cmnd[4] & 0x01;

#ifdef CONFIG_USB_FILE_STORAGE_TEST
	if ((fsg->cmnd[1] & ~0x01) != 0 ||		// Mask away Immed
			(fsg->cmnd[4] & ~0x03) != 0) {	// Mask LoEj, Start
		curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
		return -EINVAL;
	}

	if (!start) {

		/* Are we allowed to unload the media? */
		if (curlun->prevent_medium_removal) {
			LDBG(curlun, "unload attempt prevented\n");
			curlun->sense_data = SS_MEDIUM_REMOVAL_PREVENTED;
			return -EINVAL;
		}
		if (loej) {		// Simulate an unload/eject
			up_read(&fsg->filesem);
			down_write(&fsg->filesem);
			close_backin