1 /*
2 * storage_common.c -- Common definitions for mass storage functionality
3 *
4 * Copyright (C) 2003-2008 Alan Stern
5 * Copyeight (C) 2009 Samsung Electronics
6 * Author: Michal Nazarewicz (mina86@mina86.com)
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
12 */
13
14 /*
15 * This file requires the following identifiers used in USB strings to
16 * be defined (each of type pointer to char):
17 * - fsg_string_interface -- name of the interface
18 */
19
20 /*
21 * When USB_GADGET_DEBUG_FILES is defined the module param num_buffers
22 * sets the number of pipeline buffers (length of the fsg_buffhd array).
23 * The valid range of num_buffers is: num >= 2 && num <= 4.
24 */
25
26
27 #include <linux/usb/storage.h>
28 #include <scsi/scsi.h>
29 #include <asm/unaligned.h>
30
31
32 /*
33 * Thanks to NetChip Technologies for donating this product ID.
34 *
35 * DO NOT REUSE THESE IDs with any other driver!! Ever!!
36 * Instead: allocate your own, using normal USB-IF procedures.
37 */
38 #define FSG_VENDOR_ID 0x0525 /* NetChip */
39 #define FSG_PRODUCT_ID 0xa4a5 /* Linux-USB File-backed Storage Gadget */
40
41
42 /*-------------------------------------------------------------------------*/
43
44
45 #ifndef DEBUG
46 #undef VERBOSE_DEBUG
47 #undef DUMP_MSGS
48 #endif /* !DEBUG */
49
50 #ifdef VERBOSE_DEBUG
51 #define VLDBG LDBG
52 #else
53 #define VLDBG(lun, fmt, args...) do { } while (0)
54 #endif /* VERBOSE_DEBUG */
55
56 #define LDBG(lun, fmt, args...) dev_dbg (&(lun)->dev, fmt, ## args)
57 #define LERROR(lun, fmt, args...) dev_err (&(lun)->dev, fmt, ## args)
58 #define LWARN(lun, fmt, args...) dev_warn(&(lun)->dev, fmt, ## args)
59 #define LINFO(lun, fmt, args...) dev_info(&(lun)->dev, fmt, ## args)
60
61
62 #ifdef DUMP_MSGS
63
64 # define dump_msg(fsg, /* const char * */ label, \
65 /* const u8 * */ buf, /* unsigned */ length) do { \
66 if (length < 512) { \
67 DBG(fsg, "%s, length %u:\n", label, length); \
68 print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, \
69 16, 1, buf, length, 0); \
70 } \
71 } while (0)
72
73 # define dump_cdb(fsg) do { } while (0)
74
75 #else
76
77 # define dump_msg(fsg, /* const char * */ label, \
78 /* const u8 * */ buf, /* unsigned */ length) do { } while (0)
79
80 # ifdef VERBOSE_DEBUG
81
82 # define dump_cdb(fsg) \
83 print_hex_dump(KERN_DEBUG, "SCSI CDB: ", DUMP_PREFIX_NONE, \
84 16, 1, (fsg)->cmnd, (fsg)->cmnd_size, 0) \
85
86 # else
87
88 # define dump_cdb(fsg) do { } while (0)
89
90 # endif /* VERBOSE_DEBUG */
91
92 #endif /* DUMP_MSGS */
93
94 /*-------------------------------------------------------------------------*/
95
96 /* Length of a SCSI Command Data Block */
97 #define MAX_COMMAND_SIZE 16
98
99 /* SCSI Sense Key/Additional Sense Code/ASC Qualifier values */
100 #define SS_NO_SENSE 0
101 #define SS_COMMUNICATION_FAILURE 0x040800
102 #define SS_INVALID_COMMAND 0x052000
103 #define SS_INVALID_FIELD_IN_CDB 0x052400
104 #define SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE 0x052100
105 #define SS_LOGICAL_UNIT_NOT_SUPPORTED 0x052500
106 #define SS_MEDIUM_NOT_PRESENT 0x023a00
107 #define SS_MEDIUM_REMOVAL_PREVENTED 0x055302
108 #define SS_NOT_READY_TO_READY_TRANSITION 0x062800
109 #define SS_RESET_OCCURRED 0x062900
110 #define SS_SAVING_PARAMETERS_NOT_SUPPORTED 0x053900
111 #define SS_UNRECOVERED_READ_ERROR 0x031100
112 #define SS_WRITE_ERROR 0x030c02
113 #define SS_WRITE_PROTECTED 0x072700
114
115 #define SK(x) ((u8) ((x) >> 16)) /* Sense Key byte, etc. */
116 #define ASC(x) ((u8) ((x) >> 8))
117 #define ASCQ(x) ((u8) (x))
118
119
120 /*-------------------------------------------------------------------------*/
121
122
123 struct fsg_lun {
124 struct file *filp;
125 loff_t file_length;
126 loff_t num_sectors;
127
128 unsigned int initially_ro:1;
129 unsigned int ro:1;
130 unsigned int removable:1;
131 unsigned int cdrom:1;
132 unsigned int prevent_medium_removal:1;
133 unsigned int registered:1;
134 unsigned int info_valid:1;
135 unsigned int nofua:1;
136
137 u32 sense_data;
138 u32 sense_data_info;
139 u32 unit_attention_data;
140
141 unsigned int blkbits; /* Bits of logical block size of bound block device */
142 unsigned int blksize; /* logical block size of bound block device */
143 struct device dev;
144 };
145
fsg_lun_is_open(struct fsg_lun * curlun)146 static inline bool fsg_lun_is_open(struct fsg_lun *curlun)
147 {
148 return curlun->filp != NULL;
149 }
150
fsg_lun_from_dev(struct device * dev)151 static inline struct fsg_lun *fsg_lun_from_dev(struct device *dev)
152 {
153 return container_of(dev, struct fsg_lun, dev);
154 }
155
156
157 /* Big enough to hold our biggest descriptor */
158 #define EP0_BUFSIZE 256
159 #define DELAYED_STATUS (EP0_BUFSIZE + 999) /* An impossibly large value */
160
161 #ifdef CONFIG_USB_GADGET_DEBUG_FILES
162
163 static unsigned int fsg_num_buffers = CONFIG_USB_GADGET_STORAGE_NUM_BUFFERS;
164 module_param_named(num_buffers, fsg_num_buffers, uint, S_IRUGO);
165 MODULE_PARM_DESC(num_buffers, "Number of pipeline buffers");
166
167 #else
168
169 /*
170 * Number of buffers we will use.
171 * 2 is usually enough for good buffering pipeline
172 */
173 #define fsg_num_buffers CONFIG_USB_GADGET_STORAGE_NUM_BUFFERS
174
175 #endif /* CONFIG_USB_DEBUG */
176
177 /* check if fsg_num_buffers is within a valid range */
fsg_num_buffers_validate(void)178 static inline int fsg_num_buffers_validate(void)
179 {
180 if (fsg_num_buffers >= 2 && fsg_num_buffers <= 4)
181 return 0;
182 pr_err("fsg_num_buffers %u is out of range (%d to %d)\n",
183 fsg_num_buffers, 2 ,4);
184 return -EINVAL;
185 }
186
187 /* Default size of buffer length. */
188 #define FSG_BUFLEN ((u32)16384)
189
190 /* Maximal number of LUNs supported in mass storage function */
191 #define FSG_MAX_LUNS 8
192
193 enum fsg_buffer_state {
194 BUF_STATE_EMPTY = 0,
195 BUF_STATE_FULL,
196 BUF_STATE_BUSY
197 };
198
199 struct fsg_buffhd {
200 void *buf;
201 enum fsg_buffer_state state;
202 struct fsg_buffhd *next;
203
204 /*
205 * The NetChip 2280 is faster, and handles some protocol faults
206 * better, if we don't submit any short bulk-out read requests.
207 * So we will record the intended request length here.
208 */
209 unsigned int bulk_out_intended_length;
210
211 struct usb_request *inreq;
212 int inreq_busy;
213 struct usb_request *outreq;
214 int outreq_busy;
215 };
216
217 enum fsg_state {
218 /* This one isn't used anywhere */
219 FSG_STATE_COMMAND_PHASE = -10,
220 FSG_STATE_DATA_PHASE,
221 FSG_STATE_STATUS_PHASE,
222
223 FSG_STATE_IDLE = 0,
224 FSG_STATE_ABORT_BULK_OUT,
225 FSG_STATE_RESET,
226 FSG_STATE_INTERFACE_CHANGE,
227 FSG_STATE_CONFIG_CHANGE,
228 FSG_STATE_DISCONNECT,
229 FSG_STATE_EXIT,
230 FSG_STATE_TERMINATED
231 };
232
233 enum data_direction {
234 DATA_DIR_UNKNOWN = 0,
235 DATA_DIR_FROM_HOST,
236 DATA_DIR_TO_HOST,
237 DATA_DIR_NONE
238 };
239
240
241 /*-------------------------------------------------------------------------*/
242
243
get_unaligned_be24(u8 * buf)244 static inline u32 get_unaligned_be24(u8 *buf)
245 {
246 return 0xffffff & (u32) get_unaligned_be32(buf - 1);
247 }
248
249
250 /*-------------------------------------------------------------------------*/
251
252
253 enum {
254 FSG_STRING_INTERFACE
255 };
256
257
258 /* There is only one interface. */
259
260 static struct usb_interface_descriptor
261 fsg_intf_desc = {
262 .bLength = sizeof fsg_intf_desc,
263 .bDescriptorType = USB_DT_INTERFACE,
264
265 .bNumEndpoints = 2, /* Adjusted during fsg_bind() */
266 .bInterfaceClass = USB_CLASS_MASS_STORAGE,
267 .bInterfaceSubClass = USB_SC_SCSI, /* Adjusted during fsg_bind() */
268 .bInterfaceProtocol = USB_PR_BULK, /* Adjusted during fsg_bind() */
269 .iInterface = FSG_STRING_INTERFACE,
270 };
271
272 /*
273 * Three full-speed endpoint descriptors: bulk-in, bulk-out, and
274 * interrupt-in.
275 */
276
277 static struct usb_endpoint_descriptor
278 fsg_fs_bulk_in_desc = {
279 .bLength = USB_DT_ENDPOINT_SIZE,
280 .bDescriptorType = USB_DT_ENDPOINT,
281
282 .bEndpointAddress = USB_DIR_IN,
283 .bmAttributes = USB_ENDPOINT_XFER_BULK,
284 /* wMaxPacketSize set by autoconfiguration */
285 };
286
287 static struct usb_endpoint_descriptor
288 fsg_fs_bulk_out_desc = {
289 .bLength = USB_DT_ENDPOINT_SIZE,
290 .bDescriptorType = USB_DT_ENDPOINT,
291
292 .bEndpointAddress = USB_DIR_OUT,
293 .bmAttributes = USB_ENDPOINT_XFER_BULK,
294 /* wMaxPacketSize set by autoconfiguration */
295 };
296
297 static struct usb_descriptor_header *fsg_fs_function[] = {
298 (struct usb_descriptor_header *) &fsg_intf_desc,
299 (struct usb_descriptor_header *) &fsg_fs_bulk_in_desc,
300 (struct usb_descriptor_header *) &fsg_fs_bulk_out_desc,
301 NULL,
302 };
303
304
305 /*
306 * USB 2.0 devices need to expose both high speed and full speed
307 * descriptors, unless they only run at full speed.
308 *
309 * That means alternate endpoint descriptors (bigger packets)
310 * and a "device qualifier" ... plus more construction options
311 * for the configuration descriptor.
312 */
313 static struct usb_endpoint_descriptor
314 fsg_hs_bulk_in_desc = {
315 .bLength = USB_DT_ENDPOINT_SIZE,
316 .bDescriptorType = USB_DT_ENDPOINT,
317
318 /* bEndpointAddress copied from fs_bulk_in_desc during fsg_bind() */
319 .bmAttributes = USB_ENDPOINT_XFER_BULK,
320 .wMaxPacketSize = cpu_to_le16(512),
321 };
322
323 static struct usb_endpoint_descriptor
324 fsg_hs_bulk_out_desc = {
325 .bLength = USB_DT_ENDPOINT_SIZE,
326 .bDescriptorType = USB_DT_ENDPOINT,
327
328 /* bEndpointAddress copied from fs_bulk_out_desc during fsg_bind() */
329 .bmAttributes = USB_ENDPOINT_XFER_BULK,
330 .wMaxPacketSize = cpu_to_le16(512),
331 .bInterval = 1, /* NAK every 1 uframe */
332 };
333
334
335 static struct usb_descriptor_header *fsg_hs_function[] = {
336 (struct usb_descriptor_header *) &fsg_intf_desc,
337 (struct usb_descriptor_header *) &fsg_hs_bulk_in_desc,
338 (struct usb_descriptor_header *) &fsg_hs_bulk_out_desc,
339 NULL,
340 };
341
342 static struct usb_endpoint_descriptor
343 fsg_ss_bulk_in_desc = {
344 .bLength = USB_DT_ENDPOINT_SIZE,
345 .bDescriptorType = USB_DT_ENDPOINT,
346
347 /* bEndpointAddress copied from fs_bulk_in_desc during fsg_bind() */
348 .bmAttributes = USB_ENDPOINT_XFER_BULK,
349 .wMaxPacketSize = cpu_to_le16(1024),
350 };
351
352 static struct usb_ss_ep_comp_descriptor fsg_ss_bulk_in_comp_desc = {
353 .bLength = sizeof(fsg_ss_bulk_in_comp_desc),
354 .bDescriptorType = USB_DT_SS_ENDPOINT_COMP,
355
356 /*.bMaxBurst = DYNAMIC, */
357 };
358
359 static struct usb_endpoint_descriptor
360 fsg_ss_bulk_out_desc = {
361 .bLength = USB_DT_ENDPOINT_SIZE,
362 .bDescriptorType = USB_DT_ENDPOINT,
363
364 /* bEndpointAddress copied from fs_bulk_out_desc during fsg_bind() */
365 .bmAttributes = USB_ENDPOINT_XFER_BULK,
366 .wMaxPacketSize = cpu_to_le16(1024),
367 };
368
369 static struct usb_ss_ep_comp_descriptor fsg_ss_bulk_out_comp_desc = {
370 .bLength = sizeof(fsg_ss_bulk_in_comp_desc),
371 .bDescriptorType = USB_DT_SS_ENDPOINT_COMP,
372
373 /*.bMaxBurst = DYNAMIC, */
374 };
375
376 static struct usb_descriptor_header *fsg_ss_function[] = {
377 (struct usb_descriptor_header *) &fsg_intf_desc,
378 (struct usb_descriptor_header *) &fsg_ss_bulk_in_desc,
379 (struct usb_descriptor_header *) &fsg_ss_bulk_in_comp_desc,
380 (struct usb_descriptor_header *) &fsg_ss_bulk_out_desc,
381 (struct usb_descriptor_header *) &fsg_ss_bulk_out_comp_desc,
382 NULL,
383 };
384
385 /* Static strings, in UTF-8 (for simplicity we use only ASCII characters) */
386 static struct usb_string fsg_strings[] = {
387 {FSG_STRING_INTERFACE, fsg_string_interface},
388 {}
389 };
390
391 static struct usb_gadget_strings fsg_stringtab = {
392 .language = 0x0409, /* en-us */
393 .strings = fsg_strings,
394 };
395
396
397 /*-------------------------------------------------------------------------*/
398
399 /*
400 * If the next two routines are called while the gadget is registered,
401 * the caller must own fsg->filesem for writing.
402 */
403
fsg_lun_close(struct fsg_lun * curlun)404 static void fsg_lun_close(struct fsg_lun *curlun)
405 {
406 if (curlun->filp) {
407 LDBG(curlun, "close backing file\n");
408 fput(curlun->filp);
409 curlun->filp = NULL;
410 }
411 }
412
413
fsg_lun_open(struct fsg_lun * curlun,const char * filename)414 static int fsg_lun_open(struct fsg_lun *curlun, const char *filename)
415 {
416 int ro;
417 struct file *filp = NULL;
418 int rc = -EINVAL;
419 struct inode *inode = NULL;
420 loff_t size;
421 loff_t num_sectors;
422 loff_t min_sectors;
423 unsigned int blkbits;
424 unsigned int blksize;
425
426 /* R/W if we can, R/O if we must */
427 ro = curlun->initially_ro;
428 if (!ro) {
429 filp = filp_open(filename, O_RDWR | O_LARGEFILE, 0);
430 if (PTR_ERR(filp) == -EROFS || PTR_ERR(filp) == -EACCES)
431 ro = 1;
432 }
433 if (ro)
434 filp = filp_open(filename, O_RDONLY | O_LARGEFILE, 0);
435 if (IS_ERR(filp)) {
436 LINFO(curlun, "unable to open backing file: %s\n", filename);
437 return PTR_ERR(filp);
438 }
439
440 if (!(filp->f_mode & FMODE_WRITE))
441 ro = 1;
442
443 inode = file_inode(filp);
444 if ((!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))) {
445 LINFO(curlun, "invalid file type: %s\n", filename);
446 goto out;
447 }
448
449 /*
450 * If we can't read the file, it's no good.
451 * If we can't write the file, use it read-only.
452 */
453 if (!(filp->f_op->read || filp->f_op->aio_read)) {
454 LINFO(curlun, "file not readable: %s\n", filename);
455 goto out;
456 }
457 if (!(filp->f_op->write || filp->f_op->aio_write))
458 ro = 1;
459
460 size = i_size_read(inode->i_mapping->host);
461 if (size < 0) {
462 LINFO(curlun, "unable to find file size: %s\n", filename);
463 rc = (int) size;
464 goto out;
465 }
466
467 if (curlun->cdrom) {
468 blksize = 2048;
469 blkbits = 11;
470 } else if (inode->i_bdev) {
471 blksize = bdev_logical_block_size(inode->i_bdev);
472 blkbits = blksize_bits(blksize);
473 } else {
474 blksize = 512;
475 blkbits = 9;
476 }
477
478 num_sectors = size >> blkbits; /* File size in logic-block-size blocks */
479 min_sectors = 1;
480 if (curlun->cdrom) {
481 min_sectors = 300; /* Smallest track is 300 frames */
482 if (num_sectors >= 256*60*75) {
483 num_sectors = 256*60*75 - 1;
484 LINFO(curlun, "file too big: %s\n", filename);
485 LINFO(curlun, "using only first %d blocks\n",
486 (int) num_sectors);
487 }
488 }
489 if (num_sectors < min_sectors) {
490 LINFO(curlun, "file too small: %s\n", filename);
491 rc = -ETOOSMALL;
492 goto out;
493 }
494
495 if (fsg_lun_is_open(curlun))
496 fsg_lun_close(curlun);
497
498 curlun->blksize = blksize;
499 curlun->blkbits = blkbits;
500 curlun->ro = ro;
501 curlun->filp = filp;
502 curlun->file_length = size;
503 curlun->num_sectors = num_sectors;
504 LDBG(curlun, "open backing file: %s\n", filename);
505 return 0;
506
507 out:
508 fput(filp);
509 return rc;
510 }
511
512
513 /*-------------------------------------------------------------------------*/
514
515 /*
516 * Sync the file data, don't bother with the metadata.
517 * This code was copied from fs/buffer.c:sys_fdatasync().
518 */
fsg_lun_fsync_sub(struct fsg_lun * curlun)519 static int fsg_lun_fsync_sub(struct fsg_lun *curlun)
520 {
521 struct file *filp = curlun->filp;
522
523 if (curlun->ro || !filp)
524 return 0;
525 return vfs_fsync(filp, 1);
526 }
527
store_cdrom_address(u8 * dest,int msf,u32 addr)528 static void store_cdrom_address(u8 *dest, int msf, u32 addr)
529 {
530 if (msf) {
531 /* Convert to Minutes-Seconds-Frames */
532 addr >>= 2; /* Convert to 2048-byte frames */
533 addr += 2*75; /* Lead-in occupies 2 seconds */
534 dest[3] = addr % 75; /* Frames */
535 addr /= 75;
536 dest[2] = addr % 60; /* Seconds */
537 addr /= 60;
538 dest[1] = addr; /* Minutes */
539 dest[0] = 0; /* Reserved */
540 } else {
541 /* Absolute sector */
542 put_unaligned_be32(addr, dest);
543 }
544 }
545
546
547 /*-------------------------------------------------------------------------*/
548
549
fsg_show_ro(struct device * dev,struct device_attribute * attr,char * buf)550 static ssize_t fsg_show_ro(struct device *dev, struct device_attribute *attr,
551 char *buf)
552 {
553 struct fsg_lun *curlun = fsg_lun_from_dev(dev);
554
555 return sprintf(buf, "%d\n", fsg_lun_is_open(curlun)
556 ? curlun->ro
557 : curlun->initially_ro);
558 }
559
fsg_show_nofua(struct device * dev,struct device_attribute * attr,char * buf)560 static ssize_t fsg_show_nofua(struct device *dev, struct device_attribute *attr,
561 char *buf)
562 {
563 struct fsg_lun *curlun = fsg_lun_from_dev(dev);
564
565 return sprintf(buf, "%u\n", curlun->nofua);
566 }
567
fsg_show_file(struct device * dev,struct device_attribute * attr,char * buf)568 static ssize_t fsg_show_file(struct device *dev, struct device_attribute *attr,
569 char *buf)
570 {
571 struct fsg_lun *curlun = fsg_lun_from_dev(dev);
572 struct rw_semaphore *filesem = dev_get_drvdata(dev);
573 char *p;
574 ssize_t rc;
575
576 down_read(filesem);
577 if (fsg_lun_is_open(curlun)) { /* Get the complete pathname */
578 p = d_path(&curlun->filp->f_path, buf, PAGE_SIZE - 1);
579 if (IS_ERR(p))
580 rc = PTR_ERR(p);
581 else {
582 rc = strlen(p);
583 memmove(buf, p, rc);
584 buf[rc] = '\n'; /* Add a newline */
585 buf[++rc] = 0;
586 }
587 } else { /* No file, return 0 bytes */
588 *buf = 0;
589 rc = 0;
590 }
591 up_read(filesem);
592 return rc;
593 }
594
595
fsg_store_ro(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)596 static ssize_t fsg_store_ro(struct device *dev, struct device_attribute *attr,
597 const char *buf, size_t count)
598 {
599 ssize_t rc;
600 struct fsg_lun *curlun = fsg_lun_from_dev(dev);
601 struct rw_semaphore *filesem = dev_get_drvdata(dev);
602 unsigned ro;
603
604 rc = kstrtouint(buf, 2, &ro);
605 if (rc)
606 return rc;
607
608 /*
609 * Allow the write-enable status to change only while the
610 * backing file is closed.
611 */
612 down_read(filesem);
613 if (fsg_lun_is_open(curlun)) {
614 LDBG(curlun, "read-only status change prevented\n");
615 rc = -EBUSY;
616 } else {
617 curlun->ro = ro;
618 curlun->initially_ro = ro;
619 LDBG(curlun, "read-only status set to %d\n", curlun->ro);
620 rc = count;
621 }
622 up_read(filesem);
623 return rc;
624 }
625
fsg_store_nofua(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)626 static ssize_t fsg_store_nofua(struct device *dev,
627 struct device_attribute *attr,
628 const char *buf, size_t count)
629 {
630 struct fsg_lun *curlun = fsg_lun_from_dev(dev);
631 unsigned nofua;
632 int ret;
633
634 ret = kstrtouint(buf, 2, &nofua);
635 if (ret)
636 return ret;
637
638 /* Sync data when switching from async mode to sync */
639 if (!nofua && curlun->nofua)
640 fsg_lun_fsync_sub(curlun);
641
642 curlun->nofua = nofua;
643
644 return count;
645 }
646
fsg_store_file(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)647 static ssize_t fsg_store_file(struct device *dev, struct device_attribute *attr,
648 const char *buf, size_t count)
649 {
650 struct fsg_lun *curlun = fsg_lun_from_dev(dev);
651 struct rw_semaphore *filesem = dev_get_drvdata(dev);
652 int rc = 0;
653
654 if (curlun->prevent_medium_removal && fsg_lun_is_open(curlun)) {
655 LDBG(curlun, "eject attempt prevented\n");
656 return -EBUSY; /* "Door is locked" */
657 }
658
659 /* Remove a trailing newline */
660 if (count > 0 && buf[count-1] == '\n')
661 ((char *) buf)[count-1] = 0; /* Ugh! */
662
663 /* Load new medium */
664 down_write(filesem);
665 if (count > 0 && buf[0]) {
666 /* fsg_lun_open() will close existing file if any. */
667 rc = fsg_lun_open(curlun, buf);
668 if (rc == 0)
669 curlun->unit_attention_data =
670 SS_NOT_READY_TO_READY_TRANSITION;
671 } else if (fsg_lun_is_open(curlun)) {
672 fsg_lun_close(curlun);
673 curlun->unit_attention_data = SS_MEDIUM_NOT_PRESENT;
674 }
675 up_write(filesem);
676 return (rc < 0 ? rc : count);
677 }
678