4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 only,
8 * as published by the Free Software Foundation.
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * General Public License version 2 for more details (a copy is included
14 * in the LICENSE file that accompanied this code).
16 * You should have received a copy of the GNU General Public License
17 * version 2 along with this program; If not, see
18 * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
20 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
21 * CA 95054 USA or visit www.sun.com if you need additional information or
27 * Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
28 * Use is subject to license terms.
30 * Copyright (c) 2011, Whamcloud, Inc.
33 * This file is part of Lustre, http://www.lustre.org/
34 * Lustre is a trademark of Sun Microsystems, Inc.
36 * lustre/utils/mount_utils_ldiskfs.c
38 * Author: Nathan Rutman <nathan@clusterfs.com>
41 /* This source file is compiled into both mkfs.lustre and tunefs.lustre */
45 #endif /* HAVE_CONFIG_H */
57 #include <sys/types.h>
59 #include <sys/mount.h>
60 #include <sys/utsname.h>
68 /* libcfs.h is not really needed here, but on SLES10/PPC, fs.h includes idr.h
69 * which requires BITS_PER_LONG to be defined */
70 #include <libcfs/libcfs.h>
72 #include <linux/fs.h> /* for BLKGETSIZE64 */
74 #include <linux/version.h>
76 #include <lustre_disk.h>
77 #include <lustre_param.h>
78 #include <lnet/lnetctl.h>
79 #include <lustre_ver.h>
80 #include "mount_utils.h"
82 extern char *progname;
84 #define L_BLOCK_SIZE 4096
85 /* keep it less than LL_FID_NAMELEN */
86 #define DUMMY_FILE_NAME_LEN 25
87 #define EXT3_DIRENT_SIZE DUMMY_FILE_NAME_LEN
89 /* Write the server config files */
90 int write_local_files(struct mkfs_opts *mop)
92 char mntpt[] = "/tmp/mntXXXXXX";
99 /* Mount this device temporarily in order to write these files */
100 if (!mkdtemp(mntpt)) {
101 fprintf(stderr, "%s: Can't create temp mount point %s: %s\n",
102 progname, mntpt, strerror(errno));
106 dev = mop->mo_device;
107 if (mop->mo_flags & MO_IS_LOOP)
108 dev = mop->mo_loopdev;
110 ret = mount(dev, mntpt, MT_STR(&mop->mo_ldd), 0,
111 mop->mo_ldd.ldd_mount_opts);
113 fprintf(stderr, "%s: Unable to mount %s: %s\n",
114 progname, dev, strerror(errno));
116 if (errno == ENODEV) {
117 fprintf(stderr, "Is the %s module available?\n",
118 MT_STR(&mop->mo_ldd));
123 /* Set up initial directories */
124 sprintf(filepnm, "%s/%s", mntpt, MOUNT_CONFIGS_DIR);
125 ret = mkdir(filepnm, 0777);
126 if ((ret != 0) && (errno != EEXIST)) {
127 fprintf(stderr, "%s: Can't make configs dir %s (%s)\n",
128 progname, filepnm, strerror(errno));
130 } else if (errno == EEXIST) {
134 /* Save the persistent mount data into a file. Lustre must pre-read
135 this file to get the real mount options. */
136 vprint("Writing %s\n", MOUNT_DATA_FILE);
137 sprintf(filepnm, "%s/%s", mntpt, MOUNT_DATA_FILE);
138 filep = fopen(filepnm, "w");
140 fprintf(stderr, "%s: Unable to create %s file: %s\n",
141 progname, filepnm, strerror(errno));
144 num = fwrite(&mop->mo_ldd, sizeof(mop->mo_ldd), 1, filep);
145 if (num < 1 && ferror(filep)) {
146 fprintf(stderr, "%s: Unable to write to file (%s): %s\n",
147 progname, filepnm, strerror(errno));
159 int read_local_files(struct mkfs_opts *mop)
161 char tmpdir[] = "/tmp/dirXXXXXX";
167 int cmdsz = sizeof(cmd);
169 /* Make a temporary directory to hold Lustre data files. */
170 if (!mkdtemp(tmpdir)) {
171 fprintf(stderr, "%s: Can't create temporary directory %s: %s\n",
172 progname, tmpdir, strerror(errno));
176 dev = mop->mo_device;
178 /* TODO: it's worth observing the get_mountdata() function that is
179 in mount_utils.c for getting the mountdata out of the
182 /* Construct debugfs command line. */
183 snprintf(cmd, cmdsz, "%s -c -R 'dump /%s %s/mountdata' '%s'",
184 DEBUGFS, MOUNT_DATA_FILE, tmpdir, dev);
186 ret = run_command(cmd, cmdsz);
188 verrprint("%s: Unable to dump %s dir (%d)\n",
189 progname, MOUNT_CONFIGS_DIR, ret);
191 sprintf(filepnm, "%s/mountdata", tmpdir);
192 filep = fopen(filepnm, "r");
195 vprint("Reading %s\n", MOUNT_DATA_FILE);
196 num_read = fread(&mop->mo_ldd, sizeof(mop->mo_ldd), 1, filep);
197 if (num_read < 1 && ferror(filep)) {
198 fprintf(stderr, "%s: Unable to read from file %s: %s\n",
199 progname, filepnm, strerror(errno));
206 snprintf(cmd, cmdsz, "rm -rf %s", tmpdir);
207 run_command(cmd, cmdsz);
209 verrprint("Failed to read old data (%d)\n", ret);
214 /* Display the need for the latest e2fsprogs to be installed. make_backfs
215 * indicates if the caller is make_lustre_backfs() or not. */
216 void disp_old_e2fsprogs_msg(const char *feature, int make_backfs)
218 static int msg_displayed;
221 fprintf(stderr, "WARNING: %s does not support %s "
222 "feature.\n\n", E2FSPROGS, feature);
228 fprintf(stderr, "WARNING: The %s package currently installed on "
229 "your system does not support \"%s\" feature.\n",
231 #if !(HAVE_LDISKFSPROGS)
232 fprintf(stderr, "Please install the latest version of e2fsprogs from\n"
233 "http://downloads.whamcloud.com/public/e2fsprogs/latest/\n"
234 "to enable this feature.\n");
237 fprintf(stderr, "Feature will not be enabled until %s"
238 "is updated and '%s -O %s %%{device}' "
239 "is run.\n\n", E2FSPROGS, TUNE2FS, feature);
242 /* Check whether the file exists in the device */
243 static int file_in_dev(char *file_name, char *dev_name)
246 char debugfs_cmd[256];
247 unsigned int inode_num;
250 /* Construct debugfs command line. */
251 snprintf(debugfs_cmd, sizeof(debugfs_cmd),
252 "%s -c -R 'stat %s' '%s' 2>&1 | egrep '(Inode|unsupported)'",
253 DEBUGFS, file_name, dev_name);
255 fp = popen(debugfs_cmd, "r");
257 fprintf(stderr, "%s: %s\n", progname, strerror(errno));
261 if (fscanf(fp, "Inode: %u", &inode_num) == 1) { /* exist */
265 i = fread(debugfs_cmd, 1, sizeof(debugfs_cmd), fp);
268 fprintf(stderr, "%s", debugfs_cmd);
269 if (strstr(debugfs_cmd, "unsupported feature")) {
270 disp_old_e2fsprogs_msg("an unknown", 0);
279 /* Check whether the device has already been used with lustre */
280 int is_lustre_target(struct mkfs_opts *mop)
284 vprint("checking for existing Lustre data: ");
286 if ((rc = file_in_dev(MOUNT_DATA_FILE, mop->mo_device))) {
288 (rc == 1) ? MOUNT_DATA_FILE : "extents");
289 /* in the -1 case, 'extents' means this really IS a lustre
294 if ((rc = file_in_dev(LAST_RCVD, mop->mo_device))) {
295 vprint("found %s\n", LAST_RCVD);
299 vprint("not found\n");
300 return 0; /* The device is not a lustre target. */
305 /* Check if a certain feature is supported by e2fsprogs.
306 * Firstly we try to use "debugfs supported_features" command to check if
307 * the feature is supported. If this fails we try to set this feature with
308 * mke2fs to check for its support. */
309 static int is_e2fsprogs_feature_supp(const char *feature)
311 static char supp_features[4096] = "";
314 char imgname[] = "/tmp/test-img-XXXXXX";
318 if (supp_features[0] == '\0') {
319 snprintf(cmd, sizeof(cmd), "%s -c -R supported_features 2>&1",
322 /* Using popen() instead of run_command() since debugfs does
323 * not return proper error code if command is not supported */
324 fp = popen(cmd, "r");
326 fprintf(stderr, "%s: %s\n", progname, strerror(errno));
329 ret = fread(supp_features, 1, sizeof(supp_features), fp);
332 if (ret > 0 && strstr(supp_features,
333 strncmp(feature, "-O ", 3) ? feature : feature+3))
336 if ((fd = mkstemp(imgname)) < 0)
341 snprintf(cmd, sizeof(cmd), "%s -F %s %s 100 >/dev/null 2>&1",
342 MKE2FS, feature, imgname);
343 /* run_command() displays the output of mke2fs when it fails for
344 * some feature, so use system() directly */
353 * append_unique: append @key or @key=@val pair to @buf only if @key does not
355 * @buf: buffer to hold @key or @key=@val
356 * @prefix: prefix string before @key
358 * @val: value string if it's a @key=@val pair
360 static void append_unique(char *buf, char *prefix, char *key, char *val,
369 anchor = end = strstr(buf, key);
370 /* try to find exact match string in @buf */
371 while (end && *end != '\0' && *end != ',' && *end != ' ' && *end != '=')
374 if (anchor == NULL || strlen(key) != len ||
375 strncmp(anchor, key, len) != 0) {
377 strscat(buf, prefix, maxbuflen);
379 strscat(buf, key, maxbuflen);
381 strscat(buf, "=", maxbuflen);
382 strscat(buf, val, maxbuflen);
387 static void enable_default_ext4_features(struct mkfs_opts *mop, char *anchor,
388 size_t maxbuflen, int user_spec)
390 if (IS_OST(&mop->mo_ldd)) {
391 append_unique(anchor, user_spec ? "," : " -O ",
392 "extents", NULL, sizeof(mop->mo_mkfsopts));
393 append_unique(anchor, ",", "uninit_bg", NULL, maxbuflen);
394 } else if (IS_MDT(&mop->mo_ldd)) {
395 append_unique(anchor, user_spec ? "," : " -O ",
396 "dirdata", NULL, maxbuflen);
397 append_unique(anchor, ",", "uninit_bg", NULL, maxbuflen);
398 append_unique(anchor, ",", "^extents", NULL, maxbuflen);
400 append_unique(anchor, user_spec ? "," : " -O ",
401 "uninit_bg", NULL, maxbuflen);
404 /* Multiple mount protection enabled only if failover node specified */
405 if (mop->mo_flags & MO_FAILOVER) {
406 if (is_e2fsprogs_feature_supp("-O mmp") == 0)
407 append_unique(anchor, ",", "mmp", NULL, maxbuflen);
409 disp_old_e2fsprogs_msg("mmp", 1);
412 /* Allow more than 65000 subdirectories */
413 if (is_e2fsprogs_feature_supp("-O dir_nlink") == 0)
414 append_unique(anchor, ",", "dir_nlink", NULL, maxbuflen);
416 /* The following options are only valid for ext4-based ldiskfs.
417 * If --backfstype=ext3 is specified, do not enable them. */
418 if (mop->mo_ldd.ldd_mount_type == LDD_MT_EXT3)
421 /* Allow files larger than 2TB. Also needs LU-16, but not harmful. */
422 if (is_e2fsprogs_feature_supp("-O huge_file") == 0)
423 append_unique(anchor, ",", "huge_file", NULL, maxbuflen);
425 /* Enable large block addresses if the LUN is over 2^32 blocks. */
426 if (mop->mo_device_sz / (L_BLOCK_SIZE >> 10) >= 0x100002000ULL &&
427 is_e2fsprogs_feature_supp("-O 64bit") == 0)
428 append_unique(anchor, ",", "64bit", NULL, maxbuflen);
430 /* Cluster inode/block bitmaps and inode table for more efficient IO.
431 * Align the flex groups on a 1MB boundary for better performance. */
432 /* This -O feature needs to go last, since it adds the "-G" option. */
433 if (is_e2fsprogs_feature_supp("-O flex_bg") == 0) {
436 append_unique(anchor, ",", "flex_bg", NULL, maxbuflen);
438 if (IS_OST(&mop->mo_ldd)) {
439 snprintf(tmp_buf, sizeof(tmp_buf), " -G %u",
440 (1 << 20) / L_BLOCK_SIZE);
441 strscat(anchor, tmp_buf, maxbuflen);
444 /* Don't add any more "-O" options here, see last comment above */
448 * moveopts_to_end: find the option string, move remaining strings to
449 * where option string starts, and append the option
451 * @start: where the option string starts before the move
452 * RETURN: where the option string starts after the move
454 static char *moveopts_to_end(char *start)
459 /* skip whitespace before options */
464 /* find end of option characters */
465 while (*end != ' ' && *end != '\0')
469 strncpy(save, start, end - start);
470 save[end - start] = '\0';
472 /* move remaining options up front */
474 memmove(start, end, strlen(end));
475 *(start + strlen(end)) = '\0';
477 /* append the specified options */
478 if (*(start + strlen(start) - 1) != ' ')
480 idx = start + strlen(start);
486 /* Build fs according to type */
487 int make_lustre_backfs(struct mkfs_opts *mop)
489 __u64 device_sz = mop->mo_device_sz, block_count = 0;
490 char mkfs_cmd[PATH_MAX];
494 int ret = 0, ext_opts = 0;
497 if (!(mop->mo_flags & MO_IS_LOOP)) {
498 mop->mo_device_sz = get_device_size(mop->mo_device);
500 if (mop->mo_device_sz == 0)
503 /* Compare to real size */
504 if (device_sz == 0 || device_sz > mop->mo_device_sz)
505 device_sz = mop->mo_device_sz;
507 mop->mo_device_sz = device_sz;
510 if (mop->mo_device_sz != 0) {
511 if (mop->mo_device_sz < 8096){
512 fprintf(stderr, "%s: size of filesystem must be larger "
513 "than 8MB, but is set to %lldKB\n",
514 progname, (long long)mop->mo_device_sz);
517 block_count = mop->mo_device_sz / (L_BLOCK_SIZE >> 10);
518 /* If the LUN size is just over 2^32 blocks, limit the
519 * filesystem size to 2^32-1 blocks to avoid problems with
520 * ldiskfs/mkfs not handling this size. Bug 22906 */
521 if (block_count > 0xffffffffULL && block_count < 0x100002000ULL)
522 block_count = 0xffffffffULL;
525 if ((mop->mo_ldd.ldd_mount_type == LDD_MT_EXT3) ||
526 (mop->mo_ldd.ldd_mount_type == LDD_MT_LDISKFS) ||
527 (mop->mo_ldd.ldd_mount_type == LDD_MT_LDISKFS2)) {
530 /* Journal size in MB */
531 if (strstr(mop->mo_mkfsopts, "-J") == NULL) {
532 /* Choose our own default journal size */
533 long journal_sz = 0, max_sz;
534 if (device_sz > 1024 * 1024) /* 1GB */
535 journal_sz = (device_sz / 102400) * 4;
536 /* cap journal size at 1GB */
537 if (journal_sz > 1024L)
540 max_sz = (102400 * L_BLOCK_SIZE) >> 20; /* 400MB */
541 if (journal_sz > max_sz)
544 sprintf(buf, " -J size=%ld", journal_sz);
545 strscat(mop->mo_mkfsopts, buf,
546 sizeof(mop->mo_mkfsopts));
550 /* Inode size (for extended attributes). The LOV EA size is
551 * 32 (EA hdr) + 32 (lov_mds_md) + stripes * 24 (lov_ost_data),
552 * and we want some margin above that for ACLs, other EAs... */
553 if (strstr(mop->mo_mkfsopts, "-I") == NULL) {
554 if (IS_MDT(&mop->mo_ldd)) {
555 if (mop->mo_stripe_count > 72)
556 inode_size = 512; /* bz 7241 */
557 /* see also "-i" below for EA blocks */
558 else if (mop->mo_stripe_count > 32)
560 else if (mop->mo_stripe_count > 10)
564 } else if (IS_OST(&mop->mo_ldd)) {
565 /* We store MDS FID and OST objid in EA on OST
566 * we need to make inode bigger as well. */
570 if (inode_size > 0) {
571 sprintf(buf, " -I %ld", inode_size);
572 strscat(mop->mo_mkfsopts, buf,
573 sizeof(mop->mo_mkfsopts));
577 /* Bytes_per_inode: disk size / num inodes */
578 if (strstr(mop->mo_mkfsopts, "-i") == NULL &&
579 strstr(mop->mo_mkfsopts, "-N") == NULL) {
580 long bytes_per_inode = 0;
582 /* Allocate more inodes on MDT devices. There is
583 * no data stored on the MDT, and very little extra
584 * metadata beyond the inode. It could go down as
585 * low as 1024 bytes, but this is conservative.
586 * Account for external EA blocks for wide striping. */
587 if (IS_MDT(&mop->mo_ldd)) {
588 bytes_per_inode = inode_size + 1536;
590 if (mop->mo_stripe_count > 72) {
591 int extra = mop->mo_stripe_count * 24;
592 extra = ((extra - 1) | 4095) + 1;
593 bytes_per_inode += extra;
597 /* Allocate fewer inodes on large OST devices. Most
598 * filesystems can be much more aggressive than even
599 * this, but it is impossible to know in advance. */
600 if (IS_OST(&mop->mo_ldd)) {
601 /* OST > 16TB assume average file size 1MB */
602 if (device_sz > (16ULL << 30))
603 bytes_per_inode = 1024 * 1024;
604 /* OST > 4TB assume average file size 512kB */
605 else if (device_sz > (4ULL << 30))
606 bytes_per_inode = 512 * 1024;
607 /* OST > 1TB assume average file size 256kB */
608 else if (device_sz > (1ULL << 30))
609 bytes_per_inode = 256 * 1024;
610 /* OST > 10GB assume average file size 64kB,
611 * plus a bit so that inodes will fit into a
612 * 256x flex_bg without overflowing */
613 else if (device_sz > (10ULL << 20))
614 bytes_per_inode = 69905;
617 if (bytes_per_inode > 0) {
618 sprintf(buf, " -i %ld", bytes_per_inode);
619 strscat(mop->mo_mkfsopts, buf,
620 sizeof(mop->mo_mkfsopts));
625 strscat(mop->mo_mkfsopts, " -q",
626 sizeof(mop->mo_mkfsopts));
629 /* start handle -O mkfs options */
630 if ((start = strstr(mop->mo_mkfsopts, "-O")) != NULL) {
631 if (strstr(start + 2, "-O") != NULL) {
633 "%s: don't specify multiple -O options\n",
637 start = moveopts_to_end(start);
638 maxbuflen = sizeof(mop->mo_mkfsopts) -
639 (start - mop->mo_mkfsopts) - strlen(start);
640 enable_default_ext4_features(mop, start, maxbuflen, 1);
642 start = mop->mo_mkfsopts + strlen(mop->mo_mkfsopts),
643 maxbuflen = sizeof(mop->mo_mkfsopts) -
644 strlen(mop->mo_mkfsopts);
645 enable_default_ext4_features(mop, start, maxbuflen, 0);
647 /* end handle -O mkfs options */
649 /* start handle -E mkfs options */
650 if ((start = strstr(mop->mo_mkfsopts, "-E")) != NULL) {
651 if (strstr(start + 2, "-E") != NULL) {
653 "%s: don't specify multiple -E options\n",
657 start = moveopts_to_end(start);
658 maxbuflen = sizeof(mop->mo_mkfsopts) -
659 (start - mop->mo_mkfsopts) - strlen(start);
662 start = mop->mo_mkfsopts + strlen(mop->mo_mkfsopts);
663 maxbuflen = sizeof(mop->mo_mkfsopts) -
664 strlen(mop->mo_mkfsopts);
667 /* In order to align the filesystem metadata on 1MB boundaries,
668 * give a resize value that will reserve a power-of-two group
669 * descriptor blocks, but leave one block for the superblock.
670 * Only useful for filesystems with < 2^32 blocks due to resize
672 if (IS_OST(&mop->mo_ldd) && mop->mo_device_sz > 100 * 1024 &&
673 mop->mo_device_sz * 1024 / L_BLOCK_SIZE <= 0xffffffffULL) {
674 unsigned group_blocks = L_BLOCK_SIZE * 8;
675 unsigned desc_per_block = L_BLOCK_SIZE / 32;
676 unsigned resize_blks;
678 resize_blks = (1ULL<<32) - desc_per_block*group_blocks;
679 snprintf(buf, sizeof(buf), "%u", resize_blks);
680 append_unique(start, ext_opts ? "," : " -E ",
681 "resize", buf, maxbuflen);
685 /* Avoid zeroing out the full journal - speeds up mkfs */
686 if (is_e2fsprogs_feature_supp("-E lazy_journal_init") == 0)
687 append_unique(start, ext_opts ? "," : " -E ",
688 "lazy_journal_init", NULL, maxbuflen);
689 /* end handle -E mkfs options */
691 /* Allow reformat of full devices (as opposed to
692 partitions.) We already checked for mounted dev. */
693 strscat(mop->mo_mkfsopts, " -F", sizeof(mop->mo_mkfsopts));
695 snprintf(mkfs_cmd, sizeof(mkfs_cmd),
696 "%s -j -b %d -L %s ", MKE2FS, L_BLOCK_SIZE,
697 mop->mo_ldd.ldd_svname);
699 fprintf(stderr,"%s: unsupported fs type: %d (%s)\n",
700 progname, mop->mo_ldd.ldd_mount_type,
701 MT_STR(&mop->mo_ldd));
705 /* For loop device format the dev, not the filename */
706 dev = mop->mo_device;
707 if (mop->mo_flags & MO_IS_LOOP)
708 dev = mop->mo_loopdev;
710 vprint("formatting backing filesystem %s on %s\n",
711 MT_STR(&mop->mo_ldd), dev);
712 vprint("\ttarget name %s\n", mop->mo_ldd.ldd_svname);
713 vprint("\t4k blocks "LPU64"\n", block_count);
714 vprint("\toptions %s\n", mop->mo_mkfsopts);
716 /* mkfs_cmd's trailing space is important! */
717 strscat(mkfs_cmd, mop->mo_mkfsopts, sizeof(mkfs_cmd));
718 strscat(mkfs_cmd, " ", sizeof(mkfs_cmd));
719 strscat(mkfs_cmd, dev, sizeof(mkfs_cmd));
720 if (block_count != 0) {
721 sprintf(buf, " "LPU64, block_count);
722 strscat(mkfs_cmd, buf, sizeof(mkfs_cmd));
725 vprint("mkfs_cmd = %s\n", mkfs_cmd);
726 ret = run_command(mkfs_cmd, sizeof(mkfs_cmd));
729 fprintf(stderr, "Unable to build fs %s (%d)\n", dev, ret);
734 int ldiskfs_prepare_lustre(struct mkfs_opts *mop,
735 char *default_mountopts, int default_len,
736 char *always_mountopts, int always_len)
738 struct lustre_disk_data *ldd = &mop->mo_ldd;
741 /* Set MO_IS_LOOP to indicate a loopback device is needed */
742 ret = is_block(mop->mo_device);
745 } else if (ret == 0) {
746 mop->mo_flags |= MO_IS_LOOP;
749 strscat(default_mountopts, ",errors=remount-ro", default_len);
750 if (IS_MDT(ldd) || IS_MGS(ldd))
751 strscat(always_mountopts, ",user_xattr", always_len);
756 /* return canonicalized absolute pathname, even if the target file does not
757 * exist, unlike realpath */
758 static char *absolute_path(char *devname)
760 char buf[PATH_MAX + 1];
764 path = malloc(PATH_MAX + 1);
768 if (devname[0] != '/') {
769 if (getcwd(buf, sizeof(buf) - 1) == NULL)
772 strcat(buf, devname);
774 strcpy(buf, devname);
776 /* truncate filename before calling realpath */
777 ptr = strrchr(buf, '/');
783 if (path != realpath(buf, path)) {
787 /* add the filename back */
789 strcat(path, ptr + 1);
793 /* Determine if a device is a block device (as opposed to a file) */
794 int is_block(char* devname)
800 devpath = absolute_path(devname);
801 if (devpath == NULL) {
802 fprintf(stderr, "%s: failed to resolve path to %s\n",
807 ret = access(devname, F_OK);
809 if (strncmp(devpath, "/dev/", 5) == 0) {
810 /* nobody sane wants to create a loopback file under
811 * /dev. Let's just report the device doesn't exist */
812 fprintf(stderr, "%s: %s apparently does not exist\n",
820 ret = stat(devpath, &st);
822 fprintf(stderr, "%s: cannot stat %s\n", progname, devpath);
825 ret = S_ISBLK(st.st_mode);