losetup: add --associated option

    losetup -j | --associated <file> [-o <num>]

This new option lists all loop devices associated with given file
(and optionally file offset).

Examples:

 # losetup -a
 /dev/loop0: [0807]:21921808 (/foo/vfat-mbr.img)
 /dev/loop1: [0807]:21921808 (/foo/vfat-mbr.img), offset 100
 /dev/loop2: [0807]:21921802 (/bar/ext3.img)

 # losetup -j /foo/vfat-mbr.img
 /dev/loop0: [0807]:21921808 (/foo/vfat-mbr.img)
 /dev/loop1: [0807]:21921808 (/foo/vfat-mbr.img), offset 100

 # losetup -j /foo/vfat-mbr.img -o 100
 /dev/loop1: [0807]:21921808 (/foo/vfat-mbr.img), offset 100

Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/mount/lomount.c b/mount/lomount.c
index 43c33516b1383f99941fe05de24294077af6c8ab..c5d03c48b72609950913c5663ab28e32cbe2c889 100644 (file)
--- a/mount/lomount.c
+++ b/mount/lomount.c
@@ -29,6 +29,8 @@
 
 #ifdef LOOP_SET_FD
 
+static int is_associated(int dev, struct stat *file, unsigned long long offset, int isoff);
+
 static int
 loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info)
 {
@@ -404,6 +406,34 @@ show_used_loop_devices (void) {
        return 0;
 }
 
+/* list all associated loop devices */
+static int
+show_associated_loop_devices(char *filename, unsigned long long offset, int isoff)
+{
+       struct looplist ll;
+       struct stat filestat;
+       int fd;
+
+       if (stat(filename, &filestat) == -1) {
+               perror(filename);
+               return 1;
+       }
+
+       if (looplist_open(&ll, LLFLG_USEDONLY) == -1) {
+               error(_("%s: /dev directory does not exist."), progname);
+               return 1;
+       }
+
+       while((fd = looplist_next(&ll)) != -1) {
+               if (is_associated(fd, &filestat, offset, isoff) == 1)
+                       show_loop_fd(fd, ll.name);
+               close(fd);
+       }
+       looplist_close(&ll);
+
+       return 0;
+}
+
 #endif /* MAIN */
 
 /* check if the loopfile is already associated with the same given
@@ -414,7 +444,7 @@ show_used_loop_devices (void) {
  *           1 loop device already used
  */
 static int
-is_associated(int dev, struct stat *file, unsigned long long offset)
+is_associated(int dev, struct stat *file, unsigned long long offset, int isoff)
 {
        struct loop_info64 linfo64;
        struct loop_info64 linfo;
@@ -423,14 +453,14 @@ is_associated(int dev, struct stat *file, unsigned long long offset)
        if (ioctl(dev, LOOP_GET_STATUS64, &linfo64) == 0) {
                if (file->st_dev == linfo64.lo_device &&
                    file->st_ino == linfo64.lo_inode &&
-                   offset == linfo64.lo_offset)
+                   (isoff == 0 || offset == linfo64.lo_offset))
                        ret = 1;
                return ret;
        }
        if (ioctl(dev, LOOP_GET_STATUS, &linfo) == 0) {
                if (file->st_dev == linfo.lo_device &&
                    file->st_ino == linfo.lo_inode &&
-                   offset == linfo.lo_offset)
+                   (isoff == 0 || offset == linfo.lo_offset))
                        ret = 1;
                return ret;
        }
@@ -460,7 +490,7 @@ loopfile_used (const char *filename, unsigned long long offset) {
        }
 
        while((fd = looplist_next(&ll)) != -1) {
-               int res = is_associated(fd, &filestat, offset);
+               int res = is_associated(fd, &filestat, offset, 1);
                close(fd);
                if (res == 1) {
                        devname = xstrdup(ll.name);
@@ -491,7 +521,7 @@ loopfile_used_with(char *devname, const char *filename, unsigned long long offse
                perror(devname);
                return -1;
        }
-       ret = is_associated(fd, &statbuf, offset);
+       ret = is_associated(fd, &statbuf, offset, 1);
 
        close(fd);
        return ret;
@@ -773,11 +803,12 @@ find_unused_loop_device (void) {
 static void
 usage(void) {
        fprintf(stderr, _("\nUsage:\n"
-  " %1$s loop_device                                  # give info\n"
-  " %1$s -a | --all                                   # list all used\n"
-  " %1$s -d | --detach loop_device                    # delete\n"
-  " %1$s -f | --find                                  # find unused\n"
-  " %1$s [ options ] {-f|--find|loop_device} file     # setup\n"
+  " %1$s loop_device                             give info\n"
+  " %1$s -a | --all                              list all used\n"
+  " %1$s -d | --detach <loopdev>                 delete\n"
+  " %1$s -f | --find                             find unused\n"
+  " %1$s -j | --associated <file> [-o <num>]     list all associated with <file>\n"
+  " %1$s [ options ] {-f|--find|loopdev} <file>  setup\n"
   "\nOptions:\n"
   " -e | --encryption <type> enable data encryption with specified <name/num>\n"
   " -h | --help              this help\n"
@@ -792,7 +823,7 @@ usage(void) {
 
 int
 main(int argc, char **argv) {
-       char *p, *offset, *encryption, *passfd, *device, *file;
+       char *p, *offset, *encryption, *passfd, *device, *file, *assoc;
        int delete, find, c, all;
        int res = 0;
        int showdev = 0;
@@ -805,6 +836,7 @@ main(int argc, char **argv) {
                { "encryption", 1, 0, 'e' },
                { "find", 0, 0, 'f' },
                { "help", 0, 0, 'h' },
+               { "associated", 1, 0, 'j' },
                { "offset", 1, 0, 'o' },
                { "pass-fd", 1, 0, 'p' },
                { "read-only", 0, 0, 'r' },
@@ -819,13 +851,13 @@ main(int argc, char **argv) {
 
        delete = find = all = 0;
        off = 0;
-       offset = encryption = passfd = NULL;
+       assoc = offset = encryption = passfd = NULL;
 
        progname = argv[0];
        if ((p = strrchr(progname, '/')) != NULL)
                progname = p+1;
 
-       while ((c = getopt_long(argc, argv, "ade:E:fho:p:rsv",
+       while ((c = getopt_long(argc, argv, "ade:E:fhj:o:p:rsv",
                                longopts, NULL)) != -1) {
                switch (c) {
                case 'a':
@@ -844,6 +876,9 @@ main(int argc, char **argv) {
                case 'f':
                        find = 1;
                        break;
+               case 'j':
+                       assoc = optarg;
+                       break;
                case 'o':
                        offset = optarg;
                        break;
@@ -864,21 +899,30 @@ main(int argc, char **argv) {
        if (argc == 1) {
                usage();
        } else if (delete) {
-               if (argc != optind+1 || encryption || offset || find || all || showdev)
+               if (argc != optind+1 || encryption || offset ||
+                               find || all || showdev || assoc || ro)
                        usage();
        } else if (find) {
-               if (all || argc < optind || argc > optind+1)
+               if (all || assoc || argc < optind || argc > optind+1)
                        usage();
        } else if (all) {
                if (argc > 2)
                        usage();
+       } else if (assoc) {
+               if (encryption || showdev || passfd || ro)
+                       usage();
        } else {
                if (argc < optind+1 || argc > optind+2)
                        usage();
        }
 
+       if (offset && sscanf(offset, "%llu", &off) != 1)
+               usage();
+
        if (all)
                return show_used_loop_devices();
+       else if (assoc)
+               return show_associated_loop_devices(assoc, off, offset ? 1 : 0);
        else if (find) {
                device = find_unused_loop_device();
                if (device == NULL)
@@ -903,8 +947,6 @@ main(int argc, char **argv) {
        else if (file == NULL)
                res = show_loop(device);
        else {
-               if (offset && sscanf(offset, "%llu", &off) != 1)
-                       usage();
                if (passfd && sscanf(passfd, "%d", &pfd) != 1)
                        usage();
                do {

diff --git a/mount/losetup.8 b/mount/losetup.8
index db2929f482c2e464734ec6d6b9130feacc8dea26..400ec2cab34e55feecc717d8f7e89b4c687e1f5f 100644 (file)
--- a/mount/losetup.8
+++ b/mount/losetup.8
@@ -11,6 +11,8 @@ Get info:
 .sp
 .B losetup -a
 .sp
+.B losetup -j <file> [-o offset]
+.sp
 .in -5
 Delete loop:
 .sp
@@ -73,14 +75,17 @@ enable data encryption with specified name or number
 .IP "\fB\-f, \-\-find\fP"
 find the first unused loop device. If a
 .I file
-argument is present, use this device. Otherwise, print its name.
+argument is present, use this device. Otherwise, print its name
 .IP "\fB\-h, \-\-help\fP"
 print help
+.IP "\fB\-j, \-\-associated \fIfile\fP"
+show status of all loop devices associated with given
+.I file
 .IP "\fB\-o, \-\-offset \fIoffset\fP"
-The data start is moved \fIoffset\fP bytes into the specified file or
-device.
+the data start is moved \fIoffset\fP bytes into the specified file or
+device
 .IP "\fB\-p, \-\-pass-fd \fInum\fP"
-Read the passphrase from file descriptor with number
+read the passphrase from file descriptor with number
 .I num
 instead of from the terminal
 .IP "\fB\-r, \-\-read-only\fP"