Why the missing /dev/loop* files?

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mad_ady
SamyGO Project Donor
Posts: 264
Joined: Sun May 03, 2015 10:42 am

Why the missing /dev/loop* files?

Post by mad_ady » Thu Jan 21, 2016 12:46 pm

Hello all,

I'm puzzled by this problem (on my rooted H6400):

Code: Select all

# mknod -m 777 /dev/loop4 b 7 4
mknod: /dev/loop4: Read-only file system
# ls -l /dev/loop*
brwxrwxrwx    1 root     root        7,   0 Dec 31  2013 /dev/loop0
brwxrwxrwx    1 root     root        7,   1 Dec 31  2013 /dev/loop1
brwxrwxrwx    1 root     root        7,   2 Dec 31  2013 /dev/loop2
brwxrwxrwx    1 root     root        7, 251 Dec 31  2013 /dev/loop251
brwxrwxrwx    1 root     root        7, 252 Dec 31  2013 /dev/loop252
brwxrwxrwx    1 root     root        7, 253 Dec 31  2013 /dev/loop253
brwxrwxrwx    1 root     root        7, 254 Dec 31  2013 /dev/loop254
brwxrwxrwx    1 root     root        7, 255 Dec 31  2013 /dev/loop255
brwxrwxrwx    1 root     root        7, 256 Dec 31  2013 /dev/loop256
brwxrwxrwx    1 root     root        7, 257 Dec 31  2013 /dev/loop257
brwxrwxrwx    1 root     root        7, 258 Dec 31  2013 /dev/loop258
brwxrwxrwx    1 root     root        7, 259 Dec 31  2013 /dev/loop259
brwxrwxrwx    1 root     root        7, 260 Dec 31  2013 /dev/loop260
brwxrwxrwx    1 root     root        7, 261 Dec 31  2013 /dev/loop261
brwxrwxrwx    1 root     root        7, 262 Dec 31  2013 /dev/loop262
brwxrwxrwx    1 root     root        7, 263 Dec 31  2013 /dev/loop263
brwxrwxrwx    1 root     root        7, 264 Dec 31  2013 /dev/loop264
brwxrwxrwx    1 root     root        7, 265 Dec 31  2013 /dev/loop265
brwxrwxrwx    1 root     root        7, 266 Dec 31  2013 /dev/loop266
brwxrwxrwx    1 root     root        7, 267 Dec 31  2013 /dev/loop267
brwxrwxrwx    1 root     root        7, 268 Dec 31  2013 /dev/loop268
brwxrwxrwx    1 root     root        7, 269 Dec 31  2013 /dev/loop269
brwxrwxrwx    1 root     root        7, 270 Dec 31  2013 /dev/loop270
brwxrwxrwx    1 root     root        7, 271 Dec 31  2013 /dev/loop271
brwxrwxrwx    1 root     root        7, 272 Dec 31  2013 /dev/loop272
brwxrwxrwx    1 root     root        7, 273 Dec 31  2013 /dev/loop273
brwxrwxrwx    1 root     root        7, 274 Dec 31  2013 /dev/loop274
brwxrwxrwx    1 root     root        7, 275 Dec 31  2013 /dev/loop275
brwxrwxrwx    1 root     root        7, 276 Dec 31  2013 /dev/loop276
brwxrwxrwx    1 root     root        7, 277 Dec 31  2013 /dev/loop277
brwxrwxrwx    1 root     root        7, 278 Dec 31  2013 /dev/loop278
brwxrwxrwx    1 root     root        7, 279 Dec 31  2013 /dev/loop279
brwxrwxrwx    1 root     root        7, 280 Dec 31  2013 /dev/loop280
brwxrwxrwx    1 root     root        7, 281 Dec 31  2013 /dev/loop281
brwxrwxrwx    1 root     root        7, 282 Dec 31  2013 /dev/loop282
brwxrwxrwx    1 root     root        7, 283 Dec 31  2013 /dev/loop283
brwxrwxrwx    1 root     root        7, 284 Dec 31  2013 /dev/loop284
brwxrwxrwx    1 root     root        7, 285 Dec 31  2013 /dev/loop285
brwxrwxrwx    1 root     root        7, 286 Dec 31  2013 /dev/loop286
brwxrwxrwx    1 root     root        7, 287 Dec 31  2013 /dev/loop287
brwxrwxrwx    1 root     root        7, 288 Dec 31  2013 /dev/loop288
brwxrwxrwx    1 root     root        7, 289 Dec 31  2013 /dev/loop289
brwxrwxrwx    1 root     root        7, 290 Dec 31  2013 /dev/loop290
brwxrwxrwx    1 root     root        7, 291 Dec 31  2013 /dev/loop291
brwxrwxrwx    1 root     root        7, 292 Dec 31  2013 /dev/loop292
brwxrwxrwx    1 root     root        7, 293 Dec 31  2013 /dev/loop293
brwxrwxrwx    1 root     root        7, 294 Dec 31  2013 /dev/loop294
brwxrwxrwx    1 root     root        7, 295 Dec 31  2013 /dev/loop295
brwxrwxrwx    1 root     root        7, 296 Dec 31  2013 /dev/loop296
brwxrwxrwx    1 root     root        7, 297 Dec 31  2013 /dev/loop297
brwxrwxrwx    1 root     root        7, 298 Dec 31  2013 /dev/loop298
brwxrwxrwx    1 root     root        7, 299 Dec 31  2013 /dev/loop299
brwxrwxrwx    1 root     root        7,   3 Dec 31  2013 /dev/loop3
brwxrwxrwx    1 root     root        7, 300 Dec 31  2013 /dev/loop300

/dev/loop:
total 0
lrwxrwxrwx    1 root     root             8 Jan  1  1970 0 -> ../loop0
lrwxrwxrwx    1 root     root             8 Jan  1  1970 1 -> ../loop1
# losetup
/dev/loop0: 0 /mtd_uniro/uncompexe2.img
/dev/loop1: 0 /mtd_exe/infolink/manager/manager.img
/dev/loop2: 0 /mtd_down/widgets/caph/102710000000_img/102710000000.img
/dev/loop3: 0 /dtv/usb/sda1/SamyGO/samyext4.img

It looks like /dev/loop4 - /dev/loop250 are missing from /dev and this causes losetup to not list anything past /dev/loop3. I tried to create a file but it's on a read-only filesystem.

So, here come my questions:
1. Is this Samsung's doing? Are we still seeing the original /dev after the root or is a virtual filesystem mounted over it?
2. How can we see which loops are unused and which are used (and used by what)?
3. Has anyone tried to bind-mount a different /dev on top of /dev? Some place holding all the pseudo-files from dev, but on a writable location (such as ramdrive) to add more nodes?

Thanks
H6400, firmware 2602.2 downgraded to 2130

sectroyer
Official SamyGO Developer
Posts: 5765
Joined: Wed May 04, 2011 5:10 pm

Re: Why the missing /dev/loop* files?

Post by sectroyer » Thu Jan 21, 2016 1:11 pm

1) It's EXPECTED :) It's ORIGINAL
2) mount | grep loop
3) Yes. BAD things happen :)
I do NOT support "latest fw" at ALL. If you have one you should block updates on router and wait for it to STOP being "latest":)
If you want me to help you please paste FULL log(s) to "spoiler"/"code" bbcodes or provide link(s) to pasted file(s) on http://ctrlv.it/ Otherwise "NO HELP"!!!
If you want root DISABLE internet access to your device!!!!
DO NOT EVER INSTALL FIRMWARE UPGRADE !!!!

mad_ady
SamyGO Project Donor
Posts: 264
Joined: Sun May 03, 2015 10:42 am

Re: Why the missing /dev/loop* files?

Post by mad_ady » Thu Jan 21, 2016 2:01 pm

Thanks for the feedback. The grep option sounds great. I hadn't thought of it. Thanks

I also see some of the apps create temporary loops in /dtv, so if I need a loop I could create my own (seeing that that's the trend):

Code: Select all

[root@tv rwcommon]# ls -lh /dtv/loop*
brwxr-x---    1 app      app         7, 100 Jan  1  1970 /dtv/loop100
brwxr-x---    1 app      app         7, 252 Jan  1  1970 /dtv/loop252
brwxr-x---    1 app      app         7,   4 Jan  1  1970 /dtv/loop4
brwxr-x---    1 app      app         7,   5 Jan  1  1970 /dtv/loop5
brwxr-x---    1 app      app         7,   6 Jan  1  1970 /dtv/loop6
H6400, firmware 2602.2 downgraded to 2130

sectroyer
Official SamyGO Developer
Posts: 5765
Joined: Wed May 04, 2011 5:10 pm

Re: Why the missing /dev/loop* files?

Post by sectroyer » Thu Jan 21, 2016 8:03 pm

Yes :)
I do NOT support "latest fw" at ALL. If you have one you should block updates on router and wait for it to STOP being "latest":)
If you want me to help you please paste FULL log(s) to "spoiler"/"code" bbcodes or provide link(s) to pasted file(s) on http://ctrlv.it/ Otherwise "NO HELP"!!!
If you want root DISABLE internet access to your device!!!!
DO NOT EVER INSTALL FIRMWARE UPGRADE !!!!

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