Skip to main content
Share Your Experience: Take the 2024 Developer Survey

Questions tagged [vfs]

The tag has no usage guidance.

Filter by
Sorted by
Tagged with
5 votes
1 answer
389 views

How to solve this kernel-panic on a Debian 12 system?

Context: My PC don't boot anymore after a power hard cut. I can boot a LIVE DVD and mount all file systems. fsck is clean on my boot partition (ext2) and on my system/root partition (btrfs) smartctl -...
lalebarde's user avatar
  • 255
0 votes
0 answers
32 views

IOzone Filesystem Benchmark WEIRD Results on EXT4

I'm currently using an i7 with 32 GB of RAM to measure ext4 performance. However, I've encountered some unusual results when testing with 8 GB and 16 GB files. Shouldn't the performance increase ...
DemonioValero's user avatar
0 votes
0 answers
23 views

Error code list for vfs_mount for OpenStep 4.2 (BSD 4.3/Mach)

(Background, This is not the question) I'm having trouble installing OpenStep 4.2 (Intel) on my old laptop, It's because it can't find a OpenStep root image (which I understand) here is the error. hc0:...
Puha Technologies's user avatar
0 votes
1 answer
52 views

How to empty name cache on FreeBSD?

The name cache on FreeBSD is responsible for caching file names and their vnodes. It also provides a special database for hashing the contents of large directories. I would like to know how to empty ...
Mateusz Piotrowski's user avatar
1 vote
0 answers
179 views

Linux TCP/IP kernel stack and VFS interaction

I'm reading the Linux kernel implementation of the TCP/IP stack. Everything was ok till I encounter this figure while reading TCP/IP architecture, design and implementation in Linux As you may see ...
ca-hercor's user avatar
0 votes
1 answer
180 views

NetFS for linux

Both plan 9 and FreeBSD have a filesystem-based approach to a unified userspace interface for networking configuration. This paper for example describes the advantages of such an interface, from ...
Charles Langlois's user avatar
0 votes
1 answer
766 views

How can `cat` read a file without a file descriptor?

I'm learning Linux procfs, which utilizes a virtual file system where operations like open, read, write, and release are processed by functions registered to it. I've left the open and release to null ...
victrid's user avatar
  • 183
0 votes
1 answer
276 views

Host's VFS and Docker's OverlayFS

Linux's Virtual File System(VFS) provides a common interface to multiple file system types, for example, ext2, ext3, VFAT, etc. Imagine an ubuntu host is running several docker containers, and the ...
Ryan Lyu's user avatar
  • 194
1 vote
0 answers
83 views

vmtouch-like utility for file metadata/VFS cache?

vmtouch can query cache information about a file's content and load (or even lock) that into cache. Is there a utility which do the same with a file's metadata like dentries and inode information?
Atemu's user avatar
  • 688
1 vote
0 answers
70 views

Multiply root filesystems? In Linux? [closed]

I use Linux for a while, now. I always thought that there is only one rootfs in Linux. However, I recently read that PipeFS is mounted in "pipe:", in its own root. How is this possible. Are ...
yomol777's user avatar
  • 199
2 votes
1 answer
26 views

Usage and role of s_pins field in the VFS superblock

I study with details the structure of the VFS superblock and I noticed the field struct hlist_head s_pins; Even though I made an extensive search it was not possible to find info about this. I only ...
Athanasios Margaris's user avatar
2 votes
0 answers
25 views

How Linux system knows what files/subdirectories are under one directory [duplicate]

I'm reading the book "Linux Kernel Development", and there are some important points: inode doesn't include filename. filenames are stored in directory entry(dentry). but dentry is not ...
Ethan Xu's user avatar
  • 121
-2 votes
1 answer
36 views

Which of the following requests do not go through the Virtual File System (VFS) in Linux?

I recently got the following question in a test. Which of the following requests do not go through the Virtual File System (VFS) in Linux? Reading/writing to a Windows partition from Linux Reading ...
User567456's user avatar
0 votes
1 answer
2k views

How does an open(at) syscall result in a file being written to disk?

I'm trying to learn as as much as I can about about the interplay between syscalls, the VFS, device driver handling and ultimately, having the end device do some operation. I thought I would look at a ...
genericuser99's user avatar
0 votes
0 answers
883 views

My custom built minimal kernel linux won't boot with the error "Kernel Panic - not syncing: VFS: Unable to mount root fs on unknown-block(8,1)

Sorry about the noob question. I just built the cross compiler, created the filesystem hierarchy, compiled the kernel and BusyBox and put it on a USB and installed GRUB. When I boot it, I get this: ...
Mason M's user avatar
  • 33
0 votes
1 answer
220 views

struct file_operations vs struct vnodeops

As per my understanding kernel maintains 4 tables. Per process FD table. System wide open file table struct file Inode (in-memory) table struct vnode Inode (on-disk) table. struct file have one ...
MankPan's user avatar
  • 77
3 votes
2 answers
156 views

Is file creation totally ordered?

On Linux, the openat syscall can be used to create files and to test for their existence. Speaking in terms of the C/C++ memory model, creating a file and verifying its existence creates a ...
Kaz Wesley's user avatar
0 votes
1 answer
2k views

Where is the file creation time (birth) stored in linux?

Using debugfs -R 'stat <inode_nr> ' /dev/sda1 returns a result where there is a field crtime which i believe represents the creation date of a file pointed to by inode numbered inode_nr. I use ...
Ahmadposten's user avatar
-1 votes
1 answer
436 views

Does the virtual filesystem work on top of character devices and network subsystems?

Does the virtual filesystem work on top of character devices and network subsystems, or just on top of filesystems and block devices? Could you also explain a bit about in what sense "the VFS is ...
Tim's user avatar
  • 102k
1 vote
1 answer
322 views

using VFS to do dynamic mounting

I have what may sound like a strange situation. I have a mount point for a directory containing a variety of log files. From time to time it is necessary to unmount this directory and remount it in ...
Steve Summit's user avatar
1 vote
0 answers
2k views

NFS Server - VFS: max file limit reached

I've been trying to determine why/how my CentOS 7.3 NFS server hung, and I'm hoping to gain some insight or direction with this post. The machine's purpose is to serve NFS storage to clients. I use ...
user's user avatar
  • 83
0 votes
0 answers
4k views

How to take read all the partitions from eMMC dump

We have Beaglebone Black based custom board with 4GB eMMC and 256MB RAM. eMMC is partitioned as follows # parted --list Model: MMC MMC04G (sd/mmc) Disk /dev/mmcblk0: 3842MB Sector size (logical/...
ART's user avatar
  • 1,131
4 votes
0 answers
892 views

How does Linux resolve pathnames with the help of the dentry cache?

While dealing with the Virtual Filesystem of Linux I have come across a little problem of understanding how pathnames are resolved if they are already cached as dentries in the dentry cache. I know ...
idlmn89's user avatar
  • 225
2 votes
2 answers
123 views

Where does the file size comes from, i.e. , how does ls and cp know the file size?

Recently I had a file that reported a file size of 33P bytes in my 500GB SSD, more details here. That was through ls and cp would report that there was no enough space. In my short knowledge and ...
user3325563's user avatar
2 votes
2 answers
1k views

How do I run the usermode linux kernel?

I followed the steps here and compiled the kernel successfully in usermode: https://btrfs.wiki.kernel.org/index.php/Debugging_Btrfs_with_GDB But when I start ./linux in various ways it always gives ...
Blub's user avatar
  • 175
0 votes
1 answer
241 views

Does the content of the file ever get cached by VFS? [closed]

If you read a text file for example, does its content ever get cached or is it always the address of the disk that gets cached?
CuriousKimchi's user avatar
0 votes
1 answer
870 views

How to interpret VFS usage chart

I'm monitoring an old laptop running as LAMP server. I have trouble understanding this VFS usage chart (sorry can't include images yet) from monitorix (the monitoring tool I'm using). I don't ...
Max's user avatar
  • 111
5 votes
3 answers
914 views

confused about dd write speed and VFS page cache

After reading some articles on the Linux VFS page cache and the tunable parameters like dirty_ratio i was under the impression that page cache would operate as both read and write caching layer. But ...
Flo Woo's user avatar
  • 243
2 votes
0 answers
35 views

Which subsystem caches file reads?

I am trying to understand how exactly file reads are served from Page Cache. This will be useful when I will be implementing my own filesystem in the kernel. Is file content cached by VFS or ...
ArekBulski's user avatar
2 votes
0 answers
353 views

New inode when mounting new file system

Does kernel really create any new inode when some file system gets mounted on some directory of root file system? I don't expect it to create as there is no new files are being created. Is there some ...
Vishal Sahu's user avatar
0 votes
2 answers
250 views

is VFS a module?

While studying VFS, this question popped into my head. Is it okay to think of VFS as a module? The reason why I thought like that is because VFS has the characteristic of simplifying actual file ...
kwagjj's user avatar
  • 2,319
1 vote
1 answer
634 views

Why are the first inode of the `/` mounted partition and inode of `/` different?

[~]$ stat -c %i / 2 As you can see in above, the inode for / is 2. But the First inode of /dev/sda2 is 11. [~]$ df -h Filesystem Size Used Avail Use% Mounted on /dev/sda2 ...
Suku's user avatar
  • 163
1 vote
1 answer
2k views

What is kernel memory and user memory? (question about the term kernel page and the page cache)

Today, I have read through some documents about file system (http://tekrants.me/2014/07/14/linux-file-system-write/). And the term kernel page is mentioned several times in this article. I am now ...
Xin Li's user avatar
  • 51
1 vote
1 answer
141 views

Reading ELF file after dropping caches

I have an eMMC backed Linux 3.10 development device (Android) and I am trying to better understand when Linux is actually reading from the eMMC as opposed to the page cache. Specifically, I am ...
bangelo's user avatar
  • 23
2 votes
1 answer
1k views

Docker in Crouton - VFS consuming astronomical amounts of space

I'm attempting to help out a roommate who has installed Kubuntu on his Chromebook using Crouton (it's basically just a fancy chroot run within ChromeOS). I helped him get the Docker daemon running, ...
Wieschie's user avatar
  • 123
2 votes
1 answer
116 views

How do I merge (without copying) two directories? [duplicate]

I have: $ find 1 2 -printf '%i %p\n' 40011805 1 40011450 1/t 40011923 1/a 40014006 1/a/e 40011217 1/a/q 40011806 2 40011458 2/y 40011924 2/a 40013989 2/a/e 40013945 2/a/w I want: <inode> <...
Vi.'s user avatar
  • 5,763
1 vote
1 answer
243 views

Is there a way to achieve context-dependent path names (CDPN) on NFS?

In my GFS clusters I use the CDPN feature to have separate chrooted /dev/log directories on separate cluster nodes: /home/ftpuser/foo: lrwxrwxrwx 1 root root 18 Sep 26 2010 dev -> .sys/@hostname/...
MattBianco's user avatar
  • 3,706
5 votes
1 answer
333 views

How do I temporarily extract a flash drive or HDD in Linux?

Suppose I mounted a disk in this way: mount /dev/sdb /mnt/tmp I have some files opened on this filesystem and don't want to unmount it. However I want to temporarily extract the device, then ...
Vi.'s user avatar
  • 5,763
3 votes
0 answers
224 views

Tool for dumping Linux VFS superblock

From the dumpe2fs man page: dumpe2fs prints the super block and blocks group information for the filesystem present on device. So dumpe2fs will dump the filesystem superblock. Is there any such ...
Suku's user avatar
  • 163
0 votes
1 answer
4k views

Centos VFS cannot open root device

Yesterday I did a kernel update on a virtual machine. When I restarted the machine unfortunately I got the error Kernel panic - not syncing VFS After some searching I found out I should go to GRUB ...
MKroeders's user avatar
  • 111
1 vote
0 answers
636 views

Limiting the total size of samba's vfs_recycle by pruning oldest deleted files first

Running SerNet Samba 4.0.9 on CentOS 6.4 serving as an AD DC and fileshare for XP clients. Added recycler per the example here. My concern is that the recycle dir will eventually grow large. ...
Kev's user avatar
  • 1,739
7 votes
2 answers
3k views

Linux cache evictions

Looking at how the VFS cache on my Linux machine behaves, I can see that even when effectively idle (crond and most other daemons stopped, interfaces down) the amount of free memory gradually ...
symcbean's user avatar
  • 5,649