date int64 1,220B 1,719B | question_description stringlengths 28 29.9k | accepted_answer stringlengths 12 26.4k | question_title stringlengths 14 159 |
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1,393,437,350,000 |
This problem is related to Samba and inodes are not necessary.
I have a problem handling a certain file that has some special characters in it. If I search it by its inode it will list the file:
$ find . -inum 90505400 -exec ls {} \;
./12 String Quartet No. 16 in F Major Op. 135: Der schwer gefa?te Entschlu?: Grave,... |
All of open() (for copying), rename() and unlink() (removal) work by filenames. There's really nothing that would work on an inode directly, apart from low-level tools like debugfs.
If you can remove the file with rm *, you should be able to rename it with mv ./12* someothername.flac, or copy it with cp ./12* newfile.... | How to copy a file by using its inode number? |
1,401,431,048,000 |
I've just found some interesting information for me in man stat:
a, m, c, B
The time file was last accessed or modified, of when the inode was last changed, or the birth time of the inode.
But what's the difference between file last modified time and the inode's modified time? I'm writing a bakup-bash script which al... |
Access: 2014-05-20 11:04:27.012146373 -0700
Modify: 2014-04-05 20:59:32.000000000 -0700
Change: 2014-05-20 11:04:22.405479507 -0700
Access: last time the contents of the file were examined.
Modify: Last time the contents of the file were changed.
Change: Last time the file's inode was changed.
The change time inclu... | What's the difference between modification date and inode's modification date? |
1,401,431,048,000 |
At work we use sparse files as part of out Oracle VM environment for the guest disk images. After some questions from a colleague (which have since been answered) I am left with more questions about sparse files, and perhaps more widely about inode structure - reading the man pages of stat(2) and statfs(2) (on FreeBS... |
Some quick answers: first, you didn't create a sparse file. Try these extra commands
dd if=/tmp/BIL of=/tmp/sparse seek=1000
ls -ls /tmp/sparse
You will see the size is 512003 bytes, but only takes 8 blocks. The null bytes have to occupy a whole block, and be on a block boundary for them to be possibly sparse in the ... | Understanding sparse files, dd, seek, inode block structure |
1,401,431,048,000 |
I understand there are 12 permission bits of which there are 3 groups of 3 bits for each of user, group, and others, which are RWX respectively. RW are read and write, but for X is search for directories and execute for files.
Here is what I don't get:
What are the 3 remaining mode bits and are they all stored in the... |
stat /bin/su shows on one system:
Access: (4755/-rwsr-xr-x) Uid: ( 0/ root) Gid: ( 0/ root)
There's the octal representation 4755 of all 12 mode bits. The number corresponds to the bits:
octal 4 7 5 5
bits 100 111 101 101
sst uuu ggg ooo
ug rwx rwx rwx
Where uuu, ggg and ooo ... | What are the final 3 bits in the UNIX permission mode bits? |
1,401,431,048,000 |
I want to run a task with limits on the kernel objects that they will indirectly trigger. Note that this is not about the memory, threads, etc. used by the application, but about memory used by the kernel. Specifically, I want to limit the amount of inode cache that the task can use.
My motivating example is updatedb.... |
Following my own question on LKML this can be archived using Control Group v2:
Pre-requisits
Make sure your Linux kernel has MEMCG_KMEM enabled, e.g. grep CONFIG_MEMCG_KMEM "/boot/config-$(uname -r)"
Depending on the OS (and systemd version) enable the use of cgroups2 by specifying systemd.unified_cgroup_hierarchy=1 ... | Limit the inode cache used by a command |
1,401,431,048,000 |
This Debian server was running just fine until a week or so ago. Now it does not allow files to be allocated, despite there still being room.
The root volume is configured with LVM.
Kernel is Linux 3.16.0-4-amd64 #1 SMP Debian 3.16.51-3 (2017-12-13) x86_64 GNU/Linux
A fsck and reboot did not help. Deleting som... |
As a modern filesystem, btrfs has no fixed inode limit at all, and that's why it reports inodes as all zeroes.
Check the status of btrfs subvolumes:
btrfs subvolume list -s /
If it turns out that you have snapshots hogging your disk space, you might need something like this to remove them:
btrfs subvolume delete -c /... | Debian btrfs filesystem shows a total of zero inodes total, zero used, zero free |
1,401,431,048,000 |
Without creating a file can I use any inode which is free?
I want to write a script that will use all free inodes in the system. is it possible?
|
Yes you can consume all the inodes of a system. They are a limited resource just like diskspace is, and they're pre-allocated when you perform a mkfs.ext4, for example.
You can use tools such as tune2fs -l <device> or df -i <path> to see how many are allocated and used.
Example
$ df -i /
Filesystem Inode... | How to use all the inodes |
1,401,431,048,000 |
How can I work out the link count of an inode number? If I know the inode number is, say, 592255 - what workings out can I do to find out the link count?
I know directories have a link count of at least 2, but don't know how to work it out.
|
Finding the link count using the name
You can use the stat command to get a link count on a given file/directory:
$ stat lib/
File: ‘lib/’
Size: 4096 Blocks: 8 IO Block: 4096 directory
Device: fd02h/64770d Inode: 11666186 Links: 3
Access: (0755/drwxr-xr-x) Uid: ( 1000/ saml) Gid: ( 10... | Work out the link count of inode number? |
1,401,431,048,000 |
It appears that it is possible on a network mount to set a quota on how much space a user can consume.
# edquota ramesh
Disk quotas for user ramesh (uid 500):
Filesystem blocks soft hard inodes soft hard
/dev/sda3 1419352 0 0 1686 0 ... |
The reason you limit the number of inodes a user can access is so they don't make the system as a whole run out of inodes by creating a huge number of 0-byte files.
With most Linux file systems (e.g. ext3 and ext4), each file (including device files) or directory has an inode -- a number used to point to a given file/... | Why restrict the number of inodes a user can access? |
1,401,431,048,000 |
I'm confused because all dentries have pointers to inode objects. As far as I know, you always look through dentries to find your inode. Then, why is there an inode cache?
|
You're asking about the inode cache implemented as part of the Linux Virtual File System (VFS). Caches, including the inode cache are not just used to provide functionality, like accessing inode entries, as there are other mechanisms for this as you point out.
Caches can be used to improve performance and in this case... | Why is the inode cache needed? |
1,401,431,048,000 |
Where does the *nix system store information about number of hard links to a specific inode? I can't find any information about that. Everywhere what a hard link is but rarely a bit more advanced information that touches inodes related stuff.
An inode stores information about number of links but where does it get it f... |
The hard link count is stored in the inode. It starts at 1 when the file is created, increases by 1 each time the link system call is successful, and decreases by 1 each time the unlink system call is successful.
The only way to find all the hard links to the same file, i.e. to find all the pathnames leading to a give... | Where is information about hard/soft links stored? |
1,401,431,048,000 |
The normal way to safely, atomically write a file X on Unix is:
Write the new file contents to a temporary file Y.
rename(2) Y to X
In two steps it appears that we have done nothing but change X "in-place".
It is protected against race conditions and unintentional data loss (where X is destroyed but Y is incomplete... |
The issue
You have a (mostly) exhaustive list of systems calls here.
You will notice that there is no "replace the content of this inode" call. Modifying that content always implies:
Opening the file to get a file descriptor.
optional seek to the desired write offset
Writing to the file.
optional Truncating old data,... | Atomically write a file without changing inodes (preserve hard link) |
1,401,431,048,000 |
Just started reading a bit about the linux file system. In several places I found quotes like this one:
Unix directories are lists of association structures, each of which contains one filename and one inode number.
So I expected to find out that each directory would contain the names of the files under it, with ea... |
A directory is, semantically speaking, a mapping from file name to inode. This is how the directory tree abstraction is designed, corresponding to the interface between applications and filesystems. Applications can designate files by name and enumerate the list of files in a directory, and each file has a unique desi... | How does linux store the mapping folder -> file_name -> inode? |
1,401,431,048,000 |
I'm assuming that this means that if the average file stored (including directories etc) is less than 16384 bytes, it may be possible to run out of inodes before using the full storage capacity of the filesystem. However, should the files being stored consume over 16384 bytes, on average, a physical space storage limi... |
Yes that is about right. A couple of minor points to note are:
As far as I can see the overhead of the filsystem itself isn't considered when calculating the number of inodes from this ratio, so the actual average size that a file can be will be slightly lower than 16834 when you consider the overhead superblock, ino... | What are the implications of using an inode_ratio of 16384 in terms of storage use on ext4? |
1,401,431,048,000 |
A directory inode isn't substantially different from that of a regular file's inode, what I comprehend from Ext4 Disk Layout is that:
Directory Entries:
Therefore, it is more accurate to say that a directory is a series of data blocks and that each block contains a linear array of directory entries.
The director... |
Directory entries are stored both in inode.i_block and the data blocks. See "Inline Data" and "Inline Directories" in the document you linked to.
| How come that inodes of directories store filenames in ext4 filesystem? |
1,401,431,048,000 |
I checked manual of find , and there's an option -ctime which specify the last modification time of inode.
But on what occasion would inode change ? When is that option useful ?
|
To simplify:
Any change in file contents changes both the mtime and the ctime.
Any change in metadatas (permissions and other information shown by stat) changes only ctime.
When is it useful: I don't know… But for example, if you want an over-approximation for the time when the last link (ln) to the inode was create... | On what occasion will inode change? |
1,401,431,048,000 |
I desire to list all inodes in current directory that are regular files (i.e. not directories, links, or special files), with ls -la (ll).
I went to the man ls searching for type and found only this which I didn't quite understand in that regard:
--indicator-style=WORD
append indicator with style WORD to entry names... |
find . -maxdepth 1 -type f -ls
This would give you the regular files in the current directory in a format similar to what you would get with ls -lisa (but only showing regular files, thanks to -type -f on the command line).
Note that -ls (introduced by BSDs) and -maxdepth (introduced by GNU find) are non-standard (th... | List only regular files [duplicate] |
1,401,431,048,000 |
I wonder if storing the information about files in inodes instead of directly in the directory is worth the additional overhead. It may be well that I'm overestimating the overhead or overlooking some important thing, but that's why I'm asking.
I see that something like "inodes" is necessary for hardlinks, but in case... |
Hard links are besides the point. They are not the reason to have inodes. They're a byproduct: basically, any reasonable unix-like filesystem design (and even NTFS is close enough on this point) has hard links for free.
The inode is where all the metadata of a file is stored: its modification time, its permissions, an... | What are inodes good for? |
1,401,431,048,000 |
Each file has an inode. Is there an inode for every directory ? If not, how does Linux manage directories.
|
Directories are special files, hence they have inodes.
You can test that with ls:
ls -li
or using stat:
stat -c '%F : %i : %n' *
Example:
% stat -c '%F : %i : %n' *
regular file : 670637 : bar.csv
regular file : 656301 : file.txt
directory : 729178 : foobar
The number in the middle is the inode number.
| Is there an inode for a directory? |
1,401,431,048,000 |
Two known facts:
In linux, moving a file from one location to another on the same file system doesn't change the inode (the file remains at "the same place", only the directories involved are changed)
Copying, however, generates a truly new file, with a new inode.
Armed with this information, I observer the followin... |
How does it make this reuse of same inode?
In ext4, the inode numbers are just indexes to a table that contains the actual inode data. The lore tells that's what the "i" means, "index". It's not actually stored as a single consecutive table, but that doesn't matter.
The particular inode number you get is one that ha... | How inodes numbers are assigned |
1,401,431,048,000 |
I'm aware that Linux does not allow hard-linking to a directory. I read somewhere,
that this is to prevent unintentional loops (or graphs, instead of the more desirable tree structure) in the file-system.
that some *nix systems do allow the root user to hard-link to directories.
So, if we are on one such system (th... |
Hard links to directories aren't fundamentally different to hard links for files. In fact, many filesystems do have hard links on directories, but only in a very disciplined way.
In a filesystem that doesn't allow users to create hard links to directories, a directory's links are exactly
the . entry in the directory ... | Linux: How does hard-linking to a directory work? |
1,401,431,048,000 |
If I create a small filesystem, and grow it when I need to, will the number of inodes increase proportionally?
I want to use Docker with the overlay storage driver. This can be very inode hungry because it uses hardlinks to merge lower layers. (The original aufs driver effectively stacked union mounts, which didn't ... |
Yes. See man mkfs.ext4:
-i bytes-per-inode
Specify the bytes/inode ratio. mke2fs creates an inode for
every bytes-per-inode bytes of space on the disk. The larger
the bytes-per-inode ratio, the fewer inodes will be created.
This value generally shouldn't ... | If I grow an ext4 partition, will it increase the number of inodes available? |
1,401,431,048,000 |
Say I want to observe how the flow from file name to cluster on hard disc goes.
I get the inode number of I file (which is mapped in a directory data):
1863 autorun.inf
So, now i know that i have to look for the inode numbered 1863 which will contain the pointers to the data on the hard disc.
Where is the inode data ... |
Inode data are usually scattered around the disk (in order to cut down seeks). Being able to tell where the inode structures are is the core functionality of a filesystem driver - check LXR for current implementation of ext3 in Linux) or e2fsprogs sources if you are interested in details.
From a user's perspective yo... | Location of inodes (ext)? |
1,401,431,048,000 |
I'm trying to understand how inode numbers (as displayed by ls -i) work with ext4 partitions.
I'm trying to understand whether they are a construct of the linux kernel and mapped to inodes on disk, or if they actually are the same numbers stored on disk.
Questions:
Do inode numbers change when a computer is reboote... |
I'm trying to understand how inode numbers (as displayed by ls -i) work with ext4 partitions.
Essentially, inode is a reference for a filesystem(!), a bridge between actual data on disk (the bits and bytes) and name associated with that data (/etc/passwd for instance). Filenames are organized into directories, where... | How do inode numbers from ls -i relate to inodes on disk |
1,401,431,048,000 |
I want to make ext2 file system. I want to set "number-of-inodes" option to some number. I tried several values:
if -N 99000 then Inode count: 99552
if -N 3500 then Inode count:
3904
if -N 500 then Inode count: 976
But always my value is not the same. Why?
I call mkfs this way
sudo mkfs -q -t ext2 -F /dev/sda2 -b 40... |
The number hasn't been ignored, it's been rounded up. It looks like space for inodes are allocated in groups. See in your output:
Inodes per group: 1632
When you request 99,000 inodes, that's not divisible by 1,632. So to ensure that you get the number of inodes you requested, the number has been rounded u... | mkfs ext2 ignore number-of-inodes |
1,401,431,048,000 |
I use Vim 8.2 to edit my files in my Ubuntu 18.04. When I open a file, do some changes and quit with Vim, the inode number of this file will be changed.
As my understanding, it's because the backup mechanism of my Vim is enabled, so each edition will create a new file (.swp file) to replace the old one. A new file has... |
It seems the setting backupcopy is auto (run :set backupcopy? in Vim to confirm).
The main values are:
yes make a copy of the file and overwrite the original one
no rename the file and write a new one
auto one of the previous, what works best
[…]
The auto value is the middle way: When Vim sees that renaming file ... | Why didn't inode change anymore with a hard link |
1,401,431,048,000 |
I get the feeling I'm going insane, or tmpfs is very broken for long term use.
I have a workload that very rapidly creates and unlinks files in /dev/shm/[some directory tree]. Linux Slab usage (in size-64 and size-128) increases linearly with inodes allocated/unlinked and never drops (the memory is listed an unreclai... |
For the sake of clarity I'm adding a more-or-less scripted test of what we talked about in the comments. This is on kernel 4.7.2 where the issue does not happen either:
$ cd /dev/shm
$ free
total used free shared buff/cache available
Mem: 1794788 673948 873668 ... | Unlinking files in /dev/shm not freeing memory? |
1,401,431,048,000 |
I know a little about linux kernel. BUt for Freebsd, the "vnode" actually is similar to the "inode" in Linux kernel.
And there is a "inode" concept in FreeBSD or Solaris.
So my question is: what is "inode" in FreeBSD for?
Below is good to read.
Thank you.
http://hub.opensolaris.org/bin/view/Community+Group+advocacy/so... |
An inode is a structure in some file systems that holds a file or directory's metadata (all the information about the file, except its name and data). It holds information about permissions, ownership, creation and modification times, etc.
Systems the offer a virtualised file system access layer (FreeBSD, Solaris, Lin... | what is inode for, in FreeBSD or Solaris |
1,401,431,048,000 |
I do not really understand where the tables which contain i-nodes are located. My teacher said that each physical disk has a table of i-nodes, after which there is the files' data. But, on the Internet, I found that each directory has its own table of the inodes and names associated to the files inside it.
Are these t... |
My teacher said that each physical disk has a table of i-nodes, after which there is the files' data.
This is broadly correct. More precisely, there's a table of inodes on each filesystem, and there's a separate filesystem on each partition. (Things can get more complicated but we don't need to get into these compli... | Where are i-node tables stored? |
1,401,431,048,000 |
I am using:
debugfs -R 'stat <7473635>' /dev/sda7
to get the file creation time (crtime).
Inode: 7473635 Type: regular Mode: 0664 Flags: 0x80000
Generation: 1874934325 Version: 0x00000000:00000001
User: 1000 Group: 1000 Size: 34
File ACL: 0 Directory ACL: 0
Links: 1 Blockcount: 8
Fragment: Addr... |
It does show the timestamp (with nanoseconds precision) but in hex; it's the field after crtime:, e.g. in your output 0x55b65ebc:970fe7cc. The part after the colon is the nanoseconds.
This article gives more details and explains how to calculate the timestamp/nanoseconds. So, e.g. to convert the hex values to a timest... | Why debugfs doesn't show crtime in nanoseconds? |
1,401,431,048,000 |
Hi I am investigating tripwire and have stumbled upon something which i am unsure about. in a tripwire report generated after i modified hosts.deny to include an extra # I noticed the inode number changed from 6969 to 6915. I would like to know why this happened. I know inodes are records which store data about where ... |
Standard behavior for text editors is to rename the original file to a temporary name before writing out changes, so if there is a problem (such as out of disk space) you don't lose the file entirely. Thus the file gets a new inode number. If the editor is configured to leave the original as a backup file, you'll fi... | tripwire report - inode number |
1,401,431,048,000 |
Formatting a disk for purely large video files, I calculated what I thought was an appropriate bytes-per-inode value, in order to maximise usable disk space.
I was greeted, however, with:
mkfs.ext4: invalid inode ratio [RATIO] (min 1024/max 67108864)
I assume the minimum is derived from what could even theoretically ... |
Because of the way the filesystem is built. It's a bit messy, and by default, you can't even have the ratio as down as 1/64 MB.
From the Ext4 Disk Layout document on kernel.org, we see that the file system internals are tied to the block size (4 kB by default), which controls both the size of a block group, and the am... | Why is 67108864 the maximum bytes-per-inode ratio? Why is there a max? |
1,432,127,475,000 |
I have a large number of files that contain backslashes \ that I would like to manipulate, but whenever I try something like:
$ ls -li
2036553851 -rw-rw-r-- 1 user user 6757 May 20 00:10 Simplex_config\\B1:B3\\_1.csv
2036553766 -rw-rw-r-- 1 user user 6756 May 20 00:07 Simplex_config\\B1:B3\\_2.csv
2036554099 -rw-rw-r-... |
1.
find . -type f -name 'Simplex*.csv' -print0 | xargs -0 cat > looksee.txt
From man xargs
--null
-0
Input items are terminated by a null character instead of by whitespace, and the quotes and backslash are not special (every character is taken literally). Disables the end of file string, which is tre... | Manipulate multiple files by inode |
1,432,127,475,000 |
Setup
The following sequence of commands is setup for my question.
root@cd330f76096d:/# cd
root@cd330f76096d:~# ls
root@cd330f76096d:~# mkdir -p my_dir/my_subdir
root@cd330f76096d:~# ls -hAil
total 12K
6175969 -rw-r--r-- 1 root root 3.1K Oct 15 2021 .bashrc
6175970 -rw-r--r-- 1 root root 161 Jul 9 2... |
A pathname that find encounters (i.e., apart from the search paths given on the command line) cannot contain a . or .. component, so your command will never show these.
Why? Because the POSIX standard says so (my emphasis):
Each path operand shall be evaluated unaltered as it was provided, including all trailing <sl... | How does `ls` find hard links? |
1,432,127,475,000 |
In order to test an analysis tool, I need a file where the depth (eh.eh_depth) is greater than 1.
I've tried a couple of things:
A large file (1GiB)
Creating hundreds of smaller files (1MiB), deleting every other one, and then filling the disk with one file (hoping for massive fragmentation).
In both cases I only go... |
If you want a file with a lot of extents, just do:
$ perl -we 'for ($i=0;$i<100000;$i++) {seek STDOUT,$i*8192,0; print "."}' > a
$ ll a
-rw-r--r-- 1 stephane stephane 819191809 Dec 15 23:50 a
$ filefrag a
a: 100000 extents found
That's a sparse file where every other block is sparse, so it forces the extents to be 4K... | Can I create a file on ext4 with a depth > 1 for testing purposes? |
1,432,127,475,000 |
My root filesystem is running out of inodes. If this were an issue of disk space, I'd use du -s to get a top-level overview of where the space is going, then head down the directory tree to find particular offenders. Is there an equivalent option for inodes?
The answers in this question will point out individual dir... |
With GNU coreutils (Linux, Cygwin) since version 8.22, you can use du --inodes, as pointed out by lcd047.
If you don't have recent GNU coreutils, and there are no hard links in the tree or you don't care if they're counted once per link, you can get the same numbers by filtering the output of find. If you want the equ... | Where are my inodes going? |
1,432,127,475,000 |
Is it possible to create a "file" that, essentially, is symlinked to multiple other files.
Let's say we have a /tmp/dir/ with 100 files in it. What I want is to be able to do is "cat /tmp/dir_allfiles" which would, in essence, be the same as cat /tmp/*
The real use case is more complicated where files may be at diffe... |
That is definitely possible to do at the VFS level, e.g. using FUSE.
In particular, concat-fuse, looks pretty much like what you need:
concat-fuse is a FUSE based virtual filesystem for Linux that allows handling a collection of files as if they were a single one. It is essentially doing:
cat *.txt > large_file
But i... | Giving one file multiple inode values |
1,432,127,475,000 |
I have this command this shows me when a file has been modified under a concrete directory (excluding some paths):
inotifywait -m -q -r --format '%T % e %w%f' --excludei '/trash/' --timefmt '%d/%m/%Y-%H:%M:%S%z' /my/monitored/folder
Is there a way to combine this (or a similar) command with tail, so I can retrieve th... |
In your question you say that you want to scan if a file has been modified, but in your command there's no event specified.
So my answer will use the modify event:
inotifywait -m -q -r \
--format '%T % e %w%f' \
--excludei '/trash/' \
--timefmt '%d/%m/%Y-%H:%M:%S%z' /my/monitored/folder | \
while IFS=' ' read... | How to combine inotify with tail command to print last line of every modified file |
1,432,127,475,000 |
I have a pretty basic system running Ubuntu 16.04 (this question is not specific to Ubuntu, but rather ext4 partitions), 1 HDD, running a few partitions:
sda1 - EXT4 - 100G - /
sda2 - EXT4 - 723.5G - /home
sda3 - NTFS - 100G - (windows)
sda5 - SWAP - 8G
Whenever I try to access one of 3-4 files in a specific dir... |
Finally found the answer from somebody else on another site, just zeroed the inodes and rechecked the system, that was all!
debugfs -w /dev/sda2
:clri <1415>
:clri <1416>
:clri <1417>
:q
fsck -y /dev/sda2
To anybody else with this issue, I found my bad inodes using find on the bad mount, then checked dmesg for... | Partition Errors and Remounts Read-Only when Accessing Specific File |
1,432,127,475,000 |
I understand the size reported by ls corresponds with number of inodes inside the directory, not their actual size.
I have noticed peculiar behavior, when displaying directory size with ls. Here is how to quickly reproduce it:
first create empty directory, the size reported by ls is 4096 (as expected)
mkdir test
ll -... |
Generally, directory files are not cleaned up - their space usually is small enough (compared to their contents) that it's not effective to do this (particularly when they might grow again). Finding an authoritative answer for this might be hard... Forum comments are easy:
Shrink/reset directory size?
Linux directo... | size of directory reported by ls [duplicate] |
1,432,127,475,000 |
Is there any tools or some way in linux which can be used to view internals of filesystems ?
How to view the inode related structures and journal ? and cached pages of files (pagecache).
|
This will of course depend on what filesystem you are using,
e2fsprogs contains debugfs which will work with ext2, ext3 and ext4, and is used to manually view or modify internal structures of the file system
man page for debugfs is here
| Filesystem and journal layout |
1,432,127,475,000 |
After reading this post: https://stackoverflow.com/questions/14189944/unix-system-file-tables, I've basically understood how Linux manages the files.
But I don't know how to manage the offsets of the files.
As my understanding, one element (one line) in Open File Table maintain its own offset. For example, I have two ... |
In a word, how does the writing process knows that it should change the offset after executing > myfile?
It doesn’t. The file offset isn’t changed as a result of > myfile.
What happens to subsequent file operations depends on the circumstances. read returns 0 if the offset is past the end of the file. write adjusts ... | How does linux manage the offsets of files |
1,432,127,475,000 |
What are functions to manipulate sparse files under Linux? (let's say in C, notes about other systems highly welcome)
e.g.:
make hole inside of file by removing part of its inside
investigate structure , e.g. generate sequence of pairs denoting beginnings and ends of separated continuous blocks of data
split file int... |
Sparse files are designed to be transparent to userspace: holes are created by seeking past unused areas, and are read as blocks of zeroes. They can’t be detected using standard userspace APIs, at least not yet — as pointed out by Stéphane Chazelas, at least Solaris and Linux support the SEEK_DATA and SEEK_HOLE lseek(... | What are functions to manipulate sparse files under Linux? |
1,432,127,475,000 |
I created a hard link for the shadow file. For removing the passwd of the user I opened the shadow file in vi editor and removed the encrypted passwd and then saved. The inode value of the shadow file was changed. Then I updated the passwd of the user and again the inode value of the shadow file changed.
Why the inod... |
The usual implementation of password changing involves hardlinking /etc/shadow to /etc/stmp (or some similar name; link() being atomic on local filesystems, this constitutes a kind of lock file mechanism), writing out a new one to a temporary file, then renaming the original /etc/shadow to /etc/shadow- or similar and ... | Why the inode value of shadow file changes? |
1,432,127,475,000 |
using dumpe2fs on some ext4 partition, I get in the initial data, that the first inode is #11. However, if I ls -i on this disk root partition, I get that it's inode number is #2 (as expected). So... What is this “first partition” reported by dumpe2fs ?
|
#11 is the first "non-special" inode, that can be used for the first regularly created file or directory (usually used for lost+found). The number of that inode is saved in the filesystem superblock (s_first_ino), so technically it doesn't need to be #11, but mke2fs always sets it that way.
Most of the inodes from #0 ... | what is this “first inode” reported by dumpe2fs? |
1,432,127,475,000 |
I am using Ubuntu Linux and, just for fun, I want to create a hardlink to a directory (as seen here). Because I'm just doing this for fun, I'm not looking for any sort of pre-developed directory-hardlinking software that someone else wrote, I want to know how to do it myself. So, how do I directly, manually, modify an... |
That depends on the filesystem. For ext4, you can do this with debugfs as follows:
dennis@lightning:/tmp$ dd if=/dev/zero of=ext4.img bs=1M count=100
104857600 bytes (105 MB) copied, 0.645009 s, 163 MB/s
dennis@lightning:/tmp$ mkfs.ext4 ext4.img
mke2fs 1.42.5 (29-Jul-2012)
ext4.img is not a block special device.
Proc... | How do I manually modify an inode? |
1,432,127,475,000 |
I'm working on an assignment for my college course, and one of the questions asks for the command used to create a hard link from one file to another so that they point to the same inode. We were linked a .pdf file to refer to, but it doesn't explain said process. Is it any different from creating a standard hard link... |
Hard links are not "between" the files, there's one inode, with >1 entries in various directories all pointing to that one inode. ls -i should show the inodes, then experiment around with ln (hard link) and ln -s (soft or symbolic):
$ touch afile
$ ln -s afile symbolic
$ ln afile bfile
$ ls -1 -i afile symbolic bfile
... | Two hard linked files share inode |
1,432,127,475,000 |
I'm reading about file systems and storage medium and I can't understand why if I create a one block size file I can't have a smaller inode than a one of a bigger file. Can't the OS dynamically choose the inode size according to the file size?
|
One reason for inodes to be fixed-size is that in the traditional Unix filesystem format (which e.g. ext4 still follows pretty closely), the inodes are stored in what is essentially a single table. With fixed-size items, locating an item based on its index number is trivial. With any other data structure it would requ... | Why is inode size fixed? |
1,432,127,475,000 |
Can I safely conclude that the sticky bit is not used in current file sysems and reuse the bit for my own purpose.
|
No, you cannot assume that. It's not true for directories. You can make the narrower assumption that it's true for non-directory files.
| Is the sticky bit not used in current file systems |
1,432,127,475,000 |
when I try to resize the disk we get that
resize2fs /dev/sdb
resize2fs 1.42.9 (28-Dec-2013)
Please run 'e2fsck -f /dev/sdb' first.
so when I try to do e2fsck
I get the following
e2fsck -f /dev/sdb
e2fsck 1.42.9 (28-Dec-2013)
Pass 1: Checking inodes, blocks, and sizes
Deleted inode 142682 has zero dtime. Fix<y>?
is ... |
It’s OK to let fsck fix this, it refers to a deleted inode — the data has already been deleted, nothing more will be deleted.
| rhel + efsck + Deleted inode xxxxx has zero dtime |
1,432,127,475,000 |
I am a Unix wanderer. I just noticed that symlinks don't have data blocks allocated to them, I think the inode of the symlink file stores the filename which the symlink refers to, is this actually the case?
$ stat sdb
File: sdb -> /dev/sdb
Size: 8 Blocks: 0 IO Block: 4096 symbolic link
De... |
ext4 stores the target of a symbolic link inside the inode, if the target is less than 60 bytes long. Longer targets will be stored in a data block.
| Why symbolic links have no data blocks allocated to them in ext4fs? |
1,432,127,475,000 |
Say I have a directory with these permissions:
drwxrwx---
Inside this directory, a file with these permissions:
-rw-rw-rw-
Is the file readable/writable by everyone or not ?
If not, how secure is this access restriction?
What if a random user makes a link to my file inside his home directory? Could he access the fil... |
Yes, a file in a directory is only accessible to users who have the execute permission on the directory. It's like leaving jewelry in an unlocked drawer inside a locked house: the jewelry is under lock.
A random user cannot create a hard link to a file, only the owner file. If the file has multiple hard links, some of... | Is a -rw-rw-rw- file really inaccessible inside a drwxrwx--- directory? |
1,432,127,475,000 |
I know how hard links and symlinks work and I know why hard links can't be used for directories but in this case, is it some kind of exception?
For example I do:
ls -al Documents
total 8
drwxr-xr-x 2 piotr piotr 4096 cze 28 11:19 .
drwxrwx--- 17 piotr piotr 4096 lip 2 16:41 ..
. is a hard link to Documents itself ... |
As someone said in a comment on the question, just because hard links to directories aren't permitted (i.e., by the ln command), does not mean they are not possible. The superuser can actually use the "-d" or "-F" option to the ln command to force the creation of a hard link to a directory (though the man page says i... | Why . and .. are hard links to directories while in *nix systems hard links are not allowed for directories? |
1,432,127,475,000 |
Is there a command line tool that can be used to rewrite all regular files in a directory tree either in-place or by creating new inodes?
With rewriting a file in-place, I mean opening the file for reading and writing, reading blocks of a reasonable size and writing those blocks at the same location, doing this for th... |
I just created tool that does just that:
https://github.com/pjd/filerewrite
Alternatively with ZFS you can also use zfs send/recv where the target file system has deduplication turned on. After that you will need to rename the file systems and make sure all the other file system properties are moved over.
| Command line tool to rewrite all files in directory tree |
1,432,127,475,000 |
We have an inode number that we're trying to associate to an actual file name. The filesystem is XFS. Looking there are examples that purport to be able to accomplish this with xfs_db and/or xfs_ncheck but thus far we've been unsuccessful in doing this.
Example
We're triaging an issue where we'd like to find the filen... |
In theory the command should work, but in practice, xfs_ncheck is a shell script around xfs_db and xfs_db very much prefers cleanly unmounted filesystems:
# xfs_db /dev/SSD/root
xfs_db: /dev/SSD/root contains a mounted filesystem
fatal error -- couldn't initialize XFS library
So by default, for mounted filesystems i... | Find the filename associated with an inode number on XFS filesystem |
1,432,127,475,000 |
In the Unix File system (UFS), the file is represented as an inode structure which has 15 pointers that reference the direct blocks or indirect blocks.
Taking the below images is an example.
Each block represented as Data on the right hand side contains the actual file data. And the size of this data block usually i... |
Most filesystems don't support inserting data at the beginning of a file, and Unix doesn't have an API for that. In most operating systems, the only ways to modify a file are to overwrite a segment (e.g. change aaaaaaaaaa to aaabbbaaaa), to append data at the end (e.g. change aaaaaaaaaa to aaaaaaaaaacccc), or to trunc... | Does adding the content at the start of file result in updating all the data blocks? |
1,432,127,475,000 |
I am reading in man lsof that
+L enables the listing of file link counts. A specification of
the form "+L1" will select open files that have been unlinked.
I don't understand why deleted files should have count 1.
Should not the count for deleted files be 0 ?
|
Well, yes. The manpage on my Debian system says “When +L is followed by a number, only files having a link count less than that number will be listed.”
| link count of deleted files |
1,432,127,475,000 |
I am trying to understand what an inode is. However, this passage from Wikipedia puzzles me:
Installation of new libraries is simple with inode filesystems. A running process can access a library file while another process replaces that file, creating a new inode, and an all new mapping will exist for the new file ... |
In Unix-style file systems, everything the system knows about a file (except its name) is stored either in the inode or in a location pointed to by the inode. That includes its contents, ownership, modification dates, and permissions. A Unix directory entry is just a name and a pointer to the inode, and is only used... | Why do inode-based file systems NOT need reboot after updating library versions? [duplicate] |
1,432,127,475,000 |
I had a folder deleted from a SMB share from a windows machine. Thanks to zero confirmation a whole folder was deleted. First ran photorec that pulled most of the files except 1, the very last file copied. Further testing with extundelete was able to pull the whole folder minus 4-5 files. However the single most impor... |
See https://ext4.wiki.kernel.org/index.php/Ext4_Disk_Layout#The_Contents_of_inode.i_block
The "File flags: 524288" is 0x80000 in hex, so it is the "extents" flag. So, although your extundelete interpreted the inode.i block as direct/indirect/double indirect/triple indirect block pointers, this is not correct. But we c... | Restoring via inode that's no longer in the journal? |
1,432,127,475,000 |
A follow-up from this question.
My further reading on Docker storage drivers revealed that the overlay driver merges all the image layers into lower layers using a hard link implementation which cause excessive inode utilization. Can someone explain this? As far as I know, creating hard links does not create a new ino... |
OverlayFS is a union filesystem, and there are two storage drivers at the Docker level that make use of it: the original/older version named overlay and the newer version named overlay2. In OverlayFS, there is a lower-level directory which is exposed as read-only. On top of this directory is the upper-level directory,... | Overlay storage driver internals |
1,543,874,986,000 |
pCloud is a cloud storage service that allows Linux users to mount their cloud storage inside of their home directory, appearing as:
/home/username/pCloudDrive/
As far as I can tell, the pCloudDrive directory is only accessible by the user and not by root.
Running ls -l inside the home directory (as root) displays: ... |
I have no direct experience with it, but it looks like pCloud is mounted as a FUSE file system. A FUSE file system is not accessible by root by design. The aim is to prevent mounted file systems from doing nasty things (see an explanation in libfuse's FAQ).
To let root, or other users, access a FUSE file system, you h... | Is pCloudDrive really inaccessible to root? |
1,543,874,986,000 |
Considering rsync used for incremental OS backup creates hardlink farms for all non-differing files, if I use it to backup a large, slowly-changing system regularly to a dedicated volume, I'm worried I'll run out of inodes for the hardlinks ages before I run out of diskspace.
Would it be better to tinker with mke2fs p... |
A hardlink is by definition a link to an inode. Multiple hardlinks to an inode hence do not need additional inodes...
The only thing that will increase inode usage is that for each "generation" the directory tree itself will be duplicated, so for each directory in each generation an additional inode will be needed, wh... | Should I increase inode count for a rsync backup volume? |
1,543,874,986,000 |
After posing this question, I'm kind of confused by the action of the linxu kernel.
First of all, I know how a process writes strings into a file: a process will obtain some buffer, the buffer can be written by the process, once the buffer is full or the process flushes the buffer, the content of the buffer will be wr... |
As my understanding, the command rm will unlink the file, meaning that its inode and its data blocks will be marked as UNUSED.
This is the key to understanding what’s going on here: rm only asks the kernel to remove a given directory entry. If the directory entry pointed to an inode which is no longer referenced by ... | Will the kernel hold the whole file to which some process is writing |
1,543,874,986,000 |
The inode structure of some filesystems includes a list of pointers to the blocks used to store the file contents. This list should exist for ext2/3/4, as specified in the first comment to this question.
The addresses of the blocks used by a file can be obtained with istat, one of the Sleuthkit tools: but this is not ... |
If you have a file entry pointing to the inode, you can use debugfs:
$ debugfs /path/to/filesystem
debugfs: inode_dump -b fileentry
0000 0004 0000 0104 0000 0204 0000 0304 0000 ................
0020 0404 0000 0504 0000 0604 0000 0704 0000 ................
0040 0804 0000 0904 0000 0a04 0000 0b04 0000 ............... | inode, list block pointers |
1,543,874,986,000 |
I am trying to understand what it happens to a file when I move it from a directory to another, inside the same File System.
Here is the example I made up.
I have two directories and a file :
~/Documents/dir1
~/Documents/dir2
~/Documents/dir1/fileName.txt
Here I have some details about the file fileName.txt (ls -li... |
Within the same filesystem, mv-ing actually uses rename(2). So the inode will remain intact, just the inode is removed from one directory entry and attached to another.
| Moving a file inside the same File System |
1,543,874,986,000 |
I searched the Internet, but I was not able to find a satisfying answer to my problem. The Problem I'm encountering currently is, that I'm transitioning my data from a NTFS Partition to a ext4 partition. What surprised me was the fact, that I could store less data on the same harddrive with the ext4 filesystem. After ... |
By default, ext2/ext3/ext4 filesystems have 5% of the space reserved for the root user. This makes sense for the root filesystem in a typical configuration: it means that the system won't grind to a halt if a user fills up the disk, critical functionality will still work and in particular logs can still be written. It... | ext4 file system tuning for storage partition |
1,543,874,986,000 |
Imagine I want to access the blocks of file /hello/file.
How many inodes should I walt through?
I guess two, since I should not go through the root inode, right?
|
I would expect three /, hello and file. Changing permissions of any one of these can limit access to file.
| How many inodes do I need to access to read a file? |
1,543,874,986,000 |
I'm running a CentOS 4.6 final box with a second drive array (raid 1, the mount is /mnt/raid, as listed below in my nagios warning) that uses ntfs-3g as the file system. My nagios warnings just went off saying that I'm running out of inodes but still have 10% of the drive space available (I am aware this is common).
H... |
It is complaining that there is only 10% free space left, which is not good. It is saying 99% of the inodes are free.
| Understanding NTFS-3g Inode Use |
1,543,874,986,000 |
$sudo blkid
/dev/sda1: UUID="F959-61DE" TYPE="vfat" PARTUUID="950b18a0-1501-48b4-92ef-ba1dd15aaf21"
/dev/sda2: UUID="6dfcfc23-b076-4eeb-8fba-a1261b4ea399" TYPE="ext4" PARTUUID="ddc69ee8-40b0-49c9-9dcb-0b9064caca7d"
/dev/sda3: UUID="fec0af18-d28e-4f2a-acb7-6380ddee3dc2" TYPE="ext4" PARTUUID="e19628dc-c04a-4c9d-a3c6-469... |
debugfs’s stat command expects a path name, or an inode number “quoted” using angle brackets; you might as well use stat milad/a instead:
sudo /sbin/debugfs -R 'stat milad/a' /dev/sda6
The file path is relative to the root of the file system; since that is mounted at /home, /home/milad/a becomes milad/a.
If your vers... | debugfs not working | file not found by ext2_lookup |
1,543,874,986,000 |
I'm trying to read the contents of a file using the file's inode.
This works fine:
echo "First line" > data.txt
sync
sudo debugfs -R "cat <$(stat -c %i data.txt)>" /dev/sda3
debugfs tells me the file contents are "First line". This part of the command gets data.txt's inode number: $(stat -c %i data.txt).
Things go aw... |
It is due to caching. You have at least two options.
Use the -D flag:
-D Causes debugfs to open the device using Direct I/O, bypassing the buf‐
fer cache. Note that some Linux devices, notably device mapper as of
this writing, do not support Direct I/O.
Drop buffer cache:
echo 1 | sudo tee /proc/sys/vm/drop_cach... | Reading stale file data with debugfs cat |
1,543,874,986,000 |
Today I noticed that tripwire thinks that some Apache configuration files changed yesterday. I know I did not make any changes to those files.
Looking at the info, it shows that only the Inode number changed:
Property: Expected Observed
------------- ----------- ... |
One way:
cp -p file file.new && mv file.new file
For example:
$ ls -li file
12289 -rw-r--r-- 1 jeff jeff 0 Jun 13 14:24 file
$ cp -p file file.new && mv file.new file
$ ls -li file
12292 -rw-r--r-- 1 jeff jeff 0 Jun 13 14:24 file
Another possibility would be that the file was restored from a backup system (and... | Why does a file's Inode number change and nothing else? |
1,543,874,986,000 |
What does +0200 mean after the Access/Modify/Change timestamps?
File: task-system.md
Size: 197 Blocks: 24 IO Block: 4096 regular file
Device: 33h/51d Inode: 14155787 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 1000/ tom) Gid: ( 1000/ tom)
Access: 2018-08-26 15:19:07.047602175 +0200
... |
That’s the timezone. The times are given in a UTC+2 timezone (the timestamps are stored as seconds since the Unix epoch, and translated to whatever the current user’s timezone is for display).
| Inode Timestamp Plus/Minus Interpretation |
1,543,874,986,000 |
Why are byte offsets for a pipe/FIFO maintained in the inode rather than the file table, like for regular files?
I read this line at page 113 of The Design of The Unix Operating System (1986) by Maurice Bach.
Maintaining the byte offsets in inode allows convenient FIFO access to the pipe data and differs from the reg... |
Note that that book describes the AT&T Unix system internals as they were 30 years ago. You can't assume things are done the same in modern Unix and unix-like systems.
In any case regardless of how pipes are implemented internally, while for regular files or other seekable files, the byte offset is something that belo... | Byte Offsets for pipe/FIFO |
1,543,874,986,000 |
I have a btrfs file system, and it all the folders in the top level are inode 256.
This is not good for me, the device id is the same, So I assume these are "virtual inodes numbers", Btrfs has their own mechanism of doing this.
Is it possible to get the real unique physical inode of each directory ?
look what happen... |
I'm assuming that the three directories /home, /data and /apps are mount points.
When you mount something on /home, the inode that is reported for /home is the inode of the root directory of the mounted partition, not that of the original /home directory. It is therefore not strange that these inodes are the same as t... | btrfs same inode number |
1,543,874,986,000 |
[~]$ 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 350G 67G 266G 21% /
tmpfs 12G 44M 12G 1% /dev/shm
[~]$ sudo tune2fs -l /dev/sda2 | grep 'First... |
The value in the superblock shown by tune2fs is the first inode number usable for new files, while the root directory must always exist when the file system is created.
The kernel’s Ext4 documentation lists the inode numbers which are used internally by file systems features.
| Why are the first inode of the `/` mounted partition and inode of `/` different? |
1,543,874,986,000 |
How approximately calc bytes-per-inode for ext2?
I have 7.3GB storage (15320519 sectors 512B each). I have made ext2 filesystem with block size 4096
mke2fs /dev/sda2 -i 524288 -m 0 -L "SSD" -F -b 4096 -U 11111111-2222-3333-4444-555555555555 -O none,filetype,sparse_super,large_file
Filesystem label=SSD
OS type: Linux
... |
Your free space is roughly 7.3*1024*1024*1024 bytes. On average, the size of a file is expected to be 100*1024 bytes. This means you have room for approximately
7.3*1024*1024*1024 / (100*1024) = 7.3*1024*1024/100 ≃ 76,546
distinct files. That implies you need precisely that many inodes.
The mke2fs output indicates yo... | ext2 How to choose bytes/inode ratio |
1,543,874,986,000 |
When I run df -H, my network mount reports 100% usage:
user@system:/mnt/backup$ df -H
Filesystem Size Used Avail Use% Mounted on
...
//192.168.71.2/Linux-Database-Backup-Storage 806G 806G 0 100% /mnt/backup
Running stat -f confirms there are no free inodes/blocks:
user@system... |
There are various possible reasons for this, mostly hinging around the fact that a network share need not correspond to an entire filesystem. Here, it's possible that although the remote filesystem is 806GB, only part of it is being exported to you over the network. You have used 115GB but another party has used the r... | Discrepancy between "df" and "du" on a CIFS network drive |
1,686,470,364,000 |
Is there any way to find exactly the blocks allocated to a inode, and view that file? I don't care if I have to be on a live cd, but i need to do this for example:
cat verylongsentice > a
ls -i a
101010 a
ln a /some/random/path
rm a
inode_find 101010
verylongsentice
is there any way to do this? maybe as root or from... |
There's no inode number for a deleted files. Also: Inode numbers are not guaranteed to be immutable, or not be reused immediately.
In the comments below your question you're very insistent that what you want should work. It shouldn't:
To open a file directly by inode nr and not through file name is in direct conflict ... | open a file by inode number [duplicate] |
1,686,470,364,000 |
When I use the dumpe2fs command to look at the Block Group of the ext4 filesystem, I see "free inodes" and "unused inodes".
I want to know the difference between them ?
Why do they have different values in Group 0 ?
Group 0: (Blocks 0-32767) [ITABLE_ZEROED]
Checksum 0xd1a1, unused inodes 0
Primary superblock at 0,... |
The "unused inodes" reported are inodes at the end of the inode table for each group that have never been used in the lifetime of the filesystem, so e2fsck does not need to scan them during repair. This can speed up e2fsck pass-1 scanning significantly.
The "free inodes" are the current unallocated inodes in the grou... | Ext4 "unused inodes" "free inodes" diffrence? |
1,686,470,364,000 |
I installed debian strech through the installer in a software raid 10 configuration.There are 4 drives, each is 14TB. Partition was formatted by the installer with ext4. The inode ratio defaults to 16384.
cat /proc/mdstat
Personalities : [raid10] [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4]
md3 : act... |
Your file system is over 16 TiB in size, so mke2fs defaulted to the “huge” file system type, with an inode ratio of 65,536 bytes. See the -T option in the linked manpage, and the huge type in mke2fs.conf:
huge = {
inode_ratio = 65536
}
| ext4 inode ratio discrepancy between /etc/mke2fs.conf and tune2fs |
1,686,470,364,000 |
I have 3 computers, A, B, and C, and I perform identical operating system and software installations on them. For any specific file on A, can I expect that same file on B and C to have the same inode number for its instance of that file?
Our intrusion detection system is set up by acquiring an initial file system imag... |
[...] and I perform identical operating system and software installations on them.
For any specific file on A, can I expect that same file on B and C to have the same inode number for its instance of that file?
No, because I/O runs in parallel, and the order of I/O operations is not deterministic and affected by wha... | How does the sequence of inode numbers work? Can I expect consistency across identical installs on different computers? |
1,686,470,364,000 |
The *nix filesystems maintain an inode table at the beginning of the disk (or at some fixed location). It is indexed by the inode number, which is an integer that uniquely identifies an inode. Knowing the inode number, an inode can be found quickly. The inode contains pointers/addresses to other disk blocks, which co... |
If I understand you correctly, you want to replace the inode number with the block address. That means (1) one inode per block, which wastes a lot of space (the inode isn't that large), and (2) it's not that different from using an inode number: An inode has a fixed size, so a block contains a known number n of inodes... | Filesystem design: necessity of inode number and table [closed] |
1,686,470,364,000 |
CentOS6
I am logged in as root. It is a virtual machine running on a Windows 10 host in virtualbox as a vagrant machine.
I tried
chmod -R 777 /home/thomas/WWW
chown -R root:root /home/thomas/WWW
when trying to rm with rm -rf /home/thomas/WWW I get
remove `/home/thomas/WWW/': Is a directory
which is weird
ls -la rev... |
If you filesystem is neither /boot, /, /usr or /var things are easy
just comment your filesystem in /etc/fstab
#/dev/vgdata/archives /home/archemar/tmp365 ext4 defaults 0 2
reboot
fsck -t ext4 /dev/vgdata/archives (fsck should recognize ext4 fstype)
else
locate you filesystem (df . ) will tell you
/dev... | Cannot rm corrupt directory |
1,686,470,364,000 |
I get the same confusion in multi-level paging as well. For inodes, we have direct and indirect pointers that point to data blocks. However, for small files we prefer to use indirect pointers since they can store a lot more pointers for our purpose.
However, why is it more data-consuming to store direct pointers in se... |
The original hierarchy of the inodes levels works roughly like this:
You can store one or a few block numbers directly in the inode. This means you use a few bytes more for the inode, but for small files, you don't have to allocate a complete block, which is mostly empty.
The next level is one indirection: You allocat... | Why does using indirect pointers in inodes not incur the same amount of space? |
1,686,470,364,000 |
When I list an inode with stat command:
File: 'text'
Size: 0 Blocks: 0 IO Block: 4096 regular empty file
Device: 802h/2050d Inode: 8391119 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 1000/ cagdas) Gid: ( 1000/ cagdas)
Access: 2017-07-31 17:00:00.513753567 +0300
Modify: 2017-07-31 17:00... |
802 (hexadecimal) is the combination of the major and minor numbers (8, 2) of /dev/sda2 where the file text resides. The major number is placed in the most significant half of a 16-bit word, the minor number in the least significant half. For historical reasons the value is displayed like this, even though Linux since... | What is "Device: 802h/2050d" stands for in inode? |
1,686,470,364,000 |
Dears, I have a Redhat linux server Red Hat Enterprise Linux Server release 5.5 (Tikanga). It's a production sensitive server. now it ran out of inodes in /storage2 directory. It has many space but it almost finished inodes and I need to increase the number of inodes ASAP. with this link It has the solution but it n... |
Answer : no, you can't increase the inodes without taking the backup/restore.
man page for mkfs.ext4 (which I assume is the filesystem type in play here) is pretty clear on this:
It is not possible to change this value after the filesystem is created."
You could look into such solutions as creating a /storage2/subd... | increase the number of inodes online |
1,686,470,364,000 |
Today, I ran out of inodes on one of my VPSs.
I deleted a bunch of superfluous small files, freeing enough inodes to make the system operational again:
Filesystem Inodes IUsed IFree IUse% Mounted on
/dev/simfs 586K 529K 58K 91% /
I also hacked together a short command to give me the number of used inod... |
Use a bind mount instead of -xdev. Also, directories use inodes too.
mkdir /mnt/somewhere
mount -o bind / /mnt/somewhere
find /mnt/somewhere -printf '%i\n' | sort -u | wc -l
| Where have all my inodes gone? |
1,686,470,364,000 |
A question was given to us by a lecturer:
How many data blocks are needed to collect all the data in an EXT4
file system using inodes if the file size is 54 KB and there is a
block size of 4KB.
Answer: 15
The only explanation I can find is 54/4 = 13.5, which is round up to 14 data blocks and we add 1 inode block, so... |
It's hard to know what they're thinking exactly (you'd have to ask them), especially since they talk about "all data on the FS" (not just one file), and mention "using inodes" (in plural).
But, one thing they might be referring to, would be the basic block addressing, which addresses the first 12 data blocks directly ... | Each file gets one inode block |
1,686,470,364,000 |
When I trace the function graph when calling write(), I find that within function ext4_file_write_iter() it locks the inode->i_rwsem by calling inode_lock(inode) at the beginning. After that call __generic_file_write_iter() to write data to file. And unlock the inode in the end.
So is it the inode->i_rwsem used to pro... |
inode->i_rwsem is used internally by the kernel to ensure that the kernel itself doesn't read or write from/to a file at the same time, to avoid any corruption or race conditions. It doesn't affect the userspace; you can still have the file opened for read/write by multiple processes at the same time. But if multiple ... | What‘s different between inode->i_rwsem and i_flctx? |
1,686,470,364,000 |
I have an example to better illustrate what I'm talking about:
$ touch tas
$ ln -s /etc/leviathan_pass/leviathan3 /tmp/l2/tas
ln: failed to create symbolic link '/tmp/l2/tas': File exists
Basically I can only symlink if the file I want to link doesn't exist. I understand this issue when talking about hard links - th... |
The command ln won’t clobber existing files by default. You can use ln -sf TARGET LINK_NAME to force overwriting the destination path (LINK_NAME) with a symlink.
You can use ln -f TARGET LINK_NAME to overwrite LINK_NAME with a hard link to, your explanation doesn’t make any sense about inode conflict. It just repla... | Why can't I symlink a preexisting file to a target file? [duplicate] |
1,686,470,364,000 |
There are two groups of LSM hooks under Security hooks for inode operations: inode_* and path_*.
Many of them look identical. For example, inode_link and path_link.
What is the difference between the inode and path hooks? When each should be used?
|
Path hooks were added by TOMOYO maintainers, to allow file path calculation in LSM module.
These hooks receive a pointer to path struct.
inode hooks resides on a lower level, and receive a pointer to inode struct. The file path cannot be retrieved from this struct.
Generally speaking, if you don't need the file path... | LSM Hooks - What is the difference between inode hooks to path hooks |
1,686,470,364,000 |
I'm reading some doc about UNIX but I don't understand two things:
Why is important for the kernel to know the current working directory of the running process?
Why not keeping the inode information in the directory?
|
The system needs to keep track of the current directory of all processes because otherwise processes couldn't use relative paths for anything (including for example file open or stat, and changing directories — what does chdir("..") mean if you don't track were the process currently sits?).
There's also the matter tha... | Kernel current working directory and inode information placement |
1,686,470,364,000 |
background:
Being somewhat of a coward I have up to now dd whole filesystems for backup. Major drawback has become the excessive use of memory for those complete backups (which unfortunatelly also included free blocks)
question
I would like to backup now only the files inside the filesystem, but yet be able to recreat... |
Inode numbers don't matter to normal applications. This is partly because there's little use for inode numbers, and partly because if an application depended on inode numbers, it would stop working after a backup-and-restore cycle. So backup systems don't restore the inode numbers, so applications don't depend on them... | At Backup, when would the filesystems inode numbers matter? |
1,686,470,364,000 |
I know that it isn't possible to change the inode count of an ext filesystem after its creation, but I haven't been able to find any explanation on why it isn't.
Can anyone enlighten me?
|
Why? Because no one has written a tool that does it. And that's probably because it's a not entirely trivial change to the filesystem metadata.
There are other issues like this; for example you can't resize ext4 to >16TB. That needs 64bit structures which aren't used by default.
Same with other filesystems, for exampl... | Why is it impossible to change the inode count of an ext filesystem? |
1,686,470,364,000 |
A bit of context that I think is relevant for the appropriate solution:
I have a server that has two folders; one is ingest, the other is sorted. The source of the sorted folder is the ingest folder, all directories are unique, all files are hard links.
The result of this is that when the ingest folder has a file dele... |
I have now used find . -type f -links +1 to get all the files with more than one link, then used sed to make all links absolute, and then ncdu -X list.txt to scan for any files except for those listed.
This solution is still slow and I am looking for a better one, but it does improve my process quite a bit already so ... | Comparing two directories based on inodes |
1,686,470,364,000 |
What is the difference between FS_IOC_GETFLAGS and FS_IOC_FSGETXATTR ioctl commands? What flags do both return?
|
In the Linux context, FS_IOC_GETFLAGS and FS_IOC_FSGETXATTR both retrieve inode flags.
GETFLAGS is the older ioctl, and comes originally from ext2 (again, in Linux); it manipulates a 32-bit value and has thus limited expansion capabilities — there aren’t many unused bits available.
FSGETXATTR comes from XFS, and was r... | File system Inode flags: difference between FS_IOC_GETFLAGS and FS_IOC_FSGETXATTR |
1,686,470,364,000 |
While copying music to the sd card of my android phone, the laptop froze so I had to reboot it using sysrq magic. Now any file manager on my Ubuntu or Android shows a directory 0 bytes big, and undeletable. It's type is inode/x-corrupted The ls command ran from root user on Android, doesn't show the directory, however... |
I had a similar issue with my SD card recently. I was not able to fix it under Linux. However, as soon as I plugged the card into a Windows machine, the system came up with a message asking whether I want to repair the card as apparently it was not unmounted correctly. The repair under Windows helped.
| How to delete corrupted directory |
1,532,142,916,000 |
I know that ls lists the names of the files in a given directory and ls -i shows the names and the inode numbers.
But why is it slower?
EDIT: This happens with big directories
The names and the inode numbers are stored in the directory information block together, hence why does it take more time to query the inode num... |
strace shows me that ls -i is calling lstat() on each filename
That would explain the extra work.
Given that readdir() has already returned the inode number this appears to be sub-optimal
while this feels like a bug, this behaviour is for consistency with mount points. (see Thomas' comment)
| Why is ls -i slower than ls? |
1,532,142,916,000 |
I have an ext4 formatted disk with thousands of files that are generated automatically and are needed. A few thousand of them are only one byte long, some two bytes. All files in both groups of tiny files are identical.
How much space can I save by locating these, say 1000, files of 1 byte in length, removing each a... |
There are three parts to storing files: the blocks used to store the file contents, the inode used to store the file’s metadata, and the directory entry (or entries) pointing to the inode.
When you create multiple separate files, in the most general case you pay this cost as many times as there are files.
With inline ... | How much space can I save on ext4 by replacing 1000 identical 1-byte files with 999 hard-links and 1 file? |
1,532,142,916,000 |
How can I get the number of inodes used by files in a given directory tree?
Important: including hidden directories under it, like .git
|
As found on How do I count all the files recursively through directories
find . -printf '%i\n' | sort -u | wc -l
Or if you don't have GNU find and need a portable version:
find . -exec ls -id '{}' \; | awk '{print $1}' | sort -u | wc -l
| Get the number of inode in a tree |
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