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lsattr -v gives me the "version number" of given file(s).
What does this mean?
On Redhat 7.3, I could've sworn all the version numbers were 1 except
those I changed with chattr -v.
On Fedora 11, they appeared to be random numbers.
Setting version numbers or even having multiple versions of a file could be very useful, so I want to understand how "versioning" works in ext3.
lsattr -v invokes the EXT2_IOC_GETVERSION ioctl for the file. This, in turn, retrieves the inode's i_generation field. This is a feature primarily intended for use with NFS: each time an inode gets allocated, one has to make sure it gets a new generation. Otherwise, NFS clients with stale file handles may manage to access data that weren't meant for them. ext2/ext3/ext4 allocates the generation number from a volume-global counter s_next_generation, which is incremented on every allocation.
This is not really an answer, but just a interresting find.
I played around with lsattr -v and it seems like each new file you create gets a unique number assigned to it. Im not sure if this is correct, my expirement is documented below.
$ mkdir temp # make a new folder
$ cd temp
$ touch a b c d e f g # create a lot files in that folder.
$ lsattr -v * # checkout those files using lsattr -v
1386486996 -------------e- a
1386486997 -------------e- b
1386486998 -------------e- c
1386486999 -------------e- d
1386487000 -------------e- e
1386487001 -------------e- f
1386487002 -------------e- g
This behaviour could be limited to the distribution or the disk format.
