Re: Write file in EXT2

Sumit Narayan (sumit_uconn@lycos.com)
Tue, 06 May 2003 10:45:22 -0400


Thanks for the details,

But I would like to know when each FS is being accessed, and by which application. Isnt there a single path, say something in the driver code, from where all write/read commands pass? So that we can have a function call from that place, and create a log?

And also, how do I create a logfile on my own. With my own function within the kernel. I dont wish to go to Userland and do the write process.

Thanks in advance.

Sumit

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On Tue, 6 May 2003 10:17:08 Matti Aarnio wrote: >On Mon, May 05, 2003 at 11:14:46PM -0400, Sumit Narayan wrote: >> Hi, >> >> I would like to create a log file containing the reads and writes made >> on a disk, by adding a function in the kernel. And once this log table >> reaches a limit, say 10,000 records, I would like it to be written on >> hard disk automatically. I am unable to do this, since I dont know how >> to write to a file, while in the kernel. I tried System Calls, but they >> dont seem to work. Could someone tell me what is the list of functions >> that I need to use to do this job. I think I have to play with >> super-blocks and inodes. But I dont know how to do that. :) Please help >> me. > > > Considering how to do that log writing: > > Kernel contains several codes that are writing data to disk for > various "logging" tasks. Most promimnent example of them is: > > kernel/acct.c > > It keeps kernel internal file descriptor ("filp") for its > internal use. It has code that opens a file for writing > to it, actual writer (one smallish block at the time, but > that is merely size parameter issue), and it also closes > the file when wanted (e.g. under administrator control). > > All that completely independent of target filesystem. > > Oh, and of course it has management interface, so that > sysadmin can tell to it: > - when to activate / deactivate > - into which file to log > > > In your application there is a danger of snaring > yourself: disk activity must not stop at logging > something, when the log buffer is full and flushing > it is under way. Otherwise you are in danger of > halting the log-flush, and then you have a dead > machine. > >> Thanks. >> Sumit >> >> p.s. I am using Kernel 2.4.20 and want this in EXT2 FS > >/Matti Aarnio >- >To unsubscribe from this list: send the line "unsubscribe linux-kernel" in >the body of a message to majordomo@vger.kernel.org >More majordomo info at http://vger.kernel.org/majordomo-info.html >Please read the FAQ at http://www.tux.org/lkml/ >

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