RE: Can I allocate few bytes in a file to store info about that file; not visible to user?
Vineet Joglekar <vintya <at> excite.com>
2004-04-28 18:16:19 GMT
I was going through the functions like generic_file_write, generic_file_direct_IO,
generic_direct_IO and filemap_fdatasync. I was thinking about calling these functions or calling
functions written on similar lines to add new few bytes to the file when the inode is created by
"ext2_create()". Can any1 please tell me how to do this?
I guess it would have been simpler to call these functions in the call sys_open() when a new file is created,
but I want to make changes in kernel code only in ext2 module. playing with sys_open will be like modifying
kernel code apart from the ext2 fs module which I dont want.
Thanks and regards,
--- On Mon 04/26, Vineet Joglekar < vintya <at> excite.com > wrote:
From: Vineet Joglekar [mailto: vintya <at> excite.com]
To: linux-fsf <at> vger.kernel.org
Date: Mon, 26 Apr 2004 10:31:19 -0400
Subject: Can I allocate few bytes in a file to store info about that file; not visible to user?
Hi all,<br><br>In ext2fs, while creating a file, can I allocate a number of bytes for that file in advance,
such that those bytes are not seen by the user? that is,<br><br>suppose I am creating a new file temp, then
allocate 50 bytes immediately after creating the file. I want to use those bytes to store the file related
info; accessible only to kernel. Whatever data user wants to add, will be added after the these 50 bytes. If
user does lseek(fd,0,SEEK_SET), then the file pointer should point to the 51st byte. The 1st 50 bytes
shouldnt be visible to user. I dont care if the file size is shown as userdata+50. Is it possible to achieve?
If yes, how?<br><br>Thanks and