is there any prob in accessing new field added to inode mem structure, in some other functions?
From: Vineet Joglekar
Date: Wed Dec 15 2004 - 11:45:28 EST
I am using linux 2.4.21 and I am trying to play with the etx2 file system. My aim is to allocate a data structure dynamically to every file that is opened, at the time of opening.
What I tried to do was: added the structure pointer in the inode data structure "ext2_inode" say "x_ptr". In the function "ext2_read_inode" which reads the hard disk copy of inode into memory, I allocated memory to this pointer and filled the appropriate value. I chose this function as I thought when a file is opened, this function will be always called once. Upto this is working fine.
Now when I try to use this pointer "x_ptr" in some other function, that is, "do_generic_file_read" - which is called while reading a file, I am not getting any value in that pointer, but a null. (which is supposed to be there as I am filling up appropriate value in function ext2_read_inode)
In the do_generic_file_read, VFS inode is availavle, so I am trying to access my pointer as inode->u.ext2_i.x_ptr and I had accessed this pointer in the same way while allocating memory for it in read_inode. At the same time, in do_generic_file_read, I can access other inode parameters, but not this new one added.
Can someone please tell me where am I going wrong, or what could be the alternate solution to achieve this? This is very important for me.
Thanks and regards,
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