Messages in this thread |  | | Date | Fri, 04 May 2001 15:07:36 +0100 | From | Anton Altaparmakov <> | Subject | Re: FS Structs |
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At 22:29 03/05/01, Anders Karlsson wrote: >I am not subscribed to the list, so if I could be CC'd on eventual >replies I would be grateful.
Sure.
>I have a question regarding some of the parts of the overall >filesystem structure in the 2.4 kernel. (Kernel 2.4.[34].) >In the file fs/super.c the structure `sb' is used, that is the >superblock. As a part of that structure (reference include/linux/fs.h) >is `struct list_head s_locked_inodes;'. > >The thing I can not understand at the moment is the `struct list_head' >(reference include/linux/list.h) which looks very odd. How can I find >which inodes are in the `s_locked_inodes' list?? All I want to do is >to loop through the list and see each open inode in turn, is there any >documentation for this, or is there any helpful soul out there that >could give me any pointers?
This is how Linux kernel implements generic, circular, doubly-linked lists. The struct list_head is used both as the beginning of the list - i.e. for example sb->s_dirty is the beginning of the list of dirty inodes - and also as the anchor into the list of each dirty inode - i.e. looking at the struct inode it contains a field struct list_head i_list. This is the anchor into the list.
To walk the list you usually use list_for_each(). In the above example you would use:
struct list_head *tmp; struct inode *ino;
list_for_each(tmp, &sb->s_dirty) { ino = list_entry(tmp, struct inode, i_list); /* do what you want with the inode */ }
If that wasn't clear enough you should consider reading up on this subject. For example "Linux Kernel Internals" contains a chapter on the Linux kernel linked list implementation. The URL for the online version is: http://www.moses.uklinux.net/patches/lki.html
Hope this helps,
Anton
-- Anton Altaparmakov <aia21 at cam.ac.uk> (replace at with @) Linux NTFS Maintainer / WWW: http://sourceforge.net/projects/linux-ntfs/ ICQ: 8561279 / WWW: http://www-stu.christs.cam.ac.uk/~aia21/
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