Re: VFS not completely factored

[James Manning]

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[ Monday, February 14, 2000 ] [e-mail] wrote:
> On a related issue, if there was a char generic_data[] member in the inode
> union that had a defined size (probably the size of the largest structure),
> people (like me) writing filesystems that aren't ready to be put into the
> sources yet could put data right in the union and know that it will fit
> without having to resort to using generic_ip and allocating an info block
> to store inode specific info.  (Narly sentence huh?)

That would seem to place a restriction on the size of your inode data,
something generic_ip frees you from (at not a high cost imho). I'd
go ahead and advocate everyone having to go through the indirection
and rip out the entire union for a void *inode_info first (helping a
good bit towards freeing vfs from specific fs's).  Then do the same
for the super_block struct and you seem to be well on your way to the
factored vfs, as you'll be rid of fs-specific includes in linux/fs.h
(attached).  Whether the indirection and sacrificed cache line is worth
it is the call of another.

 fs.h |   99 +------------------------------------------------------------------ 1 files changed, 2 insertions, 97 deletions

James

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--- linux-2.3.45/include/linux/fs.h.orig	Tue Feb 15 08:34:09 2000
+++ linux-2.3.45/include/linux/fs.h	Tue Feb 15 08:36:02 2000
@@ -251,32 +251,6 @@
 
 #define touch_buffer(bh)	set_bit(PG_referenced, &bh->b_page->flags)
 
-
-#include <linux/pipe_fs_i.h>
-#include <linux/minix_fs_i.h>
-#include <linux/ext2_fs_i.h>
-#include <linux/hpfs_fs_i.h>
-#include <linux/ntfs_fs_i.h>
-#include <linux/msdos_fs_i.h>
-#include <linux/umsdos_fs_i.h>
-#include <linux/iso_fs_i.h>
-#include <linux/nfs_fs_i.h>
-#include <linux/sysv_fs_i.h>
-#include <linux/affs_fs_i.h>
-#include <linux/ufs_fs_i.h>
-#include <linux/efs_fs_i.h>
-#include <linux/coda_fs_i.h>
-#include <linux/romfs_fs_i.h>
-#include <linux/smb_fs_i.h>
-#include <linux/hfs_fs_i.h>
-#include <linux/adfs_fs_i.h>
-#include <linux/qnx4_fs_i.h>
-#include <linux/bfs_fs_i.h>
-#include <linux/udf_fs_i.h>
-#include <linux/ncp_fs_i.h>
-#include <linux/proc_fs_i.h>
-#include <linux/usbdev_fs_i.h>
-
 /*
  * Attribute flags.  These should be or-ed together to figure out what
  * has been changed!
@@ -402,33 +376,7 @@
 	atomic_t		i_writecount;
 	unsigned int		i_attr_flags;
 	__u32			i_generation;
-	union {
-		struct minix_inode_info		minix_i;
-		struct ext2_inode_info		ext2_i;
-		struct hpfs_inode_info		hpfs_i;
-		struct ntfs_inode_info		ntfs_i;
-		struct msdos_inode_info		msdos_i;
-		struct umsdos_inode_info	umsdos_i;
-		struct iso_inode_info		isofs_i;
-		struct nfs_inode_info		nfs_i;
-		struct sysv_inode_info		sysv_i;
-		struct affs_inode_info		affs_i;
-		struct ufs_inode_info		ufs_i;
-		struct efs_inode_info		efs_i;
-		struct romfs_inode_info		romfs_i;
-		struct coda_inode_info		coda_i;
-		struct smb_inode_info		smbfs_i;
-		struct hfs_inode_info		hfs_i;
-		struct adfs_inode_info		adfs_i;
-		struct qnx4_inode_info		qnx4_i;
-		struct bfs_inode_info		bfs_i;
-		struct udf_inode_info		udf_i;
-		struct ncp_inode_info		ncpfs_i;
-		struct proc_inode_info		proc_i;
-		struct socket			socket_i;
-		struct usbdev_inode_info        usbdev_i;
-		void				*generic_ip;
-	} u;
+	void			*inode_info;
 };
 
 /* Inode state bits.. */
@@ -539,27 +487,6 @@
 
 extern int fasync_helper(int, struct file *, int, struct fasync_struct **);
 
-#include <linux/minix_fs_sb.h>
-#include <linux/ext2_fs_sb.h>
-#include <linux/hpfs_fs_sb.h>
-#include <linux/ntfs_fs_sb.h>
-#include <linux/msdos_fs_sb.h>
-#include <linux/iso_fs_sb.h>
-#include <linux/nfs_fs_sb.h>
-#include <linux/sysv_fs_sb.h>
-#include <linux/affs_fs_sb.h>
-#include <linux/ufs_fs_sb.h>
-#include <linux/efs_fs_sb.h>
-#include <linux/romfs_fs_sb.h>
-#include <linux/smb_fs_sb.h>
-#include <linux/hfs_fs_sb.h>
-#include <linux/adfs_fs_sb.h>
-#include <linux/qnx4_fs_sb.h>
-#include <linux/bfs_fs_sb.h>
-#include <linux/udf_fs_sb.h>
-#include <linux/ncp_fs_sb.h>
-#include <linux/usbdev_fs_sb.h>
-
 extern struct list_head super_blocks;
 
 #define sb_entry(list)	list_entry((list), struct super_block, s_list)
@@ -586,29 +513,7 @@
 
 	struct block_device	*s_bdev;
 
-	union {
-		struct minix_sb_info	minix_sb;
-		struct ext2_sb_info	ext2_sb;
-		struct hpfs_sb_info	hpfs_sb;
-		struct ntfs_sb_info	ntfs_sb;
-		struct msdos_sb_info	msdos_sb;
-		struct isofs_sb_info	isofs_sb;
-		struct nfs_sb_info	nfs_sb;
-		struct sysv_sb_info	sysv_sb;
-		struct affs_sb_info	affs_sb;
-		struct ufs_sb_info	ufs_sb;
-		struct efs_sb_info	efs_sb;
-		struct romfs_sb_info	romfs_sb;
-		struct smb_sb_info	smbfs_sb;
-		struct hfs_sb_info	hfs_sb;
-		struct adfs_sb_info	adfs_sb;
-		struct qnx4_sb_info	qnx4_sb;
-		struct bfs_sb_info	bfs_sb;
-		struct udf_sb_info	udf_sb;
-		struct ncp_sb_info	ncpfs_sb;
-		struct usbdev_sb_info   usbdevfs_sb;
-		void			*generic_sbp;
-	} u;
+	void			*sb_info;
 	/*
 	 * The next field is for VFS *only*. No filesystems have any business
 	 * even looking at it. You had been warned.

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