/*	lfs_inode.c	4.11	82/06/07	*/

/* merged into kernel:	@(#)iget.c 2.2 4/8/82 */

#include "../h/param.h"
#include "../h/systm.h"
#include "../h/mount.h"
#include "../h/dir.h"
#include "../h/user.h"
#include "../h/inode.h"
#include "../h/fs.h"
#include "../h/conf.h"
#include "../h/buf.h"
#include "../h/inline.h"

#define	INOHSZ	63
#define	INOHASH(dev,ino)	(((dev)+(ino))%INOHSZ)
short	inohash[INOHSZ];
short	ifreel;

/*
 * Initialize hash links for inodes
 * and build inode free list.
 */
ihinit()
{
	register int i;
	register struct inode *ip = inode;

	ifreel = 0;
	for (i = 0; i < ninode-1; i++, ip++)
		ip->i_hlink = i+1;
	ip->i_hlink = -1;
	for (i = 0; i < INOHSZ; i++)
		inohash[i] = -1;
}

/*
 * Look up an inode by device,inumber.
 * If it is in core (in the inode structure),
 * honor the locking protocol.
 * If it is not in core, read it in from the
 * specified device.
 * If the inode is mounted on, perform
 * the indicated indirection.
 * In all cases, a pointer to a locked
 * inode structure is returned.
 *
 * panic: no imt -- if the mounted file
 *	system is not in the mount table.
 *	"cannot happen"
 */
struct inode *
iget(dev, fs, ino)
	dev_t dev;
	register struct fs *fs;
	ino_t ino;
{
	register struct inode *ip;
	register struct mount *mp;
	register struct buf *bp;
	register struct dinode *dp;
	register int slot;

loop:
	if (getfs(dev) != fs)
		panic("iget: bad fs");
	slot = INOHASH(dev, ino);
	ip = &inode[inohash[slot]];
	while (ip != &inode[-1]) {
		if (ino == ip->i_number && dev == ip->i_dev) {
			if ((ip->i_flag&ILOCK) != 0) {
				ip->i_flag |= IWANT;
				sleep((caddr_t)ip, PINOD);
				goto loop;
			}
			if ((ip->i_flag&IMOUNT) != 0) {
				for (mp = &mount[0]; mp < &mount[NMOUNT]; mp++)
				if (mp->m_inodp == ip) {
					dev = mp->m_dev;
					fs = mp->m_bufp->b_un.b_fs;
					ino = ROOTINO;
					goto loop;
				}
				panic("no imt");
			}
			ip->i_count++;
			ip->i_flag |= ILOCK;
			return(ip);
		}
		ip = &inode[ip->i_hlink];
	}
	if (ifreel < 0) {
		tablefull("inode");
		u.u_error = ENFILE;
		return(NULL);
	}
	ip = &inode[ifreel];
	ifreel = ip->i_hlink;
	ip->i_hlink = inohash[slot];
	inohash[slot] = ip - inode;
	ip->i_dev = dev;
	ip->i_fs = fs;
	ip->i_number = ino;
	ip->i_flag = ILOCK;
	ip->i_count++;
	ip->i_lastr = 0;
	bp = bread(dev, fsbtodb(fs, itod(fs, ino)), fs->fs_bsize);
	/*
	 * Check I/O errors
	 */
	if ((bp->b_flags&B_ERROR) != 0) {
		brelse(bp);
		iput(ip);
		return(NULL);
	}
	dp = bp->b_un.b_dino;
	dp += itoo(fs, ino);
	ip->i_ic = dp->di_ic;
	brelse(bp);
	return (ip);
}

/*
 * Decrement reference count of
 * an inode structure.
 * On the last reference,
 * write the inode out and if necessary,
 * truncate and deallocate the file.
 */
iput(ip)
	register struct inode *ip;
{

	if ((ip->i_flag & ILOCK) == 0)
		panic("iput");
	iunlock(ip);
	irele(ip);
}

irele(ip)
	register struct inode *ip;
{
	register int i, x;
	register struct inode *jp;
	int mode;

	if (ip->i_flag & ILOCK)
		panic("irele");
	if (ip->i_count == 1) {
		ip->i_flag |= ILOCK;
		if (ip->i_nlink <= 0) {
			itrunc(ip);
			mode = ip->i_mode;
			ip->i_mode = 0;
			ip->i_flag |= IUPD|ICHG;
			ifree(ip, ip->i_number, mode);
		}
		IUPDAT(ip, &time, &time, 0);
		iunlock(ip);
		i = INOHASH(ip->i_dev, ip->i_number);
		x = ip - inode;
		if (inohash[i] == x) {
			inohash[i] = ip->i_hlink;
		} else {
			for (jp = &inode[inohash[i]]; jp != &inode[-1];
			    jp = &inode[jp->i_hlink])
				if (jp->i_hlink == x) {
					jp->i_hlink = ip->i_hlink;
					goto done;
				}
			panic("iput");
		}
done:
		ip->i_hlink = ifreel;
		ifreel = x;
		ip->i_flag = 0;
		ip->i_number = 0;
	}
	ip->i_count--;
}

/*
 * Check accessed and update flags on
 * an inode structure.
 * If any is on, update the inode
 * with the current time.
 * If waitfor is given, then must insure
 * i/o order so wait for write to complete.
 */
iupdat(ip, ta, tm, waitfor)
	register struct inode *ip;
	time_t *ta, *tm;
	int waitfor;
{
	register struct buf *bp;
	struct dinode *dp;
	register struct fs *fp;

	fp = ip->i_fs;
	if ((ip->i_flag & (IUPD|IACC|ICHG)) != 0) {
		if (fp->fs_ronly)
			return;
		bp = bread(ip->i_dev, fsbtodb(fp, itod(fp, ip->i_number)),
			fp->fs_bsize);
		if (bp->b_flags & B_ERROR) {
			brelse(bp);
			return;
		}
		if (ip->i_flag&IACC)
			ip->i_atime = *ta;
		if (ip->i_flag&IUPD)
			ip->i_mtime = *tm;
		if (ip->i_flag&ICHG)
			ip->i_ctime = time;
		ip->i_flag &= ~(IUPD|IACC|ICHG);
		dp = bp->b_un.b_dino + itoo(fp, ip->i_number);
		dp->di_ic = ip->i_ic;
		if (waitfor)
			bwrite(bp);
		else
			bdwrite(bp);
	}
}

/*
 * Free all the disk blocks associated
 * with the specified inode structure.
 * The blocks of the file are removed
 * in reverse order. This FILO
 * algorithm will tend to maintain
 * a contiguous free list much longer
 * than FIFO.
 */
itrunc(ip)
	register struct inode *ip;
{
	register i;
	dev_t dev;
	daddr_t bn;
	struct inode itmp;
	register struct fs *fs;

	i = ip->i_mode & IFMT;
	if (i != IFREG && i != IFDIR && i != IFLNK)
		return;
	/*
	 * Clean inode on disk before freeing blocks
	 * to insure no duplicates if system crashes.
	 */
	itmp = *ip;
	itmp.i_size = 0;
	for (i = 0; i < NDADDR; i++)
		itmp.i_db[i] = 0;
	for (i = 0; i < NIADDR; i++)
		itmp.i_ib[i] = 0;
	itmp.i_flag |= ICHG|IUPD;
	iupdat(&itmp, &time, &time, 1);
	ip->i_flag &= ~(IUPD|IACC|ICHG);

	/*
	 * Now return blocks to free list... if machine
	 * crashes, they will be harmless MISSING blocks.
	 */
	dev = ip->i_dev;
	fs = ip->i_fs;
	/*
	 * release double indirect block first
	 */
	bn = ip->i_ib[NIADDR-1];
	if (bn != (daddr_t)0) {
		ip->i_ib[NIADDR - 1] = (daddr_t)0;
		tloop(ip, bn, 1);
	}
	/*
	 * release single indirect blocks second
	 */
	for (i = NIADDR - 2; i >= 0; i--) {
		bn = ip->i_ib[i];
		if (bn != (daddr_t)0) {
			ip->i_ib[i] = (daddr_t)0;
			tloop(ip, bn, 0);
		}
	}
	/*
	 * finally release direct blocks
	 */
	for (i = NDADDR - 1; i>=0; i--) {
		bn = ip->i_db[i];
		if (bn == (daddr_t)0)
			continue;
		ip->i_db[i] = (daddr_t)0;
		fre(ip, bn, (off_t)blksize(fs, ip, i));
	}
	ip->i_size = 0;
	/*
	 * Inode was written and flags updated above.
	 * No need to modify flags here.
	 */
}

tloop(ip, bn, indflg)
	register struct inode *ip;
	daddr_t bn;
	int indflg;
{
	register i;
	register struct buf *bp;
	register daddr_t *bap;
	register struct fs *fs;
	daddr_t nb;

	bp = NULL;
	fs = ip->i_fs;
	for (i = NINDIR(fs) - 1; i >= 0; i--) {
		if (bp == NULL) {
			bp = bread(ip->i_dev, fsbtodb(fs, bn), fs->fs_bsize);
			if (bp->b_flags & B_ERROR) {
				brelse(bp);
				return;
			}
			bap = bp->b_un.b_daddr;
		}
		nb = bap[i];
		if (nb == (daddr_t)0)
			continue;
		if (indflg)
			tloop(ip, nb, 0);
		else
			fre(ip, nb, fs->fs_bsize);
	}
	if (bp != NULL)
		brelse(bp);
	fre(ip, bn, fs->fs_bsize);
}

/*
 * Make a new file.
 */
struct inode *
maknode(mode)
	int mode;
{
	register struct inode *ip;
	ino_t ipref;

	if ((mode & IFMT) == IFDIR)
		ipref = dirpref(u.u_pdir->i_fs);
	else
		ipref = u.u_pdir->i_number;
	ip = ialloc(u.u_pdir, ipref, mode);
	if (ip == NULL) {
		iput(u.u_pdir);
		return(NULL);
	}
	ip->i_flag |= IACC|IUPD|ICHG;
	if ((mode & IFMT) == 0)
		mode |= IFREG;
	ip->i_mode = mode & ~u.u_cmask;
	ip->i_nlink = 1;
	ip->i_uid = u.u_uid;
	ip->i_gid = u.u_pdir->i_gid;

	/*
	 * Make sure inode goes to disk before directory entry.
	 */
	iupdat(ip, &time, &time, 1);
	wdir(ip);
	if (u.u_error) {
		/*
		 * write error occurred trying to update directory
		 * so must deallocate the inode
		 */
		ip->i_nlink = 0;
		ip->i_flag |= ICHG;
		iput(ip);
		return(NULL);
	}
	return(ip);
}

/*
 * Write a directory entry with
 * parameters left as side effects
 * to a call to namei.
 */
wdir(ip)
	struct inode *ip;
{
	register struct direct *dp, *ndp;
	struct fs *fs;
	struct buf *bp;
	int lbn, bn, base;
	int loc, dsize, spccnt, newsize;
	char *dirbuf;

	u.u_dent.d_ino = ip->i_number;
	u.u_segflg = 1;
	newsize = DIRSIZ(&u.u_dent);
	/*
	 * if u.u_count == 0, a new directory block must be allocated.
	 */
	if (u.u_count == 0) {
		u.u_dent.d_reclen = DIRBLKSIZ;
		u.u_count = newsize;
		u.u_base = (caddr_t)&u.u_dent;
		writei(u.u_pdir);
		iput(u.u_pdir);
		return;
	}
	/*
	 * must read in an existing directory block
	 * to prepare to place the new entry into it.
	 */
	fs = u.u_pdir->i_fs;
	lbn = lblkno(fs, u.u_offset);
	base = blkoff(fs, u.u_offset);
	bn = fsbtodb(fs, bmap(u.u_pdir, lbn, B_WRITE, base + u.u_count));
	if (u.u_offset + u.u_count > u.u_pdir->i_size)
		u.u_pdir->i_size = u.u_offset + u.u_count;
	bp = bread(u.u_pdir->i_dev, bn, blksize(fs, u.u_pdir, lbn));
	if (bp->b_flags & B_ERROR) {
		brelse(bp);
		return;
	}
	dirbuf = bp->b_un.b_addr + base;
	dp = (struct direct *)dirbuf;
	dsize = DIRSIZ(dp);
	spccnt = dp->d_reclen - dsize;
	/*
	 * if there is insufficient room to make an entry at this point
	 * namei insures that compacting from u.u_offset for u.u_count
	 * bytes will provide the necessary space.
	 */
	for (loc = dp->d_reclen; loc < u.u_count; ) {
		ndp = (struct direct *)(dirbuf + loc);
		if (dp->d_ino == 0) {
			spccnt += dsize;
		} else {
			dp->d_reclen = dsize;
			dp = (struct direct *)((char *)dp + dsize);
		}
		dsize = DIRSIZ(ndp);
		spccnt += ndp->d_reclen - dsize;
		loc += ndp->d_reclen;
		bcopy(ndp, dp, dsize);
	}
	/*
	 * Update the pointer fields in the previous entry (if any),
	 * copy in the new entry, and write out the block.
	 */
	if (dp->d_ino == 0) {
		if (spccnt + dsize < newsize)
			panic("wdir: compact failed");
		u.u_dent.d_reclen = spccnt + dsize;
	} else {
		if (spccnt < newsize)
			panic("wdir: compact failed");
		u.u_dent.d_reclen = spccnt;
		dp->d_reclen = dsize;
		dp = (struct direct *)((char *)dp + dsize);
	}
	bcopy(&u.u_dent, dp, newsize);
	bwrite(bp);
	u.u_pdir->i_flag |= IUPD|ICHG;
	iput(u.u_pdir);
}

#ifdef ilock
#undef ilock
#endif
#ifdef iunlock
#undef iunlock
#endif
/*
 * Lock an inode. If its already locked, set the WANT bit and sleep.
 */
ilock(ip)
	register struct inode *ip;
{

	while (ip->i_flag&ILOCK) {
		ip->i_flag |= IWANT;
		sleep((caddr_t)ip, PINOD);
	}
	ip->i_flag |= ILOCK;
}

/*
 * Unlock an inode.  If WANT bit is on, wakeup.
 */
iunlock(ip)
	register struct inode *ip;
{

	ip->i_flag &= ~ILOCK;
	if (ip->i_flag&IWANT) {
		ip->i_flag &= ~IWANT;
		wakeup((caddr_t)ip);
	}
}