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278786 - Set the PRECALC flag in the priority field
of our sleeping semaphore and mrlock calls.  This should
keep us from getting into situations where the inode
lock is handed from one process to another at very
high priority over and over again.  We've never seen it
with XFS, but it was a real problem with EFS.

#ident "$Revision: 1.55 $"

#ifdef SIM
#define _KERNEL 1
#endif
#include <sys/param.h>
#include <sys/mode.h>
#include <sys/stat.h>
#include <sys/buf.h>
#include <sys/sysmacros.h>
#include <sys/vnode.h>
#include <sys/grio.h>
#include <sys/sysinfo.h>
#include <sys/ksa.h>
#ifdef SIM
#undef _KERNEL
#endif
#include <sys/debug.h>
#include <sys/uuid.h>
#include <sys/kmem.h>
#ifndef SIM
#include <sys/systm.h>
#endif
#include "xfs_types.h"
#include "xfs_inum.h"
#include "xfs_log.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_mount.h"
#include "xfs_alloc_btree.h"
#include "xfs_bmap_btree.h"
#include "xfs_ialloc_btree.h"
#include "xfs_btree.h"
#include "xfs_ialloc.h"
#include "xfs_attr_sf.h"
#include "xfs_dir_sf.h"
#include "xfs_dinode.h"
#include "xfs_inode_item.h"
#include "xfs_inode.h"

#ifdef SIM
#include "sim.h"
#endif /* SIM */

extern struct vnodeops xfs_vnodeops;

/*
 * Inode hashing and hash bucket locking.
 */
#define XFS_IHASH(mp,ino)	((mp)->m_ihash + \
				 (ino & (__uint64_t)((mp)->m_ihashmask)))
#define	XFS_IHLOCK(ih)		mp_mutex_lock(&(ih)->ih_lock, PINOD)
#define	XFS_IHUNLOCK(ih)	mp_mutex_unlock(&(ih)->ih_lock)


/*
 * Initialize the inode hash table for the newly mounted file system.
 *
 * mp -- this is the mount point structure for the file system being
 *       initialized
 */
void
xfs_ihash_init(xfs_mount_t *mp)
{
	int	i;
	ulong	hsize;	
	char	name[8];
	extern int	ncsize;

	/*
	 * For now just use a fixed size hash table per file system.
	 * This MUST be changed eventually so we don't waste so much
	 * memory.
	 */
	if (ncsize < 5000) {
		hsize = 512;
	} else {
		hsize = 1024;
	}
	mp->m_ihashmask = hsize - 1;
	mp->m_ihash = (xfs_ihash_t *)kmem_zalloc(hsize * sizeof(xfs_ihash_t),
						 KM_SLEEP);
	ASSERT(mp->m_ihash != NULL);
	for (i = 0; i < hsize; i++) {
		mutex_init(&(mp->m_ihash[i].ih_lock), MUTEX_DEFAULT,
			  makesname(name, "xih", i));
	}
}

/*
 * Free up structures allocated by xfs_ihash_init, at unmount time.
 */
void
xfs_ihash_free(xfs_mount_t *mp)
{
	int	hsize, i;

	hsize = mp->m_ihashmask + 1;
	for (i = 0; i < hsize; i++)
		mutex_destroy(&mp->m_ihash[i].ih_lock);
	kmem_free(mp->m_ihash, hsize * sizeof(xfs_ihash_t));
}

/*
 * Look up an inode by number in the given file system.
 * The inode is looked up in the hash table for the file system
 * represented by the mount point parameter mp.  Each bucket of
 * the hash table is guarded by an individual semaphore.
 *
 * If the inode is found in the hash table, its corresponding vnode
 * is obtained with a call to vn_get().  This call takes care of
 * coordination with the reclamation of the inode and vnode.  Note
 * that the vmap structure is filled in while holding the hash lock.
 * This gives us the state of the inode/vnode when we found it and
 * is used for coordination in vn_get().
 *
 * If it is not in core, read it in from the file system's device and
 * add the inode into the hash table.
 *
 * The inode is locked according to the value of the lock_flags parameter.
 * This flag parameter indicates how and if the inode's IO lock and inode lock
 * should be taken.
 *
 * mp -- the mount point structure for the current file system.  It points
 *       to the inode hash table.
 * tp -- a pointer to the current transaction if there is one.  This is
 *       simply passed through to the xfs_iread() call.
 * ino -- the number of the inode desired.  This is the unique identifier
 *       within the file system for the inode being requested.
 * lock_flags -- flags indicating how to lock the inode.  See the comment
 *	 for xfs_ilock() for a list of valid values.
 */
int
xfs_iget(xfs_mount_t	*mp,
	 xfs_trans_t	*tp,
	 xfs_ino_t	ino,
	 uint		lock_flags,
	xfs_inode_t	**ipp)
{
	xfs_ihash_t	*ih;
	xfs_inode_t	*ip;
	xfs_inode_t	*iq;
	vnode_t		*vp;
	ulong		version;
	int		error;
	int		newnode;
	vmap_t		vmap;
	char		name[8];

	SYSINFO.iget++;
	XFSSTATS.xs_ig_attempts++;

	ih = XFS_IHASH(mp, ino);
again:
	XFS_IHLOCK(ih);
	for (ip = ih->ih_next; ip != NULL; ip = ip->i_next) {
		if (ip->i_ino == ino) {
			XFSSTATS.xs_ig_found++;
			vp = XFS_ITOV(ip);
			VMAP(vp, vmap);
			XFS_IHUNLOCK(ih);
			/*
			 * Get a reference to the vnode/inode.
			 * vn_get() takes care of coordination with
			 * the file system inode release and reclaim
			 * functions.  If it returns NULL, the inode
			 * has been reclaimed so just start the search
			 * over again.  We probably won't find it,
			 * but we could be racing with another cpu
			 * looking for the same inode so we have to at
			 * least look.
			 */
			if (!(vp = vn_get(vp, &vmap))) {
				XFSSTATS.xs_ig_frecycle++;
				goto again;
			}

			/*
			 * Inode cache hit: if ip is not at the front of
			 * its hash chain, move it there now.
			 */
			XFS_IHLOCK(ih);
			if (ip->i_prevp != &ih->ih_next) {
				if (iq = ip->i_next) {
					iq->i_prevp = ip->i_prevp;
				}
				*ip->i_prevp = iq;
				iq = ih->ih_next;
				iq->i_prevp = &ip->i_next;
				ip->i_next = iq;
				ip->i_prevp = &ih->ih_next;
				ih->ih_next = ip;
			}
			XFS_IHUNLOCK(ih);
			if (lock_flags != 0) {
				xfs_ilock(ip, lock_flags);
			}

			newnode = (ip->i_d.di_mode == 0);
			goto return_ip;
		}
	}

	/*
	 * Inode cache miss: save the hash chain version stamp and unlock
	 * the chain, so we don't deadlock in vn_alloc.
	 */
	XFSSTATS.xs_ig_missed++;
	version = ih->ih_version;
	XFS_IHUNLOCK(ih);

	/*
	 * Read the disk inode attributes into a new inode structure and get
	 * a new vnode for it.  Initialize the inode lock so we can idestroy
	 * it soon if it's a dup.  This should also initialize i_dev, i_ino,
	 * i_bno, i_mount, and i_index.
	 */
	error = xfs_iread(mp, tp, ino, &ip);
	if (error) {
		return error;
	}
	vp = vn_alloc(&xfs_vnodeops, mp->m_vfsp, IFTOVT(ip->i_d.di_mode),
		      ip->i_df.if_u2.if_rdev, ip);

	mrinit(&ip->i_lock, makesname(name, "xino", (int)vp->v_number));
	mrinit(&ip->i_iolock, makesname(name, "xio", (int)vp->v_number));
#ifdef NOTYET
	mutex_init(&ip->i_range_lock.r_spinlock, MUTEX_SPIN, "xrange");
#endif /* NOTYET */
	initnsema(&ip->i_flock, 1, makesname(name, "fino", vp->v_number));
	sv_init(&ip->i_pinsema, SV_DEFAULT,
		makesname(name, "pino", vp->v_number));
	xfs_inode_item_init(ip, mp);
	if (lock_flags != 0) {
		xfs_ilock(ip, lock_flags);
	}

	/*
	 * Put ip on its hash chain, unless someone else hashed a duplicate
	 * after we released the hash lock.
	 */
	XFS_IHLOCK(ih);
	if (ih->ih_version != version) {
		for (iq = ih->ih_next; iq != NULL; iq = iq->i_next) {
			if (iq->i_ino == ino) {
				XFS_IHUNLOCK(ih);
				vn_free(vp);
				xfs_idestroy(ip);
				XFSSTATS.xs_ig_dup++;
				goto again;
			}
		}
	}

	/*
	 * These values _must_ be set before releasing ihlock!
	 */
	ip->i_vnode = vp;
	ip->i_hash = ih;
	if (iq = ih->ih_next) {
		iq->i_prevp = &ip->i_next;
	}
	ip->i_next = iq;
	ip->i_prevp = &ih->ih_next;
	ih->ih_next = ip;
	ih->ih_version++;
	ip->i_dmevents = ip->i_d.di_dmevmask;	/* FIX: OR in vfs mask */
	XFS_IHUNLOCK(ih);

	/*
	 * Link ip to its mount and thread it on the mount's inode list.
	 */
	XFS_MOUNT_ILOCK(mp);
	if (iq = mp->m_inodes) {
		ASSERT(iq->i_mprev->i_mnext == iq);
		ip->i_mprev = iq->i_mprev;
		iq->i_mprev->i_mnext = ip;
		iq->i_mprev = ip;
		ip->i_mnext = iq;
	} else {
		ip->i_mnext = ip;
		ip->i_mprev = ip;
	}
	mp->m_inodes = ip;
	XFS_MOUNT_IUNLOCK(mp);

	newnode = 1;

 return_ip:
	/*
	 * Call hook for imon to see whether ip is of interest and should
	 * have its vnodeops monitored.
	 */
#ifndef SIM
	if (newnode) {
		IMON_CHECK(vp, ip->i_dev, (ino_t)ino);
	}
#endif
	*ipp = ip;
	return 0;
}

/*
 * Look for the inode corresponding to the given ino in the hash table.
 * If it is there and its i_transp pointer matches tp, return it.
 * Otherwise, return NULL.
 */
xfs_inode_t *
xfs_inode_incore(xfs_mount_t	*mp,
		 xfs_ino_t	ino,
		 xfs_trans_t	*tp)
{
	xfs_ihash_t	*ih;
	xfs_inode_t	*ip;
	xfs_inode_t	*iq;

	ih = XFS_IHASH(mp, ino);
	XFS_IHLOCK(ih);
	for (ip = ih->ih_next; ip != NULL; ip = ip->i_next) {
		if (ip->i_ino == ino) {
			/*
			 * If we find it and tp matches, return it.
			 * Also move it to the front of the hash list
			 * if we find it and it is not already there.
			 * Otherwise break from the loop and return
			 * NULL.
			 */
			if (ip->i_transp == tp) {
				if (ip->i_prevp != &ih->ih_next) {
					if (iq = ip->i_next) {
						iq->i_prevp = ip->i_prevp;
					}
					*ip->i_prevp = iq;
					iq = ih->ih_next;
					iq->i_prevp = &ip->i_next;
					ip->i_next = iq;
					ip->i_prevp = &ih->ih_next;
					ih->ih_next = ip;
				}
				XFS_IHUNLOCK(ih);
				return (ip);
			}
			break;
		}
	}	
	XFS_IHUNLOCK(ih);
	return (NULL);
}

/*
 * Decrement reference count of an inode structure and unlock it.
 *
 * ip -- the inode being released
 * lock_flags -- this parameter indicates the inode's locks to be
 *       to be released.  See the comment on xfs_iunlock() for a list
 *	 of valid values.
 */
void
xfs_iput(xfs_inode_t	*ip,
	 uint		lock_flags)
{
	xfs_iunlock(ip, lock_flags);
	VN_RELE(XFS_ITOV(ip));
}

/*
 * This routine embodies the part of the reclaim code that pulls
 * the inode from the inode hash table and the mount structure's
 * inode list.
 * This should only be called from xfs_reclaim().
 */
void
xfs_ireclaim(xfs_inode_t *ip)
{
	xfs_ihash_t	*ih;
	xfs_inode_t	*iq;
	xfs_mount_t	*mp;

	/*
	 * Remove from old hash list.
	 */
	XFSSTATS.xs_ig_reclaims++;
	ih = ip->i_hash;
	XFS_IHLOCK(ih);
	if (iq = ip->i_next) {
		iq->i_prevp = ip->i_prevp;
	}
	*ip->i_prevp = iq;
	XFS_IHUNLOCK(ih);

	/*
	 * Remove from mount's inode list.
	 */
	mp = ip->i_mount;
	XFS_MOUNT_ILOCK(mp);
	ASSERT((ip->i_mnext != NULL) && (ip->i_mprev != NULL));
	iq = ip->i_mnext;
	iq->i_mprev = ip->i_mprev;
	ip->i_mprev->i_mnext = iq;

	/*
	 * Fix up the head pointer if it points to the inode being deleted.
	 */
	if (mp->m_inodes == ip) {
		if (ip == iq) {
			mp->m_inodes = NULL;
		} else {
			mp->m_inodes = iq;
		}
	}
	mp->m_ireclaims++;
	XFS_MOUNT_IUNLOCK(mp);

	/*
	 * Here we do a spurious inode lock in order to coordinate with
	 * xfs_sync().  This is because xfs_sync() references the inodes
	 * in the mount list without taking references on the corresponding
	 * vnodes.  We make that OK here by ensuring that we wait until
	 * the inode is unlocked in xfs_sync() before we go ahead and
	 * free it.  We get both the regular lock and the io lock because
	 * the xfs_sync() code may need to drop the regular one but will
	 * still hold the io lock.
	 */
	xfs_ilock(ip, XFS_ILOCK_EXCL | XFS_IOLOCK_EXCL);

	/*
	 * Free all memory associated with the inode.
	 */
	xfs_idestroy(ip);
}


/*
 * This is a wrapper routine around the xfs_ilock() routine
 * used to centralize some grungy code.  It is used in places
 * that wish to lock the inode solely for reading the extents.
 * The reason these places can't just call xfs_ilock(SHARED)
 * is that the inode lock also guards to bringing in of the
 * extents from disk for a file in b-tree format.  If the inode
 * is in b-tree format, then we need to lock the inode exclusively
 * until the extents are read in.  Locking it exclusively all
 * the time would limit our parallelism unnecessarily, though.
 * What we do instead is check to see if the extents have been
 * read in yet, and only lock the inode exclusively if they
 * have not.
 *
 * The function returns a value which should be given to the
 * corresponding xfs_iunlock_map_shared().  This value is
 * the mode in which the lock was actually taken.
 */
uint
xfs_ilock_map_shared(
	xfs_inode_t	*ip)
{
	uint	lock_mode;

	if ((ip->i_d.di_format == XFS_DINODE_FMT_BTREE) &&
	    ((ip->i_df.if_flags & XFS_IFEXTENTS) == 0)) {
		lock_mode = XFS_ILOCK_EXCL;
	} else {
		lock_mode = XFS_ILOCK_SHARED;
	}

	xfs_ilock(ip, lock_mode);

	return lock_mode;
}

/*
 * This is simply the unlock routine to go with xfs_ilock_map_shared().
 * All it does is call xfs_iunlock() with the given lock_mode.
 */
void
xfs_iunlock_map_shared(
	xfs_inode_t	*ip,
	unsigned int	lock_mode)
{
	xfs_iunlock(ip, lock_mode);
}


/*
 * The xfs inode contains 2 locks: a multi-reader lock called the
 * i_iolock and a multi-reader lock called the i_lock.  This routine
 * allows either or both of the locks to be obtained.
 *
 * The 2 locks should always be ordered so that the IO lock is
 * obtained first in order to prevent deadlock.
 *
 * ip -- the inode being locked
 * lock_flags -- this parameter indicates the inode's locks to be
 *       to be locked.  It can be:
 *		XFS_IOLOCK_SHARED,
 *		XFS_IOLOCK_EXCL,
 *	 	XFS_ILOCK_SHARED,
 *		XFS_ILOCK_EXCL,
 *		XFS_IOLOCK_SHARED | XFS_ILOCK_SHARED,
 *		XFS_IOLOCK_SHARED | XFS_ILOCK_EXCL,
 *		XFS_IOLOCK_EXCL | XFS_ILOCK_SHARED,
 *		XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL
 *
 */
void
xfs_ilock(xfs_inode_t	*ip,
	  uint		lock_flags)
{
	/*
	 * You can't set both SHARED and EXCL for the same lock,
	 * and only XFS_IOLOCK_SHARED, XFS_IOLOCK_EXCL, XFS_ILOCK_SHARED,
	 * and XFS_ILOCK_EXCL are valid values to set in lock_flags.
	 */
	ASSERT((lock_flags & (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL)) !=
	       (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL));
	ASSERT((lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) !=
	       (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
	ASSERT((lock_flags & ~(XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL |
		XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) == 0);
	ASSERT(lock_flags != 0);

	if (lock_flags & XFS_IOLOCK_EXCL) {
		mrlock(&ip->i_iolock, MR_UPDATE, PINOD | PRECALC);
	} else if (lock_flags & XFS_IOLOCK_SHARED) {
		mrlock(&ip->i_iolock, MR_ACCESS, PINOD | PRECALC);
	}

	if (lock_flags & XFS_ILOCK_EXCL) {
		mrlock(&ip->i_lock, MR_UPDATE, PINOD | PRECALC);
	} else if (lock_flags & XFS_ILOCK_SHARED) {
		mrlock(&ip->i_lock, MR_ACCESS, PINOD | PRECALC);
	}

}

/*
 * This is just like xfs_ilock(), except that the caller
 * is guaranteed not to sleep.  It returns 1 if it gets
 * the requested locks and 0 otherwise.  If the IO lock is
 * obtained but the inode lock cannot be, then the IO lock
 * is dropped before returning.
 *
 * ip -- the inode being locked
 * lock_flags -- this parameter indicates the inode's locks to be
 *       to be locked.  See the comment for xfs_ilock() for a list
 *	 of valid values.
 *
 */
int
xfs_ilock_nowait(xfs_inode_t	*ip,
		 uint		lock_flags)
{
	int	iolocked;
	int	ilocked;

	/*
	 * You can't set both SHARED and EXCL for the same lock,
	 * and only XFS_IOLOCK_SHARED, XFS_IOLOCK_EXCL, XFS_ILOCK_SHARED,
	 * and XFS_ILOCK_EXCL are valid values to set in lock_flags.
	 */
	ASSERT((lock_flags & (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL)) !=
	       (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL));
	ASSERT((lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) !=
	       (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
	ASSERT((lock_flags & ~(XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL |
		XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) == 0);
	ASSERT(lock_flags != 0);

	iolocked = 0;
	if (lock_flags & XFS_IOLOCK_EXCL) {
		iolocked = cmrlock(&ip->i_iolock, MR_UPDATE);
		if (!iolocked) {
			return 0;
		}
	} else if (lock_flags & XFS_IOLOCK_SHARED) {
		iolocked = cmrlock(&ip->i_iolock, MR_ACCESS);
		if (!iolocked) {
			return 0;
		}
	}

	if (lock_flags & XFS_ILOCK_EXCL) {
		ilocked = cmrlock(&ip->i_lock, MR_UPDATE);
		if (!ilocked) {
			if (iolocked) {
				mrunlock(&ip->i_iolock);
			}
			return 0;
		}
	} else if (lock_flags & XFS_ILOCK_SHARED) {
		ilocked = cmrlock(&ip->i_lock, MR_ACCESS);
		if (!ilocked) {
			if (iolocked) {
				mrunlock(&ip->i_iolock);
			}
			return 0;
		}
	}
	return 1;
}

/*
 * xfs_iunlock() is used to drop the inode locks acquired with
 * xfs_ilock() and xfs_ilock_nowait().  The caller must pass
 * in the flags given to xfs_ilock() or xfs_ilock_nowait() so
 * that we know which locks to drop.
 *
 * ip -- the inode being unlocked
 * lock_flags -- this parameter indicates the inode's locks to be
 *       to be unlocked.  See the comment for xfs_ilock() for a list
 *	 of valid values for this parameter.
 *
 */
void
xfs_iunlock(xfs_inode_t	*ip,
	    uint	lock_flags)
{
	/*
	 * You can't set both SHARED and EXCL for the same lock,
	 * and only XFS_IOLOCK_SHARED, XFS_IOLOCK_EXCL, XFS_ILOCK_SHARED,
	 * and XFS_ILOCK_EXCL are valid values to set in lock_flags.
	 */
	ASSERT((lock_flags & (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL)) !=
	       (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL));
	ASSERT((lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) !=
	       (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
	ASSERT((lock_flags &
		~(XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL |
		  XFS_ILOCK_SHARED | XFS_ILOCK_EXCL |
		  XFS_IUNLOCK_NONOTIFY)) == 0);
	ASSERT(lock_flags != 0);

	if (lock_flags & (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL)) {
		ASSERT(!(lock_flags & XFS_IOLOCK_SHARED) ||
		       (ismrlocked(&ip->i_iolock, MR_ACCESS)));
		ASSERT(!(lock_flags & XFS_IOLOCK_EXCL) ||
		       (ismrlocked(&ip->i_iolock, MR_UPDATE)));
		mrunlock(&ip->i_iolock);
	}

	if (lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) {
		ASSERT(!(lock_flags & XFS_ILOCK_SHARED) ||
		       (ismrlocked(&ip->i_lock, MR_ACCESS)));
		ASSERT(!(lock_flags & XFS_ILOCK_EXCL) ||
		       (ismrlocked(&ip->i_lock, MR_UPDATE)));
		mrunlock(&ip->i_lock);
	}

	/*
	 * Let the AIL know that this item has been unlocked in case
	 * it is in the AIL and anyone is waiting on it.  Don't do
	 * this if the caller has asked us not to.
	 */
	if (!(lock_flags & XFS_IUNLOCK_NONOTIFY)) {
		xfs_trans_unlocked_item(ip->i_mount,
					(xfs_log_item_t*)&(ip->i_item));
	}
}

/*
 * The following three routines simply manage the i_flock
 * semaphore embedded in the inode.  This semaphore synchronizes
 * processes attempting to flush the in-core inode back to disk.
 */
void
xfs_iflock(xfs_inode_t *ip)
{
	psema(&(ip->i_flock), PINOD | PRECALC);
}

int
xfs_iflock_nowait(xfs_inode_t *ip)
{
	return (cpsema(&(ip->i_flock)));
}

void
xfs_ifunlock(xfs_inode_t *ip)
{
	ASSERT(valusema(&(ip->i_flock)) <= 0);
	vsema(&(ip->i_flock));
}