path: root/fs/xfs/xfs_trans_buf.c

/*
 * Copyright (c) 2000-2002,2005 Silicon Graphics, Inc.
 * All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_types.h"
#include "xfs_bit.h"
#include "xfs_log.h"
#include "xfs_inum.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_dir2.h"
#include "xfs_dmapi.h"
#include "xfs_mount.h"
#include "xfs_bmap_btree.h"
#include "xfs_alloc_btree.h"
#include "xfs_ialloc_btree.h"
#include "xfs_dir2_sf.h"
#include "xfs_attr_sf.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_buf_item.h"
#include "xfs_trans_priv.h"
#include "xfs_error.h"
#include "xfs_rw.h"


STATIC xfs_buf_t *xfs_trans_buf_item_match(xfs_trans_t *, xfs_buftarg_t *,
		xfs_daddr_t, int);
STATIC xfs_buf_t *xfs_trans_buf_item_match_all(xfs_trans_t *, xfs_buftarg_t *,
		xfs_daddr_t, int);


/*
 * Get and lock the buffer for the caller if it is not already
 * locked within the given transaction.  If it is already locked
 * within the transaction, just increment its lock recursion count
 * and return a pointer to it.
 *
 * Use the fast path function xfs_trans_buf_item_match() or the buffer
 * cache routine incore_match() to find the buffer
 * if it is already owned by this transaction.
 *
 * If we don't already own the buffer, use get_buf() to get it.
 * If it doesn't yet have an associated xfs_buf_log_item structure,
 * then allocate one and add the item to this transaction.
 *
 * If the transaction pointer is NULL, make this just a normal
 * get_buf() call.
 */
xfs_buf_t *
xfs_trans_get_buf(xfs_trans_t	*tp,
		  xfs_buftarg_t	*target_dev,
		  xfs_daddr_t	blkno,
		  int		len,
		  uint		flags)
{
	xfs_buf_t		*bp;
	xfs_buf_log_item_t	*bip;

	if (flags == 0)
		flags = XFS_BUF_LOCK | XFS_BUF_MAPPED;

	/*
	 * Default to a normal get_buf() call if the tp is NULL.
	 */
	if (tp == NULL) {
		bp = xfs_buf_get_flags(target_dev, blkno, len,
							flags | BUF_BUSY);
		return(bp);
	}

	/*
	 * If we find the buffer in the cache with this transaction
	 * pointer in its b_fsprivate2 field, then we know we already
	 * have it locked.  In this case we just increment the lock
	 * recursion count and return the buffer to the caller.
	 */
	if (tp->t_items.lic_next == NULL) {
		bp = xfs_trans_buf_item_match(tp, target_dev, blkno, len);
	} else {
		bp  = xfs_trans_buf_item_match_all(tp, target_dev, blkno, len);
	}
	if (bp != NULL) {
		ASSERT(XFS_BUF_VALUSEMA(bp) <= 0);
		if (XFS_FORCED_SHUTDOWN(tp->t_mountp)) {
			xfs_buftrace("TRANS GET RECUR SHUT", bp);
			XFS_BUF_SUPER_STALE(bp);
		}
		/*
		 * If the buffer is stale then it was binval'ed
		 * since last read.  This doesn't matter since the
		 * caller isn't allowed to use the data anyway.
		 */
		else if (XFS_BUF_ISSTALE(bp)) {
			xfs_buftrace("TRANS GET RECUR STALE", bp);
			ASSERT(!XFS_BUF_ISDELAYWRITE(bp));
		}
		ASSERT(XFS_BUF_FSPRIVATE2(bp, xfs_trans_t *) == tp);
		bip = XFS_BUF_FSPRIVATE(bp, xfs_buf_log_item_t *);
		ASSERT(bip != NULL);
		ASSERT(atomic_read(&bip->bli_refcount) > 0);
		bip->bli_recur++;
		xfs_buftrace("TRANS GET RECUR", bp);
		xfs_buf_item_trace("GET RECUR", bip);
		return (bp);
	}

	/*
	 * We always specify the BUF_BUSY flag within a transaction so
	 * that get_buf does not try to push out a delayed write buffer
	 * which might cause another transaction to take place (if the
	 * buffer was delayed alloc).  Such recursive transactions can
	 * easily deadlock with our current transaction as well as cause
	 * us to run out of stack space.
	 */
	bp = xfs_buf_get_flags(target_dev, blkno, len, flags | BUF_BUSY);
	if (bp == NULL) {
		return NULL;
	}

	ASSERT(!XFS_BUF_GETERROR(bp));

	/*
	 * The xfs_buf_log_item pointer is stored in b_fsprivate.  If
	 * it doesn't have one yet, then allocate one and initialize it.
	 * The checks to see if one is there are in xfs_buf_item_init().
	 */
	xfs_buf_item_init(bp, tp->t_mountp);

	/*
	 * Set the recursion count for the buffer within this transaction
	 * to 0.
	 */
	bip = XFS_BUF_FSPRIVATE(bp, xfs_buf_log_item_t*);
	ASSERT(!(bip->bli_flags & XFS_BLI_STALE));
	ASSERT(!(bip->bli_format.blf_flags</