xfs_dir2_data.c

linux 内核源代码

/*
 * 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_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_da_btree.h"
#include "xfs_bmap_btree.h"
#include "xfs_dir2_sf.h"
#include "xfs_attr_sf.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_dir2_data.h"
#include "xfs_dir2_leaf.h"
#include "xfs_dir2_block.h"
#include "xfs_error.h"

#ifdef DEBUG
/*
 * Check the consistency of the data block.
 * The input can also be a block-format directory.
 * Pop an assert if we find anything bad.
 */
void
xfs_dir2_data_check(
	xfs_inode_t		*dp,		/* incore inode pointer */
	xfs_dabuf_t		*bp)		/* data block's buffer */
{
	xfs_dir2_dataptr_t	addr;		/* addr for leaf lookup */
	xfs_dir2_data_free_t	*bf;		/* bestfree table */
	xfs_dir2_block_tail_t	*btp=NULL;	/* block tail */
	int			count;		/* count of entries found */
	xfs_dir2_data_t		*d;		/* data block pointer */
	xfs_dir2_data_entry_t	*dep;		/* data entry */
	xfs_dir2_data_free_t	*dfp;		/* bestfree entry */
	xfs_dir2_data_unused_t	*dup;		/* unused entry */
	char			*endp;		/* end of useful data */
	int			freeseen;	/* mask of bestfrees seen */
	xfs_dahash_t		hash;		/* hash of current name */
	int			i;		/* leaf index */
	int			lastfree;	/* last entry was unused */
	xfs_dir2_leaf_entry_t	*lep=NULL;	/* block leaf entries */
	xfs_mount_t		*mp;		/* filesystem mount point */
	char			*p;		/* current data position */
	int			stale;		/* count of stale leaves */

	mp = dp->i_mount;
	d = bp->data;
	ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
	       be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
	bf = d->hdr.bestfree;
	p = (char *)d->u;
	if (be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC) {
		btp = xfs_dir2_block_tail_p(mp, (xfs_dir2_block_t *)d);
		lep = xfs_dir2_block_leaf_p(btp);
		endp = (char *)lep;
	} else
		endp = (char *)d + mp->m_dirblksize;
	count = lastfree = freeseen = 0;
	/*
	 * Account for zero bestfree entries.
	 */
	if (!bf[0].length) {
		ASSERT(!bf[0].offset);
		freeseen |= 1 << 0;
	}
	if (!bf[1].length) {
		ASSERT(!bf[1].offset);
		freeseen |= 1 << 1;
	}
	if (!bf[2].length) {
		ASSERT(!bf[2].offset);
		freeseen |= 1 << 2;
	}
	ASSERT(be16_to_cpu(bf[0].length) >= be16_to_cpu(bf[1].length));
	ASSERT(be16_to_cpu(bf[1].length) >= be16_to_cpu(bf[2].length));
	/*
	 * Loop over the data/unused entries.
	 */
	while (p < endp) {
		dup = (xfs_dir2_data_unused_t *)p;
		/*
		 * If it's unused, look for the space in the bestfree table.
		 * If we find it, account for that, else make sure it
		 * doesn't need to be there.
		 */
		if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
			ASSERT(lastfree == 0);
			ASSERT(be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup)) ==
			       (char *)dup - (char *)d);
			dfp = xfs_dir2_data_freefind(d, dup);
			if (dfp) {
				i = (int)(dfp - bf);
				ASSERT((freeseen & (1 << i)) == 0);
				freeseen |= 1 << i;
			} else {
				ASSERT(be16_to_cpu(dup->length) <=
				       be16_to_cpu(bf[2].length));
			}
			p += be16_to_cpu(dup->length);
			lastfree = 1;
			continue;
		}
		/*
		 * It's a real entry.  Validate the fields.
		 * If this is a block directory then make sure it's
		 * in the leaf section of the block.
		 * The linear search is crude but this is DEBUG code.
		 */
		dep = (xfs_dir2_data_entry_t *)p;
		ASSERT(dep->namelen != 0);
		ASSERT(xfs_dir_ino_validate(mp, be64_to_cpu(dep->inumber)) == 0);
		ASSERT(be16_to_cpu(*xfs_dir2_data_entry_tag_p(dep)) ==
		       (char *)dep - (char *)d);
		count++;
		lastfree = 0;
		if (be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC) {
			addr = xfs_dir2_db_off_to_dataptr(mp, mp->m_dirdatablk,
				(xfs_dir2_data_aoff_t)
				((char *)dep - (char *)d));
			hash = xfs_da_hashname((char *)dep->name, dep->namelen);
			for (i = 0; i < be32_to_cpu(btp->count); i++) {
				if (be32_to_cpu(lep[i].address) == addr &&
				    be32_to_cpu(lep[i].hashval) == hash)
					break;
			}
			ASSERT(i < be32_to_cpu(btp->count));
		}
		p += xfs_dir2_data_entsize(dep->namelen);
	}
	/*
	 * Need to have seen all the entries and all the bestfree slots.
	 */
	ASSERT(freeseen == 7);
	if (be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC) {
		for (i = stale = 0; i < be32_to_cpu(btp->count); i++) {
			if (be32_to_cpu(lep[i].address) == XFS_DIR2_NULL_DATAPTR)
				stale++;
			if (i > 0)
				ASSERT(be32_to_cpu(lep[i].hashval) >= be32_to_cpu(lep[i - 1].hashval));
		}
		ASSERT(count == be32_to_cpu(btp->count) - be32_to_cpu(btp->stale));
		ASSERT(stale == be32_to_cpu(btp->stale));
	}
}
#endif

/*
 * Given a data block and an unused entry from that block,
 * return the bestfree entry if any that corresponds to it.
 */
xfs_dir2_data_free_t *
xfs_dir2_data_freefind(
	xfs_dir2_data_t		*d,		/* data block */
	xfs_dir2_data_unused_t	*dup)		/* data unused entry */
{
	xfs_dir2_data_free_t	*dfp;		/* bestfree entry */
	xfs_dir2_data_aoff_t	off;		/* offset value needed */
#if defined(DEBUG) && defined(__KERNEL__)
	int			matched;	/* matched the value */
	int			seenzero;	/* saw a 0 bestfree entry */
#endif

	off = (xfs_dir2_data_aoff_t)((char *)dup - (char *)d);
#if defined(DEBUG) && defined(__KERNEL__)
	/*
	 * Validate some consistency in the bestfree table.
	 * Check order, non-overlapping entries, and if we find the
	 * one we're looking for it has to be exact.
	 */
	ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
	       be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
	for (dfp = &d->hdr.bestfree[0], seenzero = matched = 0;
	     dfp < &d->hdr.bestfree[XFS_DIR2_DATA_FD_COUNT];
	     dfp++) {
		if (!dfp->offset) {
			ASSERT(!dfp->length);
			seenzero = 1;
			continue;
		}
		ASSERT(seenzero == 0);
		if (be16_to_cpu(dfp->offset) == off) {
			matched = 1;
			ASSERT(dfp->length == dup->length);
		} else if (off < be16_to_cpu(dfp->offset))
			ASSERT(off + be16_to_cpu(dup->length) <= be16_to_cpu(dfp->offset));
		else
			ASSERT(be16_to_cpu(dfp->offset) + be16_to_cpu(dfp->length) <= off);
		ASSERT(matched || be16_to_cpu(dfp->length) >= be16_to_cpu(dup->length));
		if (dfp > &d->hdr.bestfree[0])
			ASSERT(be16_to_cpu(dfp[-1].length) >= be16_to_cpu(dfp[0].length));
	}
#endif
	/*
	 * If this is smaller than the smallest bestfree entry,
	 * it can't be there since they're sorted.
	 */
	if (be16_to_cpu(dup->length) <
	    be16_to_cpu(d->hdr.bestfree[XFS_DIR2_DATA_FD_COUNT - 1].length))
		return NULL;
	/*
	 * Look at the three bestfree entries for our guy.
	 */
	for (dfp = &d->hdr.bestfree[0];
	     dfp < &d->hdr.bestfree[XFS_DIR2_DATA_FD_COUNT];
	     dfp++) {
		if (!dfp->offset)
			return NULL;
		if (be16_to_cpu(dfp->offset) == off)
			return dfp;
	}
	/*
	 * Didn't find it.  This only happens if there are duplicate lengths.
	 */
	return NULL;
}

/*
 * Insert an unused-space entry into the bestfree table.
 */
xfs_dir2_data_free_t *				/* entry inserted */
xfs_dir2_data_freeinsert(
	xfs_dir2_data_t		*d,		/* data block pointer */
	xfs_dir2_data_unused_t	*dup,		/* unused space */
	int			*loghead)	/* log the data header (out) */
{
	xfs_dir2_data_free_t	*dfp;		/* bestfree table pointer */
	xfs_dir2_data_free_t	new;		/* new bestfree entry */

#ifdef __KERNEL__
	ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
	       be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
#endif
	dfp = d->hdr.bestfree;
	new.length = dup->length;
	new.offset = cpu_to_be16((char *)dup - (char *)d);
	/*
	 * Insert at position 0, 1, or 2; or not at all.
	 */
	if (be16_to_cpu(new.length) > be16_to_cpu(dfp[0].length)) {
		dfp[2] = dfp[1];
		dfp[1] = dfp[0];
		dfp[0] = new;
		*loghead = 1;
		return &dfp[0];
	}
	if (be16_to_cpu(new.length) > be16_to_cpu(dfp[1].length)) {
		dfp[2] = dfp[1];
		dfp[1] = new;
		*loghead = 1;
		return &dfp[1];
	}
	if (be16_to_cpu(new.length) > be16_to_cpu(dfp[2].length)) {
		dfp[2] = new;
		*loghead = 1;
		return &dfp[2];
	}
	return NULL;
}

/*
 * Remove a bestfree entry from the table.
 */
STATIC void
xfs_dir2_data_freeremove(
	xfs_dir2_data_t		*d,		/* data block pointer */
	xfs_dir2_data_free_t	*dfp,		/* bestfree entry pointer */
	int			*loghead)	/* out: log data header */
{
#ifdef __KERNEL__
	ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
	       be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
#endif
	/*
	 * It's the first entry, slide the next 2 up.
	 */
	if (dfp == &d->hdr.bestfree[0]) {
		d->hdr.bestfree[0] = d->hdr.bestfree[1];
		d->hdr.bestfree[1] = d->hdr.bestfree[2];
	}
	/*
	 * It's the second entry, slide the 3rd entry up.
	 */
	else if (dfp == &d->hdr.bestfree[1])
		d->hdr.bestfree[1] = d->hdr.bestfree[2];
	/*
	 * Must be the last entry.
	 */
	else
		ASSERT(dfp == &d->hdr.bestfree[2]);
	/*
	 * Clear the 3rd entry, must be zero now.
	 */
	d->hdr.bestfree[2].length = 0;
	d->hdr.bestfree[2].offset = 0;
	*loghead = 1;
}

/*
 * Given a data block, reconstruct its bestfree map.
 */
void
xfs_dir2_data_freescan(
	xfs_mount_t		*mp,		/* filesystem mount point */
	xfs_dir2_data_t		*d,		/* data block pointer */
	int			*loghead)	/* out: log data header */
{
	xfs_dir2_block_tail_t	*btp;		/* block tail */
	xfs_dir2_data_entry_t	*dep;		/* active data entry */
	xfs_dir2_data_unused_t	*dup;		/* unused data entry */
	char			*endp;		/* end of block's data */
	char			*p;		/* current entry pointer */

#ifdef __KERNEL__
	ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
	       be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
#endif
	/*
	 * Start by clearing the table.
	 */
	memset(d->hdr.bestfree, 0, sizeof(d->hdr.bestfree));
	*loghead = 1;
	/*
	 * Set up pointers.
	 */
	p = (char *)d->u;
	if (be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC) {
		btp = xfs_dir2_block_tail_p(mp, (xfs_dir2_block_t *)d);
		endp = (char *)xfs_dir2_block_leaf_p(btp);
	} else
		endp = (char *)d + mp->m_dirblksize;
	/*
	 * Loop over the block's entries.
	 */
	while (p < endp) {
		dup = (xfs_dir2_data_unused_t *)p;
		/*
		 * If it's a free entry, insert it.
		 */
		if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
			ASSERT((char *)dup - (char *)d ==
			       be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup)));
			xfs_dir2_data_freeinsert(d, dup, loghead);
			p += be16_to_cpu(dup->length);
		}
		/*
		 * For active entries, check their tags and skip them.
		 */
		else {
			dep = (xfs_dir2_data_entry_t *)p;
			ASSERT((char *)dep - (char *)d ==
			       be16_to_cpu(*xfs_dir2_data_entry_tag_p(dep)));
			p += xfs_dir2_data_entsize(dep->namelen);
		}
	}
}

/*
 * Initialize a data block at the given block number in the directory.
 * Give back the buffer for the created block.
 */
int						/* error */
xfs_dir2_data_init(
	xfs_da_args_t		*args,		/* directory operation args */
	xfs_dir2_db_t		blkno,		/* logical dir block number */
	xfs_dabuf_t		**bpp)		/* output block buffer */
{
	xfs_dabuf_t		*bp;		/* block buffer */
	xfs_dir2_data_t		*d;		/* pointer to block */
	xfs_inode_t		*dp;		/* incore directory inode */
	xfs_dir2_data_unused_t	*dup;		/* unused entry pointer */
	int			error;		/* error return value */
	int			i;		/* bestfree index */
	xfs_mount_t		*mp;		/* filesystem mount point */
	xfs_trans_t		*tp;		/* transaction pointer */
	int                     t;              /* temp */

	dp = args->dp;
	mp = dp->i_mount;
	tp = args->trans;
	/*
	 * Get the buffer set up for the block.
	 */
	error = xfs_da_get_buf(tp, dp, xfs_dir2_db_to_da(mp, blkno), -1, &bp,
		XFS_DATA_FORK);
	if (error) {
		return error;
	}
	ASSERT(bp != NULL);
	/*
	 * Initialize the header.
	 */
	d = bp->data;
	d->hdr.magic = cpu_to_be32(XFS_DIR2_DATA_MAGIC);
	d->hdr.bestfree[0].offset = cpu_to_be16(sizeof(d->hdr));