xfs_dir2_data.c

linux 内核源代码

	for (i = 1; i < XFS_DIR2_DATA_FD_COUNT; i++) {
		d->hdr.bestfree[i].length = 0;
		d->hdr.bestfree[i].offset = 0;
	}
	/*
	 * Set up an unused entry for the block's body.
	 */
	dup = &d->u[0].unused;
	dup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);

	t=mp->m_dirblksize - (uint)sizeof(d->hdr);
	d->hdr.bestfree[0].length = cpu_to_be16(t);
	dup->length = cpu_to_be16(t);
	*xfs_dir2_data_unused_tag_p(dup) = cpu_to_be16((char *)dup - (char *)d);
	/*
	 * Log it and return it.
	 */
	xfs_dir2_data_log_header(tp, bp);
	xfs_dir2_data_log_unused(tp, bp, dup);
	*bpp = bp;
	return 0;
}

/*
 * Log an active data entry from the block.
 */
void
xfs_dir2_data_log_entry(
	xfs_trans_t		*tp,		/* transaction pointer */
	xfs_dabuf_t		*bp,		/* block buffer */
	xfs_dir2_data_entry_t	*dep)		/* data entry pointer */
{
	xfs_dir2_data_t		*d;		/* data block pointer */

	d = bp->data;
	ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
	       be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
	xfs_da_log_buf(tp, bp, (uint)((char *)dep - (char *)d),
		(uint)((char *)(xfs_dir2_data_entry_tag_p(dep) + 1) -
		       (char *)d - 1));
}

/*
 * Log a data block header.
 */
void
xfs_dir2_data_log_header(
	xfs_trans_t		*tp,		/* transaction pointer */
	xfs_dabuf_t		*bp)		/* block buffer */
{
	xfs_dir2_data_t		*d;		/* data block pointer */

	d = bp->data;
	ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
	       be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
	xfs_da_log_buf(tp, bp, (uint)((char *)&d->hdr - (char *)d),
		(uint)(sizeof(d->hdr) - 1));
}

/*
 * Log a data unused entry.
 */
void
xfs_dir2_data_log_unused(
	xfs_trans_t		*tp,		/* transaction pointer */
	xfs_dabuf_t		*bp,		/* block buffer */
	xfs_dir2_data_unused_t	*dup)		/* data unused pointer */
{
	xfs_dir2_data_t		*d;		/* data block pointer */

	d = bp->data;
	ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
	       be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
	/*
	 * Log the first part of the unused entry.
	 */
	xfs_da_log_buf(tp, bp, (uint)((char *)dup - (char *)d),
		(uint)((char *)&dup->length + sizeof(dup->length) -
		       1 - (char *)d));
	/*
	 * Log the end (tag) of the unused entry.
	 */
	xfs_da_log_buf(tp, bp,
		(uint)((char *)xfs_dir2_data_unused_tag_p(dup) - (char *)d),
		(uint)((char *)xfs_dir2_data_unused_tag_p(dup) - (char *)d +
		       sizeof(xfs_dir2_data_off_t) - 1));
}

/*
 * Make a byte range in the data block unused.
 * Its current contents are unimportant.
 */
void
xfs_dir2_data_make_free(
	xfs_trans_t		*tp,		/* transaction pointer */
	xfs_dabuf_t		*bp,		/* block buffer */
	xfs_dir2_data_aoff_t	offset,		/* starting byte offset */
	xfs_dir2_data_aoff_t	len,		/* length in bytes */
	int			*needlogp,	/* out: log header */
	int			*needscanp)	/* out: regen bestfree */
{
	xfs_dir2_data_t		*d;		/* data block pointer */
	xfs_dir2_data_free_t	*dfp;		/* bestfree pointer */
	char			*endptr;	/* end of data area */
	xfs_mount_t		*mp;		/* filesystem mount point */
	int			needscan;	/* need to regen bestfree */
	xfs_dir2_data_unused_t	*newdup;	/* new unused entry */
	xfs_dir2_data_unused_t	*postdup;	/* unused entry after us */
	xfs_dir2_data_unused_t	*prevdup;	/* unused entry before us */

	mp = tp->t_mountp;
	d = bp->data;
	/*
	 * Figure out where the end of the data area is.
	 */
	if (be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC)
		endptr = (char *)d + mp->m_dirblksize;
	else {
		xfs_dir2_block_tail_t	*btp;	/* block tail */

		ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
		btp = xfs_dir2_block_tail_p(mp, (xfs_dir2_block_t *)d);
		endptr = (char *)xfs_dir2_block_leaf_p(btp);
	}
	/*
	 * If this isn't the start of the block, then back up to
	 * the previous entry and see if it's free.
	 */
	if (offset > sizeof(d->hdr)) {
		__be16			*tagp;	/* tag just before us */

		tagp = (__be16 *)((char *)d + offset) - 1;
		prevdup = (xfs_dir2_data_unused_t *)((char *)d + be16_to_cpu(*tagp));
		if (be16_to_cpu(prevdup->freetag) != XFS_DIR2_DATA_FREE_TAG)
			prevdup = NULL;
	} else
		prevdup = NULL;
	/*
	 * If this isn't the end of the block, see if the entry after
	 * us is free.
	 */
	if ((char *)d + offset + len < endptr) {
		postdup =
			(xfs_dir2_data_unused_t *)((char *)d + offset + len);
		if (be16_to_cpu(postdup->freetag) != XFS_DIR2_DATA_FREE_TAG)
			postdup = NULL;
	} else
		postdup = NULL;
	ASSERT(*needscanp == 0);
	needscan = 0;
	/*
	 * Previous and following entries are both free,
	 * merge everything into a single free entry.
	 */
	if (prevdup && postdup) {
		xfs_dir2_data_free_t	*dfp2;	/* another bestfree pointer */

		/*
		 * See if prevdup and/or postdup are in bestfree table.
		 */
		dfp = xfs_dir2_data_freefind(d, prevdup);
		dfp2 = xfs_dir2_data_freefind(d, postdup);
		/*
		 * We need a rescan unless there are exactly 2 free entries
		 * namely our two.  Then we know what's happening, otherwise
		 * since the third bestfree is there, there might be more
		 * entries.
		 */
		needscan = (d->hdr.bestfree[2].length != 0);
		/*
		 * Fix up the new big freespace.
		 */
		be16_add(&prevdup->length, len + be16_to_cpu(postdup->length));
		*xfs_dir2_data_unused_tag_p(prevdup) =
			cpu_to_be16((char *)prevdup - (char *)d);
		xfs_dir2_data_log_unused(tp, bp, prevdup);
		if (!needscan) {
			/*
			 * Has to be the case that entries 0 and 1 are
			 * dfp and dfp2 (don't know which is which), and
			 * entry 2 is empty.
			 * Remove entry 1 first then entry 0.
			 */
			ASSERT(dfp && dfp2);
			if (dfp == &d->hdr.bestfree[1]) {
				dfp = &d->hdr.bestfree[0];
				ASSERT(dfp2 == dfp);
				dfp2 = &d->hdr.bestfree[1];
			}
			xfs_dir2_data_freeremove(d, dfp2, needlogp);
			xfs_dir2_data_freeremove(d, dfp, needlogp);
			/*
			 * Now insert the new entry.
			 */
			dfp = xfs_dir2_data_freeinsert(d, prevdup, needlogp);
			ASSERT(dfp == &d->hdr.bestfree[0]);
			ASSERT(dfp->length == prevdup->length);
			ASSERT(!dfp[1].length);
			ASSERT(!dfp[2].length);
		}
	}
	/*
	 * The entry before us is free, merge with it.
	 */
	else if (prevdup) {
		dfp = xfs_dir2_data_freefind(d, prevdup);
		be16_add(&prevdup->length, len);
		*xfs_dir2_data_unused_tag_p(prevdup) =
			cpu_to_be16((char *)prevdup - (char *)d);
		xfs_dir2_data_log_unused(tp, bp, prevdup);
		/*
		 * If the previous entry was in the table, the new entry
		 * is longer, so it will be in the table too.  Remove
		 * the old one and add the new one.
		 */
		if (dfp) {
			xfs_dir2_data_freeremove(d, dfp, needlogp);
			(void)xfs_dir2_data_freeinsert(d, prevdup, needlogp);
		}
		/*
		 * Otherwise we need a scan if the new entry is big enough.
		 */
		else {
			needscan = be16_to_cpu(prevdup->length) >
				   be16_to_cpu(d->hdr.bestfree[2].length);
		}
	}
	/*
	 * The following entry is free, merge with it.
	 */
	else if (postdup) {
		dfp = xfs_dir2_data_freefind(d, postdup);
		newdup = (xfs_dir2_data_unused_t *)((char *)d + offset);
		newdup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
		newdup->length = cpu_to_be16(len + be16_to_cpu(postdup->length));
		*xfs_dir2_data_unused_tag_p(newdup) =
			cpu_to_be16((char *)newdup - (char *)d);
		xfs_dir2_data_log_unused(tp, bp, newdup);
		/*
		 * If the following entry was in the table, the new entry
		 * is longer, so it will be in the table too.  Remove
		 * the old one and add the new one.
		 */
		if (dfp) {
			xfs_dir2_data_freeremove(d, dfp, needlogp);
			(void)xfs_dir2_data_freeinsert(d, newdup, needlogp);
		}
		/*
		 * Otherwise we need a scan if the new entry is big enough.
		 */
		else {
			needscan = be16_to_cpu(newdup->length) >
				   be16_to_cpu(d->hdr.bestfree[2].length);
		}
	}
	/*
	 * Neither neighbor is free.  Make a new entry.
	 */
	else {
		newdup = (xfs_dir2_data_unused_t *)((char *)d + offset);
		newdup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
		newdup->length = cpu_to_be16(len);
		*xfs_dir2_data_unused_tag_p(newdup) =
			cpu_to_be16((char *)newdup - (char *)d);
		xfs_dir2_data_log_unused(tp, bp, newdup);
		(void)xfs_dir2_data_freeinsert(d, newdup, needlogp);
	}
	*needscanp = needscan;
}

/*
 * Take a byte range out of an existing unused space and make it un-free.
 */
void
xfs_dir2_data_use_free(
	xfs_trans_t		*tp,		/* transaction pointer */
	xfs_dabuf_t		*bp,		/* data block buffer */
	xfs_dir2_data_unused_t	*dup,		/* unused entry */
	xfs_dir2_data_aoff_t	offset,		/* starting offset to use */
	xfs_dir2_data_aoff_t	len,		/* length to use */
	int			*needlogp,	/* out: need to log header */
	int			*needscanp)	/* out: need regen bestfree */
{
	xfs_dir2_data_t		*d;		/* data block */
	xfs_dir2_data_free_t	*dfp;		/* bestfree pointer */
	int			matchback;	/* matches end of freespace */
	int			matchfront;	/* matches start of freespace */
	int			needscan;	/* need to regen bestfree */
	xfs_dir2_data_unused_t	*newdup;	/* new unused entry */
	xfs_dir2_data_unused_t	*newdup2;	/* another new unused entry */
	int			oldlen;		/* old unused entry's length */

	d = bp->data;
	ASSERT(be32_to_cpu(d->hdr.magic) == XFS_DIR2_DATA_MAGIC ||
	       be32_to_cpu(d->hdr.magic) == XFS_DIR2_BLOCK_MAGIC);
	ASSERT(be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG);
	ASSERT(offset >= (char *)dup - (char *)d);
	ASSERT(offset + len <= (char *)dup + be16_to_cpu(dup->length) - (char *)d);
	ASSERT((char *)dup - (char *)d == be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup)));
	/*
	 * Look up the entry in the bestfree table.
	 */
	dfp = xfs_dir2_data_freefind(d, dup);
	oldlen = be16_to_cpu(dup->length);
	ASSERT(dfp || oldlen <= be16_to_cpu(d->hdr.bestfree[2].length));
	/*
	 * Check for alignment with front and back of the entry.
	 */
	matchfront = (char *)dup - (char *)d == offset;
	matchback = (char *)dup + oldlen - (char *)d == offset + len;
	ASSERT(*needscanp == 0);
	needscan = 0;
	/*
	 * If we matched it exactly we just need to get rid of it from
	 * the bestfree table.
	 */
	if (matchfront && matchback) {
		if (dfp) {
			needscan = (d->hdr.bestfree[2].offset != 0);
			if (!needscan)
				xfs_dir2_data_freeremove(d, dfp, needlogp);
		}
	}
	/*
	 * We match the first part of the entry.
	 * Make a new entry with the remaining freespace.
	 */
	else if (matchfront) {
		newdup = (xfs_dir2_data_unused_t *)((char *)d + offset + len);
		newdup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
		newdup->length = cpu_to_be16(oldlen - len);
		*xfs_dir2_data_unused_tag_p(newdup) =
			cpu_to_be16((char *)newdup - (char *)d);
		xfs_dir2_data_log_unused(tp, bp, newdup);
		/*
		 * If it was in the table, remove it and add the new one.
		 */
		if (dfp) {
			xfs_dir2_data_freeremove(d, dfp, needlogp);
			dfp = xfs_dir2_data_freeinsert(d, newdup, needlogp);
			ASSERT(dfp != NULL);
			ASSERT(dfp->length == newdup->length);
			ASSERT(be16_to_cpu(dfp->offset) == (char *)newdup - (char *)d);
			/*
			 * If we got inserted at the last slot,
			 * that means we don't know if there was a better
			 * choice for the last slot, or not.  Rescan.
			 */
			needscan = dfp == &d->hdr.bestfree[2];
		}
	}
	/*
	 * We match the last part of the entry.
	 * Trim the allocated space off the tail of the entry.
	 */
	else if (matchback) {
		newdup = dup;
		newdup->length = cpu_to_be16(((char *)d + offset) - (char *)newdup);
		*xfs_dir2_data_unused_tag_p(newdup) =
			cpu_to_be16((char *)newdup - (char *)d);
		xfs_dir2_data_log_unused(tp, bp, newdup);
		/*
		 * If it was in the table, remove it and add the new one.
		 */
		if (dfp) {
			xfs_dir2_data_freeremove(d, dfp, needlogp);
			dfp = xfs_dir2_data_freeinsert(d, newdup, needlogp);
			ASSERT(dfp != NULL);
			ASSERT(dfp->length == newdup->length);
			ASSERT(be16_to_cpu(dfp->offset) == (char *)newdup - (char *)d);
			/*
			 * If we got inserted at the last slot,
			 * that means we don't know if there was a better
			 * choice for the last slot, or not.  Rescan.
			 */
			needscan = dfp == &d->hdr.bestfree[2];
		}
	}
	/*
	 * Poking out the middle of an entry.
	 * Make two new entries.
	 */
	else {
		newdup = dup;
		newdup->length = cpu_to_be16(((char *)d + offset) - (char *)newdup);
		*xfs_dir2_data_unused_tag_p(newdup) =
			cpu_to_be16((char *)newdup - (char *)d);
		xfs_dir2_data_log_unused(tp, bp, newdup);
		newdup2 = (xfs_dir2_data_unused_t *)((char *)d + offset + len);
		newdup2->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
		newdup2->length = cpu_to_be16(oldlen - len - be16_to_cpu(newdup->length));
		*xfs_dir2_data_unused_tag_p(newdup2) =
			cpu_to_be16((char *)newdup2 - (char *)d);
		xfs_dir2_data_log_unused(tp, bp, newdup2);
		/*
		 * If the old entry was in the table, we need to scan
		 * if the 3rd entry was valid, since these entries
		 * are smaller than the old one.
		 * If we don't need to scan that means there were 1 or 2
		 * entries in the table, and removing the old and adding
		 * the 2 new will work.
		 */
		if (dfp) {
			needscan = (d->hdr.bestfree[2].length != 0);
			if (!needscan) {
				xfs_dir2_data_freeremove(d, dfp, needlogp);
				(void)xfs_dir2_data_freeinsert(d, newdup,
					needlogp);
				(void)xfs_dir2_data_freeinsert(d, newdup2,
					needlogp);
			}
		}
	}
	*needscanp = needscan;
}