lcnalloc.c

linux 内核源代码

				/* Empty zone. Don't bother searching it. */
				goto done_zones_check;
			}
			ntfs_debug("Continuing outer while loop.");
			continue;
		} /* done_zones == 7 */
		ntfs_debug("All zones are finished.");
		/*
		 * All zones are finished!  If DATA_ZONE, shrink mft zone.  If
		 * MFT_ZONE, we have really run out of space.
		 */
		mft_zone_size = vol->mft_zone_end - vol->mft_zone_start;
		ntfs_debug("vol->mft_zone_start 0x%llx, vol->mft_zone_end "
				"0x%llx, mft_zone_size 0x%llx.",
				(unsigned long long)vol->mft_zone_start,
				(unsigned long long)vol->mft_zone_end,
				(unsigned long long)mft_zone_size);
		if (zone == MFT_ZONE || mft_zone_size <= 0) {
			ntfs_debug("No free clusters left, going to out.");
			/* Really no more space left on device. */
			err = -ENOSPC;
			goto out;
		} /* zone == DATA_ZONE && mft_zone_size > 0 */
		ntfs_debug("Shrinking mft zone.");
		zone_end = vol->mft_zone_end;
		mft_zone_size >>= 1;
		if (mft_zone_size > 0)
			vol->mft_zone_end = vol->mft_zone_start + mft_zone_size;
		else /* mft zone and data2 zone no longer exist. */
			vol->data2_zone_pos = vol->mft_zone_start =
					vol->mft_zone_end = 0;
		if (vol->mft_zone_pos >= vol->mft_zone_end) {
			vol->mft_zone_pos = vol->mft_lcn;
			if (!vol->mft_zone_end)
				vol->mft_zone_pos = 0;
		}
		bmp_pos = zone_start = bmp_initial_pos =
				vol->data1_zone_pos = vol->mft_zone_end;
		search_zone = 2;
		pass = 2;
		done_zones &= ~2;
		ntfs_debug("After shrinking mft zone, mft_zone_size 0x%llx, "
				"vol->mft_zone_start 0x%llx, "
				"vol->mft_zone_end 0x%llx, "
				"vol->mft_zone_pos 0x%llx, search_zone 2, "
				"pass 2, dones_zones 0x%x, zone_start 0x%llx, "
				"zone_end 0x%llx, vol->data1_zone_pos 0x%llx, "
				"continuing outer while loop.",
				(unsigned long long)mft_zone_size,
				(unsigned long long)vol->mft_zone_start,
				(unsigned long long)vol->mft_zone_end,
				(unsigned long long)vol->mft_zone_pos,
				done_zones, (unsigned long long)zone_start,
				(unsigned long long)zone_end,
				(unsigned long long)vol->data1_zone_pos);
	}
	ntfs_debug("After outer while loop.");
out:
	ntfs_debug("At out.");
	/* Add runlist terminator element. */
	if (likely(rl)) {
		rl[rlpos].vcn = rl[rlpos - 1].vcn + rl[rlpos - 1].length;
		rl[rlpos].lcn = is_extension ? LCN_ENOENT : LCN_RL_NOT_MAPPED;
		rl[rlpos].length = 0;
	}
	if (likely(page && !IS_ERR(page))) {
		if (need_writeback) {
			ntfs_debug("Marking page dirty.");
			flush_dcache_page(page);
			set_page_dirty(page);
			need_writeback = 0;
		}
		ntfs_unmap_page(page);
	}
	if (likely(!err)) {
		up_write(&vol->lcnbmp_lock);
		ntfs_debug("Done.");
		return rl;
	}
	ntfs_error(vol->sb, "Failed to allocate clusters, aborting "
			"(error %i).", err);
	if (rl) {
		int err2;

		if (err == -ENOSPC)
			ntfs_debug("Not enough space to complete allocation, "
					"err -ENOSPC, first free lcn 0x%llx, "
					"could allocate up to 0x%llx "
					"clusters.",
					(unsigned long long)rl[0].lcn,
					(unsigned long long)(count - clusters));
		/* Deallocate all allocated clusters. */
		ntfs_debug("Attempting rollback...");
		err2 = ntfs_cluster_free_from_rl_nolock(vol, rl);
		if (err2) {
			ntfs_error(vol->sb, "Failed to rollback (error %i).  "
					"Leaving inconsistent metadata!  "
					"Unmount and run chkdsk.", err2);
			NVolSetErrors(vol);
		}
		/* Free the runlist. */
		ntfs_free(rl);
	} else if (err == -ENOSPC)
		ntfs_debug("No space left at all, err = -ENOSPC, first free "
				"lcn = 0x%llx.",
				(long long)vol->data1_zone_pos);
	up_write(&vol->lcnbmp_lock);
	return ERR_PTR(err);
}

/**
 * __ntfs_cluster_free - free clusters on an ntfs volume
 * @ni:		ntfs inode whose runlist describes the clusters to free
 * @start_vcn:	vcn in the runlist of @ni at which to start freeing clusters
 * @count:	number of clusters to free or -1 for all clusters
 * @ctx:	active attribute search context if present or NULL if not
 * @is_rollback:	true if this is a rollback operation
 *
 * Free @count clusters starting at the cluster @start_vcn in the runlist
 * described by the vfs inode @ni.
 *
 * If @count is -1, all clusters from @start_vcn to the end of the runlist are
 * deallocated.  Thus, to completely free all clusters in a runlist, use
 * @start_vcn = 0 and @count = -1.
 *
 * If @ctx is specified, it is an active search context of @ni and its base mft
 * record.  This is needed when __ntfs_cluster_free() encounters unmapped
 * runlist fragments and allows their mapping.  If you do not have the mft
 * record mapped, you can specify @ctx as NULL and __ntfs_cluster_free() will
 * perform the necessary mapping and unmapping.
 *
 * Note, __ntfs_cluster_free() saves the state of @ctx on entry and restores it
 * before returning.  Thus, @ctx will be left pointing to the same attribute on
 * return as on entry.  However, the actual pointers in @ctx may point to
 * different memory locations on return, so you must remember to reset any
 * cached pointers from the @ctx, i.e. after the call to __ntfs_cluster_free(),
 * you will probably want to do:
 *	m = ctx->mrec;
 *	a = ctx->attr;
 * Assuming you cache ctx->attr in a variable @a of type ATTR_RECORD * and that
 * you cache ctx->mrec in a variable @m of type MFT_RECORD *.
 *
 * @is_rollback should always be 'false', it is for internal use to rollback
 * errors.  You probably want to use ntfs_cluster_free() instead.
 *
 * Note, __ntfs_cluster_free() does not modify the runlist, so you have to
 * remove from the runlist or mark sparse the freed runs later.
 *
 * Return the number of deallocated clusters (not counting sparse ones) on
 * success and -errno on error.
 *
 * WARNING: If @ctx is supplied, regardless of whether success or failure is
 *	    returned, you need to check IS_ERR(@ctx->mrec) and if 'true' the @ctx
 *	    is no longer valid, i.e. you need to either call
 *	    ntfs_attr_reinit_search_ctx() or ntfs_attr_put_search_ctx() on it.
 *	    In that case PTR_ERR(@ctx->mrec) will give you the error code for
 *	    why the mapping of the old inode failed.
 *
 * Locking: - The runlist described by @ni must be locked for writing on entry
 *	      and is locked on return.  Note the runlist may be modified when
 *	      needed runlist fragments need to be mapped.
 *	    - The volume lcn bitmap must be unlocked on entry and is unlocked
 *	      on return.
 *	    - This function takes the volume lcn bitmap lock for writing and
 *	      modifies the bitmap contents.
 *	    - If @ctx is NULL, the base mft record of @ni must not be mapped on
 *	      entry and it will be left unmapped on return.
 *	    - If @ctx is not NULL, the base mft record must be mapped on entry
 *	      and it will be left mapped on return.
 */
s64 __ntfs_cluster_free(ntfs_inode *ni, const VCN start_vcn, s64 count,
		ntfs_attr_search_ctx *ctx, const bool is_rollback)
{
	s64 delta, to_free, total_freed, real_freed;
	ntfs_volume *vol;
	struct inode *lcnbmp_vi;
	runlist_element *rl;
	int err;

	BUG_ON(!ni);
	ntfs_debug("Entering for i_ino 0x%lx, start_vcn 0x%llx, count "
			"0x%llx.%s", ni->mft_no, (unsigned long long)start_vcn,
			(unsigned long long)count,
			is_rollback ? " (rollback)" : "");
	vol = ni->vol;
	lcnbmp_vi = vol->lcnbmp_ino;
	BUG_ON(!lcnbmp_vi);
	BUG_ON(start_vcn < 0);
	BUG_ON(count < -1);
	/*
	 * Lock the lcn bitmap for writing but only if not rolling back.  We
	 * must hold the lock all the way including through rollback otherwise
	 * rollback is not possible because once we have cleared a bit and
	 * dropped the lock, anyone could have set the bit again, thus
	 * allocating the cluster for another use.
	 */
	if (likely(!is_rollback))
		down_write(&vol->lcnbmp_lock);

	total_freed = real_freed = 0;

	rl = ntfs_attr_find_vcn_nolock(ni, start_vcn, ctx);
	if (IS_ERR(rl)) {
		if (!is_rollback)
			ntfs_error(vol->sb, "Failed to find first runlist "
					"element (error %li), aborting.",
					PTR_ERR(rl));
		err = PTR_ERR(rl);
		goto err_out;
	}
	if (unlikely(rl->lcn < LCN_HOLE)) {
		if (!is_rollback)
			ntfs_error(vol->sb, "First runlist element has "
					"invalid lcn, aborting.");
		err = -EIO;
		goto err_out;
	}
	/* Find the starting cluster inside the run that needs freeing. */
	delta = start_vcn - rl->vcn;

	/* The number of clusters in this run that need freeing. */
	to_free = rl->length - delta;
	if (count >= 0 && to_free > count)
		to_free = count;

	if (likely(rl->lcn >= 0)) {
		/* Do the actual freeing of the clusters in this run. */
		err = ntfs_bitmap_set_bits_in_run(lcnbmp_vi, rl->lcn + delta,
				to_free, likely(!is_rollback) ? 0 : 1);
		if (unlikely(err)) {
			if (!is_rollback)
				ntfs_error(vol->sb, "Failed to clear first run "
						"(error %i), aborting.", err);
			goto err_out;
		}
		/* We have freed @to_free real clusters. */
		real_freed = to_free;
	};
	/* Go to the next run and adjust the number of clusters left to free. */
	++rl;
	if (count >= 0)
		count -= to_free;

	/* Keep track of the total "freed" clusters, including sparse ones. */
	total_freed = to_free;
	/*
	 * Loop over the remaining runs, using @count as a capping value, and
	 * free them.
	 */
	for (; rl->length && count != 0; ++rl) {
		if (unlikely(rl->lcn < LCN_HOLE)) {
			VCN vcn;

			/* Attempt to map runlist. */
			vcn = rl->vcn;
			rl = ntfs_attr_find_vcn_nolock(ni, vcn, ctx);
			if (IS_ERR(rl)) {
				err = PTR_ERR(rl);
				if (!is_rollback)
					ntfs_error(vol->sb, "Failed to map "
							"runlist fragment or "
							"failed to find "
							"subsequent runlist "
							"element.");
				goto err_out;
			}
			if (unlikely(rl->lcn < LCN_HOLE)) {
				if (!is_rollback)
					ntfs_error(vol->sb, "Runlist element "
							"has invalid lcn "
							"(0x%llx).",
							(unsigned long long)
							rl->lcn);
				err = -EIO;
				goto err_out;
			}
		}
		/* The number of clusters in this run that need freeing. */
		to_free = rl->length;
		if (count >= 0 && to_free > count)
			to_free = count;

		if (likely(rl->lcn >= 0)) {
			/* Do the actual freeing of the clusters in the run. */
			err = ntfs_bitmap_set_bits_in_run(lcnbmp_vi, rl->lcn,
					to_free, likely(!is_rollback) ? 0 : 1);
			if (unlikely(err)) {
				if (!is_rollback)
					ntfs_error(vol->sb, "Failed to clear "
							"subsequent run.");
				goto err_out;
			}
			/* We have freed @to_free real clusters. */
			real_freed += to_free;
		}
		/* Adjust the number of clusters left to free. */
		if (count >= 0)
			count -= to_free;
	
		/* Update the total done clusters. */
		total_freed += to_free;
	}
	if (likely(!is_rollback))
		up_write(&vol->lcnbmp_lock);

	BUG_ON(count > 0);

	/* We are done.  Return the number of actually freed clusters. */
	ntfs_debug("Done.");
	return real_freed;
err_out:
	if (is_rollback)
		return err;
	/* If no real clusters were freed, no need to rollback. */
	if (!real_freed) {
		up_write(&vol->lcnbmp_lock);
		return err;
	}
	/*
	 * Attempt to rollback and if that succeeds just return the error code.
	 * If rollback fails, set the volume errors flag, emit an error
	 * message, and return the error code.
	 */
	delta = __ntfs_cluster_free(ni, start_vcn, total_freed, ctx, true);
	if (delta < 0) {
		ntfs_error(vol->sb, "Failed to rollback (error %i).  Leaving "
				"inconsistent metadata!  Unmount and run "
				"chkdsk.", (int)delta);
		NVolSetErrors(vol);
	}
	up_write(&vol->lcnbmp_lock);
	ntfs_error(vol->sb, "Aborting (error %i).", err);
	return err;
}

#endif /* NTFS_RW */