Add qemu 2.4.0

[kvmfornfv.git] / qemu / roms / u-boot / fs / ubifs / budget.c

diff --git a/qemu/roms/u-boot/fs/ubifs/budget.c b/qemu/roms/u-boot/fs/ubifs/budget.c
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+/*
+ * This file is part of UBIFS.
+ *
+ * Copyright (C) 2006-2008 Nokia Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will 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 to the Free Software Foundation, Inc., 51
+ * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ * Authors: Adrian Hunter
+ *          Artem Bityutskiy (Битюцкий Артём)
+ */
+
+/*
+ * This file implements the budgeting sub-system which is responsible for UBIFS
+ * space management.
+ *
+ * Factors such as compression, wasted space at the ends of LEBs, space in other
+ * journal heads, the effect of updates on the index, and so on, make it
+ * impossible to accurately predict the amount of space needed. Consequently
+ * approximations are used.
+ */
+
+#include "ubifs.h"
+#include <linux/math64.h>
+
+/**
+ * ubifs_calc_min_idx_lebs - calculate amount of eraseblocks for the index.
+ * @c: UBIFS file-system description object
+ *
+ * This function calculates and returns the number of eraseblocks which should
+ * be kept for index usage.
+ */
+int ubifs_calc_min_idx_lebs(struct ubifs_info *c)
+{
+       int idx_lebs, eff_leb_size = c->leb_size - c->max_idx_node_sz;
+       long long idx_size;
+
+       idx_size = c->old_idx_sz + c->budg_idx_growth + c->budg_uncommitted_idx;
+
+       /* And make sure we have thrice the index size of space reserved */
+       idx_size = idx_size + (idx_size << 1);
+
+       /*
+        * We do not maintain 'old_idx_size' as 'old_idx_lebs'/'old_idx_bytes'
+        * pair, nor similarly the two variables for the new index size, so we
+        * have to do this costly 64-bit division on fast-path.
+        */
+       idx_size += eff_leb_size - 1;
+       idx_lebs = div_u64(idx_size, eff_leb_size);
+       /*
+        * The index head is not available for the in-the-gaps method, so add an
+        * extra LEB to compensate.
+        */
+       idx_lebs += 1;
+       if (idx_lebs < MIN_INDEX_LEBS)
+               idx_lebs = MIN_INDEX_LEBS;
+       return idx_lebs;
+}
+
+/**
+ * ubifs_reported_space - calculate reported free space.
+ * @c: the UBIFS file-system description object
+ * @free: amount of free space
+ *
+ * This function calculates amount of free space which will be reported to
+ * user-space. User-space application tend to expect that if the file-system
+ * (e.g., via the 'statfs()' call) reports that it has N bytes available, they
+ * are able to write a file of size N. UBIFS attaches node headers to each data
+ * node and it has to write indexing nodes as well. This introduces additional
+ * overhead, and UBIFS has to report slightly less free space to meet the above
+ * expectations.
+ *
+ * This function assumes free space is made up of uncompressed data nodes and
+ * full index nodes (one per data node, tripled because we always allow enough
+ * space to write the index thrice).
+ *
+ * Note, the calculation is pessimistic, which means that most of the time
+ * UBIFS reports less space than it actually has.
+ */
+long long ubifs_reported_space(const struct ubifs_info *c, long long free)
+{
+       int divisor, factor, f;
+
+       /*
+        * Reported space size is @free * X, where X is UBIFS block size
+        * divided by UBIFS block size + all overhead one data block
+        * introduces. The overhead is the node header + indexing overhead.
+        *
+        * Indexing overhead calculations are based on the following formula:
+        * I = N/(f - 1) + 1, where I - number of indexing nodes, N - number
+        * of data nodes, f - fanout. Because effective UBIFS fanout is twice
+        * as less than maximum fanout, we assume that each data node
+        * introduces 3 * @c->max_idx_node_sz / (@c->fanout/2 - 1) bytes.
+        * Note, the multiplier 3 is because UBIFS reserves thrice as more space
+        * for the index.
+        */
+       f = c->fanout > 3 ? c->fanout >> 1 : 2;
+       factor = UBIFS_BLOCK_SIZE;
+       divisor = UBIFS_MAX_DATA_NODE_SZ;
+       divisor += (c->max_idx_node_sz * 3) / (f - 1);
+       free *= factor;
+       return div_u64(free, divisor);
+}