/*
 * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
 * Copyright (C) 2004-2008 Red Hat, Inc.  All rights reserved.
 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
 * of the GNU General Public License version 2.
 */

#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/buffer_head.h>
#include <linux/fs.h>
#include <linux/gfs2_ondisk.h>
#include <linux/prefetch.h>
#include <linux/blkdev.h>
#include <linux/rbtree.h>
#include <linux/random.h>

#include "gfs2.h"
#include "incore.h"
#include "glock.h"
#include "glops.h"
#include "lops.h"
#include "meta_io.h"
#include "quota.h"
#include "rgrp.h"
#include "super.h"
#include "trans.h"
#include "util.h"
#include "log.h"
#include "inode.h"
#include "trace_gfs2.h"

#define BFITNOENT ((u32)~0)
#define NO_BLOCK ((u64)~0)

#if BITS_PER_LONG == 32
#define LBITMASK   (0x55555555UL)
#define LBITSKIP55 (0x55555555UL)
#define LBITSKIP00 (0x00000000UL)
#else
#define LBITMASK   (0x5555555555555555UL)
#define LBITSKIP55 (0x5555555555555555UL)
#define LBITSKIP00 (0x0000000000000000UL)
#endif

/*
 * These routines are used by the resource group routines (rgrp.c)
 * to keep track of block allocation.  Each block is represented by two
 * bits.  So, each byte represents GFS2_NBBY (i.e. 4) blocks.
 *
 * 0 = Free
 * 1 = Used (not metadata)
 * 2 = Unlinked (still in use) inode
 * 3 = Used (metadata)
 */

static const char valid_change[16] = {
                /* current */
        /* n */ 0, 1, 1, 1,
        /* e */ 1, 0, 0, 0,
        /* w */ 0, 0, 0, 1,
                1, 0, 0, 0
};

static int gfs2_rbm_find(struct gfs2_rbm *rbm, u8 state, u32 minext,
                         const struct gfs2_inode *ip, bool nowrap);


/**
 * gfs2_setbit - Set a bit in the bitmaps
 * @rbm: The position of the bit to set
 * @do_clone: Also set the clone bitmap, if it exists
 * @new_state: the new state of the block
 *
 */

static inline void gfs2_setbit(const struct gfs2_rbm *rbm, bool do_clone,
                               unsigned char new_state)
{
        unsigned char *byte1, *byte2, *end, cur_state;
        unsigned int buflen = rbm->bi->bi_len;
        const unsigned int bit = (rbm->offset % GFS2_NBBY) * GFS2_BIT_SIZE;

        byte1 = rbm->bi->bi_bh->b_data + rbm->bi->bi_offset + (rbm->offset / GFS2_NBBY);
        end = rbm->bi->bi_bh->b_data + rbm->bi->bi_offset + buflen;

        BUG_ON(byte1 >= end);

        cur_state = (*byte1 >> bit) & GFS2_BIT_MASK;

        if (unlikely(!valid_change[new_state * 4 + cur_state])) {
                printk(KERN_WARNING "GFS2: buf_blk = 0x%x old_state=%d, "
                       "new_state=%d\n", rbm->offset, cur_state, new_state);
                printk(KERN_WARNING "GFS2: rgrp=0x%llx bi_start=0x%x\n",
                       (unsigned long long)rbm->rgd->rd_addr,
                       rbm->bi->bi_start);
                printk(KERN_WARNING "GFS2: bi_offset=0x%x bi_len=0x%x\n",
                       rbm->bi->bi_offset, rbm->bi->bi_len);
                dump_stack();
                gfs2_consist_rgrpd(rbm->rgd);
                return;
        }
        *byte1 ^= (cur_state ^ new_state) << bit;

        if (do_clone && rbm->bi->bi_clone) {
                byte2 = rbm->bi->bi_clone + rbm->bi->bi_offset + (rbm->offset / GFS2_NBBY);
                cur_state = (*byte2 >> bit) & GFS2_BIT_MASK;
                *byte2 ^= (cur_state ^ new_state) << bit;
        }
}

/**
 * gfs2_testbit - test a bit in the bitmaps
 * @rbm: The bit to test
 *
 * Returns: The two bit block state of the requested bit
 */

static inline u8 gfs2_testbit(const struct gfs2_rbm *rbm)
{
        const u8 *buffer = rbm->bi->bi_bh->b_data + rbm->bi->bi_offset;
        const u8 *byte;
        unsigned int bit;

        byte = buffer + (rbm->offset / GFS2_NBBY);
        bit = (rbm->offset % GFS2_NBBY) * GFS2_BIT_SIZE;

        return (*byte >> bit) & GFS2_BIT_MASK;
}

/**
 * gfs2_bit_search
 * @ptr: Pointer to bitmap data
 * @mask: Mask to use (normally 0x55555.... but adjusted for search start)
 * @state: The state we are searching for
 *
 * We xor the bitmap data with a patter which is the bitwise opposite
 * of what we are looking for, this gives rise to a pattern of ones
 * wherever there is a match. Since we have two bits per entry, we
 * take this pattern, shift it down by one place and then and it with
 * the original. All the even bit positions (0,2,4, etc) then represent
 * successful matches, so we mask with 0x55555..... to remove the unwanted
 * odd bit positions.
 *
 * This allows searching of a whole u64 at once (32 blocks) with a
 * single test (on 64 bit arches).
 */

static inline u64 gfs2_bit_search(const __le64 *ptr, u64 mask, u8 state)
{
        u64 tmp;
        static const u64 search[] = {
                [0] = 0xffffffffffffffffULL,
                [1] = 0xaaaaaaaaaaaaaaaaULL,
                [2] = 0x5555555555555555ULL,
                [3] = 0x0000000000000000ULL,
        };
        tmp = le64_to_cpu(*ptr) ^ search[state];
        tmp &= (tmp >> 1);
        tmp &= mask;
        return tmp;
}

/**
 * rs_cmp - multi-block reservation range compare
 * @blk: absolute file system block number of the new reservation
 * @len: number of blocks in the new reservation
 * @rs: existing reservation to compare against
 *
 * returns: 1 if the block range is beyond the reach of the reservation
 *         -1 if the block range is before the start of the reservation
 *          0 if the block range overlaps with the reservation
 */
static inline int rs_cmp(u64 blk, u32 len, struct gfs2_blkreserv *rs)
{
        u64 startblk = gfs2_rbm_to_block(&rs->rs_rbm);

        if (blk >= startblk + rs->rs_free)
                return 1;
        if (blk + len - 1 < startblk)
                return -1;
        return 0;
}

/**
 * gfs2_bitfit - Search an rgrp's bitmap buffer to find a bit-pair representing
 *       a block in a given allocation state.
 * @buf: the buffer that holds the bitmaps
 * @len: the length (in bytes) of the buffer
 * @goal: start search at this block's bit-pair (within @buffer)
 * @state: GFS2_BLKST_XXX the state of the block we're looking for.
 *
 * Scope of @goal and returned block number is only within this bitmap buffer,
 * not entire rgrp or filesystem.  @buffer will be offset from the actual
 * beginning of a bitmap block buffer, skipping any header structures, but
 * headers are always a multiple of 64 bits long so that the buffer is
 * always aligned to a 64 bit boundary.
 *
 * The size of the buffer is in bytes, but is it assumed that it is
 * always ok to read a complete multiple of 64 bits at the end
 * of the block in case the end is no aligned to a natural boundary.
 *
 * Return: the block number (bitmap buffer scope) that was found
 */

static u32 gfs2_bitfit(const u8 *buf, const unsigned int len,
                       u32 goal, u8 state)
{
        u32 spoint = (goal << 1) & ((8*sizeof(u64)) - 1);
        const __le64 *ptr = ((__le64 *)buf) + (goal >> 5);
        const __le64 *end = (__le64 *)(buf + ALIGN(len, sizeof(u64)));
        u64 tmp;
        u64 mask = 0x5555555555555555ULL;
        u32 bit;

        /* Mask off bits we don't care about at the start of the search */
        mask <<= spoint;
        tmp = gfs2_bit_search(ptr, mask, state);
        ptr++;
        while(tmp == 0 && ptr < end) {
                tmp = gfs2_bit_search(ptr, 0x5555555555555555ULL, state);
                ptr++;
        }
        /* Mask off any bits which are more than len bytes from the start */
        if (ptr == end && (len & (sizeof(u64) - 1)))
                tmp &= (((u64)~0) >> (64 - 8*(len & (sizeof(u64) - 1))));
        /* Didn't find anything, so return */
        if (tmp == 0)
                return BFITNOENT;
        ptr--;
        bit = __ffs64(tmp);
        bit /= 2;       /* two bits per entry in the bitmap */
        return (((const unsigned char *)ptr - buf) * GFS2_NBBY) + bit;
}

/**
 * gfs2_rbm_from_block - Set the rbm based upon rgd and block number
 * @rbm: The rbm with rgd already set correctly
 * @block: The block number (filesystem relative)
 *
 * This sets the bi and offset members of an rbm based on a
 * resource group and a filesystem relative block number. The
 * resource group must be set in the rbm on entry, the bi and
 * offset members will be set by this function.
 *
 * Returns: 0 on success, or an error code
 */

static int gfs2_rbm_from_block(struct gfs2_rbm *rbm, u64 block)
{
        u64 rblock = block - rbm->rgd->rd_data0;
        u32 x;

        if (WARN_ON_ONCE(rblock > UINT_MAX))
                return -EINVAL;
        if (block >= rbm->rgd->rd_data0 + rbm->rgd->rd_data)
                return -E2BIG;

        rbm->bi = rbm->rgd->rd_bits;
        rbm->offset = (u32)(rblock);
        /* Check if the block is within the first block */
        if (rbm->offset < (rbm->bi->bi_start + rbm->bi->bi_len) * GFS2_NBBY)
                return 0;

        /* Adjust for the size diff between gfs2_meta_header and gfs2_rgrp */
        rbm->offset += (sizeof(struct gfs2_rgrp) -
                        sizeof(struct gfs2_meta_header)) * GFS2_NBBY;
        x = rbm->offset / rbm->rgd->rd_sbd->sd_blocks_per_bitmap;
        rbm->offset -= x * rbm->rgd->rd_sbd->sd_blocks_per_bitmap;
        rbm->bi += x;
        return 0;
}

/**
 * gfs2_unaligned_extlen - Look for free blocks which are not byte aligned
 * @rbm: Position to search (value/result)
 * @n_unaligned: Number of unaligned blocks to check
 * @len: Decremented for each block found (terminate on zero)
 *
 * Returns: true if a non-free block is encountered
 */

static bool gfs2_unaligned_extlen(struct gfs2_rbm *rbm, u32 n_unaligned, u32 *len)
{
        u64 block;
        u32 n;
        u8 res;

        for (n = 0; n < n_unaligned; n++) {
                res = gfs2_testbit(rbm);
                if (res != GFS2_BLKST_FREE)
                        return true;
                (*len)--;
                if (*len == 0)
                        return true;
                block = gfs2_rbm_to_block(rbm);
                if (gfs2_rbm_from_block(rbm, block + 1))
                        return true;
        }

        return false;
}

/**
 * gfs2_free_extlen - Return extent length of free blocks
 * @rbm: Starting position
 * @len: Max length to check
 *
 * Starting at the block specified by the rbm, see how many free blocks
 * there are, not reading more than len blocks ahead. This can be done
 * using memchr_inv when the blocks are byte aligned, but has to be done
 * on a block by block basis in case of unaligned blocks. Also this
 * function can cope with bitmap boundaries (although it must stop on
 * a resource group boundary)
 *
 * Returns: Number of free blocks in the extent
 */

static u32 gfs2_free_extlen(const struct gfs2_rbm *rrbm, u32 len)
{
        struct gfs2_rbm rbm = *rrbm;
        u32 n_unaligned = rbm.offset & 3;
        u32 size = len;
        u32 bytes;
        u32 chunk_size;
        u8 *ptr, *start, *end;
        u64 block;

        if (n_unaligned &&
            gfs2_unaligned_extlen(&rbm, 4 - n_unaligned, &len))
                goto out;

        n_unaligned = len & 3;
        /* Start is now byte aligned */
        while (len > 3) {
                start = rbm.bi->bi_bh->b_data;
                if (rbm.bi->bi_clone)
                        start = rbm.bi->bi_clone;
                end = start + rbm.bi->bi_bh->b_size;
                start += rbm.bi->bi_offset;
                BUG_ON(rbm.offset & 3);
                start += (rbm.offset / GFS2_NBBY);
                bytes = min_t(u32, len / GFS2_NBBY, (end - start));
                ptr = memchr_inv(start, 0, bytes);
                chunk_size = ((ptr == NULL) ? bytes : (ptr - start));
                chunk_size *= GFS2_NBBY;
                BUG_ON(len < chunk_size);
                len -= chunk_size;
                block = gfs2_rbm_to_block(&rbm);
                if (gfs2_rbm_from_block(&rbm, block + chunk_size)) {
                        n_unaligned = 0;
                        break;
                }
                if (ptr) {
                        n_unaligned = 3;
                        break;
                }
                n_unaligned = len & 3;
        }

        /* Deal with any bits left over at the end */
        if (n_unaligned)
                gfs2_unaligned_extlen(&rbm, n_unaligned, &len);
out:
        return size - len;
}

/**
 * gfs2_bitcount - count the number of bits in a certain state
 * @rgd: the resource group descriptor
 * @buffer: the buffer that holds the bitmaps
 * @buflen: the length (in bytes) of the buffer
 * @state: the state of the block we're looking for
 *
 * Returns: The number of bits
 */

static u32 gfs2_bitcount(struct gfs2_rgrpd *rgd, const u8 *buffer,
                         unsigned int buflen, u8 state)
{
        const u8 *byte = buffer;
        const u8 *end = buffer + buflen;
        const u8 state1 = state << 2;
        const u8 state2 = state << 4;
        const u8 state3 = state << 6;
        u32 count = 0;

        for (; byte < end; byte++) {
                if (((*byte) & 0x03) == state)
                        count++;
                if (((*byte) & 0x0C) == state1)
                        count++;
                if (((*byte) & 0x30) == state2)
                        count++;
                if (((*byte) & 0xC0) == state3)
                        count++;
        }

        return count;
}

/**
 * gfs2_rgrp_verify - Verify that a resource group is consistent
 * @rgd: the rgrp
 *
 */

void gfs2_rgrp_verify(struct gfs2_rgrpd *rgd)
{
        struct gfs2_sbd *sdp = rgd->rd_sbd;
        struct gfs2_bitmap *bi = NULL;
        u32 length = rgd->rd_length;
        u32 count[4], tmp;
        int buf, x;

        memset(count, 0, 4 * sizeof(u32));

        /* Count # blocks in each of 4 possible allocation states */
        for (buf = 0; buf < length; buf++) {
                bi = rgd->rd_bits + buf;
                for (x = 0; x < 4; x++)
                        count[x] += gfs2_bitcount(rgd,
                                                  bi->bi_bh->b_data +
                                                  bi->bi_offset,
                                                  bi->bi_len, x);
        }

        if (count[0] != rgd->rd_free) {
                if (gfs2_consist_rgrpd(rgd))
                        fs_err(sdp, "free data mismatch:  %u != %u\n",
                               count[0], rgd->rd_free);
                return;
        }

        tmp = rgd->rd_data - rgd->rd_free - rgd->rd_dinodes;
        if (count[1] != tmp) {
                if (gfs2_consist_rgrpd(rgd))
                        fs_err(sdp, "used data mismatch:  %u != %u\n",
                               count[1], tmp);
                return;
        }

        if (count[2] + count[3] != rgd->rd_dinodes) {
                if (gfs2_consist_rgrpd(rgd))
                        fs_err(sdp, "used metadata mismatch:  %u != %u\n",
                               count[2] + count[3], rgd->rd_dinodes);
                return;
        }
}

static inline int rgrp_contains_block(struct gfs2_rgrpd *rgd, u64 block)
{
        u64 first = rgd->rd_data0;
        u64 last = first + rgd->rd_data;
        return first <= block && block < last;
}

/**
 * gfs2_blk2rgrpd - Find resource group for a given data/meta block number
 * @sdp: The GFS2 superblock
 * @blk: The data block number
 * @exact: True if this needs to be an exact match
 *
 * Returns: The resource group, or NULL if not found
 */

struct gfs2_rgrpd *gfs2_blk2rgrpd(struct gfs2_sbd *sdp, u64 blk, bool exact)
{
        struct rb_node *n, *next;
        struct gfs2_rgrpd *cur;

        spin_lock(&sdp->sd_rindex_spin);
        n = sdp->sd_rindex_tree.rb_node;
        while (n) {
                cur = rb_entry(n, struct gfs2_rgrpd, rd_node);
                next = NULL;
                if (blk < cur->rd_addr)
                        next = n->rb_left;
                else if (blk >= cur->rd_data0 + cur->rd_data)
                        next = n->rb_right;
                if (next == NULL) {
                        spin_unlock(&sdp->sd_rindex_spin);
                        if (exact) {
                                if (blk < cur->rd_addr)
                                        return NULL;
                                if (blk >= cur->rd_data0 + cur->rd_data)
                                        return NULL;
                        }
                        return cur;
                }
                n = next;
        }
        spin_unlock(&sdp->sd_rindex_spin);

        return NULL;
}

/**
 * gfs2_rgrpd_get_first - get the first Resource Group in the filesystem
 * @sdp: The GFS2 superblock
 *
 * Returns: The first rgrp in the filesystem
 */

struct gfs2_rgrpd *gfs2_rgrpd_get_first(struct gfs2_sbd *sdp)
{
        const struct rb_node *n;
        struct gfs2_rgrpd *rgd;

        spin_lock(&sdp->sd_rindex_spin);
        n = rb_first(&sdp->sd_rindex_tree);
        rgd = rb_entry(n, struct gfs2_rgrpd, rd_node);
        spin_unlock(&sdp->sd_rindex_spin);

        return rgd;
}

/**
 * gfs2_rgrpd_get_next - get the next RG
 * @rgd: the resource group descriptor
 *
 * Returns: The next rgrp
 */

struct gfs2_rgrpd *gfs2_rgrpd_get_next(struct gfs2_rgrpd *rgd)
{
        struct gfs2_sbd *sdp = rgd->rd_sbd;
        const struct rb_node *n;

        spin_lock(&sdp->sd_rindex_spin);
        n = rb_next(&rgd->rd_node);
        if (n == NULL)
                n = rb_first(&sdp->sd_rindex_tree);

        if (unlikely(&rgd->rd_node == n)) {
                spin_unlock(&sdp->sd_rindex_spin);
                return NULL;
        }
        rgd = rb_entry(n, struct gfs2_rgrpd, rd_node);
        spin_unlock(&sdp->sd_rindex_spin);
        return rgd;
}

void gfs2_free_clones(struct gfs2_rgrpd *rgd)
{
        int x;

        for (x = 0; x < rgd->rd_length; x++) {
                struct gfs2_bitmap *bi = rgd->rd_bits + x;
                kfree(bi->bi_clone);
                bi->bi_clone = NULL;
        }
}

/**
 * gfs2_rs_alloc - make sure we have a reservation assigned to the inode
 * @ip: the inode for this reservation
 */
int gfs2_rs_alloc(struct gfs2_inode *ip)
{
        int error = 0;

        down_write(&ip->i_rw_mutex);
        if (ip->i_res)
                goto out;

        ip->i_res = kmem_cache_zalloc(gfs2_rsrv_cachep, GFP_NOFS);
        if (!ip->i_res) {
                error = -ENOMEM;
                goto out;
        }

        RB_CLEAR_NODE(&ip->i_res->rs_node);
out:
        up_write(&ip->i_rw_mutex);
        return error;
}

static void dump_rs(struct seq_file *seq, const struct gfs2_blkreserv *rs)
{
        gfs2_print_dbg(seq, "  B: n:%llu s:%llu b:%u f:%u\n",
                       (unsigned long long)rs->rs_inum,
                       (unsigned long long)gfs2_rbm_to_block(&rs->rs_rbm),
                       rs->rs_rbm.offset, rs->rs_free);
}

/**
 * __rs_deltree - remove a multi-block reservation from the rgd tree
 * @rs: The reservation to remove
 *
 */
static void __rs_deltree(struct gfs2_blkreserv *rs)
{
        struct gfs2_rgrpd *rgd;

        if (!gfs2_rs_active(rs))
                return;

        rgd = rs->rs_rbm.rgd;
        trace_gfs2_rs(rs, TRACE_RS_TREEDEL);
        rb_erase(&rs->rs_node, &rgd->rd_rstree);
        RB_CLEAR_NODE(&rs->rs_node);

        if (rs->rs_free) {
                /* return reserved blocks to the rgrp */
                BUG_ON(rs->rs_rbm.rgd->rd_reserved < rs->rs_free);
                rs->rs_rbm.rgd->rd_reserved -= rs->rs_free;
                rs->rs_free = 0;
                clear_bit(GBF_FULL, &rs->rs_rbm.bi->bi_flags);
                smp_mb__after_clear_bit();
        }
}

/**
 * gfs2_rs_deltree - remove a multi-block reservation from the rgd tree
 * @rs: The reservation to remove
 *
 */
void gfs2_rs_deltree(struct gfs2_blkreserv *rs)
{
        struct gfs2_rgrpd *rgd;

        rgd = rs->rs_rbm.rgd;
        if (rgd) {
                spin_lock(&rgd->rd_rsspin);
                __rs_deltree(rs);
                spin_unlock(&rgd->rd_rsspin);
        }
}

/**
 * gfs2_rs_delete - delete a multi-block reservation
 * @ip: The inode for this reservation
 *
 */
void gfs2_rs_delete(struct gfs2_inode *ip)
{
        struct inode *inode = &ip->i_inode;

        down_write(&ip->i_rw_mutex);
        if (ip->i_res && atomic_read(&inode->i_writecount) <= 1) {
                gfs2_rs_deltree(ip->i_res);
                BUG_ON(ip->i_res->rs_free);
                kmem_cache_free(gfs2_rsrv_cachep, ip->i_res);
                ip->i_res = NULL;
        }
        up_write(&ip->i_rw_mutex);
}

/**
 * return_all_reservations - return all reserved blocks back to the rgrp.
 * @rgd: the rgrp that needs its space back
 *
 * We previously reserved a bunch of blocks for allocation. Now we need to
 * give them back. This leave the reservation structures in tact, but removes
 * all of their corresponding "no-fly zones".
 */
static void return_all_reservations(struct gfs2_rgrpd *rgd)
{
        struct rb_node *n;
        struct gfs2_blkreserv *rs;

        spin_lock(&rgd->rd_rsspin);
        while ((n = rb_first(&rgd->rd_rstree))) {
                rs = rb_entry(n, struct gfs2_blkreserv, rs_node);
                __rs_deltree(rs);
        }
        spin_unlock(&rgd->rd_rsspin);
}

void gfs2_clear_rgrpd(struct gfs2_sbd *sdp)
{
        struct rb_node *n;
        struct gfs2_rgrpd *rgd;
        struct gfs2_glock *gl;

        while ((n = rb_first(&sdp->sd_rindex_tree))) {
                rgd = rb_entry(n, struct gfs2_rgrpd, rd_node);
                gl = rgd->rd_gl;

                rb_erase(n, &sdp->sd_rindex_tree);

                if (gl) {
                        spin_lock(&gl->gl_spin);
                        gl->gl_object = NULL;
                        spin_unlock(&gl->gl_spin);
                        gfs2_glock_add_to_lru(gl);
                        gfs2_glock_put(gl);
                }

                gfs2_free_clones(rgd);
                kfree(rgd->rd_bits);
                return_all_reservations(rgd);
                kmem_cache_free(gfs2_rgrpd_cachep, rgd);
        }
}

static void gfs2_rindex_print(const struct gfs2_rgrpd *rgd)
{
        printk(KERN_INFO "  ri_addr = %llu\n", (unsigned long long)rgd->rd_addr);
        printk(KERN_INFO "  ri_length = %u\n", rgd->rd_length);
        printk(KERN_INFO "  ri_data0 = %llu\n", (unsigned long long)rgd->rd_data0);
        printk(KERN_INFO "  ri_data = %u\n", rgd->rd_data);
        printk(KERN_INFO "  ri_bitbytes = %u\n", rgd->rd_bitbytes);
}

/**
 * gfs2_compute_bitstructs - Compute the bitmap sizes
 * @rgd: The resource group descriptor
 *
 * Calculates bitmap descriptors, one for each block that contains bitmap data
 *
 * Returns: errno
 */

static int compute_bitstructs(struct gfs2_rgrpd *rgd)
{
        struct gfs2_sbd *sdp = rgd->rd_sbd;
        struct gfs2_bitmap *bi;
        u32 length = rgd->rd_length; /* # blocks in hdr & bitmap */
        u32 bytes_left, bytes;
        int x;

        if (!length)
                return -EINVAL;

        rgd->rd_bits = kcalloc(length, sizeof(struct gfs2_bitmap), GFP_NOFS);
        if (!rgd->rd_bits)
                return -ENOMEM;

        bytes_left = rgd->rd_bitbytes;

        for (x = 0; x < length; x++) {
                bi = rgd->rd_bits + x;

                bi->bi_flags = 0;
                /* small rgrp; bitmap stored completely in header block */
                if (length == 1) {
                        bytes = bytes_left;
                        bi->bi_offset = sizeof(struct gfs2_rgrp);
                        bi->bi_start = 0;
                        bi->bi_len = bytes;
                /* header block */
                } else if (x == 0) {
                        bytes = sdp->sd_sb.sb_bsize - sizeof(struct gfs2_rgrp);
                        bi->bi_offset = sizeof(struct gfs2_rgrp);
                        bi->bi_start = 0;
                        bi->bi_len = bytes;
                /* last block */
                } else if (x + 1 == length) {
                        bytes = bytes_left;
                        bi->bi_offset = sizeof(struct gfs2_meta_header);
                        bi->bi_start = rgd->rd_bitbytes - bytes_left;
                        bi->bi_len = bytes;
                /* other blocks */
                } else {
                        bytes = sdp->sd_sb.sb_bsize -
                                sizeof(struct gfs2_meta_header);
                        bi->bi_offset = sizeof(struct gfs2_meta_header);
                        bi->bi_start = rgd->rd_bitbytes - bytes_left;
                        bi->bi_len = bytes;
                }

                bytes_left -= bytes;
        }

        if (bytes_left) {
                gfs2_consist_rgrpd(rgd);
                return -EIO;
        }
        bi = rgd->rd_bits + (length - 1);
        if ((bi->bi_start + bi->bi_len) * GFS2_NBBY != rgd->rd_data) {
                if (gfs2_consist_rgrpd(rgd)) {
                        gfs2_rindex_print(rgd);
                        fs_err(sdp, "start=%u len=%u offset=%u\n",
                               bi->bi_start, bi->bi_len, bi->bi_offset);
                }
                return -EIO;
        }

        return 0;
}

/**
 * gfs2_ri_total - Total up the file system space, according to the rindex.
 * @sdp: the filesystem
 *
 */
u64 gfs2_ri_total(struct gfs2_sbd *sdp)
{
        u64 total_data = 0;     
        struct inode *inode = sdp->sd_rindex;
        struct gfs2_inode *ip = GFS2_I(inode);
        char buf[sizeof(struct gfs2_rindex)];
        int error, rgrps;

        for (rgrps = 0;; rgrps++) {
                loff_t pos = rgrps * sizeof(struct gfs2_rindex);

                if (pos + sizeof(struct gfs2_rindex) > i_size_read(inode))
                        break;
                error = gfs2_internal_read(ip, buf, &pos,
                                           sizeof(struct gfs2_rindex));
                if (error != sizeof(struct gfs2_rindex))
                        break;
                total_data += be32_to_cpu(((struct gfs2_rindex *)buf)->ri_data);
        }
        return total_data;
}

static int rgd_insert(struct gfs2_rgrpd *rgd)
{
        struct gfs2_sbd *sdp = rgd->rd_sbd;
        struct rb_node **newn = &sdp->sd_rindex_tree.rb_node, *parent = NULL;

        /* Figure out where to put new node */
        while (*newn) {
                struct gfs2_rgrpd *cur = rb_entry(*newn, struct gfs2_rgrpd,
                                                  rd_node);

                parent = *newn;
                if (rgd->rd_addr < cur->rd_addr)
                        newn = &((*newn)->rb_left);
                else if (rgd->rd_addr > cur->rd_addr)
                        newn = &((*newn)->rb_right);
                else
                        return -EEXIST;
        }

        rb_link_node(&rgd->rd_node, parent, newn);
        rb_insert_color(&rgd->rd_node, &sdp->sd_rindex_tree);
        sdp->sd_rgrps++;
        return 0;
}

/**
 * read_rindex_entry - Pull in a new resource index entry from the disk
 * @ip: Pointer to the rindex inode
 *
 * Returns: 0 on success, > 0 on EOF, error code otherwise
 */

static int read_rindex_entry(struct gfs2_inode *ip)
{
        struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
        loff_t pos = sdp->sd_rgrps * sizeof(struct gfs2_rindex);
        struct gfs2_rindex buf;
        int error;
        struct gfs2_rgrpd *rgd;

        if (pos >= i_size_read(&ip->i_inode))
                return 1;

        error = gfs2_internal_read(ip, (char *)&buf, &pos,
                                   sizeof(struct gfs2_rindex));

        if (error != sizeof(struct gfs2_rindex))
                return (error == 0) ? 1 : error;

        rgd = kmem_cache_zalloc(gfs2_rgrpd_cachep, GFP_NOFS);
        error = -ENOMEM;
        if (!rgd)
                return error;

        rgd->rd_sbd = sdp;
        rgd->rd_addr = be64_to_cpu(buf.ri_addr);
        rgd->rd_length = be32_to_cpu(buf.ri_length);
        rgd->rd_data0 = be64_to_cpu(buf.ri_data0);
        rgd->rd_data = be32_to_cpu(buf.ri_data);
        rgd->rd_bitbytes = be32_to_cpu(buf.ri_bitbytes);
        spin_lock_init(&rgd->rd_rsspin);

        error = compute_bitstructs(rgd);
        if (error)
                goto fail;

        error = gfs2_glock_get(sdp, rgd->rd_addr,
                               &gfs2_rgrp_glops, CREATE, &rgd->rd_gl);
        if (error)
                goto fail;

        rgd->rd_gl->gl_object = rgd;
        rgd->rd_rgl = (struct gfs2_rgrp_lvb *)rgd->rd_gl->gl_lksb.sb_lvbptr;
        rgd->rd_flags &= ~GFS2_RDF_UPTODATE;
        if (rgd->rd_data > sdp->sd_max_rg_data)
                sdp->sd_max_rg_data = rgd->rd_data;
        spin_lock(&sdp->sd_rindex_spin);
        error = rgd_insert(rgd);
        spin_unlock(&sdp->sd_rindex_spin);
        if (!error)
                return 0;

        error = 0; /* someone else read in the rgrp; free it and ignore it */
        gfs2_glock_put(rgd->rd_gl);

fail:
        kfree(rgd->rd_bits);
        kmem_cache_free(gfs2_rgrpd_cachep, rgd);
        return error;
}

/**
 * gfs2_ri_update - Pull in a new resource index from the disk
 * @ip: pointer to the rindex inode
 *
 * Returns: 0 on successful update, error code otherwise
 */

static int gfs2_ri_update(struct gfs2_inode *ip)
{
        struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
        int error;

        do {
                error = read_rindex_entry(ip);
        } while (error == 0);

        if (error < 0)
                return error;

        sdp->sd_rindex_uptodate = 1;
        return 0;
}

/**
 * gfs2_rindex_update - Update the rindex if required
 * @sdp: The GFS2 superblock
 *
 * We grab a lock on the rindex inode to make sure that it doesn't
 * change whilst we are performing an operation. We keep this lock
 * for quite long periods of time compared to other locks. This
 * doesn't matter, since it is shared and it is very, very rarely
 * accessed in the exclusive mode (i.e. only when expanding the filesystem).
 *
 * This makes sure that we're using the latest copy of the resource index
 * special file, which might have been updated if someone expanded the
 * filesystem (via gfs2_grow utility), which adds new resource groups.
 *
 * Returns: 0 on succeess, error code otherwise
 */

int gfs2_rindex_update(struct gfs2_sbd *sdp)
{
        struct gfs2_inode *ip = GFS2_I(sdp->sd_rindex);
        struct gfs2_glock *gl = ip->i_gl;
        struct gfs2_holder ri_gh;
        int error = 0;
        int unlock_required = 0;

        /* Read new copy from disk if we don't have the latest */
        if (!sdp->sd_rindex_uptodate) {
                if (!gfs2_glock_is_locked_by_me(gl)) {
                        error = gfs2_glock_nq_init(gl, LM_ST_SHARED, 0, &ri_gh);
                        if (error)
                                return error;
                        unlock_required = 1;
                }
                if (!sdp->sd_rindex_uptodate)
                        error = gfs2_ri_update(ip);
                if (unlock_required)
                        gfs2_glock_dq_uninit(&ri_gh);
        }

        return error;
}

static void gfs2_rgrp_in(struct gfs2_rgrpd *rgd, const void *buf)
{
        const struct gfs2_rgrp *str = buf;
        u32 rg_flags;

        rg_flags = be32_to_cpu(str->rg_flags);
        rg_flags &= ~GFS2_RDF_MASK;
        rgd->rd_flags &= GFS2_RDF_MASK;
        rgd->rd_flags |= rg_flags;
        rgd->rd_free = be32_to_cpu(str->rg_free);
        rgd->rd_dinodes = be32_to_cpu(str->rg_dinodes);
        rgd->rd_igeneration = be64_to_cpu(str->rg_igeneration);
}

static void gfs2_rgrp_out(struct gfs2_rgrpd *rgd, void *buf)
{
        struct gfs2_rgrp *str = buf;

        str->rg_flags = cpu_to_be32(rgd->rd_flags & ~GFS2_RDF_MASK);
        str->rg_free = cpu_to_be32(rgd->rd_free);
        str->rg_dinodes = cpu_to_be32(rgd->rd_dinodes);
        str->__pad = cpu_to_be32(0);
        str->rg_igeneration = cpu_to_be64(rgd->rd_igeneration);
        memset(&str->rg_reserved, 0, sizeof(str->rg_reserved));
}

static int gfs2_rgrp_lvb_valid(struct gfs2_rgrpd *rgd)
{
        struct gfs2_rgrp_lvb *rgl = rgd->rd_rgl;
        struct gfs2_rgrp *str = (struct gfs2_rgrp *)rgd->rd_bits[0].bi_bh->b_data;

        if (rgl->rl_flags != str->rg_flags || rgl->rl_free != str->rg_free ||
            rgl->rl_dinodes != str->rg_dinodes ||
            rgl->rl_igeneration != str->rg_igeneration)
                return 0;
        return 1;
}

static void gfs2_rgrp_ondisk2lvb(struct gfs2_rgrp_lvb *rgl, const void *buf)
{
        const struct gfs2_rgrp *str = buf;

        rgl->rl_magic = cpu_to_be32(GFS2_MAGIC);
        rgl->rl_flags = str->rg_flags;
        rgl->rl_free = str->rg_free;
        rgl->rl_dinodes = str->rg_dinodes;
        rgl->rl_igeneration = str->rg_igeneration;
        rgl->__pad = 0UL;
}

static void update_rgrp_lvb_unlinked(struct gfs2_rgrpd *rgd, u32 change)
{
        struct gfs2_rgrp_lvb *rgl = rgd->rd_rgl;
        u32 unlinked = be32_to_cpu(rgl->rl_unlinked) + change;
        rgl->rl_unlinked = cpu_to_be32(unlinked);
}

static u32 count_unlinked(struct gfs2_rgrpd *rgd)
{
        struct gfs2_bitmap *bi;
        const u32 length = rgd->rd_length;
        const u8 *buffer = NULL;
        u32 i, goal, count = 0;

        for (i = 0, bi = rgd->rd_bits; i < length; i++, bi++) {
                goal = 0;
                buffer = bi->bi_bh->b_data + bi->bi_offset;
                WARN_ON(!buffer_uptodate(bi->bi_bh));
                while (goal < bi->bi_len * GFS2_NBBY) {
                        goal = gfs2_bitfit(buffer, bi->bi_len, goal,
                                           GFS2_BLKST_UNLINKED);
                        if (goal == BFITNOENT)
                                break;
                        count++;
                        goal++;
                }
        }

        return count;
}


/**
 * gfs2_rgrp_bh_get - Read in a RG's header and bitmaps
 * @rgd: the struct gfs2_rgrpd describing the RG to read in
 *
 * Read in all of a Resource Group's header and bitmap blocks.
 * Caller must eventually call gfs2_rgrp_relse() to free the bitmaps.
 *
 * Returns: errno
 */

int gfs2_rgrp_bh_get(struct gfs2_rgrpd *rgd)
{
        struct gfs2_sbd *sdp = rgd->rd_sbd;
        struct gfs2_glock *gl = rgd->rd_gl;
        unsigned int length = rgd->rd_length;
        struct gfs2_bitmap *bi;
        unsigned int x, y;
        int error;

        if (rgd->rd_bits[0].bi_bh != NULL)
                return 0;

        for (x = 0; x < length; x++) {
                bi = rgd->rd_bits + x;
                error = gfs2_meta_read(gl, rgd->rd_addr + x, 0, &bi->bi_bh);
                if (error)
                        goto fail;
        }

        for (y = length; y--;) {
                bi = rgd->rd_bits + y;
                error = gfs2_meta_wait(sdp, bi->bi_bh);
                if (error)
                        goto fail;
                if (gfs2_metatype_check(sdp, bi->bi_bh, y ? GFS2_METATYPE_RB :
                                              GFS2_METATYPE_RG)) {
                        error = -EIO;
                        goto fail;
                }
        }

        if (!(rgd->rd_flags & GFS2_RDF_UPTODATE)) {
                for (x = 0; x < length; x++)
                        clear_bit(GBF_FULL, &rgd->rd_bits[x].bi_flags);
                gfs2_rgrp_in(rgd, (rgd->rd_bits[0].bi_bh)->b_data);
                rgd->rd_flags |= (GFS2_RDF_UPTODATE | GFS2_RDF_CHECK);
                rgd->rd_free_clone = rgd->rd_free;
        }
        if (be32_to_cpu(GFS2_MAGIC) != rgd->rd_rgl->rl_magic) {
                rgd->rd_rgl->rl_unlinked = cpu_to_be32(count_unlinked(rgd));
                gfs2_rgrp_ondisk2lvb(rgd->rd_rgl,
                                     rgd->rd_bits[0].bi_bh->b_data);
        }
        else if (sdp->sd_args.ar_rgrplvb) {
                if (!gfs2_rgrp_lvb_valid(rgd)){
                        gfs2_consist_rgrpd(rgd);
                        error = -EIO;
                        goto fail;
                }
                if (rgd->rd_rgl->rl_unlinked == 0)
                        rgd->rd_flags &= ~GFS2_RDF_CHECK;
        }
        return 0;

fail:
        while (x--) {
                bi = rgd->rd_bits + x;
                brelse(bi->bi_bh);
                bi->bi_bh = NULL;
                gfs2_assert_warn(sdp, !bi->bi_clone);
        }

        return error;
}

int update_rgrp_lvb(struct gfs2_rgrpd *rgd)
{
        u32 rl_flags;

        if (rgd->rd_flags & GFS2_RDF_UPTODATE)
                return 0;

        if (be32_to_cpu(GFS2_MAGIC) != rgd->rd_rgl->rl_magic)
                return gfs2_rgrp_bh_get(rgd);

        rl_flags = be32_to_cpu(rgd->rd_rgl->rl_flags);
        rl_flags &= ~GFS2_RDF_MASK;
        rgd->rd_flags &= GFS2_RDF_MASK;
        rgd->rd_flags |= (rl_flags | GFS2_RDF_UPTODATE | GFS2_RDF_CHECK);
        if (rgd->rd_rgl->rl_unlinked == 0)
                rgd->rd_flags &= ~GFS2_RDF_CHECK;
        rgd->rd_free = be32_to_cpu(rgd->rd_rgl->rl_free);
        rgd->rd_free_clone = rgd->rd_free;
        rgd->rd_dinodes = be32_to_cpu(rgd->rd_rgl->rl_dinodes);
        rgd->rd_igeneration = be64_to_cpu(rgd->rd_rgl->rl_igeneration);
        return 0;
}

int gfs2_rgrp_go_lock(struct gfs2_holder *gh)
{
        struct gfs2_rgrpd *rgd = gh->gh_gl->gl_object;
        struct gfs2_sbd *sdp = rgd->rd_sbd;

        if (gh->gh_flags & GL_SKIP && sdp->sd_args.ar_rgrplvb)
                return 0;
        return gfs2_rgrp_bh_get((struct gfs2_rgrpd *)gh->gh_gl->gl_object);
}

/**
 * gfs2_rgrp_go_unlock - Release RG bitmaps read in with gfs2_rgrp_bh_get()
 * @gh: The glock holder for the resource group
 *
 */

void gfs2_rgrp_go_unlock(struct gfs2_holder *gh)
{
        struct gfs2_rgrpd *rgd = gh->gh_gl->gl_object;
        int x, length = rgd->rd_length;

        for (x = 0; x < length; x++) {
                struct gfs2_bitmap *bi = rgd->rd_bits + x;
                if (bi->bi_bh) {
                        brelse(bi->bi_bh);
                        bi->bi_bh = NULL;
                }
        }

}

int gfs2_rgrp_send_discards(struct gfs2_sbd *sdp, u64 offset,
                             struct buffer_head *bh,
                             const struct gfs2_bitmap *bi, unsigned minlen, u64 *ptrimmed)
{
        struct super_block *sb = sdp->sd_vfs;
        u64 blk;
        sector_t start = 0;
        sector_t nr_blks = 0;
        int rv;
        unsigned int x;
        u32 trimmed = 0;
        u8 diff;

        for (x = 0; x < bi->bi_len; x++) {
                const u8 *clone = bi->bi_clone ? bi->bi_clone : bi->bi_bh->b_data;
                clone += bi->bi_offset;
                clone += x;
                if (bh) {
                        const u8 *orig = bh->b_data + bi->bi_offset + x;
                        diff = ~(*orig | (*orig >> 1)) & (*clone | (*clone >> 1));
                } else {
                        diff = ~(*clone | (*clone >> 1));
                }
                diff &= 0x55;
                if (diff == 0)
                        continue;
                blk = offset + ((bi->bi_start + x) * GFS2_NBBY);
                while(diff) {
                        if (diff & 1) {
                                if (nr_blks == 0)
                                        goto start_new_extent;
                                if ((start + nr_blks) != blk) {
                                        if (nr_blks >= minlen) {
                                                rv = sb_issue_discard(sb,
                                                        start, nr_blks,
                                                        GFP_NOFS, 0);
                                                if (rv)
                                                        goto fail;
                                                trimmed += nr_blks;
                                        }
                                        nr_blks = 0;
start_new_extent:
                                        start = blk;
                                }
                                nr_blks++;
                        }
                        diff >>= 2;
                        blk++;
                }
        }
        if (nr_blks >= minlen) {
                rv = sb_issue_discard(sb, start, nr_blks, GFP_NOFS, 0);
                if (rv)
                        goto fail;
                trimmed += nr_blks;
        }
        if (ptrimmed)
                *ptrimmed = trimmed;
        return 0;

fail:
        if (sdp->sd_args.ar_discard)
                fs_warn(sdp, "error %d on discard request, turning discards off for this filesystem", rv);
        sdp->sd_args.ar_discard = 0;
        return -EIO;
}

/**
 * gfs2_fitrim - Generate discard requests for unused bits of the filesystem
 * @filp: Any file on the filesystem
 * @argp: Pointer to the arguments (also used to pass result)
 *
 * Returns: 0 on success, otherwise error code
 */

int gfs2_fitrim(struct file *filp, void __user *argp)
{
        struct inode *inode = file_inode(filp);
        struct gfs2_sbd *sdp = GFS2_SB(inode);
        struct request_queue *q = bdev_get_queue(sdp->sd_vfs->s_bdev);
        struct buffer_head *bh;
        struct gfs2_rgrpd *rgd;
        struct gfs2_rgrpd *rgd_end;
        struct gfs2_holder gh;
        struct fstrim_range r;
        int ret = 0;
        u64 amt;
        u64 trimmed = 0;
        u64 start, end, minlen;
        unsigned int x;
        unsigned bs_shift = sdp->sd_sb.sb_bsize_shift;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        if (!blk_queue_discard(q))
                return -EOPNOTSUPP;

        if (copy_from_user(&r, argp, sizeof(r)))
                return -EFAULT;

        ret = gfs2_rindex_update(sdp);
        if (ret)
                return ret;

        start = r.start >> bs_shift;
        end = start + (r.len >> bs_shift);
        minlen = max_t(u64, r.minlen,
                       q->limits.discard_granularity) >> bs_shift;

        rgd = gfs2_blk2rgrpd(sdp, start, 0);
        rgd_end = gfs2_blk2rgrpd(sdp, end - 1, 0);

        if (end <= start ||
            minlen > sdp->sd_max_rg_data ||
            start > rgd_end->rd_data0 + rgd_end->rd_data)
                return -EINVAL;

        while (1) {

                ret = gfs2_glock_nq_init(rgd->rd_gl, LM_ST_EXCLUSIVE, 0, &gh);
                if (ret)
                        goto out;

                if (!(rgd->rd_flags & GFS2_RGF_TRIMMED)) {
                        /* Trim each bitmap in the rgrp */
                        for (x = 0; x < rgd->rd_length; x++) {
                                struct gfs2_bitmap *bi = rgd->rd_bits + x;
                                ret = gfs2_rgrp_send_discards(sdp,
                                                rgd->rd_data0, NULL, bi, minlen,
                                                &amt);
                                if (ret) {
                                        gfs2_glock_dq_uninit(&gh);
                                        goto out;
                                }
                                trimmed += amt;
                        }

                        /* Mark rgrp as having been trimmed */
                        ret = gfs2_trans_begin(sdp, RES_RG_HDR, 0);
                        if (ret == 0) {
                                bh = rgd->rd_bits[0].bi_bh;
                                rgd->rd_flags |= GFS2_RGF_TRIMMED;
                                gfs2_trans_add_meta(rgd->rd_gl, bh);
                                gfs2_rgrp_out(rgd, bh->b_data);
                                gfs2_rgrp_ondisk2lvb(rgd->rd_rgl, bh->b_data);
                                gfs2_trans_end(sdp);
                        }
                }
                gfs2_glock_dq_uninit(&gh);

                if (rgd == rgd_end)
                        break;

                rgd = gfs2_rgrpd_get_next(rgd);
        }

out:
        r.len = trimmed << 9;
        if (copy_to_user(argp, &r, sizeof(r)))
                return -EFAULT;

        return ret;
}

/**
 * rs_insert - insert a new multi-block reservation into the rgrp's rb_tree
 * @ip: the inode structure
 *
 */
static void rs_insert(struct gfs2_inode *ip)
{
        struct rb_node **newn, *parent = NULL;
        int rc;
        struct gfs2_blkreserv *rs = ip->i_res;
        struct gfs2_rgrpd *rgd = rs->rs_rbm.rgd;
        u64 fsblock = gfs2_rbm_to_block(&rs->rs_rbm);

        BUG_ON(gfs2_rs_active(rs));

        spin_lock(&rgd->rd_rsspin);
        newn = &rgd->rd_rstree.rb_node;
        while (*newn) {
                struct gfs2_blkreserv *cur =
                        rb_entry(*newn, struct gfs2_blkreserv, rs_node);

                parent = *newn;
                rc = rs_cmp(fsblock, rs->rs_free, cur);
                if (rc > 0)
                        newn = &((*newn)->rb_right);
                else if (rc < 0)
                        newn = &((*newn)->rb_left);
                else {
                        spin_unlock(&rgd->rd_rsspin);
                        WARN_ON(1);
                        return;
                }
        }

        rb_link_node(&rs->rs_node, parent, newn);
        rb_insert_color(&rs->rs_node, &rgd->rd_rstree);

        /* Do our rgrp accounting for the reservation */
        rgd->rd_reserved += rs->rs_free; /* blocks reserved */
        spin_unlock(&rgd->rd_rsspin);
        trace_gfs2_rs(rs, TRACE_RS_INSERT);
}

/**
 * rg_mblk_search - find a group of multiple free blocks to form a reservation
 * @rgd: the resource group descriptor
 * @ip: pointer to the inode for which we're reserving blocks
 * @requested: number of blocks required for this allocation
 *
 */

static void rg_mblk_search(struct gfs2_rgrpd *rgd, struct gfs2_inode *ip,
                           unsigned requested)
{
        struct gfs2_rbm rbm = { .rgd = rgd, };
        u64 goal;
        struct gfs2_blkreserv *rs = ip->i_res;
        u32 extlen;
        u32 free_blocks = rgd->rd_free_clone - rgd->rd_reserved;
        int ret;
        struct inode *inode = &ip->i_inode;

        if (S_ISDIR(inode->i_mode))
                extlen = 1;
        else {
                extlen = max_t(u32, atomic_read(&rs->rs_sizehint), requested);
                extlen = clamp(extlen, RGRP_RSRV_MINBLKS, free_blocks);
        }
        if ((rgd->rd_free_clone < rgd->rd_reserved) || (free_blocks < extlen))
                return;

        /* Find bitmap block that contains bits for goal block */
        if (rgrp_contains_block(rgd, ip->i_goal))
                goal = ip->i_goal;
        else
                goal = rgd->rd_last_alloc + rgd->rd_data0;

        if (WARN_ON(gfs2_rbm_from_block(&rbm, goal)))
                return;

        ret = gfs2_rbm_find(&rbm, GFS2_BLKST_FREE, extlen, ip, true);
        if (ret == 0) {
                rs->rs_rbm = rbm;
                rs->rs_free = extlen;
                rs->rs_inum = ip->i_no_addr;
                rs_insert(ip);
        } else {
                if (goal == rgd->rd_last_alloc + rgd->rd_data0)
                        rgd->rd_last_alloc = 0;
        }
}

/**
 * gfs2_next_unreserved_block - Return next block that is not reserved
 * @rgd: The resource group
 * @block: The starting block
 * @length: The required length
 * @ip: Ignore any reservations for this inode
 *
 * If the block does not appear in any reservation, then return the
 * block number unchanged. If it does appear in the reservation, then
 * keep looking through the tree of reservations in order to find the
 * first block number which is not reserved.
 */

static u64 gfs2_next_unreserved_block(struct gfs2_rgrpd *rgd, u64 block,
                                      u32 length,
                                      const struct gfs2_inode *ip)
{
        struct gfs2_blkreserv *rs;
        struct rb_node *n;
        int rc;

        spin_lock(&rgd->rd_rsspin);
        n = rgd->rd_rstree.rb_node;
        while (n) {
                rs = rb_entry(n, struct gfs2_blkreserv, rs_node);
                rc = rs_cmp(block, length, rs);
                if (rc < 0)
                        n = n->rb_left;
                else if (rc > 0)
                        n = n->rb_right;
                else
                        break;
        }

        if (n) {
                while ((rs_cmp(block, length, rs) == 0) && (ip->i_res != rs)) {
                        block = gfs2_rbm_to_block(&rs->rs_rbm) + rs->rs_free;
                        n = n->rb_right;
                        if (n == NULL)
                                break;
                        rs = rb_entry(n, struct gfs2_blkreserv, rs_node);
                }
        }

        spin_unlock(&rgd->rd_rsspin);
        return block;
}

/**
 * gfs2_reservation_check_and_update - Check for reservations during block alloc
 * @rbm: The current position in the resource group
 * @ip: The inode for which we are searching for blocks
 * @minext: The minimum extent length
 *
 * This checks the current position in the rgrp to see whether there is
 * a reservation covering this block. If not then this function is a
 * no-op. If there is, then the position is moved to the end of the
 * contiguous reservation(s) so that we are pointing at the first
 * non-reserved block.
 *
 * Returns: 0 if no reservation, 1 if @rbm has changed, otherwise an error
 */

static int gfs2_reservation_check_and_update(struct gfs2_rbm *rbm,
                                             const struct gfs2_inode *ip,
                                             u32 minext)
{
        u64 block = gfs2_rbm_to_block(rbm);
        u32 extlen = 1;
        u64 nblock;
        int ret;

        /*
         * If we have a minimum extent length, then skip over any extent
         * which is less than the min extent length in size.
         */
        if (minext) {
                extlen = gfs2_free_extlen(rbm, minext);
                nblock = block + extlen;
                if (extlen < minext)
                        goto fail;
        }

        /*
         * Check the extent which has been found against the reservations
         * and skip if parts of it are already reserved
         */
        nblock = gfs2_next_unreserved_block(rbm->rgd, block, extlen, ip);
        if (nblock == block)
                return 0;
fail:
        ret = gfs2_rbm_from_block(rbm, nblock);
        if (ret < 0)
                return ret;
        return 1;
}

/**
 * gfs2_rbm_find - Look for blocks of a particular state
 * @rbm: Value/result starting position and final position
 * @state: The state which we want to find
 * @minext: The requested extent length (0 for a single block)
 * @ip: If set, check for reservations
 * @nowrap: Stop looking at the end of the rgrp, rather than wrapping
 *          around until we've reached the starting point.
 *
 * Side effects:
 * - If looking for free blocks, we set GBF_FULL on each bitmap which
 *   has no free blocks in it.
 *
 * Returns: 0 on success, -ENOSPC if there is no block of the requested state
 */

static int gfs2_rbm_find(struct gfs2_rbm *rbm, u8 state, u32 minext,
                         const struct gfs2_inode *ip, bool nowrap)
{
        struct buffer_head *bh;
        struct gfs2_bitmap *initial_bi;
        u32 initial_offset;
        u32 offset;
        u8 *buffer;
        int index;
        int n = 0;
        int iters = rbm->rgd->rd_length;
        int ret;

        /* If we are not starting at the beginning of a bitmap, then we
         * need to add one to the bitmap count to ensure that we search
         * the starting bitmap twice.
         */
        if (rbm->offset != 0)
                iters++;

        while(1) {
                if (test_bit(GBF_FULL, &rbm->bi->bi_flags) &&
                    (state == GFS2_BLKST_FREE))
                        goto next_bitmap;

                bh = rbm->bi->bi_bh;
                buffer = bh->b_data + rbm->bi->bi_offset;
                WARN_ON(!buffer_uptodate(bh));
                if (state != GFS2_BLKST_UNLINKED && rbm->bi->bi_clone)
                        buffer = rbm->bi->bi_clone + rbm->bi->bi_offset;
                initial_offset = rbm->offset;
                offset = gfs2_bitfit(buffer, rbm->bi->bi_len, rbm->offset, state);
                if (offset == BFITNOENT)
                        goto bitmap_full;
                rbm->offset = offset;
                if (ip == NULL)
                        return 0;

                initial_bi = rbm->bi;
                ret = gfs2_reservation_check_and_update(rbm, ip, minext);
                if (ret == 0)
                        return 0;
                if (ret > 0) {
                        n += (rbm->bi - initial_bi);
                        goto next_iter;
                }
                if (ret == -E2BIG) {
                        index = 0;
                        rbm->offset = 0;
                        n += (rbm->bi - initial_bi);
                        goto res_covered_end_of_rgrp;
                }
                return ret;

bitmap_full:    /* Mark bitmap as full and fall through */
                if ((state == GFS2_BLKST_FREE) && initial_offset == 0)
                        set_bit(GBF_FULL, &rbm->bi->bi_flags);

next_bitmap:    /* Find next bitmap in the rgrp */
                rbm->offset = 0;
                index = rbm->bi - rbm->rgd->rd_bits;
                index++;
                if (index == rbm->rgd->rd_length)
                        index = 0;
res_covered_end_of_rgrp:
                rbm->bi = &rbm->rgd->rd_bits[index];
                if ((index == 0) && nowrap)
                        break;
                n++;
next_iter:
                if (n >= iters)
                        break;
        }

        return -ENOSPC;
}

/**
 * try_rgrp_unlink - Look for any unlinked, allocated, but unused inodes
 * @rgd: The rgrp
 * @last_unlinked: block address of the last dinode we unlinked
 * @skip: block address we should explicitly not unlink
 *
 * Returns: 0 if no error
 *          The inode, if one has been found, in inode.
 */

static void try_rgrp_unlink(struct gfs2_rgrpd *rgd, u64 *last_unlinked, u64 skip)
{
        u64 block;
        struct gfs2_sbd *sdp = rgd->rd_sbd;
        struct gfs2_glock *gl;
        struct gfs2_inode *ip;
        int error;
        int found = 0;
        struct gfs2_rbm rbm = { .rgd = rgd, .bi = rgd->rd_bits, .offset = 0 };

        while (1) {
                down_write(&sdp->sd_log_flush_lock);
                error = gfs2_rbm_find(&rbm, GFS2_BLKST_UNLINKED, 0, NULL, true);
                up_write(&sdp->sd_log_flush_lock);
                if (error == -ENOSPC)
                        break;
                if (WARN_ON_ONCE(error))
                        break;

                block = gfs2_rbm_to_block(&rbm);
                if (gfs2_rbm_from_block(&rbm, block + 1))
                        break;
                if (*last_unlinked != NO_BLOCK && block <= *last_unlinked)
                        continue;
                if (block == skip)
                        continue;
                *last_unlinked = block;

                error = gfs2_glock_get(sdp, block, &gfs2_inode_glops, CREATE, &gl);
                if (error)
                        continue;

                /* If the inode is already in cache, we can ignore it here
                 * because the existing inode disposal code will deal with
                 * it when all refs have gone away. Accessing gl_object like
                 * this is not safe in general. Here it is ok because we do
                 * not dereference the pointer, and we only need an approx
                 * answer to whether it is NULL or not.
                 */
                ip = gl->gl_object;

                if (ip || queue_work(gfs2_delete_workqueue, &gl->gl_delete) == 0)
                        gfs2_glock_put(gl);
                else
                        found++;

                /* Limit reclaim to sensible number of tasks */
                if (found > NR_CPUS)
                        return;
        }

        rgd->rd_flags &= ~GFS2_RDF_CHECK;
        return;
}

/**
 * gfs2_rgrp_congested - Use stats to figure out whether an rgrp is congested
 * @rgd: The rgrp in question
 * @loops: An indication of how picky we can be (0=very, 1=less so)
 *
 * This function uses the recently added glock statistics in order to
 * figure out whether a parciular resource group is suffering from
 * contention from multiple nodes. This is done purely on the basis
 * of timings, since this is the only data we have to work with and
 * our aim here is to reject a resource group which is highly contended
 * but (very important) not to do this too often in order to ensure that
 * we do not land up introducing fragmentation by changing resource
 * groups when not actually required.
 *
 * The calculation is fairly simple, we want to know whether the SRTTB
 * (i.e. smoothed round trip time for blocking operations) to acquire
 * the lock for this rgrp's glock is significantly greater than the
 * time taken for resource groups on average. We introduce a margin in
 * the form of the variable @var which is computed as the sum of the two
 * respective variences, and multiplied by a factor depending on @loops
 * and whether we have a lot of data to base the decision on. This is
 * then tested against the square difference of the means in order to
 * decide whether the result is statistically significant or not.
 *
 * Returns: A boolean verdict on the congestion status
 */

static bool gfs2_rgrp_congested(const struct gfs2_rgrpd *rgd, int loops)
{
        const struct gfs2_glock *gl = rgd->rd_gl;
        const struct gfs2_sbd *sdp = gl->gl_sbd;
        struct gfs2_lkstats *st;
        s64 r_dcount, l_dcount;
        s64 r_srttb, l_srttb;
        s64 srttb_diff;
        s64 sqr_diff;
        s64 var;

        preempt_disable();
        st = &this_cpu_ptr(sdp->sd_lkstats)->lkstats[LM_TYPE_RGRP];
        r_srttb = st->stats[GFS2_LKS_SRTTB];
        r_dcount = st->stats[GFS2_LKS_DCOUNT];
        var = st->stats[GFS2_LKS_SRTTVARB] +
              gl->gl_stats.stats[GFS2_LKS_SRTTVARB];
        preempt_enable();

        l_srttb = gl->gl_stats.stats[GFS2_LKS_SRTTB];
        l_dcount = gl->gl_stats.stats[GFS2_LKS_DCOUNT];

        if ((l_dcount < 1) || (r_dcount < 1) || (r_srttb == 0))
                return false;

        srttb_diff = r_srttb - l_srttb;
        sqr_diff = srttb_diff * srttb_diff;

        var *= 2;
        if (l_dcount < 8 || r_dcount < 8)
                var *= 2;
        if (loops == 1)
                var *= 2;

        return ((srttb_diff < 0) && (sqr_diff > var));
}

/**
 * gfs2_rgrp_used_recently
 * @rs: The block reservation with the rgrp to test
 * @msecs: The time limit in milliseconds
 *
 * Returns: True if the rgrp glock has been used within the time limit
 */
static bool gfs2_rgrp_used_recently(const struct gfs2_blkreserv *rs,
                                    u64 msecs)
{
        u64 tdiff;

        tdiff = ktime_to_ns(ktime_sub(ktime_get_real(),
                            rs->rs_rbm.rgd->rd_gl->gl_dstamp));

        return tdiff > (msecs * 1000 * 1000);
}

static u32 gfs2_orlov_skip(const struct gfs2_inode *ip)
{
        const struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
        u32 skip;

        get_random_bytes(&skip, sizeof(skip));
        return skip % sdp->sd_rgrps;
}

static bool gfs2_select_rgrp(struct gfs2_rgrpd **pos, const struct gfs2_rgrpd *begin)
{
        struct gfs2_rgrpd *rgd = *pos;
        struct gfs2_sbd *sdp = rgd->rd_sbd;

        rgd = gfs2_rgrpd_get_next(rgd);
        if (rgd == NULL)
                rgd = gfs2_rgrpd_get_first(sdp);
        *pos = rgd;
        if (rgd != begin) /* If we didn't wrap */
                return true;
        return false;
}

/**
 * gfs2_inplace_reserve - Reserve space in the filesystem
 * @ip: the inode to reserve space for
 * @requested: the number of blocks to be reserved
 *
 * Returns: errno
 */

int gfs2_inplace_reserve(struct gfs2_inode *ip, u32 requested, u32 aflags)
{
        struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
        struct gfs2_rgrpd *begin = NULL;
        struct gfs2_blkreserv *rs = ip->i_res;
        int error = 0, rg_locked, flags = 0;
        u64 last_unlinked = NO_BLOCK;
        int loops = 0;
        u32 skip = 0;

        if (sdp->sd_args.ar_rgrplvb)
                flags |= GL_SKIP;
        if (gfs2_assert_warn(sdp, requested))
                return -EINVAL;
        if (gfs2_rs_active(rs)) {
                begin = rs->rs_rbm.rgd;
                flags = 0; /* Yoda: Do or do not. There is no try */
        } else if (ip->i_rgd && rgrp_contains_block(ip->i_rgd, ip->i_goal)) {
                rs->rs_rbm.rgd = begin = ip->i_rgd;
        } else {
                rs->rs_rbm.rgd = begin = gfs2_blk2rgrpd(sdp, ip->i_goal, 1);
        }
        if (S_ISDIR(ip->i_inode.i_mode) && (aflags & GFS2_AF_ORLOV))
                skip = gfs2_orlov_skip(ip);
        if (rs->rs_rbm.rgd == NULL)
                return -EBADSLT;

        while (loops < 3) {
                rg_locked = 1;

                if (!gfs2_glock_is_locked_by_me(rs->rs_rbm.rgd->rd_gl)) {
                        rg_locked = 0;
                        if (skip && skip--)
                                goto next_rgrp;
                        if (!gfs2_rs_active(rs) && (loops < 2) &&
                             gfs2_rgrp_used_recently(rs, 1000) &&
                             gfs2_rgrp_congested(rs->rs_rbm.rgd, loops))
                                goto next_rgrp;
                        error = gfs2_glock_nq_init(rs->rs_rbm.rgd->rd_gl,
                                                   LM_ST_EXCLUSIVE, flags,
                                                   &rs->rs_rgd_gh);
                        if (unlikely(error))
                                return error;
                        if (!gfs2_rs_active(rs) && (loops < 2) &&
                            gfs2_rgrp_congested(rs->rs_rbm.rgd, loops))
                                goto skip_rgrp;
                        if (sdp->sd_args.ar_rgrplvb) {
                                error = update_rgrp_lvb(rs->rs_rbm.rgd);
                                if (unlikely(error)) {
                                        gfs2_glock_dq_uninit(&rs->rs_rgd_gh);
                                        return error;
                                }
                        }
                }

                /* Skip unuseable resource groups */
                if (rs->rs_rbm.rgd->rd_flags & (GFS2_RGF_NOALLOC | GFS2_RDF_ERROR))
                        goto skip_rgrp;

                if (sdp->sd_args.ar_rgrplvb)
                        gfs2_rgrp_bh_get(rs->rs_rbm.rgd);

                /* Get a reservation if we don't already have one */
                if (!gfs2_rs_active(rs))
                        rg_mblk_search(rs->rs_rbm.rgd, ip, requested);

                /* Skip rgrps when we can't get a reservation on first pass */
                if (!gfs2_rs_active(rs) && (loops < 1))
                        goto check_rgrp;

                /* If rgrp has enough free space, use it */
                if (rs->rs_rbm.rgd->rd_free_clone >= requested) {
                        ip->i_rgd = rs->rs_rbm.rgd;
                        return 0;
                }

                /* Drop reservation, if we couldn't use reserved rgrp */
                if (gfs2_rs_active(rs))
                        gfs2_rs_deltree(rs);
check_rgrp:
                /* Check for unlinked inodes which can be reclaimed */
                if (rs->rs_rbm.rgd->rd_flags & GFS2_RDF_CHECK)
                        try_rgrp_unlink(rs->rs_rbm.rgd, &last_unlinked,
                                        ip->i_no_addr);
skip_rgrp:
                /* Unlock rgrp if required */
                if (!rg_locked)
                        gfs2_glock_dq_uninit(&rs->rs_rgd_gh);
next_rgrp:
                /* Find the next rgrp, and continue looking */
                if (gfs2_select_rgrp(&rs->rs_rbm.rgd, begin))
                        continue;
                if (skip)
                        continue;

                /* If we've scanned all the rgrps, but found no free blocks
                 * then this checks for some less likely conditions before
                 * trying again.
                 */
                loops++;
                /* Check that fs hasn't grown if writing to rindex */
                if (ip == GFS2_I(sdp->sd_rindex) && !sdp->sd_rindex_uptodate) {
                        error = gfs2_ri_update(ip);
                        if (error)
                                return error;
                }
                /* Flushing the log may release space */
                if (loops == 2)
                        gfs2_log_flush(sdp, NULL);
        }

        return -ENOSPC;
}

/**
 * gfs2_inplace_release - release an inplace reservation
 * @ip: the inode the reservation was taken out on
 *
 * Release a reservation made by gfs2_inplace_reserve().
 */

void gfs2_inplace_release(struct gfs2_inode *ip)
{
        struct gfs2_blkreserv *rs = ip->i_res;

        if (rs->rs_rgd_gh.gh_gl)
                gfs2_glock_dq_uninit(&rs->rs_rgd_gh);
}

/**
 * gfs2_get_block_type - Check a block in a RG is of given type
 * @rgd: the resource group holding the block
 * @block: the block number
 *
 * Returns: The block type (GFS2_BLKST_*)
 */

static unsigned char gfs2_get_block_type(struct gfs2_rgrpd *rgd, u64 block)
{
        struct gfs2_rbm rbm = { .rgd = rgd, };
        int ret;

        ret = gfs2_rbm_from_block(&rbm, block);
        WARN_ON_ONCE(ret != 0);

        return gfs2_testbit(&rbm);
}


/**
 * gfs2_alloc_extent - allocate an extent from a given bitmap
 * @rbm: the resource group information
 * @dinode: TRUE if the first block we allocate is for a dinode
 * @n: The extent length (value/result)
 *
 * Add the bitmap buffer to the transaction.
 * Set the found bits to @new_state to change block's allocation state.
 */
static void gfs2_alloc_extent(const struct gfs2_rbm *rbm, bool dinode,
                             unsigned int *n)
{
        struct gfs2_rbm pos = { .rgd = rbm->rgd, };
        const unsigned int elen = *n;
        u64 block;
        int ret;

        *n = 1;
        block = gfs2_rbm_to_block(rbm);
        gfs2_trans_add_meta(rbm->rgd->rd_gl, rbm->bi->bi_bh);
        gfs2_setbit(rbm, true, dinode ? GFS2_BLKST_DINODE : GFS2_BLKST_USED);
        block++;
        while (*n < elen) {
                ret = gfs2_rbm_from_block(&pos, block);
                if (ret || gfs2_testbit(&pos) != GFS2_BLKST_FREE)
                        break;
                gfs2_trans_add_meta(pos.rgd->rd_gl, pos.bi->bi_bh);
                gfs2_setbit(&pos, true, GFS2_BLKST_USED);
                (*n)++;
                block++;
        }
}

/**
 * rgblk_free - Change alloc state of given block(s)
 * @sdp: the filesystem
 * @bstart: the start of a run of blocks to free
 * @blen: the length of the block run (all must lie within ONE RG!)
 * @new_state: GFS2_BLKST_XXX the after-allocation block state
 *
 * Returns:  Resource group containing the block(s)
 */

static struct gfs2_rgrpd *rgblk_free(struct gfs2_sbd *sdp, u64 bstart,
                                     u32 blen, unsigned char new_state)
{

        struct gfs2_rbm rbm;

        rbm.rgd = gfs2_blk2rgrpd(sdp, bstart, 1);
        if (!rbm.rgd) {
                if (gfs2_consist(sdp))
                        fs_err(sdp, "block = %llu\n", (unsigned long long)bstart);
                return NULL;
        }

        while (blen--) {
                gfs2_rbm_from_block(&rbm, bstart);
                bstart++;
                if (!rbm.bi->bi_clone) {
                        rbm.bi->bi_clone = kmalloc(rbm.bi->bi_bh->b_size,
                                                   GFP_NOFS | __GFP_NOFAIL);
                        memcpy(rbm.bi->bi_clone + rbm.bi->bi_offset,
                               rbm.bi->bi_bh->b_data + rbm.bi->bi_offset,
                               rbm.bi->bi_len);
                }
                gfs2_trans_add_meta(rbm.rgd->rd_gl, rbm.bi->bi_bh);
                gfs2_setbit(&rbm, false, new_state);
        }

        return rbm.rgd;
}

/**
 * gfs2_rgrp_dump - print out an rgrp
 * @seq: The iterator
 * @gl: The glock in question
 *
 */

int gfs2_rgrp_dump(struct seq_file *seq, const struct gfs2_glock *gl)
{
        struct gfs2_rgrpd *rgd = gl->gl_object;
        struct gfs2_blkreserv *trs;
        const struct rb_node *n;

        if (rgd == NULL)
                return 0;
        gfs2_print_dbg(seq, " R: n:%llu f:%02x b:%u/%u i:%u r:%u\n",
                       (unsigned long long)rgd->rd_addr, rgd->rd_flags,
                       rgd->rd_free, rgd->rd_free_clone, rgd->rd_dinodes,
                       rgd->rd_reserved);
        spin_lock(&rgd->rd_rsspin);
        for (n = rb_first(&rgd->rd_rstree); n; n = rb_next(&trs->rs_node)) {
                trs = rb_entry(n, struct gfs2_blkreserv, rs_node);
                dump_rs(seq, trs);
        }
        spin_unlock(&rgd->rd_rsspin);
        return 0;
}

static void gfs2_rgrp_error(struct gfs2_rgrpd *rgd)
{
        struct gfs2_sbd *sdp = rgd->rd_sbd;
        fs_warn(sdp, "rgrp %llu has an error, marking it readonly until umount\n",
                (unsigned long long)rgd->rd_addr);
        fs_warn(sdp, "umount on all nodes and run fsck.gfs2 to fix the error\n");
        gfs2_rgrp_dump(NULL, rgd->rd_gl);
        rgd->rd_flags |= GFS2_RDF_ERROR;
}

/**
 * gfs2_adjust_reservation - Adjust (or remove) a reservation after allocation
 * @ip: The inode we have just allocated blocks for
 * @rbm: The start of the allocated blocks
 * @len: The extent length
 *
 * Adjusts a reservation after an allocation has taken place. If the
 * reservation does not match the allocation, or if it is now empty
 * then it is removed.
 */

static void gfs2_adjust_reservation(struct gfs2_inode *ip,
                                    const struct gfs2_rbm *rbm, unsigned len)
{
        struct gfs2_blkreserv *rs = ip->i_res;
        struct gfs2_rgrpd *rgd = rbm->rgd;
        unsigned rlen;
        u64 block;
        int ret;

        spin_lock(&rgd->rd_rsspin);
        if (gfs2_rs_active(rs)) {
                if (gfs2_rbm_eq(&rs->rs_rbm, rbm)) {
                        block = gfs2_rbm_to_block(rbm);
                        ret = gfs2_rbm_from_block(&rs->rs_rbm, block + len);
                        rlen = min(rs->rs_free, len);
                        rs->rs_free -= rlen;
                        rgd->rd_reserved -= rlen;
                        trace_gfs2_rs(rs, TRACE_RS_CLAIM);
                        if (rs->rs_free && !ret)
                                goto out;
                }
                __rs_deltree(rs);
        }
out:
        spin_unlock(&rgd->rd_rsspin);
}

/**
 * gfs2_alloc_blocks - Allocate one or more blocks of data and/or a dinode
 * @ip: the inode to allocate the block for
 * @bn: Used to return the starting block number
 * @nblocks: requested number of blocks/extent length (value/result)
 * @dinode: 1 if we're allocating a dinode block, else 0
 * @generation: the generation number of the inode
 *
 * Returns: 0 or error
 */

int gfs2_alloc_blocks(struct gfs2_inode *ip, u64 *bn, unsigned int *nblocks,
                      bool dinode, u64 *generation)
{
        struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
        struct buffer_head *dibh;
        struct gfs2_rbm rbm = { .rgd = ip->i_rgd, };
        unsigned int ndata;
        u64 goal;
        u64 block; /* block, within the file system scope */
        int error;

        if (gfs2_rs_active(ip->i_res))
                goal = gfs2_rbm_to_block(&ip->i_res->rs_rbm);
        else if (!dinode && rgrp_contains_block(rbm.rgd, ip->i_goal))
                goal = ip->i_goal;
        else
                goal = rbm.rgd->rd_last_alloc + rbm.rgd->rd_data0;

        gfs2_rbm_from_block(&rbm, goal);
        error = gfs2_rbm_find(&rbm, GFS2_BLKST_FREE, 0, ip, false);

        if (error == -ENOSPC) {
                gfs2_rbm_from_block(&rbm, goal);
                error = gfs2_rbm_find(&rbm, GFS2_BLKST_FREE, 0, NULL, false);
        }

        /* Since all blocks are reserved in advance, this shouldn't happen */
        if (error) {
                fs_warn(sdp, "inum=%llu error=%d, nblocks=%u, full=%d\n",
                        (unsigned long long)ip->i_no_addr, error, *nblocks,
                        test_bit(GBF_FULL, &rbm.rgd->rd_bits->bi_flags));
                goto rgrp_error;
        }

        gfs2_alloc_extent(&rbm, dinode, nblocks);
        block = gfs2_rbm_to_block(&rbm);
        rbm.rgd->rd_last_alloc = block - rbm.rgd->rd_data0;
        if (gfs2_rs_active(ip->i_res))
                gfs2_adjust_reservation(ip, &rbm, *nblocks);
        ndata = *nblocks;
        if (dinode)
                ndata--;

        if (!dinode) {
                ip->i_goal = block + ndata - 1;
                error = gfs2_meta_inode_buffer(ip, &dibh);
                if (error == 0) {
                        struct gfs2_dinode *di =
                                (struct gfs2_dinode *)dibh->b_data;
                        gfs2_trans_add_meta(ip->i_gl, dibh);
                        di->di_goal_meta = di->di_goal_data =
                                cpu_to_be64(ip->i_goal);
                        brelse(dibh);
                }
        }
        if (rbm.rgd->rd_free < *nblocks) {
                printk(KERN_WARNING "nblocks=%u\n", *nblocks);
                goto rgrp_error;
        }

        rbm.rgd->rd_free -= *nblocks;
        if (dinode) {
                rbm.rgd->rd_dinodes++;
                *generation = rbm.rgd->rd_igeneration++;
                if (*generation == 0)
                        *generation = rbm.rgd->rd_igeneration++;
        }

        gfs2_trans_add_meta(rbm.rgd->rd_gl, rbm.rgd->rd_bits[0].bi_bh);
        gfs2_rgrp_out(rbm.rgd, rbm.rgd->rd_bits[0].bi_bh->b_data);
        gfs2_rgrp_ondisk2lvb(rbm.rgd->rd_rgl, rbm.rgd->rd_bits[0].bi_bh->b_data);

        gfs2_statfs_change(sdp, 0, -(s64)*nblocks, dinode ? 1 : 0);
        if (dinode)
                gfs2_trans_add_unrevoke(sdp, block, 1);

        gfs2_quota_change(ip, *nblocks, ip->i_inode.i_uid, ip->i_inode.i_gid);

        rbm.rgd->rd_free_clone -= *nblocks;
        trace_gfs2_block_alloc(ip, rbm.rgd, block, *nblocks,
                               dinode ? GFS2_BLKST_DINODE : GFS2_BLKST_USED);
        *bn = block;
        return 0;

rgrp_error:
        gfs2_rgrp_error(rbm.rgd);
        return -EIO;
}

/**
 * __gfs2_free_blocks - free a contiguous run of block(s)
 * @ip: the inode these blocks are being freed from
 * @bstart: first block of a run of contiguous blocks
 * @blen: the length of the block run
 * @meta: 1 if the blocks represent metadata
 *
 */

void __gfs2_free_blocks(struct gfs2_inode *ip, u64 bstart, u32 blen, int meta)
{
        struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
        struct gfs2_rgrpd *rgd;

        rgd = rgblk_free(sdp, bstart, blen, GFS2_BLKST_FREE);
        if (!rgd)
                return;
        trace_gfs2_block_alloc(ip, rgd, bstart, blen, GFS2_BLKST_FREE);
        rgd->rd_free += blen;
        rgd->rd_flags &= ~GFS2_RGF_TRIMMED;
        gfs2_trans_add_meta(rgd->rd_gl, rgd->rd_bits[0].bi_bh);
        gfs2_rgrp_out(rgd, rgd->rd_bits[0].bi_bh->b_data);
        gfs2_rgrp_ondisk2lvb(rgd->rd_rgl, rgd->rd_bits[0].bi_bh->b_data);

        /* Directories keep their data in the metadata address space */
        if (meta || ip->i_depth)
                gfs2_meta_wipe(ip, bstart, blen);
}

/**
 * gfs2_free_meta - free a contiguous run of data block(s)
 * @ip: the inode these blocks are being freed from
 * @bstart: first block of a run of contiguous blocks
 * @blen: the length of the block run
 *
 */

void gfs2_free_meta(struct gfs2_inode *ip, u64 bstart, u32 blen)
{
        struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);

        __gfs2_free_blocks(ip, bstart, blen, 1);
        gfs2_statfs_change(sdp, 0, +blen, 0);
        gfs2_quota_change(ip, -(s64)blen, ip->i_inode.i_uid, ip->i_inode.i_gid);
}

void gfs2_unlink_di(struct inode *inode)
{
        struct gfs2_inode *ip = GFS2_I(inode);
        struct gfs2_sbd *sdp = GFS2_SB(inode);
        struct gfs2_rgrpd *rgd;
        u64 blkno = ip->i_no_addr;

        rgd = rgblk_free(sdp, blkno, 1, GFS2_BLKST_UNLINKED);
        if (!rgd)
                return;
        trace_gfs2_block_alloc(ip, rgd, blkno, 1, GFS2_BLKST_UNLINKED);
        gfs2_trans_add_meta(rgd->rd_gl, rgd->rd_bits[0].bi_bh);
        gfs2_rgrp_out(rgd, rgd->rd_bits[0].bi_bh->b_data);
        gfs2_rgrp_ondisk2lvb(rgd->rd_rgl, rgd->rd_bits[0].bi_bh->b_data);
        update_rgrp_lvb_unlinked(rgd, 1);
}

static void gfs2_free_uninit_di(struct gfs2_rgrpd *rgd, u64 blkno)
{
        struct gfs2_sbd *sdp = rgd->rd_sbd;
        struct gfs2_rgrpd *tmp_rgd;

        tmp_rgd = rgblk_free(sdp, blkno, 1, GFS2_BLKST_FREE);
        if (!tmp_rgd)
                return;
        gfs2_assert_withdraw(sdp, rgd == tmp_rgd);

        if (!rgd->rd_dinodes)
                gfs2_consist_rgrpd(rgd);
        rgd->rd_dinodes--;
        rgd->rd_free++;

        gfs2_trans_add_meta(rgd->rd_gl, rgd->rd_bits[0].bi_bh);
        gfs2_rgrp_out(rgd, rgd->rd_bits[0].bi_bh->b_data);
        gfs2_rgrp_ondisk2lvb(rgd->rd_rgl, rgd->rd_bits[0].bi_bh->b_data);
        update_rgrp_lvb_unlinked(rgd, -1);

        gfs2_statfs_change(sdp, 0, +1, -1);
}


void gfs2_free_di(struct gfs2_rgrpd *rgd, struct gfs2_inode *ip)
{
        gfs2_free_uninit_di(rgd, ip->i_no_addr);
        trace_gfs2_block_alloc(ip, rgd, ip->i_no_addr, 1, GFS2_BLKST_FREE);
        gfs2_quota_change(ip, -1, ip->i_inode.i_uid, ip->i_inode.i_gid);
        gfs2_meta_wipe(ip, ip->i_no_addr, 1);
}

/**
 * gfs2_check_blk_type - Check the type of a block
 * @sdp: The superblock
 * @no_addr: The block number to check
 * @type: The block type we are looking for
 *
 * Returns: 0 if the block type matches the expected type
 *          -ESTALE if it doesn't match
 *          or -ve errno if something went wrong while checking
 */

int gfs2_check_blk_type(struct gfs2_sbd *sdp, u64 no_addr, unsigned int type)
{
        struct gfs2_rgrpd *rgd;
        struct gfs2_holder rgd_gh;
        int error = -EINVAL;

        rgd = gfs2_blk2rgrpd(sdp, no_addr, 1);
        if (!rgd)
                goto fail;

        error = gfs2_glock_nq_init(rgd->rd_gl, LM_ST_SHARED, 0, &rgd_gh);
        if (error)
                goto fail;

        if (gfs2_get_block_type(rgd, no_addr) != type)
                error = -ESTALE;

        gfs2_glock_dq_uninit(&rgd_gh);
fail:
        return error;
}

/**
 * gfs2_rlist_add - add a RG to a list of RGs
 * @ip: the inode
 * @rlist: the list of resource groups
 * @block: the block
 *
 * Figure out what RG a block belongs to and add that RG to the list
 *
 * FIXME: Don't use NOFAIL
 *
 */

void gfs2_rlist_add(struct gfs2_inode *ip, struct gfs2_rgrp_list *rlist,
                    u64 block)
{
        struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
        struct gfs2_rgrpd *rgd;
        struct gfs2_rgrpd **tmp;
        unsigned int new_space;
        unsigned int x;

        if (gfs2_assert_warn(sdp, !rlist->rl_ghs))
                return;

        if (ip->i_rgd && rgrp_contains_block(ip->i_rgd, block))
                rgd = ip->i_rgd;
        else
                rgd = gfs2_blk2rgrpd(sdp, block, 1);
        if (!rgd) {
                fs_err(sdp, "rlist_add: no rgrp for block %llu\n", (unsigned long long)block);
                return;
        }
        ip->i_rgd = rgd;

        for (x = 0; x < rlist->rl_rgrps; x++)
                if (rlist->rl_rgd[x] == rgd)
                        return;

        if (rlist->rl_rgrps == rlist->rl_space) {
                new_space = rlist->rl_space + 10;

                tmp = kcalloc(new_space, sizeof(struct gfs2_rgrpd *),
                              GFP_NOFS | __GFP_NOFAIL);

                if (rlist->rl_rgd) {
                        memcpy(tmp, rlist->rl_rgd,
                               rlist->rl_space * sizeof(struct gfs2_rgrpd *));
                        kfree(rlist->rl_rgd);
                }

                rlist->rl_space = new_space;
                rlist->rl_rgd = tmp;
        }

        rlist->rl_rgd[rlist->rl_rgrps++] = rgd;
}

/**
 * gfs2_rlist_alloc - all RGs have been added to the rlist, now allocate
 *      and initialize an array of glock holders for them
 * @rlist: the list of resource groups
 * @state: the lock state to acquire the RG lock in
 *
 * FIXME: Don't use NOFAIL
 *
 */

void gfs2_rlist_alloc(struct gfs2_rgrp_list *rlist, unsigned int state)
{
        unsigned int x;

        rlist->rl_ghs = kcalloc(rlist->rl_rgrps, sizeof(struct gfs2_holder),
                                GFP_NOFS | __GFP_NOFAIL);
        for (x = 0; x < rlist->rl_rgrps; x++)
                gfs2_holder_init(rlist->rl_rgd[x]->rd_gl,
                                state, 0,
                                &rlist->rl_ghs[x]);
}

/**
 * gfs2_rlist_free - free a resource group list
 * @list: the list of resource groups
 *
 */

void gfs2_rlist_free(struct gfs2_rgrp_list *rlist)
{
        unsigned int x;

        kfree(rlist->rl_rgd);

        if (rlist->rl_ghs) {
                for (x = 0; x < rlist->rl_rgrps; x++)
                        gfs2_holder_uninit(&rlist->rl_ghs[x]);
                kfree(rlist->rl_ghs);
                rlist->rl_ghs = NULL;
        }
}