ext4_extents.c

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/*
 * 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 Licens
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-
 */
 
#include "ext2fs.h"
#include <linux/ext4.h>
 
#ifdef _MSC_VER
#pragma warning(push)
#pragma warning(disable: 4018)
#pragma warning(disable: 4242)
#pragma warning(disable: 4244)
#endif
 
 
/*
 * used by extent splitting.
 */
#define EXT4_EXT_MAY_ZEROOUT    0x1  /* safe to zeroout if split fails \
                    due to ENOSPC */
#define EXT4_EXT_MARK_UNWRIT1   0x2  /* mark first half unwritten */
#define EXT4_EXT_MARK_UNWRIT2   0x4  /* mark second half unwritten */
 
#define EXT4_EXT_DATA_VALID1    0x8  /* first half contains valid data */
#define EXT4_EXT_DATA_VALID2    0x10 /* second half contains valid data */
 
#define CONFIG_EXTENT_TEST
#ifdef CONFIG_EXTENT_TEST
 
#define ext4_mark_inode_dirty(icb, handle, n) ext3_mark_inode_dirty(icb, n)
static inline ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode)
{
    PEXT2_VCB Vcb;
    Vcb = inode->i_sb->s_priv;
    return (inode->i_ino - 1) / BLOCKS_PER_GROUP;
}
 
static ext4_fsblk_t ext4_new_meta_blocks(void *icb, handle_t *handle, struct inode *inode,
        ext4_fsblk_t goal,
        unsigned int flags,
        unsigned long *count, int *errp)
{
    NTSTATUS status;
    ULONG blockcnt = (count)?*count:1;
    ULONG block = 0;
 
    status = Ext2NewBlock((PEXT2_IRP_CONTEXT)icb,
            inode->i_sb->s_priv,
            0, goal,
            &block,
            &blockcnt);
    if (count)
        *count = blockcnt;
 
    if (!NT_SUCCESS(status)) {
        *errp = Ext2LinuxError(status);
        return 0;
    }
    inode->i_blocks += (blockcnt * (inode->i_sb->s_blocksize >> 9));
    return block;
}
 
static void ext4_free_blocks(void *icb, handle_t *handle, struct inode *inode, void *fake,
        ext4_fsblk_t block, int count, int flags)
{
    Ext2FreeBlock((PEXT2_IRP_CONTEXT)icb, inode->i_sb->s_priv, block, count);
    inode->i_blocks -= count * (inode->i_sb->s_blocksize >> 9);
    return;
}
 
static inline void ext_debug(char *str, ...)
{
}
#if TRUE
#define EXT4_ERROR_INODE(inode, str, ...) do {                      \
            DbgPrint("inode[%p]: " str "\n", inode, ##__VA_ARGS__); \
        } while(0)
#else
#define EXT4_ERROR_INODE
#endif
 
#define ext4_std_error(s, err)
#define assert ASSERT
 
#endif
 
/*
 * Return the right sibling of a tree node(either leaf or indexes node)
 */
 
#define EXT_MAX_BLOCKS 0xffffffff
 
 
static inline int ext4_ext_space_block(struct inode *inode, int check)
{
    int size;
 
    size = (inode->i_sb->s_blocksize - sizeof(struct ext4_extent_header))
        / sizeof(struct ext4_extent);
#ifdef AGGRESSIVE_TEST
    if (!check && size > 6)
        size = 6;
#endif
    return size;
}
 
static inline int ext4_ext_space_block_idx(struct inode *inode, int check)
{
    int size;
 
    size = (inode->i_sb->s_blocksize - sizeof(struct ext4_extent_header))
        / sizeof(struct ext4_extent_idx);
#ifdef AGGRESSIVE_TEST
    if (!check && size > 5)
        size = 5;
#endif
    return size;
}
 
static inline int ext4_ext_space_root(struct inode *inode, int check)
{
    int size;
 
    size = sizeof(EXT4_I(inode)->i_block);
    size -= sizeof(struct ext4_extent_header);
    size /= sizeof(struct ext4_extent);
#ifdef AGGRESSIVE_TEST
    if (!check && size > 3)
        size = 3;
#endif
    return size;
}
 
static inline int ext4_ext_space_root_idx(struct inode *inode, int check)
{
    int size;
 
    size = sizeof(EXT4_I(inode)->i_block);
    size -= sizeof(struct ext4_extent_header);
    size /= sizeof(struct ext4_extent_idx);
#ifdef AGGRESSIVE_TEST
    if (!check && size > 4)
        size = 4;
#endif
    return size;
}
 
static int
ext4_ext_max_entries(struct inode *inode, int depth)
{
    int max;
 
    if (depth == ext_depth(inode)) {
        if (depth == 0)
            max = ext4_ext_space_root(inode, 1);
        else
            max = ext4_ext_space_root_idx(inode, 1);
    } else {
        if (depth == 0)
            max = ext4_ext_space_block(inode, 1);
        else
            max = ext4_ext_space_block_idx(inode, 1);
    }
 
    return max;
}
 
static int __ext4_ext_check(const char *function, unsigned int line,
        struct inode *inode,
        struct ext4_extent_header *eh, int depth,
        ext4_fsblk_t pblk);
 
/*
 * read_extent_tree_block:
 * Get a buffer_head by extents_bread, and read fresh data from the storage.
 */
static struct buffer_head *
__read_extent_tree_block(const char *function, unsigned int line,
        struct inode *inode, ext4_fsblk_t pblk, int depth,
        int flags)
{
    struct buffer_head      *bh;
    int             err;
 
    bh = extents_bread(inode->i_sb, pblk);
    if (!bh)
        return ERR_PTR(-ENOMEM);
 
    if (!buffer_uptodate(bh)) {
        err = -EIO;
        goto errout;
    }
    if (buffer_verified(bh))
        return bh;
    err = __ext4_ext_check(function, line, inode,
            ext_block_hdr(bh), depth, pblk);
    if (err)
        goto errout;
    set_buffer_verified(bh);
    return bh;
errout:
    extents_brelse(bh);
    return ERR_PTR(err);
 
}
 
#define read_extent_tree_block(inode, pblk, depth, flags)       \
    __read_extent_tree_block("", __LINE__, (inode), (pblk),   \
            (depth), (flags))
 
#define ext4_ext_check(inode, eh, depth, pblk)          \
    __ext4_ext_check("", __LINE__, (inode), (eh), (depth), (pblk))
 
int ext4_ext_check_inode(struct inode *inode)
{
    return ext4_ext_check(inode, ext_inode_hdr(inode), ext_depth(inode), 0);
}
 
static uint32_t ext4_ext_block_csum(struct inode *inode,
        struct ext4_extent_header *eh)
{
    /*return ext4_crc32c(inode->i_csum, eh, EXT4_EXTENT_TAIL_OFFSET(eh));*/
    return 0;
}
 
static void ext4_extent_block_csum_set(struct inode *inode,
        struct ext4_extent_header *eh)
{
    struct ext4_extent_tail *tail;
 
    tail = find_ext4_extent_tail(eh);
    tail->et_checksum = ext4_ext_block_csum(
            inode, eh);
}
 
static int ext4_split_extent_at(void *icb,
                 handle_t *handle,
                 struct inode *inode,
                 struct ext4_ext_path **ppath,
                 ext4_lblk_t split,
                 int split_flag,
                 int flags);
 
static inline int
ext4_force_split_extent_at(void *icb, handle_t *handle, struct inode *inode,
        struct ext4_ext_path **ppath, ext4_lblk_t lblk,
        int nofail)
{
    struct ext4_ext_path *path = *ppath;
    int unwritten = ext4_ext_is_unwritten(path[path->p_depth].p_ext);
 
    return ext4_split_extent_at(icb, handle, inode, ppath, lblk, unwritten ?
            EXT4_EXT_MARK_UNWRIT1|EXT4_EXT_MARK_UNWRIT2 : 0,
            EXT4_EX_NOCACHE | EXT4_GET_BLOCKS_PRE_IO |
            (nofail ? EXT4_GET_BLOCKS_METADATA_NOFAIL:0));
}
 
/*
 * could return:
 *  - EROFS
 *  - ENOMEM
 */
 
static int ext4_ext_get_access(void *icb, handle_t *handle, struct inode *inode,
        struct ext4_ext_path *path)
{
    if (path->p_bh) {
        /* path points to block */
 
        return ext4_journal_get_write_access(icb, handle, path->p_bh);
 
    }
    /* path points to leaf/index in inode body */
    /* we use in-core data, no need to protect them */
    return 0;
}
 
 
static ext4_fsblk_t ext4_ext_find_goal(struct inode *inode,
        struct ext4_ext_path *path,
        ext4_lblk_t block)
{
    if (path) {
        int depth = path->p_depth;
        struct ext4_extent *ex;
 
        /*
         * Try to predict block placement assuming that we are
         * filling in a file which will eventually be
         * non-sparse --- i.e., in the case of libbfd writing
         * an ELF object sections out-of-order but in a way
         * the eventually results in a contiguous object or
         * executable file, or some database extending a table
         * space file.  However, this is actually somewhat
         * non-ideal if we are writing a sparse file such as
         * qemu or KVM writing a raw image file that is going
         * to stay fairly sparse, since it will end up
         * fragmenting the file system's free space.  Maybe we
         * should have some hueristics or some way to allow
         * userspace to pass a hint to file system,
         * especially if the latter case turns out to be
         * common.
         */
        ex = path[depth].p_ext;
        if (ex) {
            ext4_fsblk_t ext_pblk = ext4_ext_pblock(ex);
            ext4_lblk_t ext_block = le32_to_cpu(ex->ee_block);
 
            if (block > ext_block)
                return ext_pblk + (block - ext_block);
            else
                return ext_pblk - (ext_block - block);
        }
 
        /* it looks like index is empty;
         * try to find starting block from index itself */
        if (path[depth].p_bh)
            return path[depth].p_bh->b_blocknr;
    }
 
    /* OK. use inode's group */
    return ext4_inode_to_goal_block(inode);
}
 
/*
 * Allocation for a meta data block
 */
static ext4_fsblk_t
ext4_ext_new_meta_block(void *icb, handle_t *handle, struct inode *inode,
        struct ext4_ext_path *path,
        struct ext4_extent *ex, int *err, unsigned int flags)
{
    ext4_fsblk_t goal, newblock;
 
    goal = ext4_ext_find_goal(inode, path, le32_to_cpu(ex->ee_block));
    newblock = ext4_new_meta_blocks(icb, handle, inode, goal, flags,
            NULL, err);
    return newblock;
}
 
int __ext4_ext_dirty(const char *where, unsigned int line,
        void *icb, handle_t *handle,
        struct inode *inode,
        struct ext4_ext_path *path)
{
    int err;
 
    if (path->p_bh) {
        ext4_extent_block_csum_set(inode, ext_block_hdr(path->p_bh));
        /* path points to block */
        err = __ext4_handle_dirty_metadata(where, line, icb, handle, inode, path->p_bh);
    } else {
        /* path points to leaf/index in inode body */
        err = ext4_mark_inode_dirty(icb, handle, inode);
    }
    return err;
}
 
void ext4_ext_drop_refs(struct ext4_ext_path *path)
{
    int depth, i;
 
    if (!path)
        return;
    depth = path->p_depth;
    for (i = 0; i <= depth; i++, path++)
        if (path->p_bh) {
            extents_brelse(path->p_bh);
            path->p_bh = NULL;
        }
}
 
/*
 * Check that whether the basic information inside the extent header
 * is correct or not.
 */
static int __ext4_ext_check(const char *function, unsigned int line,
        struct inode *inode,
        struct ext4_extent_header *eh, int depth,
        ext4_fsblk_t pblk)
{
    struct ext4_extent_tail *tail;
    const char *error_msg;
#ifndef __REACTOS__
    int max = 0;
#endif
    if (eh->eh_magic != EXT4_EXT_MAGIC) {
        error_msg = "invalid magic";
        goto corrupted;
    }
    if (le16_to_cpu(eh->eh_depth) != depth) {
        error_msg = "unexpected eh_depth";
        goto corrupted;
    }
    if (eh->eh_max == 0) {
        error_msg = "invalid eh_max";
        goto corrupted;
    }
    if (eh->eh_entries > eh->eh_max) {
        error_msg = "invalid eh_entries";
        goto corrupted;
    }
 
    tail = find_ext4_extent_tail(eh);
    if (tail->et_checksum != ext4_ext_block_csum(inode, eh)) {
        ext_debug("Warning: extent checksum damaged? tail->et_checksum = "
                "%lu, ext4_ext_block_csum = %lu\n",
                tail->et_checksum, ext4_ext_block_csum(inode, eh));
    }
 
    return 0;
 
corrupted:
    ext_debug("corrupted! %s\n", error_msg);
    return -EIO;
}
 
/*
 * ext4_ext_binsearch_idx:
 * binary search for the closest index of the given block
 * the header must be checked before calling this
 */
static void
ext4_ext_binsearch_idx(struct inode *inode,
        struct ext4_ext_path *path, ext4_lblk_t block)
{
    struct ext4_extent_header *eh = path->p_hdr;
    struct ext4_extent_idx *r, *l, *m;
 
    ext_debug("binsearch for %u(idx):  ", block);
 
    l = EXT_FIRST_INDEX(eh) + 1;
    r = EXT_LAST_INDEX(eh);
    while (l <= r) {
        m = l + (r - l) / 2;
        if (block < (m->ei_block))
            r = m - 1;
        else
            l = m + 1;
        ext_debug("%p(%u):%p(%u):%p(%u) ", l, (l->ei_block),
                m, (m->ei_block),
                r, (r->ei_block));
    }
 
    path->p_idx = l - 1;
    ext_debug("  -> %u->%lld ", (path->p_idx->ei_block),
            ext4_idx_pblock(path->p_idx));
 
#ifdef CHECK_BINSEARCH
    {
        struct ext4_extent_idx *chix, *ix;
        int k;
 
        chix = ix = EXT_FIRST_INDEX(eh);
        for (k = 0; k < (eh->eh_entries); k++, ix++) {
            if (k != 0 &&
                    (ix->ei_block) <= (ix[-1].ei_block)) {
                printk(KERN_DEBUG "k=%d, ix=0x%p, "
                        "first=0x%p\n", k,
                        ix, EXT_FIRST_INDEX(eh));
                printk(KERN_DEBUG "%u <= %u\n",
                        (ix->ei_block),
                        (ix[-1].ei_block));
            }
            BUG_ON(k && (ix->ei_block)
                    <= (ix[-1].ei_block));
            if (block < (ix->ei_block))
                break;
            chix = ix;
        }
        BUG_ON(chix != path->p_idx);
    }
#endif
 
}
 
/*
 * ext4_ext_binsearch:
 * binary search for closest extent of the given block
 * the header must be checked before calling this
 */
static void
ext4_ext_binsearch(struct inode *inode,
        struct ext4_ext_path *path, ext4_lblk_t block)
{
    struct ext4_extent_header *eh = path->p_hdr;
    struct ext4_extent *r, *l, *m;
 
    if (eh->eh_entries == 0) {
        /*
         * this leaf is empty:
         * we get such a leaf in split/add case
         */
        return;
    }
 
    ext_debug("binsearch for %u:  ", block);
 
    l = EXT_FIRST_EXTENT(eh) + 1;
    r = EXT_LAST_EXTENT(eh);
 
    while (l <= r) {
        m = l + (r - l) / 2;
        if (block < m->ee_block)
            r = m - 1;
        else
            l = m + 1;
        ext_debug("%p(%u):%p(%u):%p(%u) ", l, l->ee_block,
                m, (m->ee_block),
                r, (r->ee_block));
    }
 
    path->p_ext = l - 1;
    ext_debug("  -> %d:%llu:[%d]%d ",
            (path->p_ext->ee_block),
            ext4_ext_pblock(path->p_ext),
            ext4_ext_is_unwritten(path->p_ext),
            ext4_ext_get_actual_len(path->p_ext));
 
#ifdef CHECK_BINSEARCH
    {
        struct ext4_extent *chex, *ex;
        int k;
 
        chex = ex = EXT_FIRST_EXTENT(eh);
        for (k = 0; k < le16_to_cpu(eh->eh_entries); k++, ex++) {
            BUG_ON(k && (ex->ee_block)
                    <= (ex[-1].ee_block));
            if (block < (ex->ee_block))
                break;
            chex = ex;
        }
        BUG_ON(chex != path->p_ext);
    }
#endif
 
}
 
#ifdef EXT_DEBUG
static void ext4_ext_show_path(struct inode *inode, struct ext4_ext_path *path)
{
    int k, l = path->p_depth;
 
    ext_debug("path:");
    for (k = 0; k <= l; k++, path++) {
        if (path->p_idx) {
            ext_debug("  %d->%llu", le32_to_cpu(path->p_idx->ei_block),
                    ext4_idx_pblock(path->p_idx));
        } else if (path->p_ext) {
            ext_debug("  %d:[%d]%d:%llu ",
                    le32_to_cpu(path->p_ext->ee_block),
                    ext4_ext_is_unwritten(path->p_ext),
                    ext4_ext_get_actual_len(path->p_ext),
                    ext4_ext_pblock(path->p_ext));
        } else
            ext_debug("  []");
    }
    ext_debug("\n");
}
 
static void ext4_ext_show_leaf(struct inode *inode, struct ext4_ext_path *path)
{
    int depth = ext_depth(inode);
    struct ext4_extent_header *eh;
    struct ext4_extent *ex;
    int i;
 
    if (!path)
        return;
 
    eh = path[depth].p_hdr;
    ex = EXT_FIRST_EXTENT(eh);
 
    ext_debug("Displaying leaf extents for inode %lu\n", inode->i_ino);
 
    for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ex++) {
        ext_debug("%d:[%d]%d:%llu ", le32_to_cpu(ex->ee_block),
                ext4_ext_is_unwritten(ex),
                ext4_ext_get_actual_len(ex), ext4_ext_pblock(ex));
    }
    ext_debug("\n");
}
 
static void ext4_ext_show_move(struct inode *inode, struct ext4_ext_path *path,
        ext4_fsblk_t newblock, int level)
{
    int depth = ext_depth(inode);
    struct ext4_extent *ex;
 
    if (depth != level) {
        struct ext4_extent_idx *idx;
        idx = path[level].p_idx;
        while (idx <= EXT_MAX_INDEX(path[level].p_hdr)) {
            ext_debug("%d: move %d:%llu in new index %llu\n", level,
                    le32_to_cpu(idx->ei_block),
                    ext4_idx_pblock(idx),
                    newblock);
            idx++;
        }
 
        return;
    }
 
    ex = path[depth].p_ext;
    while (ex <= EXT_MAX_EXTENT(path[depth].p_hdr)) {
        ext_debug("move %d:%llu:[%d]%d in new leaf %llu\n",
                le32_to_cpu(ex->ee_block),
                ext4_ext_pblock(ex),
                ext4_ext_is_unwritten(ex),
                ext4_ext_get_actual_len(ex),
                newblock);
        ex++;
    }
}
 
#else
#define ext4_ext_show_path(inode, path)
#define ext4_ext_show_leaf(inode, path)
#define ext4_ext_show_move(inode, path, newblock, level)
#endif
 
struct ext4_ext_path *
ext4_find_extent(struct inode *inode, ext4_lblk_t block,
        struct ext4_ext_path **orig_path, int flags)
{
    struct ext4_extent_header *eh;
    struct buffer_head *bh;
    struct ext4_ext_path *path = orig_path ? *orig_path : NULL;
    short int depth, i, ppos = 0;
    int ret;
 
    eh = ext_inode_hdr(inode);
    depth = ext_depth(inode);
 
    if (path) {
        ext4_ext_drop_refs(path);
        if (depth > path[0].p_maxdepth) {
            kfree(path);
            *orig_path = path = NULL;
        }
    }
    if (!path) {
        /* account possible depth increase */
        path = kzalloc(sizeof(struct ext4_ext_path) * (depth + 2),
                GFP_NOFS);
        if (unlikely(!path))
            return ERR_PTR(-ENOMEM);
        path[0].p_maxdepth = depth + 1;
    }
    path[0].p_hdr = eh;
    path[0].p_bh = NULL;
 
    i = depth;
    /* walk through the tree */
    while (i) {
        ext_debug("depth %d: num %d, max %d\n",
                ppos, le16_to_cpu(eh->eh_entries), le16_to_cpu(eh->eh_max));
 
        ext4_ext_binsearch_idx(inode, path + ppos, block);
        path[ppos].p_block = ext4_idx_pblock(path[ppos].p_idx);
        path[ppos].p_depth = i;
        path[ppos].p_ext = NULL;
 
        bh = read_extent_tree_block(inode, path[ppos].p_block, --i,
                flags);
        if (unlikely(IS_ERR(bh))) {
            ret = PTR_ERR(bh);
            goto err;
        }
 
        eh = ext_block_hdr(bh);
        ppos++;
        if (unlikely(ppos > depth)) {
            extents_brelse(bh);
            EXT4_ERROR_INODE(inode,
                    "ppos %d > depth %d", ppos, depth);
            ret = -EIO;
            goto err;
        }
        path[ppos].p_bh = bh;
        path[ppos].p_hdr = eh;
    }
 
    path[ppos].p_depth = i;
    path[ppos].p_ext = NULL;
    path[ppos].p_idx = NULL;
 
    /* find extent */
    ext4_ext_binsearch(inode, path + ppos, block);
    /* if not an empty leaf */
    if (path[ppos].p_ext)
        path[ppos].p_block = ext4_ext_pblock(path[ppos].p_ext);
 
    ext4_ext_show_path(inode, path);
 
    return path;
 
err:
    ext4_ext_drop_refs(path);
    if (path) {
        kfree(path);
        if (orig_path)
            *orig_path = NULL;
    }
    return ERR_PTR(ret);
}
 
/*
 * ext4_ext_insert_index:
 * insert new index [@logical;@ptr] into the block at @curp;
 * check where to insert: before @curp or after @curp
 */
static int ext4_ext_insert_index(void *icb, handle_t *handle, struct inode *inode,
        struct ext4_ext_path *curp,
        int logical, ext4_fsblk_t ptr)
{
    struct ext4_extent_idx *ix;
    int len, err;
 
    err = ext4_ext_get_access(icb, handle, inode, curp);
    if (err)
        return err;
 
    if (unlikely(logical == le32_to_cpu(curp->p_idx->ei_block))) {
        EXT4_ERROR_INODE(inode,
                "logical %d == ei_block %d!",
                logical, le32_to_cpu(curp->p_idx->ei_block));
        return -EIO;
    }
 
    if (unlikely(le16_to_cpu(curp->p_hdr->eh_entries)
                >= le16_to_cpu(curp->p_hdr->eh_max))) {
        EXT4_ERROR_INODE(inode,
                "eh_entries %d >= eh_max %d!",
                le16_to_cpu(curp->p_hdr->eh_entries),
                le16_to_cpu(curp->p_hdr->eh_max));
        return -EIO;
    }
 
    if (logical > le32_to_cpu(curp->p_idx->ei_block)) {
        /* insert after */
        ext_debug("insert new index %d after: %llu\n", logical, ptr);
        ix = curp->p_idx + 1;
    } else {
        /* insert before */
        ext_debug("insert new index %d before: %llu\n", logical, ptr);
        ix = curp->p_idx;
    }
 
    len = EXT_LAST_INDEX(curp->p_hdr) - ix + 1;
    BUG_ON(len < 0);
    if (len > 0) {
        ext_debug("insert new index %d: "
                "move %d indices from 0x%p to 0x%p\n",
                logical, len, ix, ix + 1);
        memmove(ix + 1, ix, len * sizeof(struct ext4_extent_idx));
    }
 
    if (unlikely(ix > EXT_MAX_INDEX(curp->p_hdr))) {
        EXT4_ERROR_INODE(inode, "ix > EXT_MAX_INDEX!");
        return -EIO;
    }
 
    ix->ei_block = cpu_to_le32(logical);
    ext4_idx_store_pblock(ix, ptr);
    le16_add_cpu(&curp->p_hdr->eh_entries, 1);
 
    if (unlikely(ix > EXT_LAST_INDEX(curp->p_hdr))) {
        EXT4_ERROR_INODE(inode, "ix > EXT_LAST_INDEX!");
        return -EIO;
    }
 
    err = ext4_ext_dirty(icb, handle, inode, curp);
    ext4_std_error(inode->i_sb, err);
 
    return err;
}
 
/*
 * ext4_ext_split:
 * inserts new subtree into the path, using free index entry
 * at depth @at:
 * - allocates all needed blocks (new leaf and all intermediate index blocks)
 * - makes decision where to split
 * - moves remaining extents and index entries (right to the split point)
 *   into the newly allocated blocks
 * - initializes subtree
 */
static int ext4_ext_split(void *icb, handle_t *handle, struct inode *inode,
        unsigned int flags,
        struct ext4_ext_path *path,
        struct ext4_extent *newext, int at)
{
    struct buffer_head *bh = NULL;
    int depth = ext_depth(inode);
    struct ext4_extent_header *neh;
    struct ext4_extent_idx *fidx;
    int i = at, k, m, a;
    ext4_fsblk_t newblock, oldblock;
    __le32 border;
    ext4_fsblk_t *ablocks = NULL; /* array of allocated blocks */
    int err = 0;
 
    /* make decision: where to split? */
    /* FIXME: now decision is simplest: at current extent */
 
    /* if current leaf will be split, then we should use
     * border from split point */
    if (unlikely(path[depth].p_ext > EXT_MAX_EXTENT(path[depth].p_hdr))) {
        EXT4_ERROR_INODE(inode, "p_ext > EXT_MAX_EXTENT!");
        return -EIO;
    }
    if (path[depth].p_ext != EXT_MAX_EXTENT(path[depth].p_hdr)) {
        border = path[depth].p_ext[1].ee_block;
        ext_debug("leaf will be split."
                " next leaf starts at %d\n",
                le32_to_cpu(border));
    } else {
        border = newext->ee_block;
        ext_debug("leaf will be added."
                " next leaf starts at %d\n",
                le32_to_cpu(border));
    }
 
    /*
     * If error occurs, then we break processing
     * and mark filesystem read-only. index won't
     * be inserted and tree will be in consistent
     * state. Next mount will repair buffers too.
     */
 
    /*
     * Get array to track all allocated blocks.
     * We need this to handle errors and free blocks
     * upon them.
     */
    ablocks = kzalloc(sizeof(ext4_fsblk_t) * depth, GFP_NOFS);
    if (!ablocks)
        return -ENOMEM;
 
    /* allocate all needed blocks */
    ext_debug("allocate %d blocks for indexes/leaf\n", depth - at);
    for (a = 0; a < depth - at; a++) {
        newblock = ext4_ext_new_meta_block(icb, handle, inode, path,
                newext, &err, flags);
        if (newblock == 0)
            goto cleanup;
        ablocks[a] = newblock;
    }
 
    /* initialize new leaf */
    newblock = ablocks[--a];
    if (unlikely(newblock == 0)) {
        EXT4_ERROR_INODE(inode, "newblock == 0!");
        err = -EIO;
        goto cleanup;
    }
    bh = extents_bwrite(inode->i_sb, newblock);
    if (unlikely(!bh)) {
        err = -ENOMEM;
        goto cleanup;
    }
 
    err = ext4_journal_get_create_access(icb, handle, bh);
    if (err)
        goto cleanup;
 
    neh = ext_block_hdr(bh);
    neh->eh_entries = 0;
    neh->eh_max = cpu_to_le16(ext4_ext_space_block(inode, 0));
    neh->eh_magic = cpu_to_le16(EXT4_EXT_MAGIC);
    neh->eh_depth = 0;
 
    /* move remainder of path[depth] to the new leaf */
    if (unlikely(path[depth].p_hdr->eh_entries !=
                path[depth].p_hdr->eh_max)) {
        EXT4_ERROR_INODE(inode, "eh_entries %d != eh_max %d!",
                path[depth].p_hdr->eh_entries,
                path[depth].p_hdr->eh_max);
        err = -EIO;
        goto cleanup;
    }
    /* start copy from next extent */
    m = EXT_MAX_EXTENT(path[depth].p_hdr) - path[depth].p_ext++;
    ext4_ext_show_move(inode, path, newblock, depth);
    if (m) {
        struct ext4_extent *ex;
        ex = EXT_FIRST_EXTENT(neh);
        memmove(ex, path[depth].p_ext, sizeof(struct ext4_extent) * m);
        le16_add_cpu(&neh->eh_entries, m);
    }
 
    ext4_extent_block_csum_set(inode, neh);
    set_buffer_uptodate(bh);
 
    err = ext4_handle_dirty_metadata(icb, handle, inode, bh);
    if (err)
        goto cleanup;
    extents_brelse(bh);
    bh = NULL;
 
    /* correct old leaf */
    if (m) {
        err = ext4_ext_get_access(icb, handle, inode, path + depth);
        if (err)
            goto cleanup;
        le16_add_cpu(&path[depth].p_hdr->eh_entries, -m);
        err = ext4_ext_dirty(icb, handle, inode, path + depth);
        if (err)
            goto cleanup;
 
    }
 
    /* create intermediate indexes */
    k = depth - at - 1;
    if (unlikely(k < 0)) {
        EXT4_ERROR_INODE(inode, "k %d < 0!", k);
        err = -EIO;
        goto cleanup;
    }
    if (k)
        ext_debug("create %d intermediate indices\n", k);
    /* insert new index into current index block */
    /* current depth stored in i var */
    i = depth - 1;
    while (k--) {
        oldblock = newblock;
        newblock = ablocks[--a];
        bh = extents_bwrite(inode->i_sb, newblock);
        if (unlikely(!bh)) {
            err = -ENOMEM;
            goto cleanup;
        }
 
        err = ext4_journal_get_create_access(icb, handle, bh);
        if (err)
            goto cleanup;
 
        neh = ext_block_hdr(bh);
        neh->eh_entries = cpu_to_le16(1);
        neh->eh_magic = cpu_to_le16(EXT4_EXT_MAGIC);
        neh->eh_max = cpu_to_le16(ext4_ext_space_block_idx(inode, 0));
        neh->eh_depth = cpu_to_le16(depth - i);
        fidx = EXT_FIRST_INDEX(neh);
        fidx->ei_block = border;
        ext4_idx_store_pblock(fidx, oldblock);
 
        ext_debug("int.index at %d (block %llu): %u -> %llu\n",
                i, newblock, le32_to_cpu(border), oldblock);
 
        /* move remainder of path[i] to the new index block */
        if (unlikely(EXT_MAX_INDEX(path[i].p_hdr) !=
                    EXT_LAST_INDEX(path[i].p_hdr))) {
            EXT4_ERROR_INODE(inode,
                    "EXT_MAX_INDEX != EXT_LAST_INDEX ee_block %d!",
                    le32_to_cpu(path[i].p_ext->ee_block));
            err = -EIO;
            goto cleanup;
        }
        /* start copy indexes */
        m = EXT_MAX_INDEX(path[i].p_hdr) - path[i].p_idx++;
        ext_debug("cur 0x%p, last 0x%p\n", path[i].p_idx,
                EXT_MAX_INDEX(path[i].p_hdr));
        ext4_ext_show_move(inode, path, newblock, i);
        if (m) {
            memmove(++fidx, path[i].p_idx,
                    sizeof(struct ext4_extent_idx) * m);
            le16_add_cpu(&neh->eh_entries, m);
        }
        ext4_extent_block_csum_set(inode, neh);
        set_buffer_uptodate(bh);
 
        err = ext4_handle_dirty_metadata(icb, handle, inode, bh);
        if (err)
            goto cleanup;
        extents_brelse(bh);
        bh = NULL;
 
        /* correct old index */
        if (m) {
            err = ext4_ext_get_access(icb, handle, inode, path + i);
            if (err)
                goto cleanup;
            le16_add_cpu(&path[i].p_hdr->eh_entries, -m);
            err = ext4_ext_dirty(icb, handle, inode, path + i);
            if (err)
                goto cleanup;
        }
 
        i--;
    }
 
    /* insert new index */
    err = ext4_ext_insert_index(icb, handle, inode, path + at,
            le32_to_cpu(border), newblock);
 
cleanup:
    if (bh)
        extents_brelse(bh);
 
    if (err) {
        /* free all allocated blocks in error case */
        for (i = 0; i < depth; i++) {
            if (!ablocks[i])
                continue;
            ext4_free_blocks(icb, handle, inode, NULL, ablocks[i], 1,
                    EXT4_FREE_BLOCKS_METADATA);
        }
    }
    kfree(ablocks);
 
    return err;
}
 
/*
 * ext4_ext_grow_indepth:
 * implements tree growing procedure:
 * - allocates new block
 * - moves top-level data (index block or leaf) into the new block
 * - initializes new top-level, creating index that points to the
 *   just created block
 */
static int ext4_ext_grow_indepth(void *icb, handle_t *handle, struct inode *inode,
        unsigned int flags)
{
    struct ext4_extent_header *neh;
    struct buffer_head *bh;
    ext4_fsblk_t newblock, goal = 0;
    int err = 0;
 
    /* Try to prepend new index to old one */
    if (ext_depth(inode))
        goal = ext4_idx_pblock(EXT_FIRST_INDEX(ext_inode_hdr(inode)));
    goal = ext4_inode_to_goal_block(inode);
    newblock = ext4_new_meta_blocks(icb, handle, inode, goal, flags,
            NULL, &err);
    if (newblock == 0)
        return err;
 
    bh = extents_bwrite(inode->i_sb, newblock);
    if (!bh)
        return -ENOMEM;
 
    err = ext4_journal_get_create_access(icb, handle, bh);
    if (err)
        goto out;
 
    /* move top-level index/leaf into new block */
    memmove(bh->b_data, EXT4_I(inode)->i_block,
            sizeof(EXT4_I(inode)->i_block));
 
    /* set size of new block */
    neh = ext_block_hdr(bh);
    /* old root could have indexes or leaves
     * so calculate e_max right way */
    if (ext_depth(inode))
        neh->eh_max = cpu_to_le16(ext4_ext_space_block_idx(inode, 0));
    else
        neh->eh_max = cpu_to_le16(ext4_ext_space_block(inode, 0));
    neh->eh_magic = cpu_to_le16(EXT4_EXT_MAGIC);
    ext4_extent_block_csum_set(inode, neh);
    set_buffer_uptodate(bh);
 
    err = ext4_handle_dirty_metadata(icb, handle, inode, bh);
    if (err)
        goto out;
 
    /* Update top-level index: num,max,pointer */
    neh = ext_inode_hdr(inode);
    neh->eh_entries = cpu_to_le16(1);
    ext4_idx_store_pblock(EXT_FIRST_INDEX(neh), newblock);
    if (neh->eh_depth == 0) {
        /* Root extent block becomes index block */
        neh->eh_max = cpu_to_le16(ext4_ext_space_root_idx(inode, 0));
        EXT_FIRST_INDEX(neh)->ei_block =
            EXT_FIRST_EXTENT(neh)->ee_block;
    }
    ext_debug("new root: num %d(%d), lblock %d, ptr %llu\n",
            (neh->eh_entries), (neh->eh_max),
            (EXT_FIRST_INDEX(neh)->ei_block),
            ext4_idx_pblock(EXT_FIRST_INDEX(neh)));
 
    le16_add_cpu(&neh->eh_depth, 1);
    ext4_mark_inode_dirty(icb, handle, inode);
out:
    extents_brelse(bh);
 
    return err;
}
 
/*
 * ext4_ext_create_new_leaf:
 * finds empty index and adds new leaf.
 * if no free index is found, then it requests in-depth growing.
 */
static int ext4_ext_create_new_leaf(void *icb, handle_t *handle, struct inode *inode,
        unsigned int mb_flags,
        unsigned int gb_flags,
        struct ext4_ext_path **ppath,
        struct ext4_extent *newext)
{
    struct ext4_ext_path *path = *ppath;
    struct ext4_ext_path *curp;
    int depth, i, err = 0;
 
repeat:
    i = depth = ext_depth(inode);
 
    /* walk up to the tree and look for free index entry */
    curp = path + depth;
    while (i > 0 && !EXT_HAS_FREE_INDEX(curp)) {
        i--;
        curp--;
    }
 
    /* we use already allocated block for index block,
     * so subsequent data blocks should be contiguous */
    if (EXT_HAS_FREE_INDEX(curp)) {
        /* if we found index with free entry, then use that
         * entry: create all needed subtree and add new leaf */
        err = ext4_ext_split(icb, handle, inode, mb_flags, path, newext, i);
        if (err)
            goto out;
 
        /* refill path */
        path = ext4_find_extent(inode,
                (ext4_lblk_t)le32_to_cpu(newext->ee_block),
                ppath, gb_flags);
        if (IS_ERR(path))
            err = PTR_ERR(path);
    } else {
        /* tree is full, time to grow in depth */
        err = ext4_ext_grow_indepth(icb, handle, inode, mb_flags);
        if (err)
            goto out;
 
        /* refill path */
        path = ext4_find_extent(inode,
                (ext4_lblk_t)le32_to_cpu(newext->ee_block),
                ppath, gb_flags);
        if (IS_ERR(path)) {
            err = PTR_ERR(path);
            goto out;
        }
 
        /*
         * only first (depth 0 -> 1) produces free space;
         * in all other cases we have to split the grown tree
         */
        depth = ext_depth(inode);
        if (path[depth].p_hdr->eh_entries == path[depth].p_hdr->eh_max) {
            /* now we need to split */
            goto repeat;
        }
    }
 
out:
    return err;
}
 
/*
 * search the closest allocated block to the left for *logical
 * and returns it at @logical + it's physical address at @phys
 * if *logical is the smallest allocated block, the function
 * returns 0 at @phys
 * return value contains 0 (success) or error code
 */
static int ext4_ext_search_left(struct inode *inode,
        struct ext4_ext_path *path,
        ext4_lblk_t *logical, ext4_fsblk_t *phys)
{
    struct ext4_extent_idx *ix;
    struct ext4_extent *ex;
    int depth, ee_len;
 
    if (unlikely(path == NULL)) {
        EXT4_ERROR_INODE(inode, "path == NULL *logical %d!", *logical);
        return -EIO;
    }
    depth = path->p_depth;
    *phys = 0;
 
    if (depth == 0 && path->p_ext == NULL)
        return 0;
 
    /* usually extent in the path covers blocks smaller
     * then *logical, but it can be that extent is the
     * first one in the file */
 
    ex = path[depth].p_ext;
    ee_len = ext4_ext_get_actual_len(ex);
    if (*logical < le32_to_cpu(ex->ee_block)) {
        if (unlikely(EXT_FIRST_EXTENT(path[depth].p_hdr) != ex)) {
            EXT4_ERROR_INODE(inode,
                    "EXT_FIRST_EXTENT != ex *logical %d ee_block %d!",
                    *logical, le32_to_cpu(ex->ee_block));
            return -EIO;
        }
        while (--depth >= 0) {
            ix = path[depth].p_idx;
            if (unlikely(ix != EXT_FIRST_INDEX(path[depth].p_hdr))) {
                EXT4_ERROR_INODE(inode,
                        "ix (%d) != EXT_FIRST_INDEX (%d) (depth %d)!",
                        ix != NULL ? le32_to_cpu(ix->ei_block) : 0,
                        EXT_FIRST_INDEX(path[depth].p_hdr) != NULL ?
                        le32_to_cpu(EXT_FIRST_INDEX(path[depth].p_hdr)->ei_block) : 0,
                        depth);
                return -EIO;
            }
        }
        return 0;
    }
 
    if (unlikely(*logical < (le32_to_cpu(ex->ee_block) + ee_len))) {
        EXT4_ERROR_INODE(inode,
                "logical %d < ee_block %d + ee_len %d!",
                *logical, le32_to_cpu(ex->ee_block), ee_len);
        return -EIO;
    }
 
    *logical = le32_to_cpu(ex->ee_block) + ee_len - 1;
    *phys = ext4_ext_pblock(ex) + ee_len - 1;
    return 0;
}
 
/*
 * search the closest allocated block to the right for *logical
 * and returns it at @logical + it's physical address at @phys
 * if *logical is the largest allocated block, the function
 * returns 0 at @phys
 * return value contains 0 (success) or error code
 */
static int ext4_ext_search_right(struct inode *inode,
        struct ext4_ext_path *path,
        ext4_lblk_t *logical, ext4_fsblk_t *phys,
        struct ext4_extent **ret_ex)
{
    struct buffer_head *bh = NULL;
    struct ext4_extent_header *eh;
    struct ext4_extent_idx *ix;
    struct ext4_extent *ex;
    ext4_fsblk_t block;
    int depth;  /* Note, NOT eh_depth; depth from top of tree */
    int ee_len;
 
    if ((path == NULL)) {
        EXT4_ERROR_INODE(inode, "path == NULL *logical %d!", *logical);
        return -EIO;
    }
    depth = path->p_depth;
    *phys = 0;
 
    if (depth == 0 && path->p_ext == NULL)
        return 0;
 
    /* usually extent in the path covers blocks smaller
     * then *logical, but it can be that extent is the
     * first one in the file */
 
    ex = path[depth].p_ext;
    ee_len = ext4_ext_get_actual_len(ex);
    /*if (*logical < le32_to_cpu(ex->ee_block)) {*/
    if (*logical < (ex->ee_block)) {
        if (unlikely(EXT_FIRST_EXTENT(path[depth].p_hdr) != ex)) {
            EXT4_ERROR_INODE(inode,
                    "first_extent(path[%d].p_hdr) != ex",
                    depth);
            return -EIO;
        }
        while (--depth >= 0) {
            ix = path[depth].p_idx;
            if (unlikely(ix != EXT_FIRST_INDEX(path[depth].p_hdr))) {
                EXT4_ERROR_INODE(inode,
                        "ix != EXT_FIRST_INDEX *logical %d!",
                        *logical);
                return -EIO;
            }
        }
        goto found_extent;
    }
 
    /*if (unlikely(*logical < (le32_to_cpu(ex->ee_block) + ee_len))) {*/
    if (unlikely(*logical < ((ex->ee_block) + ee_len))) {
        EXT4_ERROR_INODE(inode,
                "logical %d < ee_block %d + ee_len %d!",
            *logical, (ex->ee_block), ee_len);
        return -EIO;
    }
 
    if (ex != EXT_LAST_EXTENT(path[depth].p_hdr)) {
        /* next allocated block in this leaf */
        ex++;
        goto found_extent;
    }
 
    /* go up and search for index to the right */
    while (--depth >= 0) {
        ix = path[depth].p_idx;
        if (ix != EXT_LAST_INDEX(path[depth].p_hdr))
            goto got_index;
    }
 
    /* we've gone up to the root and found no index to the right */
    return 0;
 
got_index:
    /* we've found index to the right, let's
     * follow it and find the closest allocated
     * block to the right */
    ix++;
    block = ext4_idx_pblock(ix);
    while (++depth < path->p_depth) {
        /* subtract from p_depth to get proper eh_depth */
        bh = read_extent_tree_block(inode, block,
                path->p_depth - depth, 0);
        if (IS_ERR(bh))
            return PTR_ERR(bh);
        eh = ext_block_hdr(bh);
        ix = EXT_FIRST_INDEX(eh);
        block = ext4_idx_pblock(ix);
        extents_brelse(bh);
    }
 
    bh = read_extent_tree_block(inode, block, path->p_depth - depth, 0);
    if (IS_ERR(bh))
        return PTR_ERR(bh);
    eh = ext_block_hdr(bh);
    ex = EXT_FIRST_EXTENT(eh);
found_extent:
    *logical = (ex->ee_block);
    *phys = ext4_ext_pblock(ex);
    *ret_ex = ex;
    if (bh)
        extents_brelse(bh);
    return 0;
}
 
/*
 * ext4_ext_next_allocated_block:
 * returns allocated block in subsequent extent or EXT_MAX_BLOCKS.
 * NOTE: it considers block number from index entry as
 * allocated block. Thus, index entries have to be consistent
 * with leaves.
 */
ext4_lblk_t
ext4_ext_next_allocated_block(struct ext4_ext_path *path)
{
    int depth;
 
    depth = path->p_depth;
 
    if (depth == 0 && path->p_ext == NULL)
        return EXT_MAX_BLOCKS;
 
    while (depth >= 0) {
        if (depth == path->p_depth) {
            /* leaf */
            if (path[depth].p_ext &&
                    path[depth].p_ext !=
                    EXT_LAST_EXTENT(path[depth].p_hdr))
                return le32_to_cpu(path[depth].p_ext[1].ee_block);
        } else {
            /* index */
            if (path[depth].p_idx !=
                    EXT_LAST_INDEX(path[depth].p_hdr))
                return le32_to_cpu(path[depth].p_idx[1].ei_block);
        }
        depth--;
    }
 
    return EXT_MAX_BLOCKS;
}
 
/*
 * ext4_ext_next_leaf_block:
 * returns first allocated block from next leaf or EXT_MAX_BLOCKS
 */
static ext4_lblk_t ext4_ext_next_leaf_block(struct ext4_ext_path *path)
{
    int depth;
 
    BUG_ON(path == NULL);
    depth = path->p_depth;
 
    /* zero-tree has no leaf blocks at all */
    if (depth == 0)
        return EXT_MAX_BLOCKS;
 
    /* go to index block */
    depth--;
 
    while (depth >= 0) {
        if (path[depth].p_idx !=
                EXT_LAST_INDEX(path[depth].p_hdr))
            return (ext4_lblk_t)
                le32_to_cpu(path[depth].p_idx[1].ei_block);
        depth--;
    }
 
    return EXT_MAX_BLOCKS;
}
 
/*
 * ext4_ext_correct_indexes:
 * if leaf gets modified and modified extent is first in the leaf,
 * then we have to correct all indexes above.
 * TODO: do we need to correct tree in all cases?
 */
static int ext4_ext_correct_indexes(void *icb, handle_t *handle, struct inode *inode,
        struct ext4_ext_path *path)
{
    struct ext4_extent_header *eh;
    int depth = ext_depth(inode);
    struct ext4_extent *ex;
    __le32 border;
    int k, err = 0;
 
    eh = path[depth].p_hdr;
    ex = path[depth].p_ext;
 
    if (unlikely(ex == NULL || eh == NULL)) {
        EXT4_ERROR_INODE(inode,
                "ex %p == NULL or eh %p == NULL", ex, eh);
        return -EIO;
    }
 
    if (depth == 0) {
        /* there is no tree at all */
        return 0;
    }
 
    if (ex != EXT_FIRST_EXTENT(eh)) {
        /* we correct tree if first leaf got modified only */
        return 0;
    }
 
    /*
     * TODO: we need correction if border is smaller than current one
     */
    k = depth - 1;
    border = path[depth].p_ext->ee_block;
    err = ext4_ext_get_access(icb, handle, inode, path + k);
    if (err)
        return err;
    path[k].p_idx->ei_block = border;
    err = ext4_ext_dirty(icb, handle, inode, path + k);
    if (err)
        return err;
 
    while (k--) {
        /* change all left-side indexes */
        if (path[k+1].p_idx != EXT_FIRST_INDEX(path[k+1].p_hdr))
            break;
        err = ext4_ext_get_access(icb, handle, inode, path + k);
        if (err)
            break;
        path[k].p_idx->ei_block = border;
        err = ext4_ext_dirty(icb, handle, inode, path + k);
        if (err)
            break;
    }
 
    return err;
}
 
int
ext4_can_extents_be_merged(struct inode *inode, struct ext4_extent *ex1,
        struct ext4_extent *ex2)
{
    unsigned short ext1_ee_len, ext2_ee_len;
 
    /*
     * Make sure that both extents are initialized. We don't merge
     * unwritten extents so that we can be sure that end_io code has
     * the extent that was written properly split out and conversion to
     * initialized is trivial.
     */
    if (ext4_ext_is_unwritten(ex1) != ext4_ext_is_unwritten(ex2))
        return 0;
 
    ext1_ee_len = ext4_ext_get_actual_len(ex1);
    ext2_ee_len = ext4_ext_get_actual_len(ex2);
 
    if (le32_to_cpu(ex1->ee_block) + ext1_ee_len !=
            le32_to_cpu(ex2->ee_block))
        return 0;
 
    /*
     * To allow future support for preallocated extents to be added
     * as an RO_COMPAT feature, refuse to merge to extents if
     * this can result in the top bit of ee_len being set.
     */
    if (ext1_ee_len + ext2_ee_len > EXT_INIT_MAX_LEN)
        return 0;
    if (ext4_ext_is_unwritten(ex1) &&
            (ext1_ee_len + ext2_ee_len > EXT_UNWRITTEN_MAX_LEN))
        return 0;
#ifdef AGGRESSIVE_TEST
    if (ext1_ee_len >= 4)
        return 0;
#endif
 
    if (ext4_ext_pblock(ex1) + ext1_ee_len == ext4_ext_pblock(ex2))
        return 1;
    return 0;
}
 
/*
 * This function tries to merge the "ex" extent to the next extent in the tree.
 * It always tries to merge towards right. If you want to merge towards
 * left, pass "ex - 1" as argument instead of "ex".
 * Returns 0 if the extents (ex and ex+1) were _not_ merged and returns
 * 1 if they got merged.
 */
static int ext4_ext_try_to_merge_right(struct inode *inode,
        struct ext4_ext_path *path,
        struct ext4_extent *ex)
{
    struct ext4_extent_header *eh;
    unsigned int depth, len;
    int merge_done = 0, unwritten;
 
    depth = ext_depth(inode);
    assert(path[depth].p_hdr != NULL);
    eh = path[depth].p_hdr;
 
    while (ex < EXT_LAST_EXTENT(eh)) {
        if (!ext4_can_extents_be_merged(inode, ex, ex + 1))
            break;
        /* merge with next extent! */
        unwritten = ext4_ext_is_unwritten(ex);
        ex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ex)
                + ext4_ext_get_actual_len(ex + 1));
        if (unwritten)
            ext4_ext_mark_unwritten(ex);
 
        if (ex + 1 < EXT_LAST_EXTENT(eh)) {
            len = (EXT_LAST_EXTENT(eh) - ex - 1)
                * sizeof(struct ext4_extent);
            memmove(ex + 1, ex + 2, len);
        }
        le16_add_cpu(&eh->eh_entries, -1);
        merge_done = 1;
        if (!eh->eh_entries)
            EXT4_ERROR_INODE(inode, "eh->eh_entries = 0!");
    }
 
    return merge_done;
}
 
/*
 * This function does a very simple check to see if we can collapse
 * an extent tree with a single extent tree leaf block into the inode.
 */
static void ext4_ext_try_to_merge_up(void *icb, handle_t *handle,
        struct inode *inode,
        struct ext4_ext_path *path)
{
    size_t s;
    unsigned max_root = ext4_ext_space_root(inode, 0);
    ext4_fsblk_t blk;
 
    if ((path[0].p_depth != 1) ||
            (le16_to_cpu(path[0].p_hdr->eh_entries) != 1) ||
            (le16_to_cpu(path[1].p_hdr->eh_entries) > max_root))
        return;
 
    /*
     * We need to modify the block allocation bitmap and the block
     * group descriptor to release the extent tree block.  If we
     * can't get the journal credits, give up.
     */
    if (ext4_journal_extend(icb, handle, 2))
        return;
 
    /*
     * Copy the extent data up to the inode
     */
    blk = ext4_idx_pblock(path[0].p_idx);
    s = le16_to_cpu(path[1].p_hdr->eh_entries) *
        sizeof(struct ext4_extent_idx);
    s += sizeof(struct ext4_extent_header);
 
    path[1].p_maxdepth = path[0].p_maxdepth;
    memcpy(path[0].p_hdr, path[1].p_hdr, s);
    path[0].p_depth = 0;
    path[0].p_ext = EXT_FIRST_EXTENT(path[0].p_hdr) +
        (path[1].p_ext - EXT_FIRST_EXTENT(path[1].p_hdr));
    path[0].p_hdr->eh_max = cpu_to_le16(max_root);
 
    extents_brelse(path[1].p_bh);
    ext4_free_blocks(icb, handle, inode, NULL, blk, 1,
            EXT4_FREE_BLOCKS_METADATA | EXT4_FREE_BLOCKS_FORGET);
}
 
/*
 * This function tries to merge the @ex extent to neighbours in the tree.
 * return 1 if merge left else 0.
 */
static void ext4_ext_try_to_merge(void *icb, handle_t *handle,
        struct inode *inode,
        struct ext4_ext_path *path,
        struct ext4_extent *ex) {
    struct ext4_extent_header *eh;
    unsigned int depth;
    int merge_done = 0;
 
    depth = ext_depth(inode);
    BUG_ON(path[depth].p_hdr == NULL);
    eh = path[depth].p_hdr;
 
    if (ex > EXT_FIRST_EXTENT(eh))
        merge_done = ext4_ext_try_to_merge_right(inode, path, ex - 1);
 
    if (!merge_done)
        (void) ext4_ext_try_to_merge_right(inode, path, ex);
 
    ext4_ext_try_to_merge_up(icb, handle, inode, path);
}
 
/*
 * ext4_ext_insert_extent:
 * tries to merge requsted extent into the existing extent or
 * inserts requested extent as new one into the tree,
 * creating new leaf in the no-space case.
 */
int ext4_ext_insert_extent(void *icb, handle_t *handle, struct inode *inode,
        struct ext4_ext_path **ppath,
        struct ext4_extent *newext,
        int gb_flags)
{
    struct ext4_ext_path *path = *ppath;
    struct ext4_extent_header *eh;
    struct ext4_extent *ex, *fex;
    struct ext4_extent *nearex; /* nearest extent */
    struct ext4_ext_path *npath = NULL;
    int depth, len, err;
    ext4_lblk_t next;
    int mb_flags = 0, unwritten;
 
    if (gb_flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
        mb_flags |= EXT4_MB_DELALLOC_RESERVED;
    if (unlikely(ext4_ext_get_actual_len(newext) == 0)) {
        EXT4_ERROR_INODE(inode, "ext4_ext_get_actual_len(newext) == 0");
        return -EIO;
    }
    depth = ext_depth(inode);
    ex = path[depth].p_ext;
    eh = path[depth].p_hdr;
    if (unlikely(path[depth].p_hdr == NULL)) {
        EXT4_ERROR_INODE(inode, "path[%d].p_hdr == NULL", depth);
        return -EIO;
    }
 
    /* try to insert block into found extent and return */
    if (ex && !(gb_flags & EXT4_GET_BLOCKS_PRE_IO)) {
 
        /*
         * Try to see whether we should rather test the extent on
         * right from ex, or from the left of ex. This is because
         * ext4_find_extent() can return either extent on the
         * left, or on the right from the searched position. This
         * will make merging more effective.
         */
        if (ex < EXT_LAST_EXTENT(eh) &&
                (le32_to_cpu(ex->ee_block) +
                 ext4_ext_get_actual_len(ex) <
                 le32_to_cpu(newext->ee_block))) {
            ex += 1;
            goto prepend;
        } else if ((ex > EXT_FIRST_EXTENT(eh)) &&
                (le32_to_cpu(newext->ee_block) +
                 ext4_ext_get_actual_len(newext) <
                 le32_to_cpu(ex->ee_block)))
            ex -= 1;
 
        /* Try to append newex to the ex */
        if (ext4_can_extents_be_merged(inode, ex, newext)) {
            ext_debug("append [%d]%d block to %u:[%d]%d"
                    "(from %llu)\n",
                    ext4_ext_is_unwritten(newext),
                    ext4_ext_get_actual_len(newext),
                    le32_to_cpu(ex->ee_block),
                    ext4_ext_is_unwritten(ex),
                    ext4_ext_get_actual_len(ex),
                    ext4_ext_pblock(ex));
            err = ext4_ext_get_access(icb, handle, inode,
                    path + depth);
            if (err)
                return err;
            unwritten = ext4_ext_is_unwritten(ex);
            ex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ex)
                    + ext4_ext_get_actual_len(newext));
            if (unwritten)
                ext4_ext_mark_unwritten(ex);
            eh = path[depth].p_hdr;
            nearex = ex;
            goto merge;
        }
 
prepend:
        /* Try to prepend newex to the ex */
        if (ext4_can_extents_be_merged(inode, newext, ex)) {
            ext_debug("prepend %u[%d]%d block to %u:[%d]%d"
                    "(from %llu)\n",
                    le32_to_cpu(newext->ee_block),
                    ext4_ext_is_unwritten(newext),
                    ext4_ext_get_actual_len(newext),
                    le32_to_cpu(ex->ee_block),
                    ext4_ext_is_unwritten(ex),
                    ext4_ext_get_actual_len(ex),
                    ext4_ext_pblock(ex));
            err = ext4_ext_get_access(icb, handle, inode,
                    path + depth);
            if (err)
                return err;
 
            unwritten = ext4_ext_is_unwritten(ex);
            ex->ee_block = newext->ee_block;
            ext4_ext_store_pblock(ex, ext4_ext_pblock(newext));
            ex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ex)
                    + ext4_ext_get_actual_len(newext));
            if (unwritten)
                ext4_ext_mark_unwritten(ex);
            eh = path[depth].p_hdr;
            nearex = ex;
            goto merge;
        }
    }
 
    depth = ext_depth(inode);
    eh = path[depth].p_hdr;
    if (le16_to_cpu(eh->eh_entries) < le16_to_cpu(eh->eh_max))
        goto has_space;
 
    /* probably next leaf has space for us? */
    fex = EXT_LAST_EXTENT(eh);
    next = EXT_MAX_BLOCKS;
    if (le32_to_cpu(newext->ee_block) > le32_to_cpu(fex->ee_block))
        next = ext4_ext_next_leaf_block(path);
    if (next != EXT_MAX_BLOCKS) {
        ext_debug("next leaf block - %u\n", next);
        BUG_ON(npath != NULL);
        npath = ext4_find_extent(inode, next, NULL, 0);
        if (IS_ERR(npath))
            return PTR_ERR(npath);
        BUG_ON(npath->p_depth != path->p_depth);
        eh = npath[depth].p_hdr;
        if (le16_to_cpu(eh->eh_entries) < le16_to_cpu(eh->eh_max)) {
            ext_debug("next leaf isn't full(%d)\n",
                    le16_to_cpu(eh->eh_entries));
            path = npath;
            goto has_space;
        }
        ext_debug("next leaf has no free space(%d,%d)\n",
                le16_to_cpu(eh->eh_entries), le16_to_cpu(eh->eh_max));
    }
 
    /*
     * There is no free space in the found leaf.
     * We're gonna add a new leaf in the tree.
     */
    if (gb_flags & EXT4_GET_BLOCKS_METADATA_NOFAIL)
        mb_flags |= EXT4_MB_USE_RESERVED;
    err = ext4_ext_create_new_leaf(icb, handle, inode, mb_flags, gb_flags,
            ppath, newext);
    if (err)
        goto cleanup;
    depth = ext_depth(inode);
    eh = path[depth].p_hdr;
 
has_space:
    nearex = path[depth].p_ext;
 
    err = ext4_ext_get_access(icb, handle, inode, path + depth);
    if (err)
        goto cleanup;
 
    if (!nearex) {
        /* there is no extent in this leaf, create first one */
        ext_debug("first extent in the leaf: %u:%llu:[%d]%d\n",
                le32_to_cpu(newext->ee_block),
                ext4_ext_pblock(newext),
                ext4_ext_is_unwritten(newext),
                ext4_ext_get_actual_len(newext));
        nearex = EXT_FIRST_EXTENT(eh);
    } else {
        if (le32_to_cpu(newext->ee_block)
                > le32_to_cpu(nearex->ee_block)) {
            /* Insert after */
            ext_debug("insert %u:%llu:[%d]%d before: "
                    "nearest %p\n",
                    le32_to_cpu(newext->ee_block),
                    ext4_ext_pblock(newext),
                    ext4_ext_is_unwritten(newext),
                    ext4_ext_get_actual_len(newext),
                    nearex);
            nearex++;
        } else {
            /* Insert before */
            BUG_ON(newext->ee_block == nearex->ee_block);
            ext_debug("insert %u:%llu:[%d]%d after: "
                    "nearest %p\n",
                    le32_to_cpu(newext->ee_block),
                    ext4_ext_pblock(newext),
                    ext4_ext_is_unwritten(newext),
                    ext4_ext_get_actual_len(newext),
                    nearex);
        }
        len = EXT_LAST_EXTENT(eh) - nearex + 1;
        if (len > 0) {
            ext_debug("insert %u:%llu:[%d]%d: "
                    "move %d extents from 0x%p to 0x%p\n",
                    le32_to_cpu(newext->ee_block),
                    ext4_ext_pblock(newext),
                    ext4_ext_is_unwritten(newext),
                    ext4_ext_get_actual_len(newext),
                    len, nearex, nearex + 1);
            memmove(nearex + 1, nearex,
                    len * sizeof(struct ext4_extent));
        }
    }
 
    le16_add_cpu(&eh->eh_entries, 1);
    path[depth].p_ext = nearex;
    nearex->ee_block = newext->ee_block;
    ext4_ext_store_pblock(nearex, ext4_ext_pblock(newext));
    nearex->ee_len = newext->ee_len;
 
merge:
    /* try to merge extents */
    if (!(gb_flags & EXT4_GET_BLOCKS_PRE_IO))
        ext4_ext_try_to_merge(icb, handle, inode, path, nearex);
 
 
    /* time to correct all indexes above */
    err = ext4_ext_correct_indexes(icb, handle, inode, path);
    if (err)
        goto cleanup;
 
    err = ext4_ext_dirty(icb, handle, inode, path + path->p_depth);
 
cleanup:
    if (npath) {
        ext4_ext_drop_refs(npath);
        kfree(npath);
    }
    return err;
}
 
static inline int get_default_free_blocks_flags(struct inode *inode)
{
    return 0;
}
 
/* FIXME!! we need to try to merge to left or right after zero-out  */
static int ext4_ext_zeroout(struct inode *inode, struct ext4_extent *ex)
{
    ext4_fsblk_t ee_pblock;
    unsigned int ee_len;
    int ret;
 
    ee_len    = ext4_ext_get_actual_len(ex);
    ee_pblock = ext4_ext_pblock(ex);
 
    ret = 0;
 
    return ret;
}
 
static int ext4_remove_blocks(void *icb, handle_t *handle, struct inode *inode,
        struct ext4_extent *ex,
        unsigned long from, unsigned long to)
{
    struct buffer_head *bh;
    int i;
 
    if (from >= le32_to_cpu(ex->ee_block)
            && to == le32_to_cpu(ex->ee_block) + ext4_ext_get_actual_len(ex) - 1) {
        /* tail removal */
        unsigned long num, start;
        num = le32_to_cpu(ex->ee_block) + ext4_ext_get_actual_len(ex) - from;
        start = ext4_ext_pblock(ex) + ext4_ext_get_actual_len(ex) - num;
        ext4_free_blocks(icb, handle, inode, NULL, start, num, 0);
    } else if (from == le32_to_cpu(ex->ee_block)
            && to <= le32_to_cpu(ex->ee_block) + ext4_ext_get_actual_len(ex) - 1) {
    } else {
    }
    return 0;
}
 
/*
 * routine removes index from the index block
 * it's used in truncate case only. thus all requests are for
 * last index in the block only
 */
int ext4_ext_rm_idx(void *icb, handle_t *handle, struct inode *inode,
        struct ext4_ext_path *path)
{
    int err;
    ext4_fsblk_t leaf;
 
    /* free index block */
    path--;
    leaf = ext4_idx_pblock(path->p_idx);
    BUG_ON(path->p_hdr->eh_entries == 0);
    if ((err = ext4_ext_get_access(icb, handle, inode, path)))
        return err;
    path->p_hdr->eh_entries = cpu_to_le16(le16_to_cpu(path->p_hdr->eh_entries)-1);
    if ((err = ext4_ext_dirty(icb, handle, inode, path)))
        return err;
    ext4_free_blocks(icb, handle, inode, NULL, leaf, 1, 0);
    return err;
}
 
static int
ext4_ext_rm_leaf(void *icb, handle_t *handle, struct inode *inode,
        struct ext4_ext_path *path, unsigned long start)
{
    int err = 0, correct_index = 0;
    int depth = ext_depth(inode), credits;
    struct ext4_extent_header *eh;
    unsigned a, b, block, num;
    unsigned long ex_ee_block;
    unsigned short ex_ee_len;
    struct ext4_extent *ex;
 
    /* the header must be checked already in ext4_ext_remove_space() */
    if (!path[depth].p_hdr)
        path[depth].p_hdr = ext_block_hdr(path[depth].p_bh);
    eh = path[depth].p_hdr;
    BUG_ON(eh == NULL);
 
    /* find where to start removing */
    ex = EXT_LAST_EXTENT(eh);
 
    ex_ee_block = le32_to_cpu(ex->ee_block);
    ex_ee_len = ext4_ext_get_actual_len(ex);
 
    while (ex >= EXT_FIRST_EXTENT(eh) &&
            ex_ee_block + ex_ee_len > start) {
        path[depth].p_ext = ex;
 
        a = ex_ee_block > start ? ex_ee_block : start;
        b = (unsigned long long)ex_ee_block + ex_ee_len - 1 <
            EXT_MAX_BLOCKS ? ex_ee_block + ex_ee_len - 1 : EXT_MAX_BLOCKS;
 
 
        if (a != ex_ee_block && b != ex_ee_block + ex_ee_len - 1) {
            block = 0;
            num = 0;
            BUG();
        } else if (a != ex_ee_block) {
            /* remove tail of the extent */
            block = ex_ee_block;
            num = a - block;
        } else if (b != ex_ee_block + ex_ee_len - 1) {
            /* remove head of the extent */
            block = a;
            num = b - a;
            /* there is no "make a hole" API yet */
            BUG();
        } else {
            /* remove whole extent: excellent! */
            block = ex_ee_block;
            num = 0;
            BUG_ON(a != ex_ee_block);
            BUG_ON(b != ex_ee_block + ex_ee_len - 1);
        }
 
        /* at present, extent can't cross block group */
        /* leaf + bitmap + group desc + sb + inode */
        credits = 5;
        if (ex == EXT_FIRST_EXTENT(eh)) {
            correct_index = 1;
            credits += (ext_depth(inode)) + 1;
        }
 
        /*handle = ext4_ext_journal_restart(icb, handle, credits);*/
        /*if (IS_ERR(icb, handle)) {*/
        /*err = PTR_ERR(icb, handle);*/
        /*goto out;*/
        /*}*/
 
        err = ext4_ext_get_access(icb, handle, inode, path + depth);
        if (err)
            goto out;
 
        err = ext4_remove_blocks(icb, handle, inode, ex, a, b);
        if (err)
            goto out;
 
        if (num == 0) {
            /* this extent is removed entirely mark slot unused */
            ext4_ext_store_pblock(ex, 0);
            eh->eh_entries = cpu_to_le16(le16_to_cpu(eh->eh_entries)-1);
        }
 
        ex->ee_block = cpu_to_le32(block);
        ex->ee_len = cpu_to_le16(num);
 
        err = ext4_ext_dirty(icb, handle, inode, path + depth);
        if (err)
            goto out;
 
        ex--;
        ex_ee_block = le32_to_cpu(ex->ee_block);
        ex_ee_len = ext4_ext_get_actual_len(ex);
    }
 
    if (correct_index && eh->eh_entries)
        err = ext4_ext_correct_indexes(icb, handle, inode, path);
 
    /* if this leaf is free, then we should
     * remove it from index block above */
    if (err == 0 && eh->eh_entries == 0 && path[depth].p_bh != NULL)
        err = ext4_ext_rm_idx(icb, handle, inode, path + depth);
 
out:
    return err;
}
 
/*
 * ext4_split_extent_at() splits an extent at given block.
 *
 * @handle: the journal handle
 * @inode: the file inode
 * @path: the path to the extent
 * @split: the logical block where the extent is splitted.
 * @split_flags: indicates if the extent could be zeroout if split fails, and
 *       the states(init or unwritten) of new extents.
 * @flags: flags used to insert new extent to extent tree.
 *
 *
 * Splits extent [a, b] into two extents [a, @split) and [@split, b], states
 * of which are deterimined by split_flag.
 *
 * There are two cases:
 *  a> the extent are splitted into two extent.
 *  b> split is not needed, and just mark the extent.
 *
 * return 0 on success.
 */
static int ext4_split_extent_at(void *icb, handle_t *handle,
        struct inode *inode,
        struct ext4_ext_path **ppath,
        ext4_lblk_t split,
        int split_flag,
        int flags)
{
    struct ext4_ext_path *path = *ppath;
    ext4_fsblk_t newblock;
    ext4_lblk_t ee_block;
    struct ext4_extent *ex, newex, orig_ex, zero_ex;
    struct ext4_extent *ex2 = NULL;
    unsigned int ee_len, depth;
    int err = 0;
 
    ext4_ext_show_leaf(inode, path);
 
    depth = ext_depth(inode);
    ex = path[depth].p_ext;
    ee_block = le32_to_cpu(ex->ee_block);
    ee_len = ext4_ext_get_actual_len(ex);
    newblock = split - ee_block + ext4_ext_pblock(ex);
 
    BUG_ON(split < ee_block || split >= (ee_block + ee_len));
 
    err = ext4_ext_get_access(icb, handle, inode, path + depth);
    if (err)
        goto out;
 
    if (split == ee_block) {
        /*
         * case b: block @split is the block that the extent begins with
         * then we just change the state of the extent, and splitting
         * is not needed.
         */
        if (split_flag & EXT4_EXT_MARK_UNWRIT2)
            ext4_ext_mark_unwritten(ex);
        else
            ext4_ext_mark_initialized(ex);
 
        if (!(flags & EXT4_GET_BLOCKS_PRE_IO))
            ext4_ext_try_to_merge(icb, handle, inode, path, ex);
 
        err = ext4_ext_dirty(icb, handle, inode, path + path->p_depth);
        goto out;
    }
 
    /* case a */
    memcpy(&orig_ex, ex, sizeof(orig_ex));
    ex->ee_len = cpu_to_le16(split - ee_block);
    if (split_flag & EXT4_EXT_MARK_UNWRIT1)
        ext4_ext_mark_unwritten(ex);
 
    /*
     * path may lead to new leaf, not to original leaf any more
     * after ext4_ext_insert_extent() returns,
     */
    err = ext4_ext_dirty(icb, handle, inode, path + depth);
    if (err)
        goto fix_extent_len;
 
    ex2 = &newex;
    ex2->ee_block = cpu_to_le32(split);
    ex2->ee_len   = cpu_to_le16(ee_len - (split - ee_block));
    ext4_ext_store_pblock(ex2, newblock);
    if (split_flag & EXT4_EXT_MARK_UNWRIT2)
        ext4_ext_mark_unwritten(ex2);
 
    err = ext4_ext_insert_extent(icb, handle, inode, ppath, &newex, flags);
    if (err == -ENOSPC && (EXT4_EXT_MAY_ZEROOUT & split_flag)) {
        if (split_flag & (EXT4_EXT_DATA_VALID1|EXT4_EXT_DATA_VALID2)) {
            if (split_flag & EXT4_EXT_DATA_VALID1) {
                err = ext4_ext_zeroout(inode, ex2);
                zero_ex.ee_block = ex2->ee_block;
                zero_ex.ee_len = cpu_to_le16(
                        ext4_ext_get_actual_len(ex2));
                ext4_ext_store_pblock(&zero_ex,
                        ext4_ext_pblock(ex2));
            } else {
                err = ext4_ext_zeroout(inode, ex);
                zero_ex.ee_block = ex->ee_block;
                zero_ex.ee_len = cpu_to_le16(
                        ext4_ext_get_actual_len(ex));
                ext4_ext_store_pblock(&zero_ex,
                        ext4_ext_pblock(ex));
            }
        } else {
            err = ext4_ext_zeroout(inode, &orig_ex);
            zero_ex.ee_block = orig_ex.ee_block;
            zero_ex.ee_len = cpu_to_le16(
                    ext4_ext_get_actual_len(&orig_ex));
            ext4_ext_store_pblock(&zero_ex,
                    ext4_ext_pblock(&orig_ex));
        }
 
        if (err)
            goto fix_extent_len;
        /* update the extent length and mark as initialized */
        ex->ee_len = cpu_to_le16(ee_len);
        ext4_ext_try_to_merge(icb, handle, inode, path, ex);
        err = ext4_ext_dirty(icb, handle, inode, path + path->p_depth);
        if (err)
            goto fix_extent_len;
 
        goto out;
    } else if (err)
        goto fix_extent_len;
 
out:
    ext4_ext_show_leaf(inode, path);
    return err;
 
fix_extent_len:
    ex->ee_len = orig_ex.ee_len;
    ext4_ext_dirty(icb, handle, inode, path + path->p_depth);
    return err;
}
 
/*
 * returns 1 if current index have to be freed (even partial)
 */
#ifndef __REACTOS__
static int inline
#else
inline int
#endif
ext4_ext_more_to_rm(struct ext4_ext_path *path)
{
    BUG_ON(path->p_idx == NULL);
 
    if (path->p_idx < EXT_FIRST_INDEX(path->p_hdr))
        return 0;
 
    /*
     * if truncate on deeper level happened it it wasn't partial
     * so we have to consider current index for truncation
     */
    if (le16_to_cpu(path->p_hdr->eh_entries) == path->p_block)
        return 0;
    return 1;
}
 
int ext4_ext_remove_space(void *icb, struct inode *inode, unsigned long start)
{
    struct super_block *sb = inode->i_sb;
    int depth = ext_depth(inode);
    struct ext4_ext_path *path;
    handle_t *handle = NULL;
    int i = 0, err = 0;
 
    /* probably first extent we're gonna free will be last in block */
    /*handle = ext4_journal_start(inode, depth + 1);*/
    /*if (IS_ERR(icb, handle))*/
    /*return PTR_ERR(icb, handle);*/
 
    /*
     * we start scanning from right side freeing all the blocks
     * after i_size and walking into the deep
     */
    path = kmalloc(sizeof(struct ext4_ext_path) * (depth + 1), GFP_KERNEL);
    if (path == NULL) {
        ext4_journal_stop(icb, handle);
        return -ENOMEM;
    }
    memset(path, 0, sizeof(struct ext4_ext_path) * (depth + 1));
    path[0].p_hdr = ext_inode_hdr(inode);
    if (ext4_ext_check_inode(inode)) {
        err = -EIO;
        goto out;
    }
    path[0].p_depth = depth;
 
    while (i >= 0 && err == 0) {
        if (i == depth) {
            /* this is leaf block */
            err = ext4_ext_rm_leaf(icb, handle, inode, path, start);
            /* root level have p_bh == NULL, extents_brelse() eats this */
            extents_brelse(path[i].p_bh);
            path[i].p_bh = NULL;
            i--;
            continue;
        }
 
        /* this is index block */
        if (!path[i].p_hdr) {
            path[i].p_hdr = ext_block_hdr(path[i].p_bh);
        }
 
        if (!path[i].p_idx) {
            /* this level hasn't touched yet */
            path[i].p_idx = EXT_LAST_INDEX(path[i].p_hdr);
            path[i].p_block = le16_to_cpu(path[i].p_hdr->eh_entries)+1;
        } else {
            /* we've already was here, see at next index */
            path[i].p_idx--;
        }
 
        if (ext4_ext_more_to_rm(path + i)) {
            struct buffer_head *bh;
            /* go to the next level */
            memset(path + i + 1, 0, sizeof(*path));
            bh = read_extent_tree_block(inode, ext4_idx_pblock(path[i].p_idx), path[0].p_depth - (i + 1), 0);
            if (IS_ERR(bh)) {
                /* should we reset i_size? */
                err = -EIO;
                break;
            }
            path[i+1].p_bh = bh;
 
            /* put actual number of indexes to know is this
             * number got changed at the next iteration */
            path[i].p_block = le16_to_cpu(path[i].p_hdr->eh_entries);
            i++;
        } else {
            /* we finish processing this index, go up */
            if (path[i].p_hdr->eh_entries == 0 && i > 0) {
                /* index is empty, remove it
                 * handle must be already prepared by the
                 * truncatei_leaf() */
                err = ext4_ext_rm_idx(icb, handle, inode, path + i);
            }
            /* root level have p_bh == NULL, extents_brelse() eats this */
            extents_brelse(path[i].p_bh);
            path[i].p_bh = NULL;
            i--;
        }
    }
 
    /* TODO: flexible tree reduction should be here */
    if (path->p_hdr->eh_entries == 0) {
        /*
         * truncate to zero freed all the tree
         * so, we need to correct eh_depth
         */
        err = ext4_ext_get_access(icb, handle, inode, path);
        if (err == 0) {
            ext_inode_hdr(inode)->eh_depth = 0;
            ext_inode_hdr(inode)->eh_max =
                cpu_to_le16(ext4_ext_space_root(inode, 0));
            err = ext4_ext_dirty(icb, handle, inode, path);
        }
    }
out:
    if (path) {
        ext4_ext_drop_refs(path);
        kfree(path);
    }
    ext4_journal_stop(icb, handle);
 
    return err;
}
 
int ext4_ext_tree_init(void *icb, handle_t *handle, struct inode *inode)
{
    struct ext4_extent_header *eh;
 
    eh = ext_inode_hdr(inode);
    eh->eh_depth = 0;
    eh->eh_entries = 0;
    eh->eh_magic = cpu_to_le16(EXT4_EXT_MAGIC);
    eh->eh_max = cpu_to_le16(ext4_ext_space_root(inode, 0));
    ext4_mark_inode_dirty(icb, handle, inode);
    return 0;
}
 
/*
 * called at mount time
 */
void ext4_ext_init(struct super_block *sb)
{
    /*
     * possible initialization would be here
     */
}
 
static int ext4_ext_convert_to_initialized (
        void *icb,
        handle_t *handle,
        struct inode *inode,
        struct ext4_ext_path **ppath,
        ext4_lblk_t split,
        unsigned long blocks,
        int flags)
{
    int depth = ext_depth(inode), err;
    struct ext4_extent *ex = (*ppath)[depth].p_ext;
 
    assert (le32_to_cpu(ex->ee_block) <= split);
 
    if (split + blocks == le32_to_cpu(ex->ee_block) +
                          ext4_ext_get_actual_len(ex)) {
 
        /* split and initialize right part */
        err = ext4_split_extent_at(icb, handle, inode, ppath, split,
                                   EXT4_EXT_MARK_UNWRIT1, flags);
 
    } else if (le32_to_cpu(ex->ee_block) == split) {
 
        /* split and initialize left part */
        err = ext4_split_extent_at(icb, handle, inode, ppath, split + blocks,
                                   EXT4_EXT_MARK_UNWRIT2, flags);
 
    } else {
 
        /* split 1 extent to 3 and initialize the 2nd */
        err = ext4_split_extent_at(icb, handle, inode, ppath, split + blocks,
                                   EXT4_EXT_MARK_UNWRIT1 |
                                   EXT4_EXT_MARK_UNWRIT2, flags);
        if (0 == err) {
            err = ext4_split_extent_at(icb, handle, inode, ppath, split,
                                       EXT4_EXT_MARK_UNWRIT1, flags);
        }
    }
 
    return err;
}
 
int ext4_ext_get_blocks(void *icb, handle_t *handle, struct inode *inode, ext4_fsblk_t iblock,
        unsigned long max_blocks, struct buffer_head *bh_result,
        int create, int flags)
{
    struct ext4_ext_path *path = NULL;
    struct ext4_extent newex, *ex;
    int goal, err = 0, depth;
    unsigned long allocated = 0;
    ext4_fsblk_t next, newblock;
 
    clear_buffer_new(bh_result);
    /*mutex_lock(&ext4_I(inode)->truncate_mutex);*/
 
    /* find extent for this block */
    path = ext4_find_extent(inode, iblock, NULL, 0);
    if (IS_ERR(path)) {
        err = PTR_ERR(path);
        path = NULL;
        goto out2;
    }
 
    depth = ext_depth(inode);
 
    /*
     * consistent leaf must not be empty
     * this situations is possible, though, _during_ tree modification
     * this is why assert can't be put in ext4_ext_find_extent()
     */
    BUG_ON(path[depth].p_ext == NULL && depth != 0);
 
    if ((ex = path[depth].p_ext)) {
        ext4_lblk_t ee_block = le32_to_cpu(ex->ee_block);
        ext4_fsblk_t ee_start = ext4_ext_pblock(ex);
        unsigned short ee_len  = ext4_ext_get_actual_len(ex);
        /* if found exent covers block, simple return it */
        if (iblock >= ee_block && iblock < ee_block + ee_len) {
 
            /* number of remain blocks in the extent */
            allocated = ee_len + ee_block - iblock;
 
            if (ext4_ext_is_unwritten(ex)) {
                if (create) {
                    newblock = iblock - ee_block + ee_start;
                    err = ext4_ext_convert_to_initialized (
                            icb, handle,
                            inode,
                            &path,
                            iblock,
                            allocated,
                            flags);
                    if (err)
                        goto out2;
 
                } else {
                    newblock = 0;
                }
            } else {
                newblock = iblock - ee_block + ee_start;
            }
            goto out;
        }
    }
 
    /*
     * requested block isn't allocated yet
     * we couldn't try to create block if create flag is zero
     */
    if (!create) {
        goto out2;
    }
 
    /* find next allocated block so that we know how many
     * blocks we can allocate without ovelapping next extent */
    next = ext4_ext_next_allocated_block(path);
    BUG_ON(next <= iblock);
    allocated = next - iblock;
    if (flags & EXT4_GET_BLOCKS_PRE_IO && max_blocks > EXT_UNWRITTEN_MAX_LEN)
        max_blocks = EXT_UNWRITTEN_MAX_LEN;
    if (allocated > max_blocks)
        allocated = max_blocks;
 
    /* allocate new block */
    goal = ext4_ext_find_goal(inode, path, iblock);
 
    newblock = ext4_new_meta_blocks(icb, handle, inode, goal, 0,
            &allocated, &err);
    if (!newblock)
        goto out2;
 
    /* try to insert new extent into found leaf and return */
    newex.ee_block = cpu_to_le32(iblock);
    ext4_ext_store_pblock(&newex, newblock);
    newex.ee_len = cpu_to_le16(allocated);
    /* if it's fallocate, mark ex as unwritten */
    if (flags & EXT4_GET_BLOCKS_PRE_IO) {
        ext4_ext_mark_unwritten(&newex);
    }
    err = ext4_ext_insert_extent(icb, handle, inode, &path, &newex,
                                 flags & EXT4_GET_BLOCKS_PRE_IO);
 
    if (err) {
        /* free data blocks we just allocated */
        ext4_free_blocks(icb, handle, inode, NULL, ext4_ext_pblock(&newex),
                le16_to_cpu(newex.ee_len), get_default_free_blocks_flags(inode));
        goto out2;
    }
 
    ext4_mark_inode_dirty(icb, handle, inode);
 
    /* previous routine could use block we allocated */
    if (ext4_ext_is_unwritten(&newex))
        newblock = 0;
    else
        newblock = ext4_ext_pblock(&newex);
 
    set_buffer_new(bh_result);
 
out:
    if (allocated > max_blocks)
        allocated = max_blocks;
 
    ext4_ext_show_leaf(inode, path);
    set_buffer_mapped(bh_result);
    bh_result->b_bdev = inode->i_sb->s_bdev;
    bh_result->b_blocknr = newblock;
out2:
    if (path) {
        ext4_ext_drop_refs(path);
        kfree(path);
    }
    /*mutex_unlock(&ext4_I(inode)->truncate_mutex);*/
 
    return err ? err : allocated;
}
 
int ext4_ext_truncate(void *icb, struct inode *inode, unsigned long start)
{
    int ret = ext4_ext_remove_space(icb, inode, start);
 
    /* Save modifications on i_blocks field of the inode. */
    if (!ret)
        ret = ext4_mark_inode_dirty(icb, NULL, inode);
 
    return ret;
}
 
#ifdef _MSC_VER
#pragma warning(pop)
#endif