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[/] [or1k/] [trunk/] [linux/] [linux-2.4/] [fs/] [ext3/] [balloc.c] - Blame information for rev 1275

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/*
 *  linux/fs/ext3/balloc.c
 *
 * Copyright (C) 1992, 1993, 1994, 1995
 * Remy Card (card@masi.ibp.fr)
 * Laboratoire MASI - Institut Blaise Pascal
 * Universite Pierre et Marie Curie (Paris VI)
 *
 *  Enhanced block allocation by Stephen Tweedie (sct@redhat.com), 1993
 *  Big-endian to little-endian byte-swapping/bitmaps by
 *        David S. Miller (davem@caip.rutgers.edu), 1995
 */
 
#include <linux/config.h>
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/jbd.h>
#include <linux/ext3_fs.h>
#include <linux/ext3_jbd.h>
#include <linux/locks.h>
#include <linux/quotaops.h>
 
/*
 * balloc.c contains the blocks allocation and deallocation routines
 */
 
/*
 * The free blocks are managed by bitmaps.  A file system contains several
 * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
 * block for inodes, N blocks for the inode table and data blocks.
 *
 * The file system contains group descriptors which are located after the
 * super block.  Each descriptor contains the number of the bitmap block and
 * the free blocks count in the block.  The descriptors are loaded in memory
 * when a file system is mounted (see ext3_read_super).
 */
 
 
#define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
 
struct ext3_group_desc * ext3_get_group_desc(struct super_block * sb,
                                             unsigned int block_group,
                                             struct buffer_head ** bh)
{
        unsigned long group_desc;
        unsigned long desc;
        struct ext3_group_desc * gdp;
 
        if (block_group >= sb->u.ext3_sb.s_groups_count) {
                ext3_error (sb, "ext3_get_group_desc",
                            "block_group >= groups_count - "
                            "block_group = %d, groups_count = %lu",
                            block_group, sb->u.ext3_sb.s_groups_count);
 
                return NULL;
        }
 
        group_desc = block_group / EXT3_DESC_PER_BLOCK(sb);
        desc = block_group % EXT3_DESC_PER_BLOCK(sb);
        if (!sb->u.ext3_sb.s_group_desc[group_desc]) {
                ext3_error (sb, "ext3_get_group_desc",
                            "Group descriptor not loaded - "
                            "block_group = %d, group_desc = %lu, desc = %lu",
                             block_group, group_desc, desc);
                return NULL;
        }
 
        gdp = (struct ext3_group_desc *)
              sb->u.ext3_sb.s_group_desc[group_desc]->b_data;
        if (bh)
                *bh = sb->u.ext3_sb.s_group_desc[group_desc];
        return gdp + desc;
}
 
/*
 * Read the bitmap for a given block_group, reading into the specified
 * slot in the superblock's bitmap cache.
 *
 * Return >=0 on success or a -ve error code.
 */
 
static int read_block_bitmap (struct super_block * sb,
                               unsigned int block_group,
                               unsigned long bitmap_nr)
{
        struct ext3_group_desc * gdp;
        struct buffer_head * bh = NULL;
        int retval = -EIO;
 
        gdp = ext3_get_group_desc (sb, block_group, NULL);
        if (!gdp)
                goto error_out;
        retval = 0;
        bh = sb_bread(sb, le32_to_cpu(gdp->bg_block_bitmap));
        if (!bh) {
                ext3_error (sb, "read_block_bitmap",
                            "Cannot read block bitmap - "
                            "block_group = %d, block_bitmap = %lu",
                            block_group, (unsigned long) gdp->bg_block_bitmap);
                retval = -EIO;
        }
        /*
         * On IO error, just leave a zero in the superblock's block pointer for
         * this group.  The IO will be retried next time.
         */
error_out:
        sb->u.ext3_sb.s_block_bitmap_number[bitmap_nr] = block_group;
        sb->u.ext3_sb.s_block_bitmap[bitmap_nr] = bh;
        return retval;
}
 
/*
 * load_block_bitmap loads the block bitmap for a blocks group
 *
 * It maintains a cache for the last bitmaps loaded.  This cache is managed
 * with a LRU algorithm.
 *
 * Notes:
 * 1/ There is one cache per mounted file system.
 * 2/ If the file system contains less than EXT3_MAX_GROUP_LOADED groups,
 *    this function reads the bitmap without maintaining a LRU cache.
 *
 * Return the slot used to store the bitmap, or a -ve error code.
 */
static int __load_block_bitmap (struct super_block * sb,
                                unsigned int block_group)
{
        int i, j, retval = 0;
        unsigned long block_bitmap_number;
        struct buffer_head * block_bitmap;
 
        if (block_group >= sb->u.ext3_sb.s_groups_count)
                ext3_panic (sb, "load_block_bitmap",
                            "block_group >= groups_count - "
                            "block_group = %d, groups_count = %lu",
                            block_group, sb->u.ext3_sb.s_groups_count);
 
        if (sb->u.ext3_sb.s_groups_count <= EXT3_MAX_GROUP_LOADED) {
                if (sb->u.ext3_sb.s_block_bitmap[block_group]) {
                        if (sb->u.ext3_sb.s_block_bitmap_number[block_group] ==
                            block_group)
                                return block_group;
                        ext3_error (sb, "__load_block_bitmap",
                                    "block_group != block_bitmap_number");
                }
                retval = read_block_bitmap (sb, block_group, block_group);
                if (retval < 0)
                        return retval;
                return block_group;
        }
 
        for (i = 0; i < sb->u.ext3_sb.s_loaded_block_bitmaps &&
                    sb->u.ext3_sb.s_block_bitmap_number[i] != block_group; i++)
                ;
        if (i < sb->u.ext3_sb.s_loaded_block_bitmaps &&
            sb->u.ext3_sb.s_block_bitmap_number[i] == block_group) {
                block_bitmap_number = sb->u.ext3_sb.s_block_bitmap_number[i];
                block_bitmap = sb->u.ext3_sb.s_block_bitmap[i];
                for (j = i; j > 0; j--) {
                        sb->u.ext3_sb.s_block_bitmap_number[j] =
                                sb->u.ext3_sb.s_block_bitmap_number[j - 1];
                        sb->u.ext3_sb.s_block_bitmap[j] =
                                sb->u.ext3_sb.s_block_bitmap[j - 1];
                }
                sb->u.ext3_sb.s_block_bitmap_number[0] = block_bitmap_number;
                sb->u.ext3_sb.s_block_bitmap[0] = block_bitmap;
 
                /*
                 * There's still one special case here --- if block_bitmap == 0
                 * then our last attempt to read the bitmap failed and we have
                 * just ended up caching that failure.  Try again to read it.
                 */
                if (!block_bitmap)
                        retval = read_block_bitmap (sb, block_group, 0);
        } else {
                if (sb->u.ext3_sb.s_loaded_block_bitmaps<EXT3_MAX_GROUP_LOADED)
                        sb->u.ext3_sb.s_loaded_block_bitmaps++;
                else
                        brelse (sb->u.ext3_sb.s_block_bitmap
                                        [EXT3_MAX_GROUP_LOADED - 1]);
                for (j = sb->u.ext3_sb.s_loaded_block_bitmaps - 1;
                                        j > 0;  j--) {
                        sb->u.ext3_sb.s_block_bitmap_number[j] =
                                sb->u.ext3_sb.s_block_bitmap_number[j - 1];
                        sb->u.ext3_sb.s_block_bitmap[j] =
                                sb->u.ext3_sb.s_block_bitmap[j - 1];
                }
                retval = read_block_bitmap (sb, block_group, 0);
        }
        return retval;
}
 
/*
 * Load the block bitmap for a given block group.  First of all do a couple
 * of fast lookups for common cases and then pass the request onto the guts
 * of the bitmap loader.
 *
 * Return the slot number of the group in the superblock bitmap cache's on
 * success, or a -ve error code.
 *
 * There is still one inconsistency here --- if the number of groups in this
 * filesystems is <= EXT3_MAX_GROUP_LOADED, then we have no way of
 * differentiating between a group for which we have never performed a bitmap
 * IO request, and a group for which the last bitmap read request failed.
 */
static inline int load_block_bitmap (struct super_block * sb,
                                     unsigned int block_group)
{
        int slot;
 
        /*
         * Do the lookup for the slot.  First of all, check if we're asking
         * for the same slot as last time, and did we succeed that last time?
         */
        if (sb->u.ext3_sb.s_loaded_block_bitmaps > 0 &&
            sb->u.ext3_sb.s_block_bitmap_number[0] == block_group &&
            sb->u.ext3_sb.s_block_bitmap[0]) {
                return 0;
        }
        /*
         * Or can we do a fast lookup based on a loaded group on a filesystem
         * small enough to be mapped directly into the superblock?
         */
        else if (sb->u.ext3_sb.s_groups_count <= EXT3_MAX_GROUP_LOADED &&
                 sb->u.ext3_sb.s_block_bitmap_number[block_group]==block_group
                        && sb->u.ext3_sb.s_block_bitmap[block_group]) {
                slot = block_group;
        }
        /*
         * If not, then do a full lookup for this block group.
         */
        else {
                slot = __load_block_bitmap (sb, block_group);
        }
 
        /*
         * <0 means we just got an error
         */
        if (slot < 0)
                return slot;
 
        /*
         * If it's a valid slot, we may still have cached a previous IO error,
         * in which case the bh in the superblock cache will be zero.
         */
        if (!sb->u.ext3_sb.s_block_bitmap[slot])
                return -EIO;
 
        /*
         * Must have been read in OK to get this far.
         */
        return slot;
}
 
/* Free given blocks, update quota and i_blocks field */
void ext3_free_blocks (handle_t *handle, struct inode * inode,
                        unsigned long block, unsigned long count)
{
        struct buffer_head *bitmap_bh;
        struct buffer_head *gd_bh;
        unsigned long block_group;
        unsigned long bit;
        unsigned long i;
        int bitmap_nr;
        unsigned long overflow;
        struct super_block * sb;
        struct ext3_group_desc * gdp;
        struct ext3_super_block * es;
        int err = 0, ret;
        int dquot_freed_blocks = 0;
 
        sb = inode->i_sb;
        if (!sb) {
                printk ("ext3_free_blocks: nonexistent device");
                return;
        }
        lock_super (sb);
        es = sb->u.ext3_sb.s_es;
        if (block < le32_to_cpu(es->s_first_data_block) ||
            block + count < block ||
            (block + count) > le32_to_cpu(es->s_blocks_count)) {
                ext3_error (sb, "ext3_free_blocks",
                            "Freeing blocks not in datazone - "
                            "block = %lu, count = %lu", block, count);
                goto error_return;
        }
 
        ext3_debug ("freeing block %lu\n", block);
 
do_more:
        overflow = 0;
        block_group = (block - le32_to_cpu(es->s_first_data_block)) /
                      EXT3_BLOCKS_PER_GROUP(sb);
        bit = (block - le32_to_cpu(es->s_first_data_block)) %
                      EXT3_BLOCKS_PER_GROUP(sb);
        /*
         * Check to see if we are freeing blocks across a group
         * boundary.
         */
        if (bit + count > EXT3_BLOCKS_PER_GROUP(sb)) {
                overflow = bit + count - EXT3_BLOCKS_PER_GROUP(sb);
                count -= overflow;
        }
        bitmap_nr = load_block_bitmap (sb, block_group);
        if (bitmap_nr < 0)
                goto error_return;
 
        bitmap_bh = sb->u.ext3_sb.s_block_bitmap[bitmap_nr];
        gdp = ext3_get_group_desc (sb, block_group, &gd_bh);
        if (!gdp)
                goto error_return;
 
        /*
         * We are about to start releasing blocks in the bitmap,
         * so we need undo access.
         */
        /* @@@ check errors */
        BUFFER_TRACE(bitmap_bh, "getting undo access");
        err = ext3_journal_get_undo_access(handle, bitmap_bh);
        if (err)
                goto error_return;
 
        /*
         * We are about to modify some metadata.  Call the journal APIs
         * to unshare ->b_data if a currently-committing transaction is
         * using it
         */
        BUFFER_TRACE(gd_bh, "get_write_access");
        err = ext3_journal_get_write_access(handle, gd_bh);
        if (err)
                goto error_return;
 
        BUFFER_TRACE(sb->u.ext3_sb.s_sbh, "get_write_access");
        err = ext3_journal_get_write_access(handle, sb->u.ext3_sb.s_sbh);
        if (err)
                goto error_return;
 
        for (i = 0; i < count; i++, block++) {
                if (block == le32_to_cpu(gdp->bg_block_bitmap) ||
                    block == le32_to_cpu(gdp->bg_inode_bitmap) ||
                    in_range(block, le32_to_cpu(gdp->bg_inode_table),
                             EXT3_SB(sb)->s_itb_per_group)) {
                        ext3_error(sb, __FUNCTION__,
                                   "Freeing block in system zone - block = %lu",
                                   block);
                        continue;
                }
 
                /*
                 * An HJ special.  This is expensive...
                 */
#ifdef CONFIG_JBD_DEBUG
                {
                        struct buffer_head *debug_bh;
                        debug_bh = sb_get_hash_table(sb, block);
                        if (debug_bh) {
                                BUFFER_TRACE(debug_bh, "Deleted!");
                                if (!bh2jh(bitmap_bh)->b_committed_data)
                                        BUFFER_TRACE(debug_bh,
                                                "No commited data in bitmap");
                                BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap");
                                __brelse(debug_bh);
                        }
                }
#endif
                BUFFER_TRACE(bitmap_bh, "clear bit");
                if (!ext3_clear_bit (bit + i, bitmap_bh->b_data)) {
                        ext3_error(sb, __FUNCTION__,
                                   "bit already cleared for block %lu", block);
                        BUFFER_TRACE(bitmap_bh, "bit already cleared");
                } else {
                        dquot_freed_blocks++;
                        gdp->bg_free_blocks_count =
                          cpu_to_le16(le16_to_cpu(gdp->bg_free_blocks_count)+1);
                        es->s_free_blocks_count =
                          cpu_to_le32(le32_to_cpu(es->s_free_blocks_count)+1);
                }
                /* @@@ This prevents newly-allocated data from being
                 * freed and then reallocated within the same
                 * transaction.
                 *
                 * Ideally we would want to allow that to happen, but to
                 * do so requires making journal_forget() capable of
                 * revoking the queued write of a data block, which
                 * implies blocking on the journal lock.  *forget()
                 * cannot block due to truncate races.
                 *
                 * Eventually we can fix this by making journal_forget()
                 * return a status indicating whether or not it was able
                 * to revoke the buffer.  On successful revoke, it is
                 * safe not to set the allocation bit in the committed
                 * bitmap, because we know that there is no outstanding
                 * activity on the buffer any more and so it is safe to
                 * reallocate it.
                 */
                BUFFER_TRACE(bitmap_bh, "clear in b_committed_data");
                J_ASSERT_BH(bitmap_bh,
                                bh2jh(bitmap_bh)->b_committed_data != NULL);
                ext3_set_bit(bit + i, bh2jh(bitmap_bh)->b_committed_data);
        }
 
        /* We dirtied the bitmap block */
        BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
        err = ext3_journal_dirty_metadata(handle, bitmap_bh);
 
        /* And the group descriptor block */
        BUFFER_TRACE(gd_bh, "dirtied group descriptor block");
        ret = ext3_journal_dirty_metadata(handle, gd_bh);
        if (!err) err = ret;
 
        /* And the superblock */
        BUFFER_TRACE(sb->u.ext3_sb.s_sbh, "dirtied superblock");
        ret = ext3_journal_dirty_metadata(handle, sb->u.ext3_sb.s_sbh);
        if (!err) err = ret;
 
        if (overflow && !err) {
                count = overflow;
                goto do_more;
        }
        sb->s_dirt = 1;
error_return:
        ext3_std_error(sb, err);
        unlock_super(sb);
        if (dquot_freed_blocks)
                DQUOT_FREE_BLOCK(inode, dquot_freed_blocks);
        return;
}
 
/* For ext3 allocations, we must not reuse any blocks which are
 * allocated in the bitmap buffer's "last committed data" copy.  This
 * prevents deletes from freeing up the page for reuse until we have
 * committed the delete transaction.
 *
 * If we didn't do this, then deleting something and reallocating it as
 * data would allow the old block to be overwritten before the
 * transaction committed (because we force data to disk before commit).
 * This would lead to corruption if we crashed between overwriting the
 * data and committing the delete.
 *
 * @@@ We may want to make this allocation behaviour conditional on
 * data-writes at some point, and disable it for metadata allocations or
 * sync-data inodes.
 */
static int ext3_test_allocatable(int nr, struct buffer_head *bh)
{
        if (ext3_test_bit(nr, bh->b_data))
                return 0;
        if (!buffer_jbd(bh) || !bh2jh(bh)->b_committed_data)
                return 1;
        return !ext3_test_bit(nr, bh2jh(bh)->b_committed_data);
}
 
/*
 * Find an allocatable block in a bitmap.  We honour both the bitmap and
 * its last-committed copy (if that exists), and perform the "most
 * appropriate allocation" algorithm of looking for a free block near
 * the initial goal; then for a free byte somewhere in the bitmap; then
 * for any free bit in the bitmap.
 */
static int find_next_usable_block(int start,
                        struct buffer_head *bh, int maxblocks)
{
        int here, next;
        char *p, *r;
 
        if (start > 0) {
                /*
                 * The goal was occupied; search forward for a free
                 * block within the next XX blocks.
                 *
                 * end_goal is more or less random, but it has to be
                 * less than EXT3_BLOCKS_PER_GROUP. Aligning up to the
                 * next 64-bit boundary is simple..
                 */
                int end_goal = (start + 63) & ~63;
                here = ext3_find_next_zero_bit(bh->b_data, end_goal, start);
                if (here < end_goal && ext3_test_allocatable(here, bh))
                        return here;
 
                ext3_debug ("Bit not found near goal\n");
 
        }
 
        here = start;
        if (here < 0)
                here = 0;
 
        /*
         * There has been no free block found in the near vicinity of
         * the goal: do a search forward through the block groups,
         * searching in each group first for an entire free byte in the
         * bitmap and then for any free bit.
         *
         * Search first in the remainder of the current group
         */
        p = ((char *) bh->b_data) + (here >> 3);
        r = memscan(p, 0, (maxblocks - here + 7) >> 3);
        next = (r - ((char *) bh->b_data)) << 3;
 
        if (next < maxblocks && ext3_test_allocatable(next, bh))
                return next;
 
        /* The bitmap search --- search forward alternately
         * through the actual bitmap and the last-committed copy
         * until we find a bit free in both. */
 
        while (here < maxblocks) {
                next  = ext3_find_next_zero_bit ((unsigned long *) bh->b_data,
                                                 maxblocks, here);
                if (next >= maxblocks)
                        return -1;
                if (ext3_test_allocatable(next, bh))
                        return next;
 
                J_ASSERT_BH(bh, bh2jh(bh)->b_committed_data);
                here = ext3_find_next_zero_bit
                        ((unsigned long *) bh2jh(bh)->b_committed_data,
                         maxblocks, next);
        }
        return -1;
}
 
/*
 * ext3_new_block uses a goal block to assist allocation.  If the goal is
 * free, or there is a free block within 32 blocks of the goal, that block
 * is allocated.  Otherwise a forward search is made for a free block; within
 * each block group the search first looks for an entire free byte in the block
 * bitmap, and then for any free bit if that fails.
 * This function also updates quota and i_blocks field.
 */
int ext3_new_block (handle_t *handle, struct inode * inode,
                unsigned long goal, u32 * prealloc_count,
                u32 * prealloc_block, int * errp)
{
        struct buffer_head * bh, *bhtmp;
        struct buffer_head * bh2;
#if 0
        char * p, * r;
#endif
        int i, j, k, tmp, alloctmp;
        int bitmap_nr;
        int fatal = 0, err;
        int performed_allocation = 0;
        struct super_block * sb;
        struct ext3_group_desc * gdp;
        struct ext3_super_block * es;
#ifdef EXT3FS_DEBUG
        static int goal_hits = 0, goal_attempts = 0;
#endif
        *errp = -ENOSPC;
        sb = inode->i_sb;
        if (!sb) {
                printk ("ext3_new_block: nonexistent device");
                return 0;
        }
 
        /*
         * Check quota for allocation of this block.
         */
        if (DQUOT_ALLOC_BLOCK(inode, 1)) {
                *errp = -EDQUOT;
                return 0;
        }
 
        lock_super (sb);
        es = sb->u.ext3_sb.s_es;
        if (le32_to_cpu(es->s_free_blocks_count) <=
                        le32_to_cpu(es->s_r_blocks_count) &&
            ((sb->u.ext3_sb.s_resuid != current->fsuid) &&
             (sb->u.ext3_sb.s_resgid == 0 ||
              !in_group_p (sb->u.ext3_sb.s_resgid)) &&
             !capable(CAP_SYS_RESOURCE)))
                goto out;
 
        ext3_debug ("goal=%lu.\n", goal);
 
repeat:
        /*
         * First, test whether the goal block is free.
         */
        if (goal < le32_to_cpu(es->s_first_data_block) ||
            goal >= le32_to_cpu(es->s_blocks_count))
                goal = le32_to_cpu(es->s_first_data_block);
        i = (goal - le32_to_cpu(es->s_first_data_block)) /
                        EXT3_BLOCKS_PER_GROUP(sb);
        gdp = ext3_get_group_desc (sb, i, &bh2);
        if (!gdp)
                goto io_error;
 
        if (le16_to_cpu(gdp->bg_free_blocks_count) > 0) {
                j = ((goal - le32_to_cpu(es->s_first_data_block)) %
                                EXT3_BLOCKS_PER_GROUP(sb));
#ifdef EXT3FS_DEBUG
                if (j)
                        goal_attempts++;
#endif
                bitmap_nr = load_block_bitmap (sb, i);
                if (bitmap_nr < 0)
                        goto io_error;
 
                bh = sb->u.ext3_sb.s_block_bitmap[bitmap_nr];
 
                ext3_debug ("goal is at %d:%d.\n", i, j);
 
                if (ext3_test_allocatable(j, bh)) {
#ifdef EXT3FS_DEBUG
                        goal_hits++;
                        ext3_debug ("goal bit allocated.\n");
#endif
                        goto got_block;
                }
 
                j = find_next_usable_block(j, bh, EXT3_BLOCKS_PER_GROUP(sb));
                if (j >= 0)
                        goto search_back;
        }
 
        ext3_debug ("Bit not found in block group %d.\n", i);
 
        /*
         * Now search the rest of the groups.  We assume that
         * i and gdp correctly point to the last group visited.
         */
        for (k = 0; k < sb->u.ext3_sb.s_groups_count; k++) {
                i++;
                if (i >= sb->u.ext3_sb.s_groups_count)
                        i = 0;
                gdp = ext3_get_group_desc (sb, i, &bh2);
                if (!gdp) {
                        *errp = -EIO;
                        goto out;
                }
                if (le16_to_cpu(gdp->bg_free_blocks_count) > 0) {
                        bitmap_nr = load_block_bitmap (sb, i);
                        if (bitmap_nr < 0)
                                goto io_error;
 
                        bh = sb->u.ext3_sb.s_block_bitmap[bitmap_nr];
                        j = find_next_usable_block(-1, bh,
                                                   EXT3_BLOCKS_PER_GROUP(sb));
                        if (j >= 0)
                                goto search_back;
                }
        }
 
        /* No space left on the device */
        goto out;
 
search_back:
        /*
         * We have succeeded in finding a free byte in the block
         * bitmap.  Now search backwards up to 7 bits to find the
         * start of this group of free blocks.
         */
        for (   k = 0;
                k < 7 && j > 0 && ext3_test_allocatable(j - 1, bh);
                k++, j--)
                ;
 
got_block:
 
        ext3_debug ("using block group %d(%d)\n", i, gdp->bg_free_blocks_count);
 
        /* Make sure we use undo access for the bitmap, because it is
           critical that we do the frozen_data COW on bitmap buffers in
           all cases even if the buffer is in BJ_Forget state in the
           committing transaction.  */
        BUFFER_TRACE(bh, "get undo access for marking new block");
        fatal = ext3_journal_get_undo_access(handle, bh);
        if (fatal) goto out;
 
        BUFFER_TRACE(bh2, "get_write_access");
        fatal = ext3_journal_get_write_access(handle, bh2);
        if (fatal) goto out;
 
        BUFFER_TRACE(sb->u.ext3_sb.s_sbh, "get_write_access");
        fatal = ext3_journal_get_write_access(handle, sb->u.ext3_sb.s_sbh);
        if (fatal) goto out;
 
        tmp = j + i * EXT3_BLOCKS_PER_GROUP(sb)
                                + le32_to_cpu(es->s_first_data_block);
 
        if (tmp == le32_to_cpu(gdp->bg_block_bitmap) ||
            tmp == le32_to_cpu(gdp->bg_inode_bitmap) ||
            in_range (tmp, le32_to_cpu(gdp->bg_inode_table),
                      EXT3_SB(sb)->s_itb_per_group)) {
                ext3_error(sb, __FUNCTION__,
                           "Allocating block in system zone - block = %u", tmp);
 
                /* Note: This will potentially use up one of the handle's
                 * buffer credits.  Normally we have way too many credits,
                 * so that is OK.  In _very_ rare cases it might not be OK.
                 * We will trigger an assertion if we run out of credits,
                 * and we will have to do a full fsck of the filesystem -
                 * better than randomly corrupting filesystem metadata.
                 */
                ext3_set_bit(j, bh->b_data);
                goto repeat;
        }
 
 
        /* The superblock lock should guard against anybody else beating
         * us to this point! */
        J_ASSERT_BH(bh, !ext3_test_bit(j, bh->b_data));
        BUFFER_TRACE(bh, "setting bitmap bit");
        ext3_set_bit(j, bh->b_data);
        performed_allocation = 1;
 
#ifdef CONFIG_JBD_DEBUG
        {
                struct buffer_head *debug_bh;
 
                /* Record bitmap buffer state in the newly allocated block */
                debug_bh = sb_get_hash_table(sb, tmp);
                if (debug_bh) {
                        BUFFER_TRACE(debug_bh, "state when allocated");
                        BUFFER_TRACE2(debug_bh, bh, "bitmap state");
                        brelse(debug_bh);
                }
        }
#endif
        if (buffer_jbd(bh) && bh2jh(bh)->b_committed_data)
                J_ASSERT_BH(bh, !ext3_test_bit(j, bh2jh(bh)->b_committed_data));
        bhtmp = bh;
        alloctmp = j;
 
        ext3_debug ("found bit %d\n", j);
 
        /*
         * Do block preallocation now if required.
         */
#ifdef EXT3_PREALLOCATE
        /*
         * akpm: this is not enabled for ext3.  Need to use
         * ext3_test_allocatable()
         */
        /* Writer: ->i_prealloc* */
        if (prealloc_count && !*prealloc_count) {
                int     prealloc_goal;
                unsigned long next_block = tmp + 1;
 
                prealloc_goal = es->s_prealloc_blocks ?
                        es->s_prealloc_blocks : EXT3_DEFAULT_PREALLOC_BLOCKS;
 
                *prealloc_block = next_block;
                /* Writer: end */
                for (k = 1;
                     k < prealloc_goal && (j + k) < EXT3_BLOCKS_PER_GROUP(sb);
                     k++, next_block++) {
                        if (DQUOT_PREALLOC_BLOCK(inode, 1))
                                break;
                        /* Writer: ->i_prealloc* */
                        if (*prealloc_block + *prealloc_count != next_block ||
                            ext3_set_bit (j + k, bh->b_data)) {
                                /* Writer: end */
                                DQUOT_FREE_BLOCK(inode, 1);
                                break;
                        }
                        (*prealloc_count)++;
                        /* Writer: end */
                }
                /*
                 * As soon as we go for per-group spinlocks we'll need these
                 * done inside the loop above.
                 */
                gdp->bg_free_blocks_count =
                        cpu_to_le16(le16_to_cpu(gdp->bg_free_blocks_count) -
                               (k - 1));
                es->s_free_blocks_count =
                        cpu_to_le32(le32_to_cpu(es->s_free_blocks_count) -
                               (k - 1));
                ext3_debug ("Preallocated a further %lu bits.\n",
                               (k - 1));
        }
#endif
 
        j = tmp;
 
        BUFFER_TRACE(bh, "journal_dirty_metadata for bitmap block");
        err = ext3_journal_dirty_metadata(handle, bh);
        if (!fatal) fatal = err;
 
        if (j >= le32_to_cpu(es->s_blocks_count)) {
                ext3_error (sb, "ext3_new_block",
                            "block(%d) >= blocks count(%d) - "
                            "block_group = %d, es == %p ",j,
                        le32_to_cpu(es->s_blocks_count), i, es);
                goto out;
        }
 
        /*
         * It is up to the caller to add the new buffer to a journal
         * list of some description.  We don't know in advance whether
         * the caller wants to use it as metadata or data.
         */
 
        ext3_debug ("allocating block %d. "
                    "Goal hits %d of %d.\n", j, goal_hits, goal_attempts);
 
        gdp->bg_free_blocks_count =
                        cpu_to_le16(le16_to_cpu(gdp->bg_free_blocks_count) - 1);
        es->s_free_blocks_count =
                        cpu_to_le32(le32_to_cpu(es->s_free_blocks_count) - 1);
 
        BUFFER_TRACE(bh2, "journal_dirty_metadata for group descriptor");
        err = ext3_journal_dirty_metadata(handle, bh2);
        if (!fatal) fatal = err;
 
        BUFFER_TRACE(bh, "journal_dirty_metadata for superblock");
        err = ext3_journal_dirty_metadata(handle, sb->u.ext3_sb.s_sbh);
        if (!fatal) fatal = err;
 
        sb->s_dirt = 1;
        if (fatal)
                goto out;
 
        unlock_super (sb);
        *errp = 0;
        return j;
 
io_error:
        *errp = -EIO;
out:
        if (fatal) {
                *errp = fatal;
                ext3_std_error(sb, fatal);
        }
        unlock_super (sb);
        /*
         * Undo the block allocation
         */
        if (!performed_allocation)
                DQUOT_FREE_BLOCK(inode, 1);
        return 0;
 
}
 
unsigned long ext3_count_free_blocks (struct super_block * sb)
{
#ifdef EXT3FS_DEBUG
        struct ext3_super_block * es;
        unsigned long desc_count, bitmap_count, x;
        int bitmap_nr;
        struct ext3_group_desc * gdp;
        int i;
 
        lock_super (sb);
        es = sb->u.ext3_sb.s_es;
        desc_count = 0;
        bitmap_count = 0;
        gdp = NULL;
        for (i = 0; i < sb->u.ext3_sb.s_groups_count; i++) {
                gdp = ext3_get_group_desc (sb, i, NULL);
                if (!gdp)
                        continue;
                desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
                bitmap_nr = load_block_bitmap (sb, i);
                if (bitmap_nr < 0)
                        continue;
 
                x = ext3_count_free (sb->u.ext3_sb.s_block_bitmap[bitmap_nr],
                                     sb->s_blocksize);
                printk ("group %d: stored = %d, counted = %lu\n",
                        i, le16_to_cpu(gdp->bg_free_blocks_count), x);
                bitmap_count += x;
        }
        printk("ext3_count_free_blocks: stored = %lu, computed = %lu, %lu\n",
               le32_to_cpu(es->s_free_blocks_count), desc_count, bitmap_count);
        unlock_super (sb);
        return bitmap_count;
#else
        return le32_to_cpu(sb->u.ext3_sb.s_es->s_free_blocks_count);
#endif
}
 
static inline int block_in_use (unsigned long block,
                                struct super_block * sb,
                                unsigned char * map)
{
        return ext3_test_bit ((block -
                le32_to_cpu(sb->u.ext3_sb.s_es->s_first_data_block)) %
                         EXT3_BLOCKS_PER_GROUP(sb), map);
}
 
static inline int test_root(int a, int b)
{
        if (a == 0)
                return 1;
        while (1) {
                if (a == 1)
                        return 1;
                if (a % b)
                        return 0;
                a = a / b;
        }
}
 
int ext3_group_sparse(int group)
{
        return (test_root(group, 3) || test_root(group, 5) ||
                test_root(group, 7));
}
 
/**
 *      ext3_bg_has_super - number of blocks used by the superblock in group
 *      @sb: superblock for filesystem
 *      @group: group number to check
 *
 *      Return the number of blocks used by the superblock (primary or backup)
 *      in this group.  Currently this will be only 0 or 1.
 */
int ext3_bg_has_super(struct super_block *sb, int group)
{
        if (EXT3_HAS_RO_COMPAT_FEATURE(sb,EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER)&&
            !ext3_group_sparse(group))
                return 0;
        return 1;
}
 
/**
 *      ext3_bg_num_gdb - number of blocks used by the group table in group
 *      @sb: superblock for filesystem
 *      @group: group number to check
 *
 *      Return the number of blocks used by the group descriptor table
 *      (primary or backup) in this group.  In the future there may be a
 *      different number of descriptor blocks in each group.
 */
unsigned long ext3_bg_num_gdb(struct super_block *sb, int group)
{
        if (EXT3_HAS_RO_COMPAT_FEATURE(sb,EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER)&&
            !ext3_group_sparse(group))
                return 0;
        return EXT3_SB(sb)->s_gdb_count;
}
 
#ifdef CONFIG_EXT3_CHECK
/* Called at mount-time, super-block is locked */
void ext3_check_blocks_bitmap (struct super_block * sb)
{
        struct buffer_head * bh;
        struct ext3_super_block * es;
        unsigned long desc_count, bitmap_count, x, j;
        unsigned long desc_blocks;
        int bitmap_nr;
        struct ext3_group_desc * gdp;
        int i;
 
        es = sb->u.ext3_sb.s_es;
        desc_count = 0;
        bitmap_count = 0;
        gdp = NULL;
        for (i = 0; i < sb->u.ext3_sb.s_groups_count; i++) {
                gdp = ext3_get_group_desc (sb, i, NULL);
                if (!gdp)
                        continue;
                desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
                bitmap_nr = load_block_bitmap (sb, i);
                if (bitmap_nr < 0)
                        continue;
 
                bh = EXT3_SB(sb)->s_block_bitmap[bitmap_nr];
 
                if (ext3_bg_has_super(sb, i) && !ext3_test_bit(0, bh->b_data))
                        ext3_error(sb, __FUNCTION__,
                                   "Superblock in group %d is marked free", i);
 
                desc_blocks = ext3_bg_num_gdb(sb, i);
                for (j = 0; j < desc_blocks; j++)
                        if (!ext3_test_bit(j + 1, bh->b_data))
                                ext3_error(sb, __FUNCTION__,
                                           "Descriptor block #%ld in group "
                                           "%d is marked free", j, i);
 
                if (!block_in_use (le32_to_cpu(gdp->bg_block_bitmap),
                                                sb, bh->b_data))
                        ext3_error (sb, "ext3_check_blocks_bitmap",
                                    "Block bitmap for group %d is marked free",
                                    i);
 
                if (!block_in_use (le32_to_cpu(gdp->bg_inode_bitmap),
                                                sb, bh->b_data))
                        ext3_error (sb, "ext3_check_blocks_bitmap",
                                    "Inode bitmap for group %d is marked free",
                                    i);
 
                for (j = 0; j < sb->u.ext3_sb.s_itb_per_group; j++)
                        if (!block_in_use (le32_to_cpu(gdp->bg_inode_table) + j,
                                                        sb, bh->b_data))
                                ext3_error (sb, "ext3_check_blocks_bitmap",
                                            "Block #%d of the inode table in "
                                            "group %d is marked free", j, i);
 
                x = ext3_count_free (bh, sb->s_blocksize);
                if (le16_to_cpu(gdp->bg_free_blocks_count) != x)
                        ext3_error (sb, "ext3_check_blocks_bitmap",
                                    "Wrong free blocks count for group %d, "
                                    "stored = %d, counted = %lu", i,
                                    le16_to_cpu(gdp->bg_free_blocks_count), x);
                bitmap_count += x;
        }
        if (le32_to_cpu(es->s_free_blocks_count) != bitmap_count)
                ext3_error (sb, "ext3_check_blocks_bitmap",
                        "Wrong free blocks count in super block, "
                        "stored = %lu, counted = %lu",
                        (unsigned long)le32_to_cpu(es->s_free_blocks_count),
                        bitmap_count);
}
#endif
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[/] [or1k/] [trunk/] [linux/] [linux-2.4/] [fs/] [ext3/] [balloc.c] - Blame information for rev 1275

Line No.	Rev	Author	Line
1	1275	phoenix	`/*`
2			`* linux/fs/ext3/balloc.c`
3			`*`
4			`* Copyright (C) 1992, 1993, 1994, 1995`
5			`* Remy Card (card@masi.ibp.fr)`
6			`* Laboratoire MASI - Institut Blaise Pascal`
7			`* Universite Pierre et Marie Curie (Paris VI)`
8			`*`
9			`* Enhanced block allocation by Stephen Tweedie (sct@redhat.com), 1993`
10			`* Big-endian to little-endian byte-swapping/bitmaps by`
11			`* David S. Miller (davem@caip.rutgers.edu), 1995`
12			`*/`
13
14			`#include <linux/config.h>`
15			`#include <linux/sched.h>`
16			`#include <linux/fs.h>`
17			`#include <linux/jbd.h>`
18			`#include <linux/ext3_fs.h>`
19			`#include <linux/ext3_jbd.h>`
20			`#include <linux/locks.h>`
21			`#include <linux/quotaops.h>`
22
23			`/*`
24			`* balloc.c contains the blocks allocation and deallocation routines`
25			`*/`
26
27			`/*`
28			`* The free blocks are managed by bitmaps. A file system contains several`
29			`* blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap`
30			`* block for inodes, N blocks for the inode table and data blocks.`
31			`*`
32			`* The file system contains group descriptors which are located after the`
33			`* super block. Each descriptor contains the number of the bitmap block and`
34			`* the free blocks count in the block. The descriptors are loaded in memory`
35			`* when a file system is mounted (see ext3_read_super).`
36			`*/`
37
38
39			`#define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)`
40