--- /dev/null
+/*
+ * linux/fs/ext2/ialloc.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)
+ *
+ * BSD ufs-inspired inode and directory allocation by
+ * Stephen Tweedie (sct@dcs.ed.ac.uk), 1993
+ * Big-endian to little-endian byte-swapping/bitmaps by
+ * David S. Miller (davem@caip.rutgers.edu), 1995
+ */
+
+#include <linux/quotaops.h>
+#include <linux/sched.h>
+#include <linux/backing-dev.h>
+#include <linux/buffer_head.h>
+#include <linux/random.h>
+#include "ext2.h"
+#include "xattr.h"
+#include "acl.h"
+
+/*
+ * ialloc.c contains the inodes allocation and deallocation routines
+ */
+
+/*
+ * The free inodes 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.
+ */
+
+
+/*
+ * Read the inode allocation bitmap for a given block_group, reading
+ * into the specified slot in the superblock's bitmap cache.
+ *
+ * Return buffer_head of bitmap on success or NULL.
+ */
+static struct buffer_head *
+read_inode_bitmap(struct super_block * sb, unsigned long block_group)
+{
+ struct ext2_group_desc *desc;
+ struct buffer_head *bh = NULL;
+
+ desc = ext2_get_group_desc(sb, block_group, NULL);
+ if (!desc)
+ goto error_out;
+
+ bh = sb_bread(sb, le32_to_cpu(desc->bg_inode_bitmap));
+ if (!bh)
+ ext2_error(sb, "read_inode_bitmap",
+ "Cannot read inode bitmap - "
+ "block_group = %lu, inode_bitmap = %u",
+ block_group, le32_to_cpu(desc->bg_inode_bitmap));
+error_out:
+ return bh;
+}
+
+static void ext2_release_inode(struct super_block *sb, int group, int dir)
+{
+ struct ext2_group_desc * desc;
+ struct buffer_head *bh;
+
+ desc = ext2_get_group_desc(sb, group, &bh);
+ if (!desc) {
+ ext2_error(sb, "ext2_release_inode",
+ "can't get descriptor for group %d", group);
+ return;
+ }
+
+ spin_lock(sb_bgl_lock(EXT2_SB(sb), group));
+ le16_add_cpu(&desc->bg_free_inodes_count, 1);
+ if (dir)
+ le16_add_cpu(&desc->bg_used_dirs_count, -1);
+ spin_unlock(sb_bgl_lock(EXT2_SB(sb), group));
+ if (dir)
+ percpu_counter_dec(&EXT2_SB(sb)->s_dirs_counter);
+ mark_buffer_dirty(bh);
+}
+
+/*
+ * NOTE! When we get the inode, we're the only people
+ * that have access to it, and as such there are no
+ * race conditions we have to worry about. The inode
+ * is not on the hash-lists, and it cannot be reached
+ * through the filesystem because the directory entry
+ * has been deleted earlier.
+ *
+ * HOWEVER: we must make sure that we get no aliases,
+ * which means that we have to call "clear_inode()"
+ * _before_ we mark the inode not in use in the inode
+ * bitmaps. Otherwise a newly created file might use
+ * the same inode number (not actually the same pointer
+ * though), and then we'd have two inodes sharing the
+ * same inode number and space on the harddisk.
+ */
+void ext2_free_inode (struct inode * inode)
+{
+ struct super_block * sb = inode->i_sb;
+ int is_directory;
+ unsigned long ino;
+ struct buffer_head *bitmap_bh;
+ unsigned long block_group;
+ unsigned long bit;
+ struct ext2_super_block * es;
+
+ ino = inode->i_ino;
+ ext2_debug ("freeing inode %lu\n", ino);
+
+ /*
+ * Note: we must free any quota before locking the superblock,
+ * as writing the quota to disk may need the lock as well.
+ */
+ /* Quota is already initialized in iput() */
+ dquot_free_inode(inode);
+ dquot_drop(inode);
+
+ es = EXT2_SB(sb)->s_es;
+ is_directory = S_ISDIR(inode->i_mode);
+
+ if (ino < EXT2_FIRST_INO(sb) ||
+ ino > le32_to_cpu(es->s_inodes_count)) {
+ ext2_error (sb, "ext2_free_inode",
+ "reserved or nonexistent inode %lu", ino);
+ return;
+ }
+ block_group = (ino - 1) / EXT2_INODES_PER_GROUP(sb);
+ bit = (ino - 1) % EXT2_INODES_PER_GROUP(sb);
+ bitmap_bh = read_inode_bitmap(sb, block_group);
+ if (!bitmap_bh)
+ return;
+
+ /* Ok, now we can actually update the inode bitmaps.. */
+ if (!ext2_clear_bit_atomic(sb_bgl_lock(EXT2_SB(sb), block_group),
+ bit, (void *) bitmap_bh->b_data))
+ ext2_error (sb, "ext2_free_inode",
+ "bit already cleared for inode %lu", ino);
+ else
+ ext2_release_inode(sb, block_group, is_directory);
+ mark_buffer_dirty(bitmap_bh);
+ if (sb->s_flags & MS_SYNCHRONOUS)
+ sync_dirty_buffer(bitmap_bh);
+
+ brelse(bitmap_bh);
+}
+
+/*
+ * We perform asynchronous prereading of the new inode's inode block when
+ * we create the inode, in the expectation that the inode will be written
+ * back soon. There are two reasons:
+ *
+ * - When creating a large number of files, the async prereads will be
+ * nicely merged into large reads
+ * - When writing out a large number of inodes, we don't need to keep on
+ * stalling the writes while we read the inode block.
+ *
+ * FIXME: ext2_get_group_desc() needs to be simplified.
+ */
+static void ext2_preread_inode(struct inode *inode)
+{
+ unsigned long block_group;
+ unsigned long offset;
+ unsigned long block;
+ struct ext2_group_desc * gdp;
+ struct backing_dev_info *bdi;
+
+ bdi = inode_to_bdi(inode);
+ if (bdi_read_congested(bdi))
+ return;
+ if (bdi_write_congested(bdi))
+ return;
+
+ block_group = (inode->i_ino - 1) / EXT2_INODES_PER_GROUP(inode->i_sb);
+ gdp = ext2_get_group_desc(inode->i_sb, block_group, NULL);
+ if (gdp == NULL)
+ return;
+
+ /*
+ * Figure out the offset within the block group inode table
+ */
+ offset = ((inode->i_ino - 1) % EXT2_INODES_PER_GROUP(inode->i_sb)) *
+ EXT2_INODE_SIZE(inode->i_sb);
+ block = le32_to_cpu(gdp->bg_inode_table) +
+ (offset >> EXT2_BLOCK_SIZE_BITS(inode->i_sb));
+ sb_breadahead(inode->i_sb, block);
+}
+
+/*
+ * There are two policies for allocating an inode. If the new inode is
+ * a directory, then a forward search is made for a block group with both
+ * free space and a low directory-to-inode ratio; if that fails, then of
+ * the groups with above-average free space, that group with the fewest
+ * directories already is chosen.
+ *
+ * For other inodes, search forward from the parent directory\'s block
+ * group to find a free inode.
+ */
+static int find_group_dir(struct super_block *sb, struct inode *parent)
+{
+ int ngroups = EXT2_SB(sb)->s_groups_count;
+ int avefreei = ext2_count_free_inodes(sb) / ngroups;
+ struct ext2_group_desc *desc, *best_desc = NULL;
+ int group, best_group = -1;
+
+ for (group = 0; group < ngroups; group++) {
+ desc = ext2_get_group_desc (sb, group, NULL);
+ if (!desc || !desc->bg_free_inodes_count)
+ continue;
+ if (le16_to_cpu(desc->bg_free_inodes_count) < avefreei)
+ continue;
+ if (!best_desc ||
+ (le16_to_cpu(desc->bg_free_blocks_count) >
+ le16_to_cpu(best_desc->bg_free_blocks_count))) {
+ best_group = group;
+ best_desc = desc;
+ }
+ }
+ if (!best_desc)
+ return -1;
+
+ return best_group;
+}
+
+/*
+ * Orlov's allocator for directories.
+ *
+ * We always try to spread first-level directories.
+ *
+ * If there are blockgroups with both free inodes and free blocks counts
+ * not worse than average we return one with smallest directory count.
+ * Otherwise we simply return a random group.
+ *
+ * For the rest rules look so:
+ *
+ * It's OK to put directory into a group unless
+ * it has too many directories already (max_dirs) or
+ * it has too few free inodes left (min_inodes) or
+ * it has too few free blocks left (min_blocks) or
+ * it's already running too large debt (max_debt).
+ * Parent's group is preferred, if it doesn't satisfy these
+ * conditions we search cyclically through the rest. If none
+ * of the groups look good we just look for a group with more
+ * free inodes than average (starting at parent's group).
+ *
+ * Debt is incremented each time we allocate a directory and decremented
+ * when we allocate an inode, within 0--255.
+ */
+
+#define INODE_COST 64
+#define BLOCK_COST 256
+
+static int find_group_orlov(struct super_block *sb, struct inode *parent)
+{
+ int parent_group = EXT2_I(parent)->i_block_group;
+ struct ext2_sb_info *sbi = EXT2_SB(sb);
+ struct ext2_super_block *es = sbi->s_es;
+ int ngroups = sbi->s_groups_count;
+ int inodes_per_group = EXT2_INODES_PER_GROUP(sb);
+ int freei;
+ int avefreei;
+ int free_blocks;
+ int avefreeb;
+ int blocks_per_dir;
+ int ndirs;
+ int max_debt, max_dirs, min_blocks, min_inodes;
+ int group = -1, i;
+ struct ext2_group_desc *desc;
+
+ freei = percpu_counter_read_positive(&sbi->s_freeinodes_counter);
+ avefreei = freei / ngroups;
+ free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
+ avefreeb = free_blocks / ngroups;
+ ndirs = percpu_counter_read_positive(&sbi->s_dirs_counter);
+
+ if ((parent == d_inode(sb->s_root)) ||
+ (EXT2_I(parent)->i_flags & EXT2_TOPDIR_FL)) {
+ struct ext2_group_desc *best_desc = NULL;
+ int best_ndir = inodes_per_group;
+ int best_group = -1;
+
+ group = prandom_u32();
+ parent_group = (unsigned)group % ngroups;
+ for (i = 0; i < ngroups; i++) {
+ group = (parent_group + i) % ngroups;
+ desc = ext2_get_group_desc (sb, group, NULL);
+ if (!desc || !desc->bg_free_inodes_count)
+ continue;
+ if (le16_to_cpu(desc->bg_used_dirs_count) >= best_ndir)
+ continue;
+ if (le16_to_cpu(desc->bg_free_inodes_count) < avefreei)
+ continue;
+ if (le16_to_cpu(desc->bg_free_blocks_count) < avefreeb)
+ continue;
+ best_group = group;
+ best_ndir = le16_to_cpu(desc->bg_used_dirs_count);
+ best_desc = desc;
+ }
+ if (best_group >= 0) {
+ desc = best_desc;
+ group = best_group;
+ goto found;
+ }
+ goto fallback;
+ }
+
+ if (ndirs == 0)
+ ndirs = 1; /* percpu_counters are approximate... */
+
+ blocks_per_dir = (le32_to_cpu(es->s_blocks_count)-free_blocks) / ndirs;
+
+ max_dirs = ndirs / ngroups + inodes_per_group / 16;
+ min_inodes = avefreei - inodes_per_group / 4;
+ min_blocks = avefreeb - EXT2_BLOCKS_PER_GROUP(sb) / 4;
+
+ max_debt = EXT2_BLOCKS_PER_GROUP(sb) / max(blocks_per_dir, BLOCK_COST);
+ if (max_debt * INODE_COST > inodes_per_group)
+ max_debt = inodes_per_group / INODE_COST;
+ if (max_debt > 255)
+ max_debt = 255;
+ if (max_debt == 0)
+ max_debt = 1;
+
+ for (i = 0; i < ngroups; i++) {
+ group = (parent_group + i) % ngroups;
+ desc = ext2_get_group_desc (sb, group, NULL);
+ if (!desc || !desc->bg_free_inodes_count)
+ continue;
+ if (sbi->s_debts[group] >= max_debt)
+ continue;
+ if (le16_to_cpu(desc->bg_used_dirs_count) >= max_dirs)
+ continue;
+ if (le16_to_cpu(desc->bg_free_inodes_count) < min_inodes)
+ continue;
+ if (le16_to_cpu(desc->bg_free_blocks_count) < min_blocks)
+ continue;
+ goto found;
+ }
+
+fallback:
+ for (i = 0; i < ngroups; i++) {
+ group = (parent_group + i) % ngroups;
+ desc = ext2_get_group_desc (sb, group, NULL);
+ if (!desc || !desc->bg_free_inodes_count)
+ continue;
+ if (le16_to_cpu(desc->bg_free_inodes_count) >= avefreei)
+ goto found;
+ }
+
+ if (avefreei) {
+ /*
+ * The free-inodes counter is approximate, and for really small
+ * filesystems the above test can fail to find any blockgroups
+ */
+ avefreei = 0;
+ goto fallback;
+ }
+
+ return -1;
+
+found:
+ return group;
+}
+
+static int find_group_other(struct super_block *sb, struct inode *parent)
+{
+ int parent_group = EXT2_I(parent)->i_block_group;
+ int ngroups = EXT2_SB(sb)->s_groups_count;
+ struct ext2_group_desc *desc;
+ int group, i;
+
+ /*
+ * Try to place the inode in its parent directory
+ */
+ group = parent_group;
+ desc = ext2_get_group_desc (sb, group, NULL);
+ if (desc && le16_to_cpu(desc->bg_free_inodes_count) &&
+ le16_to_cpu(desc->bg_free_blocks_count))
+ goto found;
+
+ /*
+ * We're going to place this inode in a different blockgroup from its
+ * parent. We want to cause files in a common directory to all land in
+ * the same blockgroup. But we want files which are in a different
+ * directory which shares a blockgroup with our parent to land in a
+ * different blockgroup.
+ *
+ * So add our directory's i_ino into the starting point for the hash.
+ */
+ group = (group + parent->i_ino) % ngroups;
+
+ /*
+ * Use a quadratic hash to find a group with a free inode and some
+ * free blocks.
+ */
+ for (i = 1; i < ngroups; i <<= 1) {
+ group += i;
+ if (group >= ngroups)
+ group -= ngroups;
+ desc = ext2_get_group_desc (sb, group, NULL);
+ if (desc && le16_to_cpu(desc->bg_free_inodes_count) &&
+ le16_to_cpu(desc->bg_free_blocks_count))
+ goto found;
+ }
+
+ /*
+ * That failed: try linear search for a free inode, even if that group
+ * has no free blocks.
+ */
+ group = parent_group;
+ for (i = 0; i < ngroups; i++) {
+ if (++group >= ngroups)
+ group = 0;
+ desc = ext2_get_group_desc (sb, group, NULL);
+ if (desc && le16_to_cpu(desc->bg_free_inodes_count))
+ goto found;
+ }
+
+ return -1;
+
+found:
+ return group;
+}
+
+struct inode *ext2_new_inode(struct inode *dir, umode_t mode,
+ const struct qstr *qstr)
+{
+ struct super_block *sb;
+ struct buffer_head *bitmap_bh = NULL;
+ struct buffer_head *bh2;
+ int group, i;
+ ino_t ino = 0;
+ struct inode * inode;
+ struct ext2_group_desc *gdp;
+ struct ext2_super_block *es;
+ struct ext2_inode_info *ei;
+ struct ext2_sb_info *sbi;
+ int err;
+
+ sb = dir->i_sb;
+ inode = new_inode(sb);
+ if (!inode)
+ return ERR_PTR(-ENOMEM);
+
+ ei = EXT2_I(inode);
+ sbi = EXT2_SB(sb);
+ es = sbi->s_es;
+ if (S_ISDIR(mode)) {
+ if (test_opt(sb, OLDALLOC))
+ group = find_group_dir(sb, dir);
+ else
+ group = find_group_orlov(sb, dir);
+ } else
+ group = find_group_other(sb, dir);
+
+ if (group == -1) {
+ err = -ENOSPC;
+ goto fail;
+ }
+
+ for (i = 0; i < sbi->s_groups_count; i++) {
+ gdp = ext2_get_group_desc(sb, group, &bh2);
+ brelse(bitmap_bh);
+ bitmap_bh = read_inode_bitmap(sb, group);
+ if (!bitmap_bh) {
+ err = -EIO;
+ goto fail;
+ }
+ ino = 0;
+
+repeat_in_this_group:
+ ino = ext2_find_next_zero_bit((unsigned long *)bitmap_bh->b_data,
+ EXT2_INODES_PER_GROUP(sb), ino);
+ if (ino >= EXT2_INODES_PER_GROUP(sb)) {
+ /*
+ * Rare race: find_group_xx() decided that there were
+ * free inodes in this group, but by the time we tried
+ * to allocate one, they're all gone. This can also
+ * occur because the counters which find_group_orlov()
+ * uses are approximate. So just go and search the
+ * next block group.
+ */
+ if (++group == sbi->s_groups_count)
+ group = 0;
+ continue;
+ }
+ if (ext2_set_bit_atomic(sb_bgl_lock(sbi, group),
+ ino, bitmap_bh->b_data)) {
+ /* we lost this inode */
+ if (++ino >= EXT2_INODES_PER_GROUP(sb)) {
+ /* this group is exhausted, try next group */
+ if (++group == sbi->s_groups_count)
+ group = 0;
+ continue;
+ }
+ /* try to find free inode in the same group */
+ goto repeat_in_this_group;
+ }
+ goto got;
+ }
+
+ /*
+ * Scanned all blockgroups.
+ */
+ err = -ENOSPC;
+ goto fail;
+got:
+ mark_buffer_dirty(bitmap_bh);
+ if (sb->s_flags & MS_SYNCHRONOUS)
+ sync_dirty_buffer(bitmap_bh);
+ brelse(bitmap_bh);
+
+ ino += group * EXT2_INODES_PER_GROUP(sb) + 1;
+ if (ino < EXT2_FIRST_INO(sb) || ino > le32_to_cpu(es->s_inodes_count)) {
+ ext2_error (sb, "ext2_new_inode",
+ "reserved inode or inode > inodes count - "
+ "block_group = %d,inode=%lu", group,
+ (unsigned long) ino);
+ err = -EIO;
+ goto fail;
+ }
+
+ percpu_counter_add(&sbi->s_freeinodes_counter, -1);
+ if (S_ISDIR(mode))
+ percpu_counter_inc(&sbi->s_dirs_counter);
+
+ spin_lock(sb_bgl_lock(sbi, group));
+ le16_add_cpu(&gdp->bg_free_inodes_count, -1);
+ if (S_ISDIR(mode)) {
+ if (sbi->s_debts[group] < 255)
+ sbi->s_debts[group]++;
+ le16_add_cpu(&gdp->bg_used_dirs_count, 1);
+ } else {
+ if (sbi->s_debts[group])
+ sbi->s_debts[group]--;
+ }
+ spin_unlock(sb_bgl_lock(sbi, group));
+
+ mark_buffer_dirty(bh2);
+ if (test_opt(sb, GRPID)) {
+ inode->i_mode = mode;
+ inode->i_uid = current_fsuid();
+ inode->i_gid = dir->i_gid;
+ } else
+ inode_init_owner(inode, dir, mode);
+
+ inode->i_ino = ino;
+ inode->i_blocks = 0;
+ inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME_SEC;
+ memset(ei->i_data, 0, sizeof(ei->i_data));
+ ei->i_flags =
+ ext2_mask_flags(mode, EXT2_I(dir)->i_flags & EXT2_FL_INHERITED);
+ ei->i_faddr = 0;
+ ei->i_frag_no = 0;
+ ei->i_frag_size = 0;
+ ei->i_file_acl = 0;
+ ei->i_dir_acl = 0;
+ ei->i_dtime = 0;
+ ei->i_block_alloc_info = NULL;
+ ei->i_block_group = group;
+ ei->i_dir_start_lookup = 0;
+ ei->i_state = EXT2_STATE_NEW;
+ ext2_set_inode_flags(inode);
+ spin_lock(&sbi->s_next_gen_lock);
+ inode->i_generation = sbi->s_next_generation++;
+ spin_unlock(&sbi->s_next_gen_lock);
+ if (insert_inode_locked(inode) < 0) {
+ ext2_error(sb, "ext2_new_inode",
+ "inode number already in use - inode=%lu",
+ (unsigned long) ino);
+ err = -EIO;
+ goto fail;
+ }
+
+ dquot_initialize(inode);
+ err = dquot_alloc_inode(inode);
+ if (err)
+ goto fail_drop;
+
+ err = ext2_init_acl(inode, dir);
+ if (err)
+ goto fail_free_drop;
+
+ err = ext2_init_security(inode, dir, qstr);
+ if (err)
+ goto fail_free_drop;
+
+ mark_inode_dirty(inode);
+ ext2_debug("allocating inode %lu\n", inode->i_ino);
+ ext2_preread_inode(inode);
+ return inode;
+
+fail_free_drop:
+ dquot_free_inode(inode);
+
+fail_drop:
+ dquot_drop(inode);
+ inode->i_flags |= S_NOQUOTA;
+ clear_nlink(inode);
+ unlock_new_inode(inode);
+ iput(inode);
+ return ERR_PTR(err);
+
+fail:
+ make_bad_inode(inode);
+ iput(inode);
+ return ERR_PTR(err);
+}
+
+unsigned long ext2_count_free_inodes (struct super_block * sb)
+{
+ struct ext2_group_desc *desc;
+ unsigned long desc_count = 0;
+ int i;
+
+#ifdef EXT2FS_DEBUG
+ struct ext2_super_block *es;
+ unsigned long bitmap_count = 0;
+ struct buffer_head *bitmap_bh = NULL;
+
+ es = EXT2_SB(sb)->s_es;
+ for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
+ unsigned x;
+
+ desc = ext2_get_group_desc (sb, i, NULL);
+ if (!desc)
+ continue;
+ desc_count += le16_to_cpu(desc->bg_free_inodes_count);
+ brelse(bitmap_bh);
+ bitmap_bh = read_inode_bitmap(sb, i);
+ if (!bitmap_bh)
+ continue;
+
+ x = ext2_count_free(bitmap_bh, EXT2_INODES_PER_GROUP(sb) / 8);
+ printk("group %d: stored = %d, counted = %u\n",
+ i, le16_to_cpu(desc->bg_free_inodes_count), x);
+ bitmap_count += x;
+ }
+ brelse(bitmap_bh);
+ printk("ext2_count_free_inodes: stored = %lu, computed = %lu, %lu\n",
+ (unsigned long)
+ percpu_counter_read(&EXT2_SB(sb)->s_freeinodes_counter),
+ desc_count, bitmap_count);
+ return desc_count;
+#else
+ for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
+ desc = ext2_get_group_desc (sb, i, NULL);
+ if (!desc)
+ continue;
+ desc_count += le16_to_cpu(desc->bg_free_inodes_count);
+ }
+ return desc_count;
+#endif
+}
+
+/* Called at mount-time, super-block is locked */
+unsigned long ext2_count_dirs (struct super_block * sb)
+{
+ unsigned long count = 0;
+ int i;
+
+ for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
+ struct ext2_group_desc *gdp = ext2_get_group_desc (sb, i, NULL);
+ if (!gdp)
+ continue;
+ count += le16_to_cpu(gdp->bg_used_dirs_count);
+ }
+ return count;
+}
+
Code Review / kvmfornfv.git / blobdiff