Initial import

1 files changed, 675 insertions, 0 deletions

diff --git a/fs/ext2/ialloc.c b/fs/ext2/ialloc.c
new file mode 100644
index 000000000..5c04a0dde
--- /dev/null
+++ b/fs/ext2/ialloc.c
@@ -0,0 +1,675 @@
+/*
+ *  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;
+}
+