diff options
Diffstat (limited to 'fs/ext2/ialloc.c')
| -rw-r--r-- | fs/ext2/ialloc.c | 735 |
1 files changed, 735 insertions, 0 deletions
diff --git a/fs/ext2/ialloc.c b/fs/ext2/ialloc.c new file mode 100644 index 00000000000..77e05914921 --- /dev/null +++ b/fs/ext2/ialloc.c @@ -0,0 +1,735 @@ +/* + * 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/config.h> +#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)); + desc->bg_free_inodes_count = + cpu_to_le16(le16_to_cpu(desc->bg_free_inodes_count) + 1); + if (dir) + desc->bg_used_dirs_count = + cpu_to_le16(le16_to_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); + sb->s_dirt = 1; + 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 = NULL; + 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. + */ + if (!is_bad_inode(inode)) { + /* Quota is already initialized in iput() */ + ext2_xattr_delete_inode(inode); + DQUOT_FREE_INODE(inode); + DQUOT_DROP(inode); + } + + es = EXT2_SB(sb)->s_es; + is_directory = S_ISDIR(inode->i_mode); + + /* Do this BEFORE marking the inode not in use or returning an error */ + clear_inode (inode); + + 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); + goto error_return; + } + block_group = (ino - 1) / EXT2_INODES_PER_GROUP(sb); + bit = (ino - 1) % EXT2_INODES_PER_GROUP(sb); + brelse(bitmap_bh); + bitmap_bh = read_inode_bitmap(sb, block_group); + if (!bitmap_bh) + goto error_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); +error_return: + 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 buffer_head *bh; + struct ext2_group_desc * gdp; + struct backing_dev_info *bdi; + + bdi = inode->i_mapping->backing_dev_info; + 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, &bh); + 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; + struct buffer_head *bh, *best_bh = NULL; + int group, best_group = -1; + + for (group = 0; group < ngroups; group++) { + desc = ext2_get_group_desc (sb, group, &bh); + 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; + best_bh = bh; + } + } + 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 prefered, 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; + struct buffer_head *bh; + + 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 == sb->s_root->d_inode) || + (EXT2_I(parent)->i_flags & EXT2_TOPDIR_FL)) { + struct ext2_group_desc *best_desc = NULL; + struct buffer_head *best_bh = NULL; + int best_ndir = inodes_per_group; + int best_group = -1; + + get_random_bytes(&group, sizeof(group)); + parent_group = (unsigned)group % ngroups; + for (i = 0; i < ngroups; i++) { + group = (parent_group + i) % ngroups; + desc = ext2_get_group_desc (sb, group, &bh); + 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; + best_bh = bh; + } + if (best_group >= 0) { + desc = best_desc; + bh = best_bh; + 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, &bh); + 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, &bh); + 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; + struct buffer_head *bh; + int group, i; + + /* + * Try to place the inode in its parent directory + */ + group = parent_group; + desc = ext2_get_group_desc (sb, group, &bh); + 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, &bh); + 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, &bh); + 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, int mode) +{ + 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_mod(&sbi->s_freeinodes_counter, -1); + if (S_ISDIR(mode)) + percpu_counter_inc(&sbi->s_dirs_counter); + + spin_lock(sb_bgl_lock(sbi, group)); + gdp->bg_free_inodes_count = + cpu_to_le16(le16_to_cpu(gdp->bg_free_inodes_count) - 1); + if (S_ISDIR(mode)) { + if (sbi->s_debts[group] < 255) + sbi->s_debts[group]++; + gdp->bg_used_dirs_count = + cpu_to_le16(le16_to_cpu(gdp->bg_used_dirs_count) + 1); + } else { + if (sbi->s_debts[group]) + sbi->s_debts[group]--; + } + spin_unlock(sb_bgl_lock(sbi, group)); + + sb->s_dirt = 1; + mark_buffer_dirty(bh2); + inode->i_uid = current->fsuid; + if (test_opt (sb, GRPID)) + inode->i_gid = dir->i_gid; + else if (dir->i_mode & S_ISGID) { + inode->i_gid = dir->i_gid; + if (S_ISDIR(mode)) + mode |= S_ISGID; + } else + inode->i_gid = current->fsgid; + inode->i_mode = mode; + + inode->i_ino = ino; + inode->i_blksize = PAGE_SIZE; /* This is the optimal IO size (for stat), not the fs block size */ + 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_I(dir)->i_flags & ~EXT2_BTREE_FL; + if (S_ISLNK(mode)) + ei->i_flags &= ~(EXT2_IMMUTABLE_FL|EXT2_APPEND_FL); + /* dirsync is only applied to directories */ + if (!S_ISDIR(mode)) + ei->i_flags &= ~EXT2_DIRSYNC_FL; + 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_group = group; + ei->i_next_alloc_block = 0; + ei->i_next_alloc_goal = 0; + ei->i_prealloc_block = 0; + ei->i_prealloc_count = 0; + 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); + insert_inode_hash(inode); + + if (DQUOT_ALLOC_INODE(inode)) { + DQUOT_DROP(inode); + err = -ENOSPC; + goto fail2; + } + err = ext2_init_acl(inode, dir); + if (err) { + DQUOT_FREE_INODE(inode); + goto fail2; + } + mark_inode_dirty(inode); + ext2_debug("allocating inode %lu\n", inode->i_ino); + ext2_preread_inode(inode); + return inode; + +fail2: + inode->i_flags |= S_NOQUOTA; + inode->i_nlink = 0; + 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; + + lock_super (sb); + 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", + percpu_counter_read(&EXT2_SB(sb)->s_freeinodes_counter), + desc_count, bitmap_count); + unlock_super(sb); + 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; +} + +#ifdef CONFIG_EXT2_CHECK +/* Called at mount-time, super-block is locked */ +void ext2_check_inodes_bitmap (struct super_block * sb) +{ + struct ext2_super_block * es = EXT2_SB(sb)->s_es; + unsigned long desc_count = 0, bitmap_count = 0; + struct buffer_head *bitmap_bh = NULL; + int i; + + for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) { + struct ext2_group_desc *desc; + 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); + if (le16_to_cpu(desc->bg_free_inodes_count) != x) + ext2_error (sb, "ext2_check_inodes_bitmap", + "Wrong free inodes count in group %d, " + "stored = %d, counted = %lu", i, + le16_to_cpu(desc->bg_free_inodes_count), x); + bitmap_count += x; + } + brelse(bitmap_bh); + if (percpu_counter_read(&EXT2_SB(sb)->s_freeinodes_counter) != + bitmap_count) + ext2_error(sb, "ext2_check_inodes_bitmap", + "Wrong free inodes count in super block, " + "stored = %lu, counted = %lu", + (unsigned long)le32_to_cpu(es->s_free_inodes_count), + bitmap_count); +} +#endif |