- 根目录:
- fs
- ext2
- ialloc.c
/*
* 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->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, 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 == sb->s_root->d_inode) ||
(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;
}