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WSL2-Linux-Kernel/fs/ext3/balloc.c

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43 KiB
C
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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/time.h>
#include <linux/capability.h>
#include <linux/fs.h>
#include <linux/jbd.h>
#include <linux/ext3_fs.h>
#include <linux/ext3_jbd.h>
#include <linux/quotaops.h>
#include <linux/buffer_head.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 offset;
struct ext3_group_desc * desc;
struct ext3_sb_info *sbi = EXT3_SB(sb);
if (block_group >= sbi->s_groups_count) {
ext3_error (sb, "ext3_get_group_desc",
"block_group >= groups_count - "
"block_group = %d, groups_count = %lu",
block_group, sbi->s_groups_count);
return NULL;
}
smp_rmb();
group_desc = block_group >> EXT3_DESC_PER_BLOCK_BITS(sb);
offset = block_group & (EXT3_DESC_PER_BLOCK(sb) - 1);
if (!sbi->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, offset);
return NULL;
}
desc = (struct ext3_group_desc *) sbi->s_group_desc[group_desc]->b_data;
if (bh)
*bh = sbi->s_group_desc[group_desc];
return desc + offset;
}
/*
* Read the bitmap for a given block_group, reading into the specified
* slot in the superblock's bitmap cache.
*
* Return buffer_head on success or NULL in case of failure.
*/
static struct buffer_head *
read_block_bitmap(struct super_block *sb, unsigned int block_group)
{
struct ext3_group_desc * desc;
struct buffer_head * bh = NULL;
desc = ext3_get_group_desc (sb, block_group, NULL);
if (!desc)
goto error_out;
bh = sb_bread(sb, le32_to_cpu(desc->bg_block_bitmap));
if (!bh)
ext3_error (sb, "read_block_bitmap",
"Cannot read block bitmap - "
"block_group = %d, block_bitmap = %u",
block_group, le32_to_cpu(desc->bg_block_bitmap));
error_out:
return bh;
}
/*
* The reservation window structure operations
* --------------------------------------------
* Operations include:
* dump, find, add, remove, is_empty, find_next_reservable_window, etc.
*
* We use sorted double linked list for the per-filesystem reservation
* window list. (like in vm_region).
*
* Initially, we keep those small operations in the abstract functions,
* so later if we need a better searching tree than double linked-list,
* we could easily switch to that without changing too much
* code.
*/
#if 0
static void __rsv_window_dump(struct rb_root *root, int verbose,
const char *fn)
{
struct rb_node *n;
struct ext3_reserve_window_node *rsv, *prev;
int bad;
restart:
n = rb_first(root);
bad = 0;
prev = NULL;
printk("Block Allocation Reservation Windows Map (%s):\n", fn);
while (n) {
rsv = list_entry(n, struct ext3_reserve_window_node, rsv_node);
if (verbose)
printk("reservation window 0x%p "
"start: %d, end: %d\n",
rsv, rsv->rsv_start, rsv->rsv_end);
if (rsv->rsv_start && rsv->rsv_start >= rsv->rsv_end) {
printk("Bad reservation %p (start >= end)\n",
rsv);
bad = 1;
}
if (prev && prev->rsv_end >= rsv->rsv_start) {
printk("Bad reservation %p (prev->end >= start)\n",
rsv);
bad = 1;
}
if (bad) {
if (!verbose) {
printk("Restarting reservation walk in verbose mode\n");
verbose = 1;
goto restart;
}
}
n = rb_next(n);
prev = rsv;
}
printk("Window map complete.\n");
if (bad)
BUG();
}
#define rsv_window_dump(root, verbose) \
__rsv_window_dump((root), (verbose), __FUNCTION__)
#else
#define rsv_window_dump(root, verbose) do {} while (0)
#endif
static int
goal_in_my_reservation(struct ext3_reserve_window *rsv, int goal,
unsigned int group, struct super_block * sb)
{
unsigned long group_first_block, group_last_block;
group_first_block = le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block) +
group * EXT3_BLOCKS_PER_GROUP(sb);
group_last_block = group_first_block + EXT3_BLOCKS_PER_GROUP(sb) - 1;
if ((rsv->_rsv_start > group_last_block) ||
(rsv->_rsv_end < group_first_block))
return 0;
if ((goal >= 0) && ((goal + group_first_block < rsv->_rsv_start)
|| (goal + group_first_block > rsv->_rsv_end)))
return 0;
return 1;
}
/*
* Find the reserved window which includes the goal, or the previous one
* if the goal is not in any window.
* Returns NULL if there are no windows or if all windows start after the goal.
*/
static struct ext3_reserve_window_node *
search_reserve_window(struct rb_root *root, unsigned long goal)
{
struct rb_node *n = root->rb_node;
struct ext3_reserve_window_node *rsv;
if (!n)
return NULL;
do {
rsv = rb_entry(n, struct ext3_reserve_window_node, rsv_node);
if (goal < rsv->rsv_start)
n = n->rb_left;
else if (goal > rsv->rsv_end)
n = n->rb_right;
else
return rsv;
} while (n);
/*
* We've fallen off the end of the tree: the goal wasn't inside
* any particular node. OK, the previous node must be to one
* side of the interval containing the goal. If it's the RHS,
* we need to back up one.
*/
if (rsv->rsv_start > goal) {
n = rb_prev(&rsv->rsv_node);
rsv = rb_entry(n, struct ext3_reserve_window_node, rsv_node);
}
return rsv;
}
void ext3_rsv_window_add(struct super_block *sb,
struct ext3_reserve_window_node *rsv)
{
struct rb_root *root = &EXT3_SB(sb)->s_rsv_window_root;
struct rb_node *node = &rsv->rsv_node;
unsigned int start = rsv->rsv_start;
struct rb_node ** p = &root->rb_node;
struct rb_node * parent = NULL;
struct ext3_reserve_window_node *this;
while (*p)
{
parent = *p;
this = rb_entry(parent, struct ext3_reserve_window_node, rsv_node);
if (start < this->rsv_start)
p = &(*p)->rb_left;
else if (start > this->rsv_end)
p = &(*p)->rb_right;
else
BUG();
}
rb_link_node(node, parent, p);
rb_insert_color(node, root);
}
static void rsv_window_remove(struct super_block *sb,
struct ext3_reserve_window_node *rsv)
{
rsv->rsv_start = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
rsv->rsv_end = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
rsv->rsv_alloc_hit = 0;
rb_erase(&rsv->rsv_node, &EXT3_SB(sb)->s_rsv_window_root);
}
static inline int rsv_is_empty(struct ext3_reserve_window *rsv)
{
/* a valid reservation end block could not be 0 */
return (rsv->_rsv_end == EXT3_RESERVE_WINDOW_NOT_ALLOCATED);
}
void ext3_init_block_alloc_info(struct inode *inode)
{
struct ext3_inode_info *ei = EXT3_I(inode);
struct ext3_block_alloc_info *block_i = ei->i_block_alloc_info;
struct super_block *sb = inode->i_sb;
block_i = kmalloc(sizeof(*block_i), GFP_NOFS);
if (block_i) {
struct ext3_reserve_window_node *rsv = &block_i->rsv_window_node;
rsv->rsv_start = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
rsv->rsv_end = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
/*
* if filesystem is mounted with NORESERVATION, the goal
* reservation window size is set to zero to indicate
* block reservation is off
*/
if (!test_opt(sb, RESERVATION))
rsv->rsv_goal_size = 0;
else
rsv->rsv_goal_size = EXT3_DEFAULT_RESERVE_BLOCKS;
rsv->rsv_alloc_hit = 0;
block_i->last_alloc_logical_block = 0;
block_i->last_alloc_physical_block = 0;
}
ei->i_block_alloc_info = block_i;
}
void ext3_discard_reservation(struct inode *inode)
{
struct ext3_inode_info *ei = EXT3_I(inode);
struct ext3_block_alloc_info *block_i = ei->i_block_alloc_info;
struct ext3_reserve_window_node *rsv;
spinlock_t *rsv_lock = &EXT3_SB(inode->i_sb)->s_rsv_window_lock;
if (!block_i)
return;
rsv = &block_i->rsv_window_node;
if (!rsv_is_empty(&rsv->rsv_window)) {
spin_lock(rsv_lock);
if (!rsv_is_empty(&rsv->rsv_window))
rsv_window_remove(inode->i_sb, rsv);
spin_unlock(rsv_lock);
}
}
/* Free given blocks, update quota and i_blocks field */
void ext3_free_blocks_sb(handle_t *handle, struct super_block *sb,
unsigned long block, unsigned long count,
int *pdquot_freed_blocks)
{
struct buffer_head *bitmap_bh = NULL;
struct buffer_head *gd_bh;
unsigned long block_group;
unsigned long bit;
unsigned long i;
unsigned long overflow;
struct ext3_group_desc * desc;
struct ext3_super_block * es;
struct ext3_sb_info *sbi;
int err = 0, ret;
unsigned group_freed;
*pdquot_freed_blocks = 0;
sbi = EXT3_SB(sb);
es = sbi->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(s) %lu-%lu\n", block, block + count - 1);
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;
}
brelse(bitmap_bh);
bitmap_bh = read_block_bitmap(sb, block_group);
if (!bitmap_bh)
goto error_return;
desc = ext3_get_group_desc (sb, block_group, &gd_bh);
if (!desc)
goto error_return;
if (in_range (le32_to_cpu(desc->bg_block_bitmap), block, count) ||
in_range (le32_to_cpu(desc->bg_inode_bitmap), block, count) ||
in_range (block, le32_to_cpu(desc->bg_inode_table),
sbi->s_itb_per_group) ||
in_range (block + count - 1, le32_to_cpu(desc->bg_inode_table),
sbi->s_itb_per_group))
ext3_error (sb, "ext3_free_blocks",
"Freeing blocks in system zones - "
"Block = %lu, count = %lu",
block, count);
/*
* 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;
jbd_lock_bh_state(bitmap_bh);
for (i = 0, group_freed = 0; i < count; i++) {
/*
* An HJ special. This is expensive...
*/
#ifdef CONFIG_JBD_DEBUG
jbd_unlock_bh_state(bitmap_bh);
{
struct buffer_head *debug_bh;
debug_bh = sb_find_get_block(sb, block + i);
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);
}
}
jbd_lock_bh_state(bitmap_bh);
#endif
if (need_resched()) {
jbd_unlock_bh_state(bitmap_bh);
cond_resched();
jbd_lock_bh_state(bitmap_bh);
}
/* @@@ 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, "set in b_committed_data");
J_ASSERT_BH(bitmap_bh,
bh2jh(bitmap_bh)->b_committed_data != NULL);
ext3_set_bit_atomic(sb_bgl_lock(sbi, block_group), bit + i,
bh2jh(bitmap_bh)->b_committed_data);
/*
* We clear the bit in the bitmap after setting the committed
* data bit, because this is the reverse order to that which
* the allocator uses.
*/
BUFFER_TRACE(bitmap_bh, "clear bit");
if (!ext3_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
bit + i, bitmap_bh->b_data)) {
jbd_unlock_bh_state(bitmap_bh);
ext3_error(sb, __FUNCTION__,
"bit already cleared for block %lu", block + i);
jbd_lock_bh_state(bitmap_bh);
BUFFER_TRACE(bitmap_bh, "bit already cleared");
} else {
group_freed++;
}
}
jbd_unlock_bh_state(bitmap_bh);
spin_lock(sb_bgl_lock(sbi, block_group));
desc->bg_free_blocks_count =
cpu_to_le16(le16_to_cpu(desc->bg_free_blocks_count) +
group_freed);
spin_unlock(sb_bgl_lock(sbi, block_group));
percpu_counter_mod(&sbi->s_freeblocks_counter, count);
/* 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;
*pdquot_freed_blocks += group_freed;
if (overflow && !err) {
block += count;
count = overflow;
goto do_more;
}
sb->s_dirt = 1;
error_return:
brelse(bitmap_bh);
ext3_std_error(sb, err);
return;
}
/* 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 super_block * sb;
int dquot_freed_blocks;
sb = inode->i_sb;
if (!sb) {
printk ("ext3_free_blocks: nonexistent device");
return;
}
ext3_free_blocks_sb(handle, sb, block, count, &dquot_freed_blocks);
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)
{
int ret;
struct journal_head *jh = bh2jh(bh);
if (ext3_test_bit(nr, bh->b_data))
return 0;
jbd_lock_bh_state(bh);
if (!jh->b_committed_data)
ret = 1;
else
ret = !ext3_test_bit(nr, jh->b_committed_data);
jbd_unlock_bh_state(bh);
return ret;
}
static int
bitmap_search_next_usable_block(int start, struct buffer_head *bh,
int maxblocks)
{
int next;
struct journal_head *jh = bh2jh(bh);
/*
* The bitmap search --- search forward alternately through the actual
* bitmap and the last-committed copy until we find a bit free in
* both
*/
while (start < maxblocks) {
next = ext3_find_next_zero_bit(bh->b_data, maxblocks, start);
if (next >= maxblocks)
return -1;
if (ext3_test_allocatable(next, bh))
return next;
jbd_lock_bh_state(bh);
if (jh->b_committed_data)
start = ext3_find_next_zero_bit(jh->b_committed_data,
maxblocks, next);
jbd_unlock_bh_state(bh);
}
return -1;
}
/*
* 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;
if (end_goal > maxblocks)
end_goal = maxblocks;
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;
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 && next >= start && 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
*/
here = bitmap_search_next_usable_block(here, bh, maxblocks);
return here;
}
/*
* We think we can allocate this block in this bitmap. Try to set the bit.
* If that succeeds then check that nobody has allocated and then freed the
* block since we saw that is was not marked in b_committed_data. If it _was_
* allocated and freed then clear the bit in the bitmap again and return
* zero (failure).
*/
static inline int
claim_block(spinlock_t *lock, int block, struct buffer_head *bh)
{
struct journal_head *jh = bh2jh(bh);
int ret;
if (ext3_set_bit_atomic(lock, block, bh->b_data))
return 0;
jbd_lock_bh_state(bh);
if (jh->b_committed_data && ext3_test_bit(block,jh->b_committed_data)) {
ext3_clear_bit_atomic(lock, block, bh->b_data);
ret = 0;
} else {
ret = 1;
}
jbd_unlock_bh_state(bh);
return ret;
}
/*
* If we failed to allocate the desired block then we may end up crossing to a
* new bitmap. In that case we must release write access to the old one via
* ext3_journal_release_buffer(), else we'll run out of credits.
*/
static int
ext3_try_to_allocate(struct super_block *sb, handle_t *handle, int group,
struct buffer_head *bitmap_bh, int goal, struct ext3_reserve_window *my_rsv)
{
int group_first_block, start, end;
/* we do allocation within the reservation window if we have a window */
if (my_rsv) {
group_first_block =
le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block) +
group * EXT3_BLOCKS_PER_GROUP(sb);
if (my_rsv->_rsv_start >= group_first_block)
start = my_rsv->_rsv_start - group_first_block;
else
/* reservation window cross group boundary */
start = 0;
end = my_rsv->_rsv_end - group_first_block + 1;
if (end > EXT3_BLOCKS_PER_GROUP(sb))
/* reservation window crosses group boundary */
end = EXT3_BLOCKS_PER_GROUP(sb);
if ((start <= goal) && (goal < end))
start = goal;
else
goal = -1;
} else {
if (goal > 0)
start = goal;
else
start = 0;
end = EXT3_BLOCKS_PER_GROUP(sb);
}
BUG_ON(start > EXT3_BLOCKS_PER_GROUP(sb));
repeat:
if (goal < 0 || !ext3_test_allocatable(goal, bitmap_bh)) {
goal = find_next_usable_block(start, bitmap_bh, end);
if (goal < 0)
goto fail_access;
if (!my_rsv) {
int i;
for (i = 0; i < 7 && goal > start &&
ext3_test_allocatable(goal - 1,
bitmap_bh);
i++, goal--)
;
}
}
start = goal;
if (!claim_block(sb_bgl_lock(EXT3_SB(sb), group), goal, bitmap_bh)) {
/*
* The block was allocated by another thread, or it was
* allocated and then freed by another thread
*/
start++;
goal++;
if (start >= end)
goto fail_access;
goto repeat;
}
return goal;
fail_access:
return -1;
}
/**
* find_next_reservable_window():
* find a reservable space within the given range.
* It does not allocate the reservation window for now:
* alloc_new_reservation() will do the work later.
*
* @search_head: the head of the searching list;
* This is not necessarily the list head of the whole filesystem
*
* We have both head and start_block to assist the search
* for the reservable space. The list starts from head,
* but we will shift to the place where start_block is,
* then start from there, when looking for a reservable space.
*
* @size: the target new reservation window size
*
* @group_first_block: the first block we consider to start
* the real search from
*
* @last_block:
* the maximum block number that our goal reservable space
* could start from. This is normally the last block in this
* group. The search will end when we found the start of next
* possible reservable space is out of this boundary.
* This could handle the cross boundary reservation window
* request.
*
* basically we search from the given range, rather than the whole
* reservation double linked list, (start_block, last_block)
* to find a free region that is of my size and has not
* been reserved.
*
*/
static int find_next_reservable_window(
struct ext3_reserve_window_node *search_head,
struct ext3_reserve_window_node *my_rsv,
struct super_block * sb, int start_block,
int last_block)
{
struct rb_node *next;
struct ext3_reserve_window_node *rsv, *prev;
int cur;
int size = my_rsv->rsv_goal_size;
/* TODO: make the start of the reservation window byte-aligned */
/* cur = *start_block & ~7;*/
cur = start_block;
rsv = search_head;
if (!rsv)
return -1;
while (1) {
if (cur <= rsv->rsv_end)
cur = rsv->rsv_end + 1;
/* TODO?
* in the case we could not find a reservable space
* that is what is expected, during the re-search, we could
* remember what's the largest reservable space we could have
* and return that one.
*
* For now it will fail if we could not find the reservable
* space with expected-size (or more)...
*/
if (cur > last_block)
return -1; /* fail */
prev = rsv;
next = rb_next(&rsv->rsv_node);
rsv = list_entry(next,struct ext3_reserve_window_node,rsv_node);
/*
* Reached the last reservation, we can just append to the
* previous one.
*/
if (!next)
break;
if (cur + size <= rsv->rsv_start) {
/*
* Found a reserveable space big enough. We could
* have a reservation across the group boundary here
*/
break;
}
}
/*
* we come here either :
* when we reach the end of the whole list,
* and there is empty reservable space after last entry in the list.
* append it to the end of the list.
*
* or we found one reservable space in the middle of the list,
* return the reservation window that we could append to.
* succeed.
*/
if ((prev != my_rsv) && (!rsv_is_empty(&my_rsv->rsv_window)))
rsv_window_remove(sb, my_rsv);
/*
* Let's book the whole avaliable window for now. We will check the
* disk bitmap later and then, if there are free blocks then we adjust
* the window size if it's larger than requested.
* Otherwise, we will remove this node from the tree next time
* call find_next_reservable_window.
*/
my_rsv->rsv_start = cur;
my_rsv->rsv_end = cur + size - 1;
my_rsv->rsv_alloc_hit = 0;
if (prev != my_rsv)
ext3_rsv_window_add(sb, my_rsv);
return 0;
}
/**
* alloc_new_reservation()--allocate a new reservation window
*
* To make a new reservation, we search part of the filesystem
* reservation list (the list that inside the group). We try to
* allocate a new reservation window near the allocation goal,
* or the beginning of the group, if there is no goal.
*
* We first find a reservable space after the goal, then from
* there, we check the bitmap for the first free block after
* it. If there is no free block until the end of group, then the
* whole group is full, we failed. Otherwise, check if the free
* block is inside the expected reservable space, if so, we
* succeed.
* If the first free block is outside the reservable space, then
* start from the first free block, we search for next available
* space, and go on.
*
* on succeed, a new reservation will be found and inserted into the list
* It contains at least one free block, and it does not overlap with other
* reservation windows.
*
* failed: we failed to find a reservation window in this group
*
* @rsv: the reservation
*
* @goal: The goal (group-relative). It is where the search for a
* free reservable space should start from.
* if we have a goal(goal >0 ), then start from there,
* no goal(goal = -1), we start from the first block
* of the group.
*
* @sb: the super block
* @group: the group we are trying to allocate in
* @bitmap_bh: the block group block bitmap
*
*/
static int alloc_new_reservation(struct ext3_reserve_window_node *my_rsv,
int goal, struct super_block *sb,
unsigned int group, struct buffer_head *bitmap_bh)
{
struct ext3_reserve_window_node *search_head;
int group_first_block, group_end_block, start_block;
int first_free_block;
struct rb_root *fs_rsv_root = &EXT3_SB(sb)->s_rsv_window_root;
unsigned long size;
int ret;
spinlock_t *rsv_lock = &EXT3_SB(sb)->s_rsv_window_lock;
group_first_block = le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block) +
group * EXT3_BLOCKS_PER_GROUP(sb);
group_end_block = group_first_block + EXT3_BLOCKS_PER_GROUP(sb) - 1;
if (goal < 0)
start_block = group_first_block;
else
start_block = goal + group_first_block;
size = my_rsv->rsv_goal_size;
if (!rsv_is_empty(&my_rsv->rsv_window)) {
/*
* if the old reservation is cross group boundary
* and if the goal is inside the old reservation window,
* we will come here when we just failed to allocate from
* the first part of the window. We still have another part
* that belongs to the next group. In this case, there is no
* point to discard our window and try to allocate a new one
* in this group(which will fail). we should
* keep the reservation window, just simply move on.
*
* Maybe we could shift the start block of the reservation
* window to the first block of next group.
*/
if ((my_rsv->rsv_start <= group_end_block) &&
(my_rsv->rsv_end > group_end_block) &&
(start_block >= my_rsv->rsv_start))
return -1;
if ((my_rsv->rsv_alloc_hit >
(my_rsv->rsv_end - my_rsv->rsv_start + 1) / 2)) {
/*
* if we previously allocation hit ration is greater than half
* we double the size of reservation window next time
* otherwise keep the same
*/
size = size * 2;
if (size > EXT3_MAX_RESERVE_BLOCKS)
size = EXT3_MAX_RESERVE_BLOCKS;
my_rsv->rsv_goal_size= size;
}
}
spin_lock(rsv_lock);
/*
* shift the search start to the window near the goal block
*/
search_head = search_reserve_window(fs_rsv_root, start_block);
/*
* find_next_reservable_window() simply finds a reservable window
* inside the given range(start_block, group_end_block).
*
* To make sure the reservation window has a free bit inside it, we
* need to check the bitmap after we found a reservable window.
*/
retry:
ret = find_next_reservable_window(search_head, my_rsv, sb,
start_block, group_end_block);
if (ret == -1) {
if (!rsv_is_empty(&my_rsv->rsv_window))
rsv_window_remove(sb, my_rsv);
spin_unlock(rsv_lock);
return -1;
}
/*
* On success, find_next_reservable_window() returns the
* reservation window where there is a reservable space after it.
* Before we reserve this reservable space, we need
* to make sure there is at least a free block inside this region.
*
* searching the first free bit on the block bitmap and copy of
* last committed bitmap alternatively, until we found a allocatable
* block. Search start from the start block of the reservable space
* we just found.
*/
spin_unlock(rsv_lock);
first_free_block = bitmap_search_next_usable_block(
my_rsv->rsv_start - group_first_block,
bitmap_bh, group_end_block - group_first_block + 1);
if (first_free_block < 0) {
/*
* no free block left on the bitmap, no point
* to reserve the space. return failed.
*/
spin_lock(rsv_lock);
if (!rsv_is_empty(&my_rsv->rsv_window))
rsv_window_remove(sb, my_rsv);
spin_unlock(rsv_lock);
return -1; /* failed */
}
start_block = first_free_block + group_first_block;
/*
* check if the first free block is within the
* free space we just reserved
*/
if (start_block >= my_rsv->rsv_start && start_block < my_rsv->rsv_end)
return 0; /* success */
/*
* if the first free bit we found is out of the reservable space
* continue search for next reservable space,
* start from where the free block is,
* we also shift the list head to where we stopped last time
*/
search_head = my_rsv;
spin_lock(rsv_lock);
goto retry;
}
/*
* This is the main function used to allocate a new block and its reservation
* window.
*
* Each time when a new block allocation is need, first try to allocate from
* its own reservation. If it does not have a reservation window, instead of
* looking for a free bit on bitmap first, then look up the reservation list to
* see if it is inside somebody else's reservation window, we try to allocate a
* reservation window for it starting from the goal first. Then do the block
* allocation within the reservation window.
*
* This will avoid keeping on searching the reservation list again and
* again when somebody is looking for a free block (without
* reservation), and there are lots of free blocks, but they are all
* being reserved.
*
* We use a sorted double linked list for the per-filesystem reservation list.
* The insert, remove and find a free space(non-reserved) operations for the
* sorted double linked list should be fast.
*
*/
static int
ext3_try_to_allocate_with_rsv(struct super_block *sb, handle_t *handle,
unsigned int group, struct buffer_head *bitmap_bh,
int goal, struct ext3_reserve_window_node * my_rsv,
int *errp)
{
unsigned long group_first_block;
int ret = 0;
int fatal;
*errp = 0;
/*
* 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(bitmap_bh, "get undo access for new block");
fatal = ext3_journal_get_undo_access(handle, bitmap_bh);
if (fatal) {
*errp = fatal;
return -1;
}
/*
* we don't deal with reservation when
* filesystem is mounted without reservation
* or the file is not a regular file
* or last attempt to allocate a block with reservation turned on failed
*/
if (my_rsv == NULL ) {
ret = ext3_try_to_allocate(sb, handle, group, bitmap_bh, goal, NULL);
goto out;
}
/*
* goal is a group relative block number (if there is a goal)
* 0 < goal < EXT3_BLOCKS_PER_GROUP(sb)
* first block is a filesystem wide block number
* first block is the block number of the first block in this group
*/
group_first_block = le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block) +
group * EXT3_BLOCKS_PER_GROUP(sb);
/*
* Basically we will allocate a new block from inode's reservation
* window.
*
* We need to allocate a new reservation window, if:
* a) inode does not have a reservation window; or
* b) last attempt to allocate a block from existing reservation
* failed; or
* c) we come here with a goal and with a reservation window
*
* We do not need to allocate a new reservation window if we come here
* at the beginning with a goal and the goal is inside the window, or
* we don't have a goal but already have a reservation window.
* then we could go to allocate from the reservation window directly.
*/
while (1) {
if (rsv_is_empty(&my_rsv->rsv_window) || (ret < 0) ||
!goal_in_my_reservation(&my_rsv->rsv_window, goal, group, sb)) {
ret = alloc_new_reservation(my_rsv, goal, sb,
group, bitmap_bh);
if (ret < 0)
break; /* failed */
if (!goal_in_my_reservation(&my_rsv->rsv_window, goal, group, sb))
goal = -1;
}
if ((my_rsv->rsv_start >= group_first_block + EXT3_BLOCKS_PER_GROUP(sb))
|| (my_rsv->rsv_end < group_first_block))
BUG();
ret = ext3_try_to_allocate(sb, handle, group, bitmap_bh, goal,
&my_rsv->rsv_window);
if (ret >= 0) {
my_rsv->rsv_alloc_hit++;
break; /* succeed */
}
}
out:
if (ret >= 0) {
BUFFER_TRACE(bitmap_bh, "journal_dirty_metadata for "
"bitmap block");
fatal = ext3_journal_dirty_metadata(handle, bitmap_bh);
if (fatal) {
*errp = fatal;
return -1;
}
return ret;
}
BUFFER_TRACE(bitmap_bh, "journal_release_buffer");
ext3_journal_release_buffer(handle, bitmap_bh);
return ret;
}
static int ext3_has_free_blocks(struct ext3_sb_info *sbi)
{
int free_blocks, root_blocks;
free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
root_blocks = le32_to_cpu(sbi->s_es->s_r_blocks_count);
if (free_blocks < root_blocks + 1 && !capable(CAP_SYS_RESOURCE) &&
sbi->s_resuid != current->fsuid &&
(sbi->s_resgid == 0 || !in_group_p (sbi->s_resgid))) {
return 0;
}
return 1;
}
/*
* ext3_should_retry_alloc() is called when ENOSPC is returned, and if
* it is profitable to retry the operation, this function will wait
* for the current or commiting transaction to complete, and then
* return TRUE.
*/
int ext3_should_retry_alloc(struct super_block *sb, int *retries)
{
if (!ext3_has_free_blocks(EXT3_SB(sb)) || (*retries)++ > 3)
return 0;
jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
return journal_force_commit_nested(EXT3_SB(sb)->s_journal);
}
/*
* 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, int *errp)
{
struct buffer_head *bitmap_bh = NULL;
struct buffer_head *gdp_bh;
int group_no;
int goal_group;
int ret_block;
int bgi; /* blockgroup iteration index */
int target_block;
int fatal = 0, err;
int performed_allocation = 0;
int free_blocks;
struct super_block *sb;
struct ext3_group_desc *gdp;
struct ext3_super_block *es;
struct ext3_sb_info *sbi;
struct ext3_reserve_window_node *my_rsv = NULL;
struct ext3_block_alloc_info *block_i;
unsigned short windowsz = 0;
#ifdef EXT3FS_DEBUG
static int goal_hits, goal_attempts;
#endif
unsigned long ngroups;
*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;
}
sbi = EXT3_SB(sb);
es = EXT3_SB(sb)->s_es;
ext3_debug("goal=%lu.\n", goal);
/*
* Allocate a block from reservation only when
* filesystem is mounted with reservation(default,-o reservation), and
* it's a regular file, and
* the desired window size is greater than 0 (One could use ioctl
* command EXT3_IOC_SETRSVSZ to set the window size to 0 to turn off
* reservation on that particular file)
*/
block_i = EXT3_I(inode)->i_block_alloc_info;
if (block_i && ((windowsz = block_i->rsv_window_node.rsv_goal_size) > 0))
my_rsv = &block_i->rsv_window_node;
if (!ext3_has_free_blocks(sbi)) {
*errp = -ENOSPC;
goto out;
}
/*
* 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);
group_no = (goal - le32_to_cpu(es->s_first_data_block)) /
EXT3_BLOCKS_PER_GROUP(sb);
gdp = ext3_get_group_desc(sb, group_no, &gdp_bh);
if (!gdp)
goto io_error;
goal_group = group_no;
retry:
free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
/*
* if there is not enough free blocks to make a new resevation
* turn off reservation for this allocation
*/
if (my_rsv && (free_blocks < windowsz)
&& (rsv_is_empty(&my_rsv->rsv_window)))
my_rsv = NULL;
if (free_blocks > 0) {
ret_block = ((goal - le32_to_cpu(es->s_first_data_block)) %
EXT3_BLOCKS_PER_GROUP(sb));
bitmap_bh = read_block_bitmap(sb, group_no);
if (!bitmap_bh)
goto io_error;
ret_block = ext3_try_to_allocate_with_rsv(sb, handle, group_no,
bitmap_bh, ret_block, my_rsv, &fatal);
if (fatal)
goto out;
if (ret_block >= 0)
goto allocated;
}
ngroups = EXT3_SB(sb)->s_groups_count;
smp_rmb();
/*
* Now search the rest of the groups. We assume that
* i and gdp correctly point to the last group visited.
*/
for (bgi = 0; bgi < ngroups; bgi++) {
group_no++;
if (group_no >= ngroups)
group_no = 0;
gdp = ext3_get_group_desc(sb, group_no, &gdp_bh);
if (!gdp) {
*errp = -EIO;
goto out;
}
free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
/*
* skip this group if the number of
* free blocks is less than half of the reservation
* window size.
*/
if (free_blocks <= (windowsz/2))
continue;
brelse(bitmap_bh);
bitmap_bh = read_block_bitmap(sb, group_no);
if (!bitmap_bh)
goto io_error;
ret_block = ext3_try_to_allocate_with_rsv(sb, handle, group_no,
bitmap_bh, -1, my_rsv, &fatal);
if (fatal)
goto out;
if (ret_block >= 0)
goto allocated;
}
/*
* We may end up a bogus ealier ENOSPC error due to
* filesystem is "full" of reservations, but
* there maybe indeed free blocks avaliable on disk
* In this case, we just forget about the reservations
* just do block allocation as without reservations.
*/
if (my_rsv) {
my_rsv = NULL;
group_no = goal_group;
goto retry;
}
/* No space left on the device */
*errp = -ENOSPC;
goto out;
allocated:
ext3_debug("using block group %d(%d)\n",
group_no, gdp->bg_free_blocks_count);
BUFFER_TRACE(gdp_bh, "get_write_access");
fatal = ext3_journal_get_write_access(handle, gdp_bh);
if (fatal)
goto out;
target_block = ret_block + group_no * EXT3_BLOCKS_PER_GROUP(sb)
+ le32_to_cpu(es->s_first_data_block);
if (target_block == le32_to_cpu(gdp->bg_block_bitmap) ||
target_block == le32_to_cpu(gdp->bg_inode_bitmap) ||
in_range(target_block, le32_to_cpu(gdp->bg_inode_table),
EXT3_SB(sb)->s_itb_per_group))
ext3_error(sb, "ext3_new_block",
"Allocating block in system zone - "
"block = %u", target_block);
performed_allocation = 1;
#ifdef CONFIG_JBD_DEBUG
{
struct buffer_head *debug_bh;
/* Record bitmap buffer state in the newly allocated block */
debug_bh = sb_find_get_block(sb, target_block);
if (debug_bh) {
BUFFER_TRACE(debug_bh, "state when allocated");
BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap state");
brelse(debug_bh);
}
}
jbd_lock_bh_state(bitmap_bh);
spin_lock(sb_bgl_lock(sbi, group_no));
if (buffer_jbd(bitmap_bh) && bh2jh(bitmap_bh)->b_committed_data) {
if (ext3_test_bit(ret_block,
bh2jh(bitmap_bh)->b_committed_data)) {
printk("%s: block was unexpectedly set in "
"b_committed_data\n", __FUNCTION__);
}
}
ext3_debug("found bit %d\n", ret_block);
spin_unlock(sb_bgl_lock(sbi, group_no));
jbd_unlock_bh_state(bitmap_bh);
#endif
/* ret_block was blockgroup-relative. Now it becomes fs-relative */
ret_block = target_block;
if (ret_block >= le32_to_cpu(es->s_blocks_count)) {
ext3_error(sb, "ext3_new_block",
"block(%d) >= blocks count(%d) - "
"block_group = %d, es == %p ", ret_block,
le32_to_cpu(es->s_blocks_count), group_no, 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",
ret_block, goal_hits, goal_attempts);
spin_lock(sb_bgl_lock(sbi, group_no));
gdp->bg_free_blocks_count =
cpu_to_le16(le16_to_cpu(gdp->bg_free_blocks_count) - 1);
spin_unlock(sb_bgl_lock(sbi, group_no));
percpu_counter_mod(&sbi->s_freeblocks_counter, -1);
BUFFER_TRACE(gdp_bh, "journal_dirty_metadata for group descriptor");
err = ext3_journal_dirty_metadata(handle, gdp_bh);
if (!fatal)
fatal = err;
sb->s_dirt = 1;
if (fatal)
goto out;
*errp = 0;
brelse(bitmap_bh);
return ret_block;
io_error:
*errp = -EIO;
out:
if (fatal) {
*errp = fatal;
ext3_std_error(sb, fatal);
}
/*
* Undo the block allocation
*/
if (!performed_allocation)
DQUOT_FREE_BLOCK(inode, 1);
brelse(bitmap_bh);
return 0;
}
unsigned long ext3_count_free_blocks(struct super_block *sb)
{
unsigned long desc_count;
struct ext3_group_desc *gdp;
int i;
unsigned long ngroups = EXT3_SB(sb)->s_groups_count;
#ifdef EXT3FS_DEBUG
struct ext3_super_block *es;
unsigned long bitmap_count, x;
struct buffer_head *bitmap_bh = NULL;
es = EXT3_SB(sb)->s_es;
desc_count = 0;
bitmap_count = 0;
gdp = NULL;
smp_rmb();
for (i = 0; i < ngroups; i++) {
gdp = ext3_get_group_desc(sb, i, NULL);
if (!gdp)
continue;
desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
brelse(bitmap_bh);
bitmap_bh = read_block_bitmap(sb, i);
if (bitmap_bh == NULL)
continue;
x = ext3_count_free(bitmap_bh, sb->s_blocksize);
printk("group %d: stored = %d, counted = %lu\n",
i, le16_to_cpu(gdp->bg_free_blocks_count), x);
bitmap_count += x;
}
brelse(bitmap_bh);
printk("ext3_count_free_blocks: stored = %u, computed = %lu, %lu\n",
le32_to_cpu(es->s_free_blocks_count), desc_count, bitmap_count);
return bitmap_count;
#else
desc_count = 0;
smp_rmb();
for (i = 0; i < ngroups; i++) {
gdp = ext3_get_group_desc(sb, i, NULL);
if (!gdp)
continue;
desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
}
return desc_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(EXT3_SB(sb)->s_es->s_first_data_block)) %
EXT3_BLOCKS_PER_GROUP(sb), map);
}
static inline int test_root(int a, int b)
{
int num = b;
while (a > num)
num *= b;
return num == a;
}
static int ext3_group_sparse(int group)
{
if (group <= 1)
return 1;
if (!(group & 1))
return 0;
return (test_root(group, 7) || test_root(group, 5) ||
test_root(group, 3));
}
/**
* 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;
}
Ссылка в новой задаче Показать git blame Копировать постоянную ссылку