- * ext4_free_blocks() -- Free given blocks and update quota
- * @handle: handle for this transaction
- * @inode: inode
- * @block: start physical block to free
- * @count: number of blocks to count
- * @metadata: Are these metadata blocks
- */
-void ext4_free_blocks(handle_t *handle, struct inode *inode,
- ext4_fsblk_t block, unsigned long count,
- int metadata)
-{
- struct super_block * sb;
- unsigned long dquot_freed_blocks;
-
- /* this isn't the right place to decide whether block is metadata
- * inode.c/extents.c knows better, but for safety ... */
- if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode) ||
- ext4_should_journal_data(inode))
- metadata = 1;
-
- sb = inode->i_sb;
-
- if (!test_opt(sb, MBALLOC) || !EXT4_SB(sb)->s_group_info)
- ext4_free_blocks_sb(handle, sb, block, count,
- &dquot_freed_blocks);
- else
- ext4_mb_free_blocks(handle, inode, block, count,
- metadata, &dquot_freed_blocks);
- if (dquot_freed_blocks)
- DQUOT_FREE_BLOCK(inode, dquot_freed_blocks);
- return;
-}
-
-/**
- * ext4_test_allocatable()
- * @nr: given allocation block group
- * @bh: bufferhead contains the bitmap of the given block group
- *
- * For ext4 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 ext4_test_allocatable(ext4_grpblk_t nr, struct buffer_head *bh)
-{
- int ret;
- struct journal_head *jh = bh2jh(bh);
-
- if (ext4_test_bit(nr, bh->b_data))
- return 0;
-
- jbd_lock_bh_state(bh);
- if (!jh->b_committed_data)
- ret = 1;
- else
- ret = !ext4_test_bit(nr, jh->b_committed_data);
- jbd_unlock_bh_state(bh);
- return ret;
-}
-
-/**
- * bitmap_search_next_usable_block()
- * @start: the starting block (group relative) of the search
- * @bh: bufferhead contains the block group bitmap
- * @maxblocks: the ending block (group relative) of the reservation
- *
- * The bitmap search --- search forward alternately through the actual
- * bitmap on disk and the last-committed copy in journal, until we find a
- * bit free in both bitmaps.
- */
-static ext4_grpblk_t
-bitmap_search_next_usable_block(ext4_grpblk_t start, struct buffer_head *bh,
- ext4_grpblk_t maxblocks)
-{
- ext4_grpblk_t next;
- struct journal_head *jh = bh2jh(bh);
-
- while (start < maxblocks) {
- next = ext4_find_next_zero_bit(bh->b_data, maxblocks, start);
- if (next >= maxblocks)
- return -1;
- if (ext4_test_allocatable(next, bh))
- return next;
- jbd_lock_bh_state(bh);
- if (jh->b_committed_data)
- start = ext4_find_next_zero_bit(jh->b_committed_data,
- maxblocks, next);
- jbd_unlock_bh_state(bh);
- }
- return -1;
-}
-
-/**
- * find_next_usable_block()
- * @start: the starting block (group relative) to find next
- * allocatable block in bitmap.
- * @bh: bufferhead contains the block group bitmap
- * @maxblocks: the ending block (group relative) for the search
- *
- * Find an allocatable block in a bitmap. We honor 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 ext4_grpblk_t
-find_next_usable_block(ext4_grpblk_t start, struct buffer_head *bh,
- ext4_grpblk_t maxblocks)
-{
- ext4_grpblk_t 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 EXT4_BLOCKS_PER_GROUP. Aligning up to the
- * next 64-bit boundary is simple..
- */
- ext4_grpblk_t end_goal = (start + 63) & ~63;
- if (end_goal > maxblocks)
- end_goal = maxblocks;
- here = ext4_find_next_zero_bit(bh->b_data, end_goal, start);
- if (here < end_goal && ext4_test_allocatable(here, bh))
- return here;
- ext4_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 + 7) >> 3) - (here >> 3));
- next = (r - ((char *)bh->b_data)) << 3;
-
- if (next < maxblocks && next >= start && ext4_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;
-}
-
-/**
- * claim_block()
- * @block: the free block (group relative) to allocate
- * @bh: the bufferhead containts the block group bitmap
- *
- * 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, ext4_grpblk_t block, struct buffer_head *bh)
-{
- struct journal_head *jh = bh2jh(bh);
- int ret;
-
- if (ext4_set_bit_atomic(lock, block, bh->b_data))
- return 0;
- jbd_lock_bh_state(bh);
- if (jh->b_committed_data && ext4_test_bit(block,jh->b_committed_data)) {
- ext4_clear_bit_atomic(lock, block, bh->b_data);
- ret = 0;
- } else {
- ret = 1;
- }
- jbd_unlock_bh_state(bh);
- return ret;
-}
-
-/**
- * ext4_try_to_allocate()
- * @sb: superblock
- * @handle: handle to this transaction
- * @group: given allocation block group
- * @bitmap_bh: bufferhead holds the block bitmap
- * @grp_goal: given target block within the group
- * @count: target number of blocks to allocate
- * @my_rsv: reservation window
- *
- * Attempt to allocate blocks within a give range. Set the range of allocation
- * first, then find the first free bit(s) from the bitmap (within the range),
- * and at last, allocate the blocks by claiming the found free bit as allocated.
- *
- * To set the range of this allocation:
- * if there is a reservation window, only try to allocate block(s) from the
- * file's own reservation window;
- * Otherwise, the allocation range starts from the give goal block, ends at
- * the block group's last block.
- *
- * 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
- * ext4_journal_release_buffer(), else we'll run out of credits.
- */
-static ext4_grpblk_t
-ext4_try_to_allocate(struct super_block *sb, handle_t *handle,
- ext4_group_t group, struct buffer_head *bitmap_bh,
- ext4_grpblk_t grp_goal, unsigned long *count,
- struct ext4_reserve_window *my_rsv)
-{
- ext4_fsblk_t group_first_block;
- ext4_grpblk_t start, end;
- unsigned long num = 0;
-
- /* we do allocation within the reservation window if we have a window */
- if (my_rsv) {
- group_first_block = ext4_group_first_block_no(sb, group);
- 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 > EXT4_BLOCKS_PER_GROUP(sb))
- /* reservation window crosses group boundary */
- end = EXT4_BLOCKS_PER_GROUP(sb);
- if ((start <= grp_goal) && (grp_goal < end))
- start = grp_goal;
- else
- grp_goal = -1;
- } else {
- if (grp_goal > 0)
- start = grp_goal;
- else
- start = 0;
- end = EXT4_BLOCKS_PER_GROUP(sb);
- }
-
- BUG_ON(start > EXT4_BLOCKS_PER_GROUP(sb));
-
-repeat:
- if (grp_goal < 0 || !ext4_test_allocatable(grp_goal, bitmap_bh)) {
- grp_goal = find_next_usable_block(start, bitmap_bh, end);
- if (grp_goal < 0)
- goto fail_access;
- if (!my_rsv) {
- int i;
-
- for (i = 0; i < 7 && grp_goal > start &&
- ext4_test_allocatable(grp_goal - 1,
- bitmap_bh);
- i++, grp_goal--)
- ;
- }
- }
- start = grp_goal;
-
- if (!claim_block(sb_bgl_lock(EXT4_SB(sb), group),
- grp_goal, bitmap_bh)) {
- /*
- * The block was allocated by another thread, or it was
- * allocated and then freed by another thread
- */
- start++;
- grp_goal++;
- if (start >= end)
- goto fail_access;
- goto repeat;
- }
- num++;
- grp_goal++;
- while (num < *count && grp_goal < end
- && ext4_test_allocatable(grp_goal, bitmap_bh)
- && claim_block(sb_bgl_lock(EXT4_SB(sb), group),
- grp_goal, bitmap_bh)) {
- num++;
- grp_goal++;
- }
- *count = num;
- return grp_goal - num;
-fail_access:
- *count = num;
- 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 ext4_reserve_window_node *search_head,
- struct ext4_reserve_window_node *my_rsv,
- struct super_block * sb,
- ext4_fsblk_t start_block,
- ext4_fsblk_t last_block)
-{
- struct rb_node *next;
- struct ext4_reserve_window_node *rsv, *prev;
- ext4_fsblk_t 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 = rb_entry(next,struct ext4_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)
- ext4_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
- *
- * @grp_goal: The goal (group-relative). It is where the search for a
- * free reservable space should start from.
- * if we have a grp_goal(grp_goal >0 ), then start from there,
- * no grp_goal(grp_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