/** * nilfs_palloc_desc_blkoff - get block offset of a group descriptor block * @inode: inode of metadata file using this allocator * @group: group number * * nilfs_palloc_desc_blkoff() returns block offset of the descriptor * block which contains a descriptor of the specified group. */ static unsigned long nilfs_palloc_desc_blkoff(const struct inode *inode, unsigned long group) { unsigned long desc_block = group / nilfs_palloc_groups_per_desc_block(inode); return desc_block * NILFS_MDT(inode)->mi_blocks_per_desc_block; }
/** * nilfs_palloc_init_blockgroup - initialize private variables for allocator * @inode: inode of metadata file using this allocator * @entry_size: size of the persistent object */ int nilfs_palloc_init_blockgroup(struct inode *inode, unsigned int entry_size) { struct nilfs_mdt_info *mi = NILFS_MDT(inode); mi->mi_bgl = kmalloc(sizeof(*mi->mi_bgl), GFP_NOFS); if (!mi->mi_bgl) return -ENOMEM; bgl_lock_init(mi->mi_bgl); nilfs_mdt_set_entry_size(inode, entry_size, 0); mi->mi_blocks_per_group = DIV_ROUND_UP(nilfs_palloc_entries_per_group(inode), mi->mi_entries_per_block) + 1; /* * Number of blocks in a group including entry blocks * and a bitmap block */ mi->mi_blocks_per_desc_block = nilfs_palloc_groups_per_desc_block(inode) * mi->mi_blocks_per_group + 1; /* * Number of blocks per descriptor including the * descriptor block */ return 0; }
/** * nilfs_palloc_block_get_group_desc - get kernel address of a group descriptor * @inode: inode of metadata file using this allocator * @group: group number * @bh: buffer head of the buffer storing the group descriptor block * @kaddr: kernel address mapped for the page including the buffer */ static struct nilfs_palloc_group_desc * nilfs_palloc_block_get_group_desc(const struct inode *inode, unsigned long group, const struct buffer_head *bh, void *kaddr) { return (struct nilfs_palloc_group_desc *)(kaddr + bh_offset(bh)) + group % nilfs_palloc_groups_per_desc_block(inode); }
/** * nilfs_palloc_bitmap_blkoff - get block offset of a bitmap block * @inode: inode of metadata file using this allocator * @group: group number * * nilfs_palloc_bitmap_blkoff() returns block offset of the bitmap * block used to allocate/deallocate entries in the specified group. */ static unsigned long nilfs_palloc_bitmap_blkoff(const struct inode *inode, unsigned long group) { unsigned long desc_offset = group % nilfs_palloc_groups_per_desc_block(inode); return nilfs_palloc_desc_blkoff(inode, group) + 1 + desc_offset * NILFS_MDT(inode)->mi_blocks_per_group; }
/** * nilfs_palloc_rest_groups_in_desc_block - get the remaining number of groups * in a group descriptor block * @inode: inode of metadata file using this allocator * @curr: current group number * @max: maximum number of groups */ static unsigned long nilfs_palloc_rest_groups_in_desc_block(const struct inode *inode, unsigned long curr, unsigned long max) { return min_t(unsigned long, nilfs_palloc_groups_per_desc_block(inode) - curr % nilfs_palloc_groups_per_desc_block(inode), max - curr + 1); }
/** * nilfs_palloc_desc_block_init - initialize buffer of a group descriptor block * @inode: inode of metadata file * @bh: buffer head of the buffer to be initialized * @kaddr: kernel address mapped for the page including the buffer */ static void nilfs_palloc_desc_block_init(struct inode *inode, struct buffer_head *bh, void *kaddr) { struct nilfs_palloc_group_desc *desc = kaddr + bh_offset(bh); unsigned long n = nilfs_palloc_groups_per_desc_block(inode); __le32 nfrees; nfrees = cpu_to_le32(nilfs_palloc_entries_per_group(inode)); while (n-- > 0) { desc->pg_nfrees = nfrees; desc++; } }
/** * nilfs_palloc_count_max_entries - count max number of entries that can be * described by descriptor blocks count * @inode: inode of metadata file using this allocator * @nused: current number of used entries * @nmaxp: max number of entries [out] */ int nilfs_palloc_count_max_entries(struct inode *inode, u64 nused, u64 *nmaxp) { unsigned long desc_blocks = 0; u64 entries_per_desc_block, nmax; int err; err = nilfs_palloc_count_desc_blocks(inode, &desc_blocks); if (unlikely(err)) return err; entries_per_desc_block = (u64)nilfs_palloc_entries_per_group(inode) * nilfs_palloc_groups_per_desc_block(inode); nmax = entries_per_desc_block * desc_blocks; if (nused == nmax && nilfs_palloc_mdt_file_can_grow(inode, desc_blocks)) nmax += entries_per_desc_block; if (nused > nmax) return -ERANGE; *nmaxp = nmax; return 0; }
/** * nilfs_palloc_mdt_file_can_grow - check potential opportunity for * MDT file growing * @inode: inode of metadata file using this allocator * @desc_blocks: known current descriptor blocks count */ static inline bool nilfs_palloc_mdt_file_can_grow(struct inode *inode, unsigned long desc_blocks) { return (nilfs_palloc_groups_per_desc_block(inode) * desc_blocks) < nilfs_palloc_groups_count(inode); }
/** * nilfs_palloc_prepare_alloc_entry - prepare to allocate a persistent object * @inode: inode of metadata file using this allocator * @req: nilfs_palloc_req structure exchanged for the allocation */ int nilfs_palloc_prepare_alloc_entry(struct inode *inode, struct nilfs_palloc_req *req) { struct buffer_head *desc_bh, *bitmap_bh; struct nilfs_palloc_group_desc *desc; unsigned char *bitmap; void *desc_kaddr, *bitmap_kaddr; unsigned long group, maxgroup, ngroups; unsigned long group_offset, maxgroup_offset; unsigned long n, entries_per_group, groups_per_desc_block; unsigned long i, j; int pos, ret; ngroups = nilfs_palloc_groups_count(inode); maxgroup = ngroups - 1; group = nilfs_palloc_group(inode, req->pr_entry_nr, &group_offset); entries_per_group = nilfs_palloc_entries_per_group(inode); groups_per_desc_block = nilfs_palloc_groups_per_desc_block(inode); for (i = 0; i < ngroups; i += n) { if (group >= ngroups) { /* wrap around */ group = 0; maxgroup = nilfs_palloc_group(inode, req->pr_entry_nr, &maxgroup_offset) - 1; } ret = nilfs_palloc_get_desc_block(inode, group, 1, &desc_bh); if (ret < 0) return ret; desc_kaddr = kmap(desc_bh->b_page); desc = nilfs_palloc_block_get_group_desc( inode, group, desc_bh, desc_kaddr); n = nilfs_palloc_rest_groups_in_desc_block(inode, group, maxgroup); for (j = 0; j < n; j++, desc++, group++) { if (nilfs_palloc_group_desc_nfrees(inode, group, desc) > 0) { ret = nilfs_palloc_get_bitmap_block( inode, group, 1, &bitmap_bh); if (ret < 0) goto out_desc; bitmap_kaddr = kmap(bitmap_bh->b_page); bitmap = bitmap_kaddr + bh_offset(bitmap_bh); pos = nilfs_palloc_find_available_slot( inode, group, group_offset, bitmap, entries_per_group); if (pos >= 0) { /* found a free entry */ nilfs_palloc_group_desc_add_entries( inode, group, desc, -1); req->pr_entry_nr = entries_per_group * group + pos; kunmap(desc_bh->b_page); kunmap(bitmap_bh->b_page); req->pr_desc_bh = desc_bh; req->pr_bitmap_bh = bitmap_bh; return 0; } kunmap(bitmap_bh->b_page); brelse(bitmap_bh); } group_offset = 0; } kunmap(desc_bh->b_page); brelse(desc_bh); } /* no entries left */ return -ENOSPC; out_desc: kunmap(desc_bh->b_page); brelse(desc_bh); return ret; }