diff options
Diffstat (limited to 'fs/ocfs2/extent_map.c')
| -rw-r--r-- | fs/ocfs2/extent_map.c | 255 |
1 files changed, 255 insertions, 0 deletions
diff --git a/fs/ocfs2/extent_map.c b/fs/ocfs2/extent_map.c index f35e04f27f3..ba2b2ab1c6e 100644 --- a/fs/ocfs2/extent_map.c +++ b/fs/ocfs2/extent_map.c @@ -39,6 +39,254 @@ #include "buffer_head_io.h" /* + * The extent caching implementation is intentionally trivial. + * + * We only cache a small number of extents stored directly on the + * inode, so linear order operations are acceptable. If we ever want + * to increase the size of the extent map, then these algorithms must + * get smarter. + */ + +void ocfs2_extent_map_init(struct inode *inode) +{ + struct ocfs2_inode_info *oi = OCFS2_I(inode); + + oi->ip_extent_map.em_num_items = 0; + INIT_LIST_HEAD(&oi->ip_extent_map.em_list); +} + +static void __ocfs2_extent_map_lookup(struct ocfs2_extent_map *em, + unsigned int cpos, + struct ocfs2_extent_map_item **ret_emi) +{ + unsigned int range; + struct ocfs2_extent_map_item *emi; + + *ret_emi = NULL; + + list_for_each_entry(emi, &em->em_list, ei_list) { + range = emi->ei_cpos + emi->ei_clusters; + + if (cpos >= emi->ei_cpos && cpos < range) { + list_move(&emi->ei_list, &em->em_list); + + *ret_emi = emi; + break; + } + } +} + +static int ocfs2_extent_map_lookup(struct inode *inode, unsigned int cpos, + unsigned int *phys, unsigned int *len, + unsigned int *flags) +{ + unsigned int coff; + struct ocfs2_inode_info *oi = OCFS2_I(inode); + struct ocfs2_extent_map_item *emi; + + spin_lock(&oi->ip_lock); + + __ocfs2_extent_map_lookup(&oi->ip_extent_map, cpos, &emi); + if (emi) { + coff = cpos - emi->ei_cpos; + *phys = emi->ei_phys + coff; + if (len) + *len = emi->ei_clusters - coff; + if (flags) + *flags = emi->ei_flags; + } + + spin_unlock(&oi->ip_lock); + + if (emi == NULL) + return -ENOENT; + + return 0; +} + +/* + * Forget about all clusters equal to or greater than cpos. + */ +void ocfs2_extent_map_trunc(struct inode *inode, unsigned int cpos) +{ + struct list_head *p, *n; + struct ocfs2_extent_map_item *emi; + struct ocfs2_inode_info *oi = OCFS2_I(inode); + struct ocfs2_extent_map *em = &oi->ip_extent_map; + LIST_HEAD(tmp_list); + unsigned int range; + + spin_lock(&oi->ip_lock); + list_for_each_safe(p, n, &em->em_list) { + emi = list_entry(p, struct ocfs2_extent_map_item, ei_list); + + if (emi->ei_cpos >= cpos) { + /* Full truncate of this record. */ + list_move(&emi->ei_list, &tmp_list); + BUG_ON(em->em_num_items == 0); + em->em_num_items--; + continue; + } + + range = emi->ei_cpos + emi->ei_clusters; + if (range > cpos) { + /* Partial truncate */ + emi->ei_clusters = cpos - emi->ei_cpos; + } + } + spin_unlock(&oi->ip_lock); + + list_for_each_safe(p, n, &tmp_list) { + emi = list_entry(p, struct ocfs2_extent_map_item, ei_list); + list_del(&emi->ei_list); + kfree(emi); + } +} + +/* + * Is any part of emi2 contained within emi1 + */ +static int ocfs2_ei_is_contained(struct ocfs2_extent_map_item *emi1, + struct ocfs2_extent_map_item *emi2) +{ + unsigned int range1, range2; + + /* + * Check if logical start of emi2 is inside emi1 + */ + range1 = emi1->ei_cpos + emi1->ei_clusters; + if (emi2->ei_cpos >= emi1->ei_cpos && emi2->ei_cpos < range1) + return 1; + + /* + * Check if logical end of emi2 is inside emi1 + */ + range2 = emi2->ei_cpos + emi2->ei_clusters; + if (range2 > emi1->ei_cpos && range2 <= range1) + return 1; + + return 0; +} + +static void ocfs2_copy_emi_fields(struct ocfs2_extent_map_item *dest, + struct ocfs2_extent_map_item *src) +{ + dest->ei_cpos = src->ei_cpos; + dest->ei_phys = src->ei_phys; + dest->ei_clusters = src->ei_clusters; + dest->ei_flags = src->ei_flags; +} + +/* + * Try to merge emi with ins. Returns 1 if merge succeeds, zero + * otherwise. + */ +static int ocfs2_try_to_merge_extent_map(struct ocfs2_extent_map_item *emi, + struct ocfs2_extent_map_item *ins) +{ + /* + * Handle contiguousness + */ + if (ins->ei_phys == (emi->ei_phys + emi->ei_clusters) && + ins->ei_cpos == (emi->ei_cpos + emi->ei_clusters) && + ins->ei_flags == emi->ei_flags) { + emi->ei_clusters += ins->ei_clusters; + return 1; + } else if ((ins->ei_phys + ins->ei_clusters) == emi->ei_phys && + (ins->ei_cpos + ins->ei_clusters) == emi->ei_phys && + ins->ei_flags == emi->ei_flags) { + emi->ei_phys = ins->ei_phys; + emi->ei_cpos = ins->ei_cpos; + emi->ei_clusters += ins->ei_clusters; + return 1; + } + + /* + * Overlapping extents - this shouldn't happen unless we've + * split an extent to change it's flags. That is exceedingly + * rare, so there's no sense in trying to optimize it yet. + */ + if (ocfs2_ei_is_contained(emi, ins) || + ocfs2_ei_is_contained(ins, emi)) { + ocfs2_copy_emi_fields(emi, ins); + return 1; + } + + /* No merge was possible. */ + return 0; +} + +/* + * In order to reduce complexity on the caller, this insert function + * is intentionally liberal in what it will accept. + * + * The only rule is that the truncate call *must* be used whenever + * records have been deleted. This avoids inserting overlapping + * records with different physical mappings. + */ +void ocfs2_extent_map_insert_rec(struct inode *inode, + struct ocfs2_extent_rec *rec) +{ + struct ocfs2_inode_info *oi = OCFS2_I(inode); + struct ocfs2_extent_map *em = &oi->ip_extent_map; + struct ocfs2_extent_map_item *emi, *new_emi = NULL; + struct ocfs2_extent_map_item ins; + + ins.ei_cpos = le32_to_cpu(rec->e_cpos); + ins.ei_phys = ocfs2_blocks_to_clusters(inode->i_sb, + le64_to_cpu(rec->e_blkno)); + ins.ei_clusters = le16_to_cpu(rec->e_leaf_clusters); + ins.ei_flags = rec->e_flags; + +search: + spin_lock(&oi->ip_lock); + + list_for_each_entry(emi, &em->em_list, ei_list) { + if (ocfs2_try_to_merge_extent_map(emi, &ins)) { + list_move(&emi->ei_list, &em->em_list); + spin_unlock(&oi->ip_lock); + goto out; + } + } + + /* + * No item could be merged. + * + * Either allocate and add a new item, or overwrite the last recently + * inserted. + */ + + if (em->em_num_items < OCFS2_MAX_EXTENT_MAP_ITEMS) { + if (new_emi == NULL) { + spin_unlock(&oi->ip_lock); + + new_emi = kmalloc(sizeof(*new_emi), GFP_NOFS); + if (new_emi == NULL) + goto out; + + goto search; + } + + ocfs2_copy_emi_fields(new_emi, &ins); + list_add(&new_emi->ei_list, &em->em_list); + em->em_num_items++; + new_emi = NULL; + } else { + BUG_ON(list_empty(&em->em_list) || em->em_num_items == 0); + emi = list_entry(em->em_list.prev, + struct ocfs2_extent_map_item, ei_list); + list_move(&emi->ei_list, &em->em_list); + ocfs2_copy_emi_fields(emi, &ins); + } + + spin_unlock(&oi->ip_lock); + +out: + if (new_emi) + kfree(new_emi); +} + +/* * Return the 1st index within el which contains an extent start * larger than v_cluster. */ @@ -174,6 +422,11 @@ int ocfs2_get_clusters(struct inode *inode, u32 v_cluster, struct ocfs2_extent_rec *rec; u32 coff; + ret = ocfs2_extent_map_lookup(inode, v_cluster, p_cluster, + num_clusters, extent_flags); + if (ret == 0) + goto out; + ret = ocfs2_read_block(OCFS2_SB(inode->i_sb), OCFS2_I(inode)->ip_blkno, &di_bh, OCFS2_BH_CACHED, inode); if (ret) { @@ -245,6 +498,8 @@ int ocfs2_get_clusters(struct inode *inode, u32 v_cluster, *num_clusters = ocfs2_rec_clusters(el, rec) - coff; flags = rec->e_flags; + + ocfs2_extent_map_insert_rec(inode, rec); } if (extent_flags) |