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@@ -38,6 +38,254 @@
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#include "buffer_head_io.h"
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+/*
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+ * The extent caching implementation is intentionally trivial.
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+ *
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+ * We only cache a small number of extents stored directly on the
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+ * inode, so linear order operations are acceptable. If we ever want
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+ * to increase the size of the extent map, then these algorithms must
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+ * get smarter.
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+ */
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+
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+void ocfs2_extent_map_init(struct inode *inode)
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+{
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+ struct ocfs2_inode_info *oi = OCFS2_I(inode);
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+
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+ oi->ip_extent_map.em_num_items = 0;
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+ INIT_LIST_HEAD(&oi->ip_extent_map.em_list);
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+}
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+
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+static void __ocfs2_extent_map_lookup(struct ocfs2_extent_map *em,
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+ unsigned int cpos,
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+ struct ocfs2_extent_map_item **ret_emi)
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+{
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+ unsigned int range;
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+ struct ocfs2_extent_map_item *emi;
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+
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+ *ret_emi = NULL;
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+
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+ list_for_each_entry(emi, &em->em_list, ei_list) {
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+ range = emi->ei_cpos + emi->ei_clusters;
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+
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+ if (cpos >= emi->ei_cpos && cpos < range) {
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+ list_move(&emi->ei_list, &em->em_list);
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+
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+ *ret_emi = emi;
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+ break;
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+ }
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+ }
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+}
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+
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+static int ocfs2_extent_map_lookup(struct inode *inode, unsigned int cpos,
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+ unsigned int *phys, unsigned int *len,
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+ unsigned int *flags)
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+{
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+ unsigned int coff;
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+ struct ocfs2_inode_info *oi = OCFS2_I(inode);
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+ struct ocfs2_extent_map_item *emi;
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+
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+ spin_lock(&oi->ip_lock);
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+
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+ __ocfs2_extent_map_lookup(&oi->ip_extent_map, cpos, &emi);
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+ if (emi) {
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+ coff = cpos - emi->ei_cpos;
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+ *phys = emi->ei_phys + coff;
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+ if (len)
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+ *len = emi->ei_clusters - coff;
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+ if (flags)
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+ *flags = emi->ei_flags;
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+ }
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+
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+ spin_unlock(&oi->ip_lock);
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+
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+ if (emi == NULL)
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+ return -ENOENT;
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+
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+ return 0;
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+}
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+
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+/*
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+ * Forget about all clusters equal to or greater than cpos.
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+ */
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+void ocfs2_extent_map_trunc(struct inode *inode, unsigned int cpos)
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+{
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+ struct list_head *p, *n;
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+ struct ocfs2_extent_map_item *emi;
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+ struct ocfs2_inode_info *oi = OCFS2_I(inode);
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+ struct ocfs2_extent_map *em = &oi->ip_extent_map;
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+ LIST_HEAD(tmp_list);
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+ unsigned int range;
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+
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+ spin_lock(&oi->ip_lock);
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+ list_for_each_safe(p, n, &em->em_list) {
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+ emi = list_entry(p, struct ocfs2_extent_map_item, ei_list);
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+
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+ if (emi->ei_cpos >= cpos) {
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+ /* Full truncate of this record. */
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+ list_move(&emi->ei_list, &tmp_list);
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+ BUG_ON(em->em_num_items == 0);
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+ em->em_num_items--;
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+ continue;
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+ }
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+
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+ range = emi->ei_cpos + emi->ei_clusters;
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+ if (range > cpos) {
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+ /* Partial truncate */
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+ emi->ei_clusters = cpos - emi->ei_cpos;
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+ }
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+ }
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+ spin_unlock(&oi->ip_lock);
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+
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+ list_for_each_safe(p, n, &tmp_list) {
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+ emi = list_entry(p, struct ocfs2_extent_map_item, ei_list);
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+ list_del(&emi->ei_list);
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+ kfree(emi);
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+ }
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+}
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+
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+/*
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+ * Is any part of emi2 contained within emi1
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+ */
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+static int ocfs2_ei_is_contained(struct ocfs2_extent_map_item *emi1,
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+ struct ocfs2_extent_map_item *emi2)
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+{
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+ unsigned int range1, range2;
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+
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+ /*
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+ * Check if logical start of emi2 is inside emi1
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+ */
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+ range1 = emi1->ei_cpos + emi1->ei_clusters;
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+ if (emi2->ei_cpos >= emi1->ei_cpos && emi2->ei_cpos < range1)
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+ return 1;
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+
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+ /*
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+ * Check if logical end of emi2 is inside emi1
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+ */
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+ range2 = emi2->ei_cpos + emi2->ei_clusters;
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+ if (range2 > emi1->ei_cpos && range2 <= range1)
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+ return 1;
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+
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+ return 0;
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+}
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+
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+static void ocfs2_copy_emi_fields(struct ocfs2_extent_map_item *dest,
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+ struct ocfs2_extent_map_item *src)
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+{
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+ dest->ei_cpos = src->ei_cpos;
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+ dest->ei_phys = src->ei_phys;
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+ dest->ei_clusters = src->ei_clusters;
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+ dest->ei_flags = src->ei_flags;
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+}
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+
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+/*
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+ * Try to merge emi with ins. Returns 1 if merge succeeds, zero
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+ * otherwise.
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+ */
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+static int ocfs2_try_to_merge_extent_map(struct ocfs2_extent_map_item *emi,
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+ struct ocfs2_extent_map_item *ins)
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+{
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+ /*
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+ * Handle contiguousness
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+ */
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+ if (ins->ei_phys == (emi->ei_phys + emi->ei_clusters) &&
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+ ins->ei_cpos == (emi->ei_cpos + emi->ei_clusters) &&
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+ ins->ei_flags == emi->ei_flags) {
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+ emi->ei_clusters += ins->ei_clusters;
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+ return 1;
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+ } else if ((ins->ei_phys + ins->ei_clusters) == emi->ei_phys &&
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+ (ins->ei_cpos + ins->ei_clusters) == emi->ei_phys &&
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+ ins->ei_flags == emi->ei_flags) {
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+ emi->ei_phys = ins->ei_phys;
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+ emi->ei_cpos = ins->ei_cpos;
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+ emi->ei_clusters += ins->ei_clusters;
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+ return 1;
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+ }
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+
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+ /*
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+ * Overlapping extents - this shouldn't happen unless we've
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+ * split an extent to change it's flags. That is exceedingly
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+ * rare, so there's no sense in trying to optimize it yet.
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+ */
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+ if (ocfs2_ei_is_contained(emi, ins) ||
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+ ocfs2_ei_is_contained(ins, emi)) {
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+ ocfs2_copy_emi_fields(emi, ins);
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+ return 1;
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+ }
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+
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+ /* No merge was possible. */
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+ return 0;
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+}
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+
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+/*
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+ * In order to reduce complexity on the caller, this insert function
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+ * is intentionally liberal in what it will accept.
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+ *
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+ * The only rule is that the truncate call *must* be used whenever
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+ * records have been deleted. This avoids inserting overlapping
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+ * records with different physical mappings.
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+ */
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+void ocfs2_extent_map_insert_rec(struct inode *inode,
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+ struct ocfs2_extent_rec *rec)
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+{
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+ struct ocfs2_inode_info *oi = OCFS2_I(inode);
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+ struct ocfs2_extent_map *em = &oi->ip_extent_map;
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+ struct ocfs2_extent_map_item *emi, *new_emi = NULL;
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+ struct ocfs2_extent_map_item ins;
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+
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+ ins.ei_cpos = le32_to_cpu(rec->e_cpos);
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+ ins.ei_phys = ocfs2_blocks_to_clusters(inode->i_sb,
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+ le64_to_cpu(rec->e_blkno));
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+ ins.ei_clusters = le16_to_cpu(rec->e_leaf_clusters);
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+ ins.ei_flags = rec->e_flags;
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+
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+search:
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+ spin_lock(&oi->ip_lock);
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+
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+ list_for_each_entry(emi, &em->em_list, ei_list) {
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+ if (ocfs2_try_to_merge_extent_map(emi, &ins)) {
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+ list_move(&emi->ei_list, &em->em_list);
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+ spin_unlock(&oi->ip_lock);
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+ goto out;
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+ }
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+ }
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+
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+ /*
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+ * No item could be merged.
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+ *
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+ * Either allocate and add a new item, or overwrite the last recently
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+ * inserted.
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+ */
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+
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+ if (em->em_num_items < OCFS2_MAX_EXTENT_MAP_ITEMS) {
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+ if (new_emi == NULL) {
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+ spin_unlock(&oi->ip_lock);
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+
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+ new_emi = kmalloc(sizeof(*new_emi), GFP_NOFS);
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+ if (new_emi == NULL)
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+ goto out;
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+
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+ goto search;
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+ }
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+
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+ ocfs2_copy_emi_fields(new_emi, &ins);
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+ list_add(&new_emi->ei_list, &em->em_list);
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+ em->em_num_items++;
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+ new_emi = NULL;
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+ } else {
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+ BUG_ON(list_empty(&em->em_list) || em->em_num_items == 0);
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+ emi = list_entry(em->em_list.prev,
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+ struct ocfs2_extent_map_item, ei_list);
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+ list_move(&emi->ei_list, &em->em_list);
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+ ocfs2_copy_emi_fields(emi, &ins);
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+ }
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+
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+ spin_unlock(&oi->ip_lock);
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+
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+out:
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+ if (new_emi)
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+ kfree(new_emi);
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+}
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+
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/*
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* Return the 1st index within el which contains an extent start
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* larger than v_cluster.
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@@ -174,6 +422,11 @@ int ocfs2_get_clusters(struct inode *inode, u32 v_cluster,
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struct ocfs2_extent_rec *rec;
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u32 coff;
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+ ret = ocfs2_extent_map_lookup(inode, v_cluster, p_cluster,
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+ num_clusters, extent_flags);
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+ if (ret == 0)
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+ goto out;
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+
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ret = ocfs2_read_block(OCFS2_SB(inode->i_sb), OCFS2_I(inode)->ip_blkno,
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&di_bh, OCFS2_BH_CACHED, inode);
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if (ret) {
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@@ -245,6 +498,8 @@ int ocfs2_get_clusters(struct inode *inode, u32 v_cluster,
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*num_clusters = ocfs2_rec_clusters(el, rec) - coff;
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flags = rec->e_flags;
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+
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+ ocfs2_extent_map_insert_rec(inode, rec);
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}
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if (extent_flags)
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