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-rw-r--r--volumes.c143
1 files changed, 143 insertions, 0 deletions
diff --git a/volumes.c b/volumes.c
index 013bfd5..01127e7 100644
--- a/volumes.c
+++ b/volumes.c
@@ -1774,3 +1774,146 @@ struct list_head *btrfs_scanned_uuids(void)
{
return &fs_uuids;
}
+
+static int rmw_eb(struct btrfs_fs_info *info,
+ struct extent_buffer *eb, struct extent_buffer *orig_eb)
+{
+ int ret;
+ unsigned long orig_off = 0;
+ unsigned long dest_off = 0;
+ unsigned long copy_len = eb->len;
+
+ ret = read_whole_eb(info, eb, 0);
+ if (ret)
+ return ret;
+
+ if (eb->start + eb->len <= orig_eb->start ||
+ eb->start >= orig_eb->start + orig_eb->len)
+ return 0;
+ /*
+ * | ----- orig_eb ------- |
+ * | ----- stripe ------- |
+ * | ----- orig_eb ------- |
+ * | ----- orig_eb ------- |
+ */
+ if (eb->start > orig_eb->start)
+ orig_off = eb->start - orig_eb->start;
+ if (orig_eb->start > eb->start)
+ dest_off = orig_eb->start - eb->start;
+
+ if (copy_len > orig_eb->len - orig_off)
+ copy_len = orig_eb->len - orig_off;
+ if (copy_len > eb->len - dest_off)
+ copy_len = eb->len - dest_off;
+
+ memcpy(eb->data + dest_off, orig_eb->data + orig_off, copy_len);
+ return 0;
+}
+
+static void split_eb_for_raid56(struct btrfs_fs_info *info,
+ struct extent_buffer *orig_eb,
+ struct extent_buffer **ebs,
+ u64 stripe_len, u64 *raid_map,
+ int num_stripes)
+{
+ struct extent_buffer *eb;
+ u64 start = orig_eb->start;
+ u64 this_eb_start;
+ int i;
+ int ret;
+
+ for (i = 0; i < num_stripes; i++) {
+ if (raid_map[i] >= BTRFS_RAID5_P_STRIPE)
+ break;
+
+ eb = malloc(sizeof(struct extent_buffer) + stripe_len);
+ if (!eb)
+ BUG();
+ memset(eb, 0, sizeof(struct extent_buffer) + stripe_len);
+
+ eb->start = raid_map[i];
+ eb->len = stripe_len;
+ eb->refs = 1;
+ eb->flags = 0;
+ eb->fd = -1;
+ eb->dev_bytenr = (u64)-1;
+
+ this_eb_start = raid_map[i];
+
+ if (start > this_eb_start ||
+ start + orig_eb->len < this_eb_start + stripe_len) {
+ ret = rmw_eb(info, eb, orig_eb);
+ BUG_ON(ret);
+ } else {
+ memcpy(eb->data, orig_eb->data + eb->start - start, stripe_len);
+ }
+ ebs[i] = eb;
+ }
+}
+
+int write_raid56_with_parity(struct btrfs_fs_info *info,
+ struct extent_buffer *eb,
+ struct btrfs_multi_bio *multi,
+ u64 stripe_len, u64 *raid_map)
+{
+ struct extent_buffer *ebs[multi->num_stripes], *p_eb = NULL, *q_eb = NULL;
+ int i;
+ int j;
+ int ret;
+ int alloc_size = eb->len;
+
+ if (stripe_len > alloc_size)
+ alloc_size = stripe_len;
+
+ split_eb_for_raid56(info, eb, ebs, stripe_len, raid_map,
+ multi->num_stripes);
+
+ for (i = 0; i < multi->num_stripes; i++) {
+ struct extent_buffer *new_eb;
+ if (raid_map[i] < BTRFS_RAID5_P_STRIPE) {
+ ebs[i]->dev_bytenr = multi->stripes[i].physical;
+ ebs[i]->fd = multi->stripes[i].dev->fd;
+ multi->stripes[i].dev->total_ios++;
+ BUG_ON(ebs[i]->start != raid_map[i]);
+ continue;
+ }
+ new_eb = kmalloc(sizeof(*eb) + alloc_size, GFP_NOFS);
+ BUG_ON(!new_eb);
+ new_eb->dev_bytenr = multi->stripes[i].physical;
+ new_eb->fd = multi->stripes[i].dev->fd;
+ multi->stripes[i].dev->total_ios++;
+ new_eb->len = stripe_len;
+
+ if (raid_map[i] == BTRFS_RAID5_P_STRIPE)
+ p_eb = new_eb;
+ else if (raid_map[i] == BTRFS_RAID6_Q_STRIPE)
+ q_eb = new_eb;
+ }
+ if (q_eb) {
+ void *pointers[multi->num_stripes];
+ ebs[multi->num_stripes - 2] = p_eb;
+ ebs[multi->num_stripes - 1] = q_eb;
+
+ for (i = 0; i < multi->num_stripes; i++)
+ pointers[i] = ebs[i]->data;
+
+ raid6_gen_syndrome(multi->num_stripes, stripe_len, pointers);
+ } else {
+ ebs[multi->num_stripes - 1] = p_eb;
+ memcpy(p_eb->data, ebs[0]->data, stripe_len);
+ for (j = 1; j < multi->num_stripes - 1; j++) {
+ for (i = 0; i < stripe_len; i += sizeof(unsigned long)) {
+ *(unsigned long *)(p_eb->data + i) ^=
+ *(unsigned long *)(ebs[j]->data + i);
+ }
+ }
+ }
+
+ for (i = 0; i < multi->num_stripes; i++) {
+ ret = write_extent_to_disk(ebs[i]);
+ BUG_ON(ret);
+ if (ebs[i] != eb)
+ kfree(ebs[i]);
+ }
+ return 0;
+}