Btrfs: don't mix the ordered extents of all files together during logging the inodes

There was a problem in the old code:
If we failed to log the csum, we would free all the ordered extents in the log list
including those ordered extents that were logged successfully, it would make the
log committer not to wait for the completion of the ordered extents.

This patch doesn't insert the ordered extents that is about to be logged into
a global list, instead, we insert them into a local list. If we log the ordered
extents successfully, we splice them with the global list, or we will throw them
away, then do full sync. It can also reduce the lock contention and the traverse
time of list.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>

1 files changed, 15 insertions, 26 deletions

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 39d83da03e03..7c449c699bed 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -3479,7 +3479,8 @@ static int extent_cmp(void *priv, struct list_head *a, struct list_head *b)
 
 static int log_one_extent(struct btrfs_trans_handle *trans,
                           struct inode *inode, struct btrfs_root *root,
-                          struct extent_map *em, struct btrfs_path *path)
+                          struct extent_map *em, struct btrfs_path *path,
+                          struct list_head *logged_list)
 {
         struct btrfs_root *log = root->log_root;
         struct btrfs_file_extent_item *fi;
@@ -3495,7 +3496,6 @@ static int log_one_extent(struct btrfs_trans_handle *trans,
         u64 extent_offset = em->start - em->orig_start;
         u64 block_len;
         int ret;
-        int index = log->log_transid % 2;
         bool skip_csum = BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM;
         int extent_inserted = 0;
 
@@ -3579,17 +3579,12 @@ static int log_one_extent(struct btrfs_trans_handle *trans,
          * First check and see if our csums are on our outstanding ordered
          * extents.
          */
-again:
-        spin_lock_irq(&log->log_extents_lock[index]);
-        list_for_each_entry(ordered, &log->logged_list[index], log_list) {
+        list_for_each_entry(ordered, logged_list, log_list) {
                 struct btrfs_ordered_sum *sum;
 
                 if (!mod_len)
                         break;
 
-                if (ordered->inode != inode)
-                        continue;
-
                 if (ordered->file_offset + ordered->len <= mod_start ||
                     mod_start + mod_len <= ordered->file_offset)
                         continue;
@@ -3632,12 +3627,6 @@ again:
                 if (test_and_set_bit(BTRFS_ORDERED_LOGGED_CSUM,
                                      &ordered->flags))
                         continue;
-                atomic_inc(&ordered->refs);
-                spin_unlock_irq(&log->log_extents_lock[index]);
-                /*
-                 * we've dropped the lock, we must either break or
-                 * start over after this.
-                 */
 
                 if (ordered->csum_bytes_left) {
                         btrfs_start_ordered_extent(inode, ordered, 0);
@@ -3647,16 +3636,11 @@ again:
 
                 list_for_each_entry(sum, &ordered->list, list) {
                         ret = btrfs_csum_file_blocks(trans, log, sum);
-                        if (ret) {
-                                btrfs_put_ordered_extent(ordered);
+                        if (ret)
                                 goto unlocked;
-                        }
                 }
-                btrfs_put_ordered_extent(ordered);
-                goto again;
 
         }
-        spin_unlock_irq(&log->log_extents_lock[index]);
 unlocked:
 
         if (!mod_len || ret)
@@ -3694,7 +3678,8 @@ unlocked:
 static int btrfs_log_changed_extents(struct btrfs_trans_handle *trans,
                                      struct btrfs_root *root,
                                      struct inode *inode,
-                                     struct btrfs_path *path)
+                                     struct btrfs_path *path,
+                                     struct list_head *logged_list)
 {
         struct extent_map *em, *n;
         struct list_head extents;
@@ -3752,7 +3737,7 @@ process:
 
                 write_unlock(&tree->lock);
 
-                ret = log_one_extent(trans, inode, root, em, path);
+                ret = log_one_extent(trans, inode, root, em, path, logged_list);
                 write_lock(&tree->lock);
                 clear_em_logging(tree, em);
                 free_extent_map(em);
@@ -3788,6 +3773,7 @@ static int btrfs_log_inode(struct btrfs_trans_handle *trans,
         struct btrfs_key max_key;
         struct btrfs_root *log = root->log_root;
         struct extent_buffer *src = NULL;
+        LIST_HEAD(logged_list);
         u64 last_extent = 0;
         int err = 0;
         int ret;
@@ -3836,7 +3822,7 @@ static int btrfs_log_inode(struct btrfs_trans_handle *trans,
 
         mutex_lock(&BTRFS_I(inode)->log_mutex);
 
-        btrfs_get_logged_extents(log, inode);
+        btrfs_get_logged_extents(inode, &logged_list);
 
         /*
          * a brute force approach to making sure we get the most uptodate
@@ -3962,7 +3948,8 @@ log_extents:
         btrfs_release_path(path);
         btrfs_release_path(dst_path);
         if (fast_search) {
-                ret = btrfs_log_changed_extents(trans, root, inode, dst_path);
+                ret = btrfs_log_changed_extents(trans, root, inode, dst_path,
+                                                &logged_list);
                 if (ret) {
                         err = ret;
                         goto out_unlock;
@@ -3987,8 +3974,10 @@ log_extents:
         BTRFS_I(inode)->logged_trans = trans->transid;
         BTRFS_I(inode)->last_log_commit = BTRFS_I(inode)->last_sub_trans;
 out_unlock:
-        if (err)
-                btrfs_free_logged_extents(log, log->log_transid);
+        if (unlikely(err))
+                btrfs_put_logged_extents(&logged_list);
+        else
+                btrfs_submit_logged_extents(&logged_list, log);
         mutex_unlock(&BTRFS_I(inode)->log_mutex);
 
         btrfs_free_path(path);