Btrfs: make shrink_delalloc a little friendlier

Xfstests 224 will just sit there and spin for ever until eventually we give up
flushing delalloc and exit.  On my box this took several hours.  I could not
interrupt this process either, even though we use INTERRUPTIBLE.  So do 2 things

1) Keep us from looping over and over again without reclaiming anything
2) If we get interrupted exit the loop

I tested this and the test now exits in a reasonable amount of time, and can be
interrupted with ctrl+c.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 14 insertions, 3 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index ff6bbfd75cf7..f96641a93fc9 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3345,8 +3345,10 @@ static int shrink_delalloc(struct btrfs_trans_handle *trans,
         u64 reserved;
         u64 max_reclaim;
         u64 reclaimed = 0;
+        long time_left;
         int pause = 1;
         int nr_pages = (2 * 1024 * 1024) >> PAGE_CACHE_SHIFT;
+        int loops = 0;
 
         block_rsv = &root->fs_info->delalloc_block_rsv;
         space_info = block_rsv->space_info;
@@ -3359,7 +3361,7 @@ static int shrink_delalloc(struct btrfs_trans_handle *trans,
 
         max_reclaim = min(reserved, to_reclaim);
 
-        while (1) {
+        while (loops < 1024) {
                 /* have the flusher threads jump in and do some IO */
                 smp_mb();
                 nr_pages = min_t(unsigned long, nr_pages,
@@ -3367,8 +3369,12 @@ static int shrink_delalloc(struct btrfs_trans_handle *trans,
                 writeback_inodes_sb_nr_if_idle(root->fs_info->sb, nr_pages);
 
                 spin_lock(&space_info->lock);
-                if (reserved > space_info->bytes_reserved)
+                if (reserved > space_info->bytes_reserved) {
+                        loops = 0;
                         reclaimed += reserved - space_info->bytes_reserved;
+                } else {
+                        loops++;
+                }
                 reserved = space_info->bytes_reserved;
                 spin_unlock(&space_info->lock);
 
@@ -3379,7 +3385,12 @@ static int shrink_delalloc(struct btrfs_trans_handle *trans,
                         return -EAGAIN;
 
                 __set_current_state(TASK_INTERRUPTIBLE);
-                schedule_timeout(pause);
+                time_left = schedule_timeout(pause);
+
+                /* We were interrupted, exit */
+                if (time_left)
+                        break;
+
                 pause <<= 1;
                 if (pause > HZ / 10)
                         pause = HZ / 10;