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>

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index ff6bbfd75cf7b4f0788fd5380b35461ea54615f3..f96641a93fc9c3b65da812caa2e08620b16f2f67 100644 (file)
--- 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;