1 files changed, 14 insertions, 0 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 5792816d4fca..9b43a6f303b8 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -360,6 +360,19 @@ again:
         nr_pages = (end >> PAGE_CACHE_SHIFT) - (start >> PAGE_CACHE_SHIFT) + 1;
         nr_pages = min(nr_pages, (128 * 1024UL) / PAGE_CACHE_SIZE);
 
+        /*
+         * we don't want to send crud past the end of i_size through
+         * compression, that's just a waste of CPU time.  So, if the
+         * end of the file is before the start of our current
+         * requested range of bytes, we bail out to the uncompressed
+         * cleanup code that can deal with all of this.
+         *
+         * It isn't really the fastest way to fix things, but this is a
+         * very uncommon corner.
+         */
+        if (actual_end <= start)
+                goto cleanup_and_bail_uncompressed;
+
         total_compressed = actual_end - start;
 
         /* we want to make sure that amount of ram required to uncompress
@@ -504,6 +517,7 @@ again:
                         goto again;
                 }
         } else {
+cleanup_and_bail_uncompressed:
                 /*
                  * No compression, but we still need to write the pages in
                  * the file we've been given so far.  redirty the locked