1 files changed, 24 insertions, 15 deletions

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index 7f390849343b..c4444d6f439f 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -1024,6 +1024,7 @@ int btrfs_decompress_buf2page(char *buf, unsigned long buf_start,
         unsigned long buf_offset;
         unsigned long current_buf_start;
         unsigned long start_byte;
+        unsigned long prev_start_byte;
         unsigned long working_bytes = total_out - buf_start;
         unsigned long bytes;
         char *kaddr;
@@ -1071,26 +1072,34 @@ int btrfs_decompress_buf2page(char *buf, unsigned long buf_start,
                 if (!bio->bi_iter.bi_size)
                         return 0;
                 bvec = bio_iter_iovec(bio, bio->bi_iter);
-
+                prev_start_byte = start_byte;
                 start_byte = page_offset(bvec.bv_page) - disk_start;
 
                 /*
-                 * make sure our new page is covered by this
-                 * working buffer
+                 * We need to make sure we're only adjusting
+                 * our offset into compression working buffer when
+                 * we're switching pages.  Otherwise we can incorrectly
+                 * keep copying when we were actually done.
                  */
-                if (total_out <= start_byte)
-                        return 1;
+                if (start_byte != prev_start_byte) {
+                        /*
+                         * make sure our new page is covered by this
+                         * working buffer
+                         */
+                        if (total_out <= start_byte)
+                                return 1;
 
-                /*
-                 * the next page in the biovec might not be adjacent
-                 * to the last page, but it might still be found
-                 * inside this working buffer. bump our offset pointer
-                 */
-                if (total_out > start_byte &&
-                    current_buf_start < start_byte) {
-                        buf_offset = start_byte - buf_start;
-                        working_bytes = total_out - start_byte;
-                        current_buf_start = buf_start + buf_offset;
+                        /*
+                         * the next page in the biovec might not be adjacent
+                         * to the last page, but it might still be found
+                         * inside this working buffer. bump our offset pointer
+                         */
+                        if (total_out > start_byte &&
+                            current_buf_start < start_byte) {
+                                buf_offset = start_byte - buf_start;
+                                working_bytes = total_out - start_byte;
+                                current_buf_start = buf_start + buf_offset;
+                        }
                 }
         }