ext4: remove blocks from inode prealloc list on failure

(cherry picked from commit b844167edc7fcafda9623955c05e4c1b3c32ebc7)

This fixes a leak of blocks in an inode prealloc list if device failures
cause ext4_mb_mark_diskspace_used() to fail.

Signed-off-by: Curt Wohlgemuth <curtw@google.com>
Acked-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 6e5a23a2cc25e88c61d17e4e8e4fe9f36b91626d..7d7114818f8dfe7ec709cd1ac124eccc34ffbc6b 100644 (file)
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -3010,6 +3010,24 @@ static void ext4_mb_collect_stats(struct ext4_allocation_context *ac)
                trace_ext4_mballoc_prealloc(ac);
 }
 
+/*
+ * Called on failure; free up any blocks from the inode PA for this
+ * context.  We don't need this for MB_GROUP_PA because we only change
+ * pa_free in ext4_mb_release_context(), but on failure, we've already
+ * zeroed out ac->ac_b_ex.fe_len, so group_pa->pa_free is not changed.
+ */
+static void ext4_discard_allocated_blocks(struct ext4_allocation_context *ac)
+{
+       struct ext4_prealloc_space *pa = ac->ac_pa;
+       int len;
+
+       if (pa && pa->pa_type == MB_INODE_PA) {
+               len = ac->ac_b_ex.fe_len;
+               pa->pa_free += len;
+       }
+
+}
+
 /*
  * use blocks preallocated to inode
  */
@@ -4295,6 +4313,7 @@ repeat:
                        ac->ac_status = AC_STATUS_CONTINUE;
                        goto repeat;
                } else if (*errp) {
+                       ext4_discard_allocated_blocks(ac);
                        ac->ac_b_ex.fe_len = 0;
                        ar->len = 0;
                        ext4_mb_show_ac(ac);