Merge tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

Pull ext4 fixes from Ted Ts'o:
 "Fix a variety of bugs, many of which were found by folks using fuzzing
  or error injection.

  Also fix up how test_dummy_encryption mount option is handled for the
  new mount API.

  Finally, fix/cleanup a number of comments and ext4 Documentation
  files"

* tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: fix a doubled word "need" in a comment
  ext4: add reserved GDT blocks check
  ext4: make variable "count" signed
  ext4: correct the judgment of BUG in ext4_mb_normalize_request
  ext4: fix bug_on ext4_mb_use_inode_pa
  ext4: fix up test_dummy_encryption handling for new mount API
  ext4: use kmemdup() to replace kmalloc + memcpy
  ext4: fix super block checksum incorrect after mount
  ext4: improve write performance with disabled delalloc
  ext4: fix warning when submitting superblock in ext4_commit_super()
  ext4, doc: remove unnecessary escaping
  ext4: fix incorrect comment in ext4_bio_write_page()
  fs: fix jbd2_journal_try_to_free_buffers() kernel-doc comment

1 files changed, 25 insertions, 1 deletions

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 9f12f29bc346..9e06334771a3 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4104,6 +4104,15 @@ ext4_mb_normalize_request(struct ext4_allocation_context *ac,
 	size = size >> bsbits;
 	start = start_off >> bsbits;
 
+	/*
+	 * For tiny groups (smaller than 8MB) the chosen allocation
+	 * alignment may be larger than group size. Make sure the
+	 * alignment does not move allocation to a different group which
+	 * makes mballoc fail assertions later.
+	 */
+	start = max(start, rounddown(ac->ac_o_ex.fe_logical,
+			(ext4_lblk_t)EXT4_BLOCKS_PER_GROUP(ac->ac_sb)));
+
 	/* don't cover already allocated blocks in selected range */
 	if (ar->pleft && start <= ar->lleft) {
 		size -= ar->lleft + 1 - start;
@@ -4176,7 +4185,22 @@ ext4_mb_normalize_request(struct ext4_allocation_context *ac,
 	}
 	rcu_read_unlock();
 
-	if (start + size <= ac->ac_o_ex.fe_logical &&
+	/*
+	 * In this function "start" and "size" are normalized for better
+	 * alignment and length such that we could preallocate more blocks.
+	 * This normalization is done such that original request of
+	 * ac->ac_o_ex.fe_logical & fe_len should always lie within "start" and
+	 * "size" boundaries.
+	 * (Note fe_len can be relaxed since FS block allocation API does not
+	 * provide gurantee on number of contiguous blocks allocation since that
+	 * depends upon free space left, etc).
+	 * In case of inode pa, later we use the allocated blocks
+	 * [pa_start + fe_logical - pa_lstart, fe_len/size] from the preallocated
+	 * range of goal/best blocks [start, size] to put it at the
+	 * ac_o_ex.fe_logical extent of this inode.
+	 * (See ext4_mb_use_inode_pa() for more details)
+	 */
+	if (start + size <= ac->ac_o_ex.fe_logical ||
 			start > ac->ac_o_ex.fe_logical) {
 		ext4_msg(ac->ac_sb, KERN_ERR,
 			 "start %lu, size %lu, fe_logical %lu",