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:
 "Miscellaneous ext4 bug fixes for v5.12"

* tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: initialize ret to suppress smatch warning
  ext4: stop inode update before return
  ext4: fix rename whiteout with fast commit
  ext4: fix timer use-after-free on failed mount
  ext4: fix potential error in ext4_do_update_inode
  ext4: do not try to set xattr into ea_inode if value is empty
  ext4: do not iput inode under running transaction in ext4_rename()
  ext4: find old entry again if failed to rename whiteout
  ext4: fix error handling in ext4_end_enable_verity()
  ext4: fix bh ref count on error paths
  fs/ext4: fix integer overflow in s_log_groups_per_flex
  ext4: add reclaim checks to xattr code
  ext4: shrink race window in ext4_should_retry_alloc()

1 files changed, 26 insertions, 12 deletions

diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index f45f9feebe59..74a5172c2d83 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -626,27 +626,41 @@ int ext4_claim_free_clusters(struct ext4_sb_info *sbi,
 
 /**
  * ext4_should_retry_alloc() - check if a block allocation should be retried
- * @sb:			super block
- * @retries:		number of attemps has been made
+ * @sb:			superblock
+ * @retries:		number of retry attempts made so far
  *
- * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
- * it is profitable to retry the operation, this function will wait
- * for the current or committing transaction to complete, and then
- * return TRUE.  We will only retry once.
+ * ext4_should_retry_alloc() is called when ENOSPC is returned while
+ * attempting to allocate blocks.  If there's an indication that a pending
+ * journal transaction might free some space and allow another attempt to
+ * succeed, this function will wait for the current or committing transaction
+ * to complete and then return TRUE.
  */
 int ext4_should_retry_alloc(struct super_block *sb, int *retries)
 {
-	if (!ext4_has_free_clusters(EXT4_SB(sb), 1, 0) ||
-	    (*retries)++ > 1 ||
-	    !EXT4_SB(sb)->s_journal)
+	struct ext4_sb_info *sbi = EXT4_SB(sb);
+
+	if (!sbi->s_journal)
 		return 0;
 
-	smp_mb();
-	if (EXT4_SB(sb)->s_mb_free_pending == 0)
+	if (++(*retries) > 3) {
+		percpu_counter_inc(&sbi->s_sra_exceeded_retry_limit);
 		return 0;
+	}
 
+	/*
+	 * if there's no indication that blocks are about to be freed it's
+	 * possible we just missed a transaction commit that did so
+	 */
+	smp_mb();
+	if (sbi->s_mb_free_pending == 0)
+		return ext4_has_free_clusters(sbi, 1, 0);
+
+	/*
+	 * it's possible we've just missed a transaction commit here,
+	 * so ignore the returned status
+	 */
 	jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
-	jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
+	(void) jbd2_journal_force_commit_nested(sbi->s_journal);
 	return 1;
 }