Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

Pull ext4 updates from Ted Ts'o:
 "The first two changes involve files outside of fs/ext4:

   - submit_bh() can never return an error, so change it to return void,
     and remove the unused checks from its callers

   - fix I_DIRTY_TIME handling so it will be set even if the inode
     already has I_DIRTY_INODE

  Performance:

   - Always enable i_version counter (as btrfs and xfs already do).
     Remove some uneeded i_version bumps to avoid unnecessary nfs cache
     invalidations

   - Wake up journal waiters in FIFO order, to avoid some journal users
     from not getting a journal handle for an unfairly long time

   - In ext4_write_begin() allocate any necessary buffer heads before
     starting the journal handle

   - Don't try to prefetch the block allocation bitmaps for a read-only
     file system

  Bug Fixes:

   - Fix a number of fast commit bugs, including resources leaks and out
     of bound references in various error handling paths and/or if the
     fast commit log is corrupted

   - Avoid stopping the online resize early when expanding a file system
     which is less than 16TiB to a size greater than 16TiB

   - Fix apparent metadata corruption caused by a race with a metadata
     buffer head getting migrated while it was trying to be read

   - Mark the lazy initialization thread freezable to prevent suspend
     failures

   - Other miscellaneous bug fixes

  Cleanups:

   - Break up the incredibly long ext4_full_super() function by
     refactoring to move code into more understandable, smaller
     functions

   - Remove the deprecated (and ignored) noacl and nouser_attr mount
     option

   - Factor out some common code in fast commit handling

   - Other miscellaneous cleanups"

* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (53 commits)
  ext4: fix potential out of bound read in ext4_fc_replay_scan()
  ext4: factor out ext4_fc_get_tl()
  ext4: introduce EXT4_FC_TAG_BASE_LEN helper
  ext4: factor out ext4_free_ext_path()
  ext4: remove unnecessary drop path references in mext_check_coverage()
  ext4: update 'state->fc_regions_size' after successful memory allocation
  ext4: fix potential memory leak in ext4_fc_record_regions()
  ext4: fix potential memory leak in ext4_fc_record_modified_inode()
  ext4: remove redundant checking in ext4_ioctl_checkpoint
  jbd2: add miss release buffer head in fc_do_one_pass()
  ext4: move DIOREAD_NOLOCK setting to ext4_set_def_opts()
  ext4: remove useless local variable 'blocksize'
  ext4: unify the ext4 super block loading operation
  ext4: factor out ext4_journal_data_mode_check()
  ext4: factor out ext4_load_and_init_journal()
  ext4: factor out ext4_group_desc_init() and ext4_group_desc_free()
  ext4: factor out ext4_geometry_check()
  ext4: factor out ext4_check_feature_compatibility()
  ext4: factor out ext4_init_metadata_csum()
  ext4: factor out ext4_encoding_init()
  ...

1 files changed, 10 insertions, 7 deletions

diff --git a/fs/mbcache.c b/fs/mbcache.c
index 47ccfcbe0a22..e272ad738faf 100644
--- a/fs/mbcache.c
+++ b/fs/mbcache.c
@@ -90,8 +90,14 @@ int mb_cache_entry_create(struct mb_cache *cache, gfp_t mask, u32 key,
 		return -ENOMEM;
 
 	INIT_LIST_HEAD(&entry->e_list);
-	/* Initial hash reference */
-	atomic_set(&entry->e_refcnt, 1);
+	/*
+	 * We create entry with two references. One reference is kept by the
+	 * hash table, the other reference is used to protect us from
+	 * mb_cache_entry_delete_or_get() until the entry is fully setup. This
+	 * avoids nesting of cache->c_list_lock into hash table bit locks which
+	 * is problematic for RT.
+	 */
+	atomic_set(&entry->e_refcnt, 2);
 	entry->e_key = key;
 	entry->e_value = value;
 	entry->e_reusable = reusable;
@@ -106,15 +112,12 @@ int mb_cache_entry_create(struct mb_cache *cache, gfp_t mask, u32 key,
 		}
 	}
 	hlist_bl_add_head(&entry->e_hash_list, head);
-	/*
-	 * Add entry to LRU list before it can be found by
-	 * mb_cache_entry_delete() to avoid races
-	 */
+	hlist_bl_unlock(head);
 	spin_lock(&cache->c_list_lock);
 	list_add_tail(&entry->e_list, &cache->c_list);
 	cache->c_entry_count++;
 	spin_unlock(&cache->c_list_lock);
-	hlist_bl_unlock(head);
+	mb_cache_entry_put(cache, entry);
 
 	return 0;
 }