ext4: remove EXT4_STATE_DIOREAD_LOCK flag

Commit 16c54688592c ("ext4: Allow parallel DIO reads") reworked the way
locking happens around parallel dio reads. This resulted in obviating
the need for EXT4_STATE_DIOREAD_LOCK flag and accompanying logic.
Currently this amounts to dead code so let's remove it. No functional
changes

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>

fs/ext4/ext4.h

@@ -1522,8 +1522,6 @@ enum {
 	EXT4_STATE_EXT_MIGRATE,		/* Inode is migrating */
 	EXT4_STATE_DIO_UNWRITTEN,	/* need convert on dio done*/
 	EXT4_STATE_NEWENTRY,		/* File just added to dir */
-	EXT4_STATE_DIOREAD_LOCK,	/* Disable support for dio read
-					   nolocking */
 	EXT4_STATE_MAY_INLINE_DATA,	/* may have in-inode data */
 	EXT4_STATE_EXT_PRECACHED,	/* extents have been precached */
 	EXT4_STATE_LUSTRE_EA_INODE,	/* Lustre-style ea_inode */
@@ -3181,21 +3179,6 @@ static inline void set_bitmap_uptodate(struct buffer_head *bh)
 	set_bit(BH_BITMAP_UPTODATE, &(bh)->b_state);
 }
 
-/*
- * Disable DIO read nolock optimization, so new dioreaders will be forced
- * to grab i_mutex
- */
-static inline void ext4_inode_block_unlocked_dio(struct inode *inode)
-{
-	ext4_set_inode_state(inode, EXT4_STATE_DIOREAD_LOCK);
-	smp_mb();
-}
-static inline void ext4_inode_resume_unlocked_dio(struct inode *inode)
-{
-	smp_mb();
-	ext4_clear_inode_state(inode, EXT4_STATE_DIOREAD_LOCK);
-}
-
 #define in_range(b, first, len)	((b) >= (first) && (b) <= (first) + (len) - 1)
 
 /* For ioend & aio unwritten conversion wait queues */

fs/ext4/extents.c

@@ -4796,7 +4796,6 @@ static long ext4_zero_range(struct file *file, loff_t offset,
 		flags |= EXT4_GET_BLOCKS_KEEP_SIZE;
 
 	/* Wait all existing dio workers, newcomers will block on i_mutex */
-	ext4_inode_block_unlocked_dio(inode);
 	inode_dio_wait(inode);
 
 	/* Preallocate the range including the unaligned edges */
@@ -4807,7 +4806,7 @@ static long ext4_zero_range(struct file *file, loff_t offset,
 				 round_down(offset, 1 << blkbits)) >> blkbits,
 				new_size, flags);
 		if (ret)
-			goto out_dio;
+			goto out_mutex;
 
 	}
 
@@ -4824,7 +4823,7 @@ static long ext4_zero_range(struct file *file, loff_t offset,
 		ret = ext4_update_disksize_before_punch(inode, offset, len);
 		if (ret) {
 			up_write(&EXT4_I(inode)->i_mmap_sem);
-			goto out_dio;
+			goto out_mutex;
 		}
 		/* Now release the pages and zero block aligned part of pages */
 		truncate_pagecache_range(inode, start, end - 1);
@@ -4834,10 +4833,10 @@ static long ext4_zero_range(struct file *file, loff_t offset,
 					     flags);
 		up_write(&EXT4_I(inode)->i_mmap_sem);
 		if (ret)
-			goto out_dio;
+			goto out_mutex;
 	}
 	if (!partial_begin && !partial_end)
-		goto out_dio;
+		goto out_mutex;
 
 	/*
 	 * In worst case we have to writeout two nonadjacent unwritten
@@ -4850,7 +4849,7 @@ static long ext4_zero_range(struct file *file, loff_t offset,
 	if (IS_ERR(handle)) {
 		ret = PTR_ERR(handle);
 		ext4_std_error(inode->i_sb, ret);
-		goto out_dio;
+		goto out_mutex;
 	}
 
 	inode->i_mtime = inode->i_ctime = current_time(inode);
@@ -4875,8 +4874,6 @@ static long ext4_zero_range(struct file *file, loff_t offset,
 		ext4_handle_sync(handle);
 
 	ext4_journal_stop(handle);
-out_dio:
-	ext4_inode_resume_unlocked_dio(inode);
 out_mutex:
 	inode_unlock(inode);
 	return ret;
@@ -4964,11 +4961,9 @@ long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
 	}
 
 	/* Wait all existing dio workers, newcomers will block on i_mutex */
-	ext4_inode_block_unlocked_dio(inode);
 	inode_dio_wait(inode);
 
 	ret = ext4_alloc_file_blocks(file, lblk, max_blocks, new_size, flags);
-	ext4_inode_resume_unlocked_dio(inode);
 	if (ret)
 		goto out;
 
@@ -5485,7 +5480,6 @@ int ext4_collapse_range(struct inode *inode, loff_t offset, loff_t len)
 	}
 
 	/* Wait for existing dio to complete */
-	ext4_inode_block_unlocked_dio(inode);
 	inode_dio_wait(inode);
 
 	/*
@@ -5562,7 +5556,6 @@ out_stop:
 	ext4_journal_stop(handle);
 out_mmap:
 	up_write(&EXT4_I(inode)->i_mmap_sem);
-	ext4_inode_resume_unlocked_dio(inode);
 out_mutex:
 	inode_unlock(inode);
 	return ret;
@@ -5635,7 +5628,6 @@ int ext4_insert_range(struct inode *inode, loff_t offset, loff_t len)
 	}
 
 	/* Wait for existing dio to complete */
-	ext4_inode_block_unlocked_dio(inode);
 	inode_dio_wait(inode);
 
 	/*
@@ -5737,7 +5729,6 @@ out_stop:
 	ext4_journal_stop(handle);
 out_mmap:
 	up_write(&EXT4_I(inode)->i_mmap_sem);
-	ext4_inode_resume_unlocked_dio(inode);
 out_mutex:
 	inode_unlock(inode);
 	return ret;

fs/ext4/inode.c

@@ -4252,7 +4252,6 @@ int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length)
 	}
 
 	/* Wait all existing dio workers, newcomers will block on i_mutex */
-	ext4_inode_block_unlocked_dio(inode);
 	inode_dio_wait(inode);
 
 	/*
@@ -4325,7 +4324,6 @@ out_stop:
 	ext4_journal_stop(handle);
 out_dio:
 	up_write(&EXT4_I(inode)->i_mmap_sem);
-	ext4_inode_resume_unlocked_dio(inode);
 out_mutex:
 	inode_unlock(inode);
 	return ret;
@@ -5507,9 +5505,7 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
 		 */
 		if (orphan) {
 			if (!ext4_should_journal_data(inode)) {
-				ext4_inode_block_unlocked_dio(inode);
 				inode_dio_wait(inode);
-				ext4_inode_resume_unlocked_dio(inode);
 			} else
 				ext4_wait_for_tail_page_commit(inode);
 		}
@@ -6000,7 +5996,6 @@ int ext4_change_inode_journal_flag(struct inode *inode, int val)
 		return -EROFS;
 
 	/* Wait for all existing dio workers */
-	ext4_inode_block_unlocked_dio(inode);
 	inode_dio_wait(inode);
 
 	/*
@@ -6016,7 +6011,6 @@ int ext4_change_inode_journal_flag(struct inode *inode, int val)
 		err = filemap_write_and_wait(inode->i_mapping);
 		if (err < 0) {
 			up_write(&EXT4_I(inode)->i_mmap_sem);
-			ext4_inode_resume_unlocked_dio(inode);
 			return err;
 		}
 	}
@@ -6039,7 +6033,6 @@ int ext4_change_inode_journal_flag(struct inode *inode, int val)
 		if (err < 0) {
 			jbd2_journal_unlock_updates(journal);
 			percpu_up_write(&sbi->s_journal_flag_rwsem);
-			ext4_inode_resume_unlocked_dio(inode);
 			return err;
 		}
 		ext4_clear_inode_flag(inode, EXT4_INODE_JOURNAL_DATA);
@@ -6051,7 +6044,6 @@ int ext4_change_inode_journal_flag(struct inode *inode, int val)
 
 	if (val)
 		up_write(&EXT4_I(inode)->i_mmap_sem);
-	ext4_inode_resume_unlocked_dio(inode);
 
 	/* Finally we can mark the inode as dirty. */
 

fs/ext4/ioctl.c

@@ -124,8 +124,6 @@ static long swap_inode_boot_loader(struct super_block *sb,
 	truncate_inode_pages(&inode_bl->i_data, 0);
 
 	/* Wait for all existing dio workers */
-	ext4_inode_block_unlocked_dio(inode);
-	ext4_inode_block_unlocked_dio(inode_bl);
 	inode_dio_wait(inode);
 	inode_dio_wait(inode_bl);
 
@@ -186,8 +184,6 @@ static long swap_inode_boot_loader(struct super_block *sb,
 	ext4_double_up_write_data_sem(inode, inode_bl);
 
 journal_err_out:
-	ext4_inode_resume_unlocked_dio(inode);
-	ext4_inode_resume_unlocked_dio(inode_bl);
 	unlock_two_nondirectories(inode, inode_bl);
 	iput(inode_bl);
 	return err;

fs/ext4/move_extent.c

@@ -601,8 +601,6 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp, __u64 orig_blk,
 	lock_two_nondirectories(orig_inode, donor_inode);
 
 	/* Wait for all existing dio workers */
-	ext4_inode_block_unlocked_dio(orig_inode);
-	ext4_inode_block_unlocked_dio(donor_inode);
 	inode_dio_wait(orig_inode);
 	inode_dio_wait(donor_inode);
 
@@ -693,8 +691,6 @@ out:
 	ext4_ext_drop_refs(path);
 	kfree(path);
 	ext4_double_up_write_data_sem(orig_inode, donor_inode);
-	ext4_inode_resume_unlocked_dio(orig_inode);
-	ext4_inode_resume_unlocked_dio(donor_inode);
 	unlock_two_nondirectories(orig_inode, donor_inode);
 
 	return ret;

fs/ext4/super.c

@@ -101,15 +101,13 @@ static struct inode *ext4_get_journal_inode(struct super_block *sb,
  *   i_data_sem (rw)
  *
  * truncate:
- * sb_start_write -> i_mutex -> EXT4_STATE_DIOREAD_LOCK (w) -> i_mmap_sem (w) ->
- *   i_mmap_rwsem (w) -> page lock
- * sb_start_write -> i_mutex -> EXT4_STATE_DIOREAD_LOCK (w) -> i_mmap_sem (w) ->
- *   transaction start -> i_data_sem (rw)
+ * sb_start_write -> i_mutex -> i_mmap_sem (w) -> i_mmap_rwsem (w) -> page lock
+ * sb_start_write -> i_mutex -> i_mmap_sem (w) -> transaction start ->
+ *   i_data_sem (rw)
  *
  * direct IO:
- * sb_start_write -> i_mutex -> EXT4_STATE_DIOREAD_LOCK (r) -> mmap_sem
- * sb_start_write -> i_mutex -> EXT4_STATE_DIOREAD_LOCK (r) ->
- *   transaction start -> i_data_sem (rw)
+ * sb_start_write -> i_mutex -> mmap_sem
+ * sb_start_write -> i_mutex -> transaction start -> i_data_sem (rw)
  *
  * writepages:
  * transaction start -> page lock(s) -> i_data_sem (rw)