Commit 502756b3 authored by Goldwyn Rodrigues's avatar Goldwyn Rodrigues Committed by David Sterba
Browse files

btrfs: remove btrfs_inode::dio_sem 



The inode dio_sem can be eliminated because all DIO synchronization is
now performed through inode->i_rwsem that provides the same guarantees.

This reduces btrfs_inode size by 40 bytes.

Reviewed-by: default avatarJosef Bacik <josef@toxicpanda.com>
Signed-off-by: default avatarGoldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent e9adabb9

fs/btrfs/btrfs_inode.h

+0 −10
Original line number Diff line number Diff line
@@ -203,16 +203,6 @@ struct btrfs_inode { 
	/* Hook into fs_info->delayed_iputs */

	struct list_head delayed_iput;



	/*

	 * To avoid races between lockless (i_mutex not held) direct IO writes

	 * and concurrent fsync requests. Direct IO writes must acquire read

	 * access on this semaphore for creating an extent map and its

	 * corresponding ordered extent. The fast fsync path must acquire write

	 * access on this semaphore before it collects ordered extents and

	 * extent maps.

	 */

	struct rw_semaphore dio_sem;



	struct inode vfs_inode;

};

fs/btrfs/file.c

+0 −13
Original line number Diff line number Diff line
@@ -1948,8 +1948,6 @@ static ssize_t btrfs_direct_write(struct kiocb *iocb, struct iov_iter *from) 
		goto buffered;

	}



	down_read(&BTRFS_I(inode)->dio_sem);



	/*

	 * This is actually a sync iocb, so we need our fancy endio to know if

	 * we need to sync.
@@ -1964,7 +1962,6 @@ static ssize_t btrfs_direct_write(struct kiocb *iocb, struct iov_iter *from) 
	if (written == -ENOTBLK)

		written = 0;



	up_read(&BTRFS_I(inode)->dio_sem);

	btrfs_inode_unlock(inode, ilock_flags);



	if (written < 0 || !iov_iter_count(from)) {
@@ -2172,13 +2169,6 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync) 


	inode_lock(inode);



	/*

	 * We take the dio_sem here because the tree log stuff can race with

	 * lockless dio writes and get an extent map logged for an extent we

	 * never waited on.  We need it this high up for lockdep reasons.

	 */

	down_write(&BTRFS_I(inode)->dio_sem);



	atomic_inc(&root->log_batch);



	/*
@@ -2209,7 +2199,6 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync) 
	 */

	ret = start_ordered_ops(inode, start, end);

	if (ret) {

		up_write(&BTRFS_I(inode)->dio_sem);

		inode_unlock(inode);

		goto out;

	}
@@ -2306,7 +2295,6 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync) 
	 * file again, but that will end up using the synchronization

	 * inside btrfs_sync_log to keep things safe.

	 */

	up_write(&BTRFS_I(inode)->dio_sem);

	inode_unlock(inode);



	if (ret != BTRFS_NO_LOG_SYNC) {
@@ -2337,7 +2325,6 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync) 


out_release_extents:

	btrfs_release_log_ctx_extents(&ctx);

	up_write(&BTRFS_I(inode)->dio_sem);

	inode_unlock(inode);

	goto out;

}

fs/btrfs/inode.c

+0 −1
Original line number Diff line number Diff line
@@ -8650,7 +8650,6 @@ struct inode *btrfs_alloc_inode(struct super_block *sb) 
	INIT_LIST_HEAD(&ei->delalloc_inodes);

	INIT_LIST_HEAD(&ei->delayed_iput);

	RB_CLEAR_NODE(&ei->rb_node);

	init_rwsem(&ei->dio_sem);



	return inode;

}