Commit 46d8bc34 authored by Liu Bo's avatar Liu Bo Committed by Chris Mason
Browse files

Btrfs: fix a bug in checking whether a inode is already in log 



This is based on Josef's "Btrfs: turbo charge fsync".

The current btrfs checks if an inode is in log by comparing
root's last_log_commit to inode's last_sub_trans[2].

But the problem is that this root->last_log_commit is shared among
inodes.

Say we have N inodes to be logged, after the first inode,
root's last_log_commit is updated and the N-1 remained files will
be skipped.

This fixes the bug by keeping a local copy of root's last_log_commit
inside each inode and this local copy will be maintained itself.

[1]: we regard each log transaction as a subset of btrfs's transaction,
i.e. sub_trans

Signed-off-by: default avatarLiu Bo <bo.li.liu@oracle.com>
parent 321f0e70

fs/btrfs/btrfs_inode.h

+6 −8
Original line number Diff line number Diff line
@@ -144,6 +144,9 @@ struct btrfs_inode { 
	/* flags field from the on disk inode */

	u32 flags;



	/* a local copy of root's last_log_commit */

	unsigned long last_log_commit;



	/*

	 * Counters to keep track of the number of extent item's we may use due

	 * to delalloc and such.  outstanding_extents is the number of extent
@@ -203,15 +206,10 @@ static inline bool btrfs_is_free_space_inode(struct inode *inode) 


static inline int btrfs_inode_in_log(struct inode *inode, u64 generation)

{

	struct btrfs_root *root = BTRFS_I(inode)->root;

	int ret = 0;



	mutex_lock(&root->log_mutex);

	if (BTRFS_I(inode)->logged_trans == generation &&

	    BTRFS_I(inode)->last_sub_trans <= root->last_log_commit)

		ret = 1;

	mutex_unlock(&root->log_mutex);

	return ret;

	    BTRFS_I(inode)->last_sub_trans <= BTRFS_I(inode)->last_log_commit)

		return 1;

	return 0;

}



#endif

fs/btrfs/inode.c

+2 −0
Original line number Diff line number Diff line
@@ -6774,6 +6774,7 @@ again: 


	BTRFS_I(inode)->last_trans = root->fs_info->generation;

	BTRFS_I(inode)->last_sub_trans = BTRFS_I(inode)->root->log_transid;

	BTRFS_I(inode)->last_log_commit = BTRFS_I(inode)->root->last_log_commit;



	unlock_extent_cached(io_tree, page_start, page_end, &cached_state, GFP_NOFS);
@@ -7018,6 +7019,7 @@ struct inode *btrfs_alloc_inode(struct super_block *sb) 
	ei->csum_bytes = 0;

	ei->index_cnt = (u64)-1;

	ei->last_unlink_trans = 0;

	ei->last_log_commit = 0;



	spin_lock_init(&ei->lock);

	ei->outstanding_extents = 0;

fs/btrfs/transaction.h

+1 −0
Original line number Diff line number Diff line
@@ -88,6 +88,7 @@ static inline void btrfs_set_inode_last_trans(struct btrfs_trans_handle *trans, 
{

	BTRFS_I(inode)->last_trans = trans->transaction->transid;

	BTRFS_I(inode)->last_sub_trans = BTRFS_I(inode)->root->log_transid;

	BTRFS_I(inode)->last_log_commit = BTRFS_I(inode)->root->last_log_commit;

}



int btrfs_end_transaction(struct btrfs_trans_handle *trans,

fs/btrfs/tree-log.c

+1 −0
Original line number Diff line number Diff line
@@ -3185,6 +3185,7 @@ next_slot: 
		}

	}

	BTRFS_I(inode)->logged_trans = trans->transid;

	BTRFS_I(inode)->last_log_commit = BTRFS_I(inode)->last_sub_trans;

out_unlock:

	mutex_unlock(&BTRFS_I(inode)->log_mutex);

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