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: Liu Bo <bo.li.liu@oracle.com>
diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index 7c7bf81..ed8ca7c 100644
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -144,6 +144,9 @@
/* 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 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
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index a6824bd..24745b8 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -6774,6 +6774,7 @@
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 @@
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;
diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h
index e8b8416..1a138bf 100644
--- a/fs/btrfs/transaction.h
+++ b/fs/btrfs/transaction.h
@@ -88,6 +88,7 @@
{
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,
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 71e7153..fc0df95 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -3185,6 +3185,7 @@
}
}
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);