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