In multi-thread situations, writeback of a file may span across several
sub transactions, and we need to introduce first_sub_trans to get sub_transid of
teh first sub transaction recorded, so that log code can skip file extents which
have been logged or committed onto disk.
Signed-off-by: Liu Bo <liubo2...@cn.fujitsu.com>
---
fs/btrfs/btrfs_inode.h | 9 +++++++++
fs/btrfs/inode.c | 13 ++++++++++++-
fs/btrfs/transaction.h | 17 ++++++++++++++++-
3 files changed, 37 insertions(+), 2 deletions(-)
diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index 52d7eca..8eca5de 100644
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -80,6 +80,15 @@ struct btrfs_inode {
/* sequence number for NFS changes */
u64 sequence;
+ /* used to avoid race of first_sub_trans */
+ spinlock_t sub_trans_lock;
+
+ /*
+ * sub transid of the trans that first modified this inode before
+ * a trans commit or a log sync
+ */
+ u64 first_sub_trans;
+
/*
* transid of the trans_handle that last modified this inode
*/
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index ff9d4d1..93c9d22 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -6468,7 +6468,16 @@ again:
set_page_dirty(page);
SetPageUptodate(page);
- BTRFS_I(inode)->last_trans = root->fs_info->generation;
+ spin_lock(&BTRFS_I(inode)->sub_trans_lock);
+
+ if (BTRFS_I(inode)->first_sub_trans > root->fs_info->sub_generation ||
+ BTRFS_I(inode)->last_trans <= BTRFS_I(inode)->logged_trans ||
+ BTRFS_I(inode)->last_trans <= root->fs_info->last_trans_committed)
+ BTRFS_I(inode)->first_sub_trans = root->fs_info->sub_generation;
+
+ spin_unlock(&BTRFS_I(inode)->sub_trans_lock);
+
+ BTRFS_I(inode)->last_trans = root->fs_info->sub_generation;
BTRFS_I(inode)->last_sub_trans = BTRFS_I(inode)->root->log_transid;
unlock_extent_cached(io_tree, page_start, page_end, &cached_state,
GFP_NOFS);
@@ -6714,6 +6723,7 @@ struct inode *btrfs_alloc_inode(struct super_block *sb)
ei->space_info = NULL;
ei->generation = 0;
ei->sequence = 0;
+ ei->first_sub_trans = 0;
ei->last_trans = 0;
ei->last_sub_trans = 0;
ei->logged_trans = 0;
@@ -6740,6 +6750,7 @@ struct inode *btrfs_alloc_inode(struct super_block *sb)
extent_io_tree_init(&ei->io_tree, &inode->i_data);
extent_io_tree_init(&ei->io_failure_tree, &inode->i_data);
mutex_init(&ei->log_mutex);
+ spin_lock_init(&ei->sub_trans_lock);
btrfs_ordered_inode_tree_init(&ei->ordered_tree);
INIT_LIST_HEAD(&ei->i_orphan);
INIT_LIST_HEAD(&ei->delalloc_inodes);
diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h
index 45876b0..f5ca0fd 100644
--- a/fs/btrfs/transaction.h
+++ b/fs/btrfs/transaction.h
@@ -73,7 +73,22 @@ struct btrfs_pending_snapshot {
static inline void btrfs_set_inode_last_trans(struct btrfs_trans_handle *trans,
struct inode *inode)
{
- BTRFS_I(inode)->last_trans = trans->transaction->transid;
+ spin_lock(&BTRFS_I(inode)->sub_trans_lock);
+
+ /*
+ * We have joined in a transaction, so btrfs_commit_transaction will
+ * definitely wait for us and it does not need to add a extra
+ * trans_mutex lock here.
+ */
+ if (BTRFS_I(inode)->first_sub_trans > trans->transid ||
+ BTRFS_I(inode)->last_trans <= BTRFS_I(inode)->logged_trans ||
+ BTRFS_I(inode)->last_trans <=
+ BTRFS_I(inode)->root->fs_info->last_trans_committed)
+ BTRFS_I(inode)->first_sub_trans = trans->transid;
+
+ spin_unlock(&BTRFS_I(inode)->sub_trans_lock);
+
+ BTRFS_I(inode)->last_trans = trans->transid;
BTRFS_I(inode)->last_sub_trans = BTRFS_I(inode)->root->log_transid;
}
--
1.6.5.2
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