The following commit has been merged in the linux branch: commit 257c62e1bce03e5b9f3f069fd52ad73a56de71fd Author: Chris Mason chris.mason@oracle.com Date: Tue Oct 13 13:21:08 2009 -0400
Btrfs: avoid tree log commit when there are no changes
rpm has a habit of running fdatasync when the file hasn't changed. We already detect if a file hasn't been changed in the current transaction but it might have been sent to the tree-log in this transaction and not changed since the last call to fsync.
In this case, we want to avoid a tree log sync, which includes a number of synchronous writes and barriers. This commit extends the existing tracking of the last transaction to change a file to also track the last sub-transaction.
The end result is that rpm -ivh and -Uvh are roughly twice as fast, and on par with ext3.
Signed-off-by: Chris Mason chris.mason@oracle.com
diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h index c71abec..f6783a4 100644 --- a/fs/btrfs/btrfs_inode.h +++ b/fs/btrfs/btrfs_inode.h @@ -86,6 +86,12 @@ struct btrfs_inode { * transid of the trans_handle that last modified this inode */ u64 last_trans; + + /* + * log transid when this inode was last modified + */ + u64 last_sub_trans; + /* * transid that last logged this inode */ diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 36a19cd..d0cede5 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -1009,6 +1009,7 @@ struct btrfs_root { atomic_t log_writers; atomic_t log_commit[2]; unsigned long log_transid; + unsigned long last_log_commit; unsigned long log_batch; pid_t log_start_pid; bool log_multiple_pids; diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index ac8927b..d4132aa 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -919,6 +919,7 @@ static int __setup_root(u32 nodesize, u32 leafsize, u32 sectorsize, atomic_set(&root->log_writers, 0); root->log_batch = 0; root->log_transid = 0; + root->last_log_commit = 0; extent_io_tree_init(&root->dirty_log_pages, fs_info->btree_inode->i_mapping, GFP_NOFS);
@@ -1089,6 +1090,7 @@ int btrfs_add_log_tree(struct btrfs_trans_handle *trans, WARN_ON(root->log_root); root->log_root = log_root; root->log_transid = 0; + root->last_log_commit = 0; return 0; }
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 53fb1c9..4599113 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -1087,8 +1087,10 @@ out_nolock: btrfs_end_transaction(trans, root); else btrfs_commit_transaction(trans, root); - } else { + } else if (ret != BTRFS_NO_LOG_SYNC) { btrfs_commit_transaction(trans, root); + } else { + btrfs_end_transaction(trans, root); } } if (file->f_flags & O_DIRECT) { @@ -1138,6 +1140,13 @@ int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync) int ret = 0; struct btrfs_trans_handle *trans;
+ + /* we wait first, since the writeback may change the inode */ + root->log_batch++; + /* the VFS called filemap_fdatawrite for us */ + btrfs_wait_ordered_range(inode, 0, (u64)-1); + root->log_batch++; + /* * check the transaction that last modified this inode * and see if its already been committed @@ -1145,6 +1154,11 @@ int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync) if (!BTRFS_I(inode)->last_trans) goto out;
+ /* + * if the last transaction that changed this file was before + * the current transaction, we can bail out now without any + * syncing + */ mutex_lock(&root->fs_info->trans_mutex); if (BTRFS_I(inode)->last_trans <= root->fs_info->last_trans_committed) { @@ -1154,13 +1168,6 @@ int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync) } mutex_unlock(&root->fs_info->trans_mutex);
- root->log_batch++; - filemap_fdatawrite(inode->i_mapping); - btrfs_wait_ordered_range(inode, 0, (u64)-1); - root->log_batch++; - - if (datasync && !(inode->i_state & I_DIRTY_PAGES)) - goto out; /* * ok we haven't committed the transaction yet, lets do a commit */ @@ -1189,14 +1196,18 @@ int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync) */ mutex_unlock(&dentry->d_inode->i_mutex);
- if (ret > 0) { - ret = btrfs_commit_transaction(trans, root); - } else { - ret = btrfs_sync_log(trans, root); - if (ret == 0) - ret = btrfs_end_transaction(trans, root); - else + if (ret != BTRFS_NO_LOG_SYNC) { + if (ret > 0) { ret = btrfs_commit_transaction(trans, root); + } else { + ret = btrfs_sync_log(trans, root); + if (ret == 0) + ret = btrfs_end_transaction(trans, root); + else + ret = btrfs_commit_transaction(trans, root); + } + } else { + ret = btrfs_end_transaction(trans, root); } mutex_lock(&dentry->d_inode->i_mutex); out: diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index ef399a7..5b9567c 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -3480,6 +3480,7 @@ static noinline void init_btrfs_i(struct inode *inode) bi->generation = 0; bi->sequence = 0; bi->last_trans = 0; + bi->last_sub_trans = 0; bi->logged_trans = 0; bi->delalloc_bytes = 0; bi->reserved_bytes = 0; @@ -4980,7 +4981,9 @@ again: set_page_dirty(page); SetPageUptodate(page);
- BTRFS_I(inode)->last_trans = root->fs_info->generation + 1; + BTRFS_I(inode)->last_trans = root->fs_info->generation; + BTRFS_I(inode)->last_sub_trans = BTRFS_I(inode)->root->log_transid; + unlock_extent(io_tree, page_start, page_end, GFP_NOFS);
out_unlock: @@ -5100,6 +5103,7 @@ struct inode *btrfs_alloc_inode(struct super_block *sb) if (!ei) return NULL; ei->last_trans = 0; + ei->last_sub_trans = 0; ei->logged_trans = 0; ei->outstanding_extents = 0; ei->reserved_extents = 0; diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h index 663c674..f68cbbe 100644 --- a/fs/btrfs/transaction.h +++ b/fs/btrfs/transaction.h @@ -79,6 +79,7 @@ static inline void btrfs_set_inode_last_trans(struct btrfs_trans_handle *trans, struct inode *inode) { BTRFS_I(inode)->last_trans = trans->transaction->transid; + BTRFS_I(inode)->last_sub_trans = BTRFS_I(inode)->root->log_transid; }
int btrfs_end_transaction(struct btrfs_trans_handle *trans, diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c index 6d9ec28..0a1bde2 100644 --- a/fs/btrfs/tree-log.c +++ b/fs/btrfs/tree-log.c @@ -1980,6 +1980,7 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans, int ret; struct btrfs_root *log = root->log_root; struct btrfs_root *log_root_tree = root->fs_info->log_root_tree; + u64 log_transid = 0;
mutex_lock(&root->log_mutex); index1 = root->log_transid % 2; @@ -2018,6 +2019,7 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans, btrfs_set_root_node(&log->root_item, log->node);
root->log_batch = 0; + log_transid = root->log_transid; root->log_transid++; log->log_transid = root->log_transid; root->log_start_pid = 0; @@ -2095,6 +2097,11 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans, write_ctree_super(trans, root->fs_info->tree_root, 1); ret = 0;
+ mutex_lock(&root->log_mutex); + if (root->last_log_commit < log_transid) + root->last_log_commit = log_transid; + mutex_unlock(&root->log_mutex); + out_wake_log_root: atomic_set(&log_root_tree->log_commit[index2], 0); smp_mb(); @@ -2862,6 +2869,21 @@ out: return ret; }
+static int inode_in_log(struct btrfs_trans_handle *trans, + struct inode *inode) +{ + struct btrfs_root *root = BTRFS_I(inode)->root; + int ret = 0; + + mutex_lock(&root->log_mutex); + if (BTRFS_I(inode)->logged_trans == trans->transid && + BTRFS_I(inode)->last_sub_trans <= root->last_log_commit) + ret = 1; + mutex_unlock(&root->log_mutex); + return ret; +} + + /* * helper function around btrfs_log_inode to make sure newly created * parent directories also end up in the log. A minimal inode and backref @@ -2901,6 +2923,11 @@ int btrfs_log_inode_parent(struct btrfs_trans_handle *trans, if (ret) goto end_no_trans;
+ if (inode_in_log(trans, inode)) { + ret = BTRFS_NO_LOG_SYNC; + goto end_no_trans; + } + start_log_trans(trans, root);
ret = btrfs_log_inode(trans, root, inode, inode_only); diff --git a/fs/btrfs/tree-log.h b/fs/btrfs/tree-log.h index d09c760..0776eac 100644 --- a/fs/btrfs/tree-log.h +++ b/fs/btrfs/tree-log.h @@ -19,6 +19,9 @@ #ifndef __TREE_LOG_ #define __TREE_LOG_
+/* return value for btrfs_log_dentry_safe that means we don't need to log it at all */ +#define BTRFS_NO_LOG_SYNC 256 + int btrfs_sync_log(struct btrfs_trans_handle *trans, struct btrfs_root *root); int btrfs_free_log(struct btrfs_trans_handle *trans, struct btrfs_root *root);