Btrfs: Add a write ahead tree log to optimize synchronous operations
File syncs and directory syncs are optimized by copying their
items into a special (copy-on-write) log tree. There is one log tree per
subvolume and the btrfs super block points to a tree of log tree roots.
After a crash, items are copied out of the log tree and back into the
subvolume. See tree-log.c for all the details.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index e9e86fb..84ecf3a 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -36,6 +36,8 @@
#include "btrfs_inode.h"
#include "ioctl.h"
#include "print-tree.h"
+#include "tree-log.h"
+#include "locking.h"
#include "compat.h"
@@ -988,10 +990,27 @@
*ppos = pos;
if (num_written > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
- err = sync_page_range(inode, inode->i_mapping,
- start_pos, num_written);
+ struct btrfs_trans_handle *trans;
+
+ err = btrfs_fdatawrite_range(inode->i_mapping, start_pos,
+ start_pos + num_written -1,
+ WB_SYNC_NONE);
if (err < 0)
num_written = err;
+
+ err = btrfs_wait_on_page_writeback_range(inode->i_mapping,
+ start_pos, start_pos + num_written - 1);
+ if (err < 0)
+ num_written = err;
+
+ trans = btrfs_start_transaction(root, 1);
+ ret = btrfs_log_dentry_safe(trans, root, file->f_dentry);
+ if (ret == 0) {
+ btrfs_sync_log(trans, root);
+ btrfs_end_transaction(trans, root);
+ } else {
+ btrfs_commit_transaction(trans, root);
+ }
} else if (num_written > 0 && (file->f_flags & O_DIRECT)) {
#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,22)
do_sync_file_range(file, start_pos,
@@ -1019,8 +1038,7 @@
return 0;
}
-static int btrfs_sync_file(struct file *file,
- struct dentry *dentry, int datasync)
+int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync)
{
struct inode *inode = dentry->d_inode;
struct btrfs_root *root = BTRFS_I(inode)->root;
@@ -1043,6 +1061,8 @@
}
mutex_unlock(&root->fs_info->trans_mutex);
+ filemap_fdatawait(inode->i_mapping);
+
/*
* ok we haven't committed the transaction yet, lets do a commit
*/
@@ -1054,7 +1074,16 @@
ret = -ENOMEM;
goto out;
}
- ret = btrfs_commit_transaction(trans, root);
+
+ ret = btrfs_log_dentry_safe(trans, root, file->f_dentry);
+ if (ret < 0)
+ goto out;
+ if (ret > 0) {
+ ret = btrfs_commit_transaction(trans, root);
+ } else {
+ btrfs_sync_log(trans, root);
+ ret = btrfs_end_transaction(trans, root);
+ }
out:
return ret > 0 ? EIO : ret;
}