Btrfs: Integrate metadata reservation with start_transaction

Besides simplify the code, this change makes sure all metadata
reservation for normal metadata operations are released after
committing transaction.

Changes since V1:

Add code that check if unlink and rmdir will free space.

Add ENOSPC handling for clone ioctl.

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 6 insertions, 7 deletions

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 29ff749ff4ca..41e09e24e295 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -126,8 +126,7 @@ static noinline int dirty_and_release_pages(struct btrfs_trans_handle *trans,
         end_of_last_block = start_pos + num_bytes - 1;
         err = btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block,
                                         NULL);
-        if (err)
-                return err;
+        BUG_ON(err);
 
         for (i = 0; i < num_pages; i++) {
                 struct page *p = pages[i];
@@ -142,7 +141,7 @@ static noinline int dirty_and_release_pages(struct btrfs_trans_handle *trans,
                  * at this time.
                  */
         }
-        return err;
+        return 0;
 }
 
 /*
@@ -1008,7 +1007,7 @@ out_nolock:
                         num_written = err;
 
                 if ((file->f_flags & O_DSYNC) || IS_SYNC(inode)) {
-                        trans = btrfs_start_transaction(root, 1);
+                        trans = btrfs_start_transaction(root, 0);
                         ret = btrfs_log_dentry_safe(trans, root,
                                                     file->f_dentry);
                         if (ret == 0) {
@@ -1104,9 +1103,9 @@ int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync)
         if (file && file->private_data)
                 btrfs_ioctl_trans_end(file);
 
-        trans = btrfs_start_transaction(root, 1);
-        if (!trans) {
-                ret = -ENOMEM;
+        trans = btrfs_start_transaction(root, 0);
+        if (IS_ERR(trans)) {
+                ret = PTR_ERR(trans);
                 goto out;
         }